WO2025066920A1 - Communication method and communication apparatus - Google Patents

Abstract

The present application relates to the field of communications, and in particular to a communication method and a communication apparatus. In a large-scale antenna array scenario, the larger the Rayleigh length, the easier it is for a terminal device to be in a region in line with the law of spherical waves. Due to the presence of spherical waves, the phases of signals at different antenna element positions are distorted, so that during precoding, the distance between antenna elements and scatterers, i.e., the distance of a multipath, needs to be taken into account. In the communication method, each spatial domain basis in a spatial domain basis set takes into account both the angle and distance of a multipath; the terminal device determines a first spatial domain basis from the spatial domain basis set; a combination coefficient is determined on the basis of the first spatial domain basis; then a PMI is sent, the PMI comprising an identifier of the first spatial domain basis and the combination coefficient; and a network device determines a precoding matrix on the basis of the PMI. The codebook which is set on the basis of the spatial domain basis set is more in line with the law of spherical waves, and therefore, the communication method can improve the channel estimation accuracy of codebooks in a large-scale antenna array scenario.

Description

Communication method and communication device

This application claims the priority of the Chinese patent application filed with the State Intellectual Property Office on September 28, 2023, with application number 202311290544.1 and application name “Communication Method and Communication Device”, all contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the field of communications, and in particular to a communication method and a communication device.

Background Art

In multiple-input multiple-output (MIMO) technology, network equipment can use precoding technology to reduce interference between multiple terminal devices and interference between multiple signal streams of the same terminal device, thereby improving signal quality, achieving space division multiplexing, and improving spectrum utilization.

The terminal device can determine the precoding matrix that is compatible with the downlink channel through channel measurement and other methods, and feedback the relevant information of the precoding matrix to the network device through the precoding matrix indicator (PMI). The network device can determine a precoding matrix that is the same or similar to the precoding matrix determined by the terminal device from the codebook based on the PMI.

With the development of large-scale antenna arrays, the area of antenna arrays of network devices has further increased. When the carrier frequency remains unchanged, the Rayleigh distance will increase exponentially with the area of the antenna array. As the Rayleigh distance increases, the terminal device is more likely to be in an area that conforms to the law of spherical waves. Due to the existence of spherical wavefronts, the signal phases at different antenna vibrator positions are distorted, which increases the mismatch risk of traditional codebooks. For example, the spatial position corresponding to the codebook index provided by the PMI does not match the actual position of the terminal device, resulting in a decrease in the accuracy of channel estimation.

Summary of the invention

The embodiments of the present application provide a communication method and a communication device, which can improve the channel estimation accuracy of a codebook in a large-scale antenna array scenario.

In the first aspect, the embodiment of the present application provides a communication method, the execution subject of the method can be a terminal device or a chip applied to the terminal device, and the following description is taken as an example that the execution subject is a terminal device. The method includes: determining a first spatial basis, the first spatial basis belongs to a spatial basis set, the spatial basis set includes multiple spatial basis, each of the multiple spatial basis is determined by the angle and distance of a multipath between the antenna array of the network device and the first object; determining a combination coefficient according to the first spatial basis; sending a PMI, the PMI includes an identifier of the first spatial basis and a combination coefficient.

As the Rayleigh distance increases, the terminal device is more likely to be in an area that conforms to the law of spherical waves. Due to the existence of the spherical wave front, the signal phase at the position of different antenna elements is distorted. Therefore, it is necessary to consider the distance from the antenna element to the scatterer when performing precoding, that is, it is necessary to consider the distance of the multipath. In this embodiment, each spatial basis in the spatial basis set considers the angle and distance of the multipath at the same time, and the codebook set based on the spatial basis set is more in line with the law of spherical waves. Therefore, the PMI sent by the terminal device, which includes the identifier of the first spatial basis and the combination coefficient, can match the spatial position determined by the network device with the actual position of the terminal device, thereby improving the accuracy of channel estimation.

Optionally, before determining the first spatial basis, the communication method further includes: determining a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a number of quantization bits Δd of the distance between the terminal device and the antenna array; determining a distance candidate value set according to r _max , r _min and Δd; determining an angle candidate value set; and determining a spatial basis set according to the distance candidate value set and the angle candidate value set.

The spatial basis set is determined based on the maximum value r _max and the minimum value r _min of the distance between the terminal device and the antenna array. When the distance between the terminal device and the antenna array changes, the spatial basis set also changes accordingly. Therefore, the spatial basis set determined in this embodiment is more adapted to the actual position of the terminal device.

Optionally, determining a distance candidate value set according to r _max , r _min and Δd includes: determining a distance interval d _gap according to r _max , r _min and Δd; determining a distance candidate value set according to r _max , r _min and d _gap , the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , and the difference between any two distance candidate values in the distance candidate value set is an integer multiple of d _gap .

In this embodiment, the distance intervals d _gap between different distance candidate values are the same, and the terminal device can determine d _gap by receiving Δd. Compared with receiving multiple d _gaps (or the relationship between d _gap and distance), this embodiment can reduce signaling complexity.

Optionally,

Optionally, before determining the first spatial basis, the communication method further includes: determining a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a distance interval d _gap ; determining a distance candidate value set according to r _max , r _min and d _gap , wherein the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , the difference between two adjacent distance candidate values in the distance candidate value set is d _gap , and d _gap is associated with the distance between the terminal device and the antenna array; determining an angle candidate value set; and determining a spatial basis set according to the distance candidate value set and the angle candidate value set.

The correlation relationship is, for example, that d _gap is positively correlated with the distance between the terminal device and the antenna array. That is, the greater the distance between the terminal device and the antenna array, the greater the d _gap ; the smaller the distance between the terminal device and the antenna array, the smaller the d _gap . The greater the distance between the terminal device and the antenna array, the lower the estimated accuracy of the distance. Considering the resolution of the distance, the positive correlation between d _gap and the distance can reduce the computational complexity of channel estimation.

Optionally, r _max and r _min are determined based on a timing advance (TA) of a signal between the antenna array and the terminal device.

The multiplexing TA determines r _max and r _min , and there is no need to send a special ranging signal, which can save signaling overhead.

Optionally, the identifier of the first spatial basis includes: the identifier of the angle basis corresponding to the first spatial basis, and the identifier of the distance basis corresponding to the first spatial basis; the PMI also includes: a bitmap of non-zero coefficients, the number of bits of the bitmap is 2*L*D*M, L is the number of angle basis corresponding to multiple spatial basis, D is the number of distance basis corresponding to multiple spatial basis, and M is the number of frequency domain basis; the oversampling rate of the distance basis corresponding to the first spatial basis.

A non-zero coefficient is a combination coefficient that is not equal to 0. A bitmap with a bit number of 2*L*D*M can adapt to scenarios including angle basis, distance basis, and frequency domain basis. The oversampling rate of the distance basis can be used to expand the number of distance basis, thereby expanding the number of spatial basis in the spatial basis set. A larger spatial basis set is conducive to the network device to recover a precoding matrix that is closer to the precoding matrix determined by the terminal device, thereby improving the accuracy of channel estimation.

Optionally, the antenna array includes a first subarray and a second subarray, and determining a first spatial basis includes: determining first received data, second received data, r _max , r _min and δ, wherein the first received data is data from the first subarray, the second received data is data from the second subarray, r _min is the maximum value of the distance between the terminal device and the antenna array, r _min is the minimum value of the distance between the terminal device and the antenna array, and δ is the spacing between the first subarray and the second subarray; processing the first received data, the second received data, r _min , r _min and δ through dictionary learning to obtain an angle basis of the first subarray, a distance basis of the first subarray, an angle basis of the second subarray and a distance basis of the second subarray; wherein the first spatial basis includes: an angle basis of the first subarray, and a distance basis of the first subarray; and/or an angle basis of the second subarray, and a distance basis of the second subarray.

Since the codebook of the embodiment of the present application adds the distance dimension, the complexity of the channel estimation of the terminal device increases, the feedback overhead increases, and the power consumption increases. After the antenna array is divided into multiple subarrays, the terminal device can estimate the basis of different subarrays respectively, and finally jointly feed back the PMI of multiple subarrays. The network device can reconstruct the channel according to the geometric relationship between the multiple subarrays and the PMI of the multiple subarrays. Since the amount of received data that the terminal device needs to process when estimating the basis of a subarray is reduced, the number of times the dictionary learning process performs loop nesting of distance and angle is reduced, thereby reducing the complexity and power consumption of the channel estimation of the terminal device.

Optionally, the first spatial domain basis includes: an angle basis of a first subarray, and a distance basis of the first subarray; the combination coefficient is the combination coefficient of the first subarray, and the PMI also includes an identifier of the frequency domain basis of the first subarray; or, the first spatial domain basis includes: an angle basis of a second subarray, and a distance basis of the second subarray; the combination coefficient is the combination coefficient of the second subarray, and the PMI also includes an identifier of the frequency domain basis of the second subarray.

Different subarrays can share some parameters. For example, the first subarray and the second subarray can share the frequency domain basis and the combined system. In the first subarray and the second subarray, the spatial domain basis of one subarray can also be derived based on the spatial domain set of the other subarray and the geometric relationship between the two subarrays. Therefore, when sending PMI, the terminal device can send the identifier of the frequency domain basis, the identifier of the spatial domain basis and the coefficient of one subarray in the first subarray and the second subarray, thereby reducing the feedback overhead.

Optionally, before determining the first spatial basis, the communication method also includes: determining the distance d _TA between the terminal device and the antenna array; determining a target channel model based on d _TA , the target channel model being a first channel model or a second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determining the first spatial basis includes: determining the first spatial basis when the target channel model is the first channel model.

Different distances are suitable for different target channel models. The target channel model determined based on the distance between the terminal device and the antenna array can match the actual position of the terminal device and improve the accuracy of channel estimation.

Optionally, determining the target channel model according to d _TA includes: determining d _FF , where d _FF is each vibrator in the antenna array in the second channel model. distance to the first object; if the absolute value of the difference between d _TA and d _FF is less than the first distance threshold, the target channel model is determined to be the first channel model; if the absolute value of the difference between d _TA and d _FF is greater than the second distance threshold, the target channel model is determined to be the second channel model; wherein the first distance threshold is less than or equal to the second distance threshold.

If the absolute value of the difference between d _TA and d _FF is less than the first distance threshold, it means that the distance between the terminal device and the antenna array is relatively close, the distances between the vibrators in the antenna array and the terminal device are relatively different, and the actual position of the terminal device is more consistent with the first channel model. If the absolute value of the difference between d _TA and d _FF is greater than the second distance threshold, it means that the distance between the terminal device and the antenna array is relatively far, the distances between the vibrators in the antenna array and the terminal device are relatively different and can be considered equal, and the actual position of the terminal device is more consistent with the second channel model. Based on the difference between d _TA and d _FF , the currently applicable channel model can be accurately determined to improve the accuracy of channel estimation.

Optionally, determining the target channel model according to d _TA includes: determining d _FF , where d _FF is the distance from each vibrator in the antenna array in the second channel model to the first object; if the ratio of d _FF to d _FF is less than a third distance threshold, determining that the target channel model is the first channel model; if the ratio of d _FF to d _FF is greater than a fourth distance threshold, determining that the target channel model is the second channel model; wherein the third distance threshold is less than or equal to the fourth distance threshold.

If the ratio of d _TA to d _FF is less than the third distance threshold, it means that the distance between the terminal device and the antenna array is relatively close, the distances between the various vibrators in the antenna array and the terminal device are relatively different, and the actual position of the terminal device is more consistent with the first channel model. If the ratio of d _TA to d _FF is greater than the fourth distance threshold, it means that the distance between the terminal device and the antenna array is relatively far, the distances between the various vibrators in the antenna array and the terminal device are relatively different and can be considered equal, and the actual position of the terminal device is more consistent with the second channel model. Based on the ratio of d _TA to d _FF , the currently applicable channel model can be accurately determined to improve the accuracy of channel estimation.

Optionally, determining the distance d _TA between the terminal device and the antenna array includes: determining a TA of the first signal; and determining d _TA according to the TA of the first signal.

The multiplexing TA determines d _TA , and there is no need to send a special ranging signal, which can save signaling overhead.

Optionally, the first signal is one of multiple signals; the multiple signals include a random access preamble, a sounding reference signal (SRS) and a demodulation reference signal (DMRS), and the first signal is SRS; or, the multiple signals include a random access preamble and DMRS, and the first signal is DMRS.

The TA measured by SRS is more accurate than the TA measured by DMRS or random access preamble code, and the TA measured by DMRS is more accurate than the TA measured by random access preamble code. Therefore, by selecting the first signal based on the above priority, a more accurate TA can be obtained, thereby making the target channel model determined based on TA more accurate.

Optionally, before determining the TA of the first signal, the communication method also includes: receiving first indication information, the first indication information is used to indicate the TA; determining the TA of the first signal includes: determining the TA of the first signal according to the first indication information.

The network device can determine TA based on the first signal and inform the terminal device of TA. The terminal device can determine d _TA based on TA, and then determine the target channel model according to d _TA . Therefore, this embodiment can reuse the existing process (the process of the terminal device obtaining TA) to determine the target channel model, thereby reducing the overhead of determining the target channel model.

Optionally, before determining the first spatial basis, the communication method further includes: determining the trace tra _cur of the spatial correlation matrix of the antenna array; determining a target channel model according to tra _cur , the target channel model being a first channel model or a second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determining the first spatial basis includes: determining the first spatial basis when the target channel model is the first channel model.

There is a correlation between tra _cur and the target channel model. Different tra _cur are suitable for different target channel models. The target channel model determined based on tra _cur can match the actual position of the terminal device and improve the accuracy of channel estimation.

Optionally, determining the target channel model according to tra _cur includes: determining tra _ref , tra _ref being the trace of the spatial correlation matrix corresponding to the second channel model; if the absolute value of the difference between tra _cur and tra _ref is greater than a first trace threshold, determining that the target channel model is the first channel model; if the absolute value of the difference between tra _cur and tra _ref is less than a second trace threshold, determining that the target channel model is the second channel model; wherein the first trace threshold is greater than or equal to the second trace threshold.

If the absolute value of the difference between tra _cur and tra _ref is greater than the first trace threshold, it means that the distance between the terminal device and the antenna array is relatively close, the distances between the various oscillators in the antenna array and the terminal device are quite different, and the actual position of the terminal device is more consistent with the first channel model. If the absolute value of the difference between tra _cur and tra _ref is less than the second trace threshold, it means that the distance between the terminal device and the antenna array is relatively far, the distances between the various oscillators in the antenna array and the terminal device are relatively different and can be considered equal, and the actual position of the terminal device is more consistent with the second channel model. Based on the difference between tra _cur and tra _ref, the currently applicable channel model can be accurately determined to improve the accuracy of channel estimation.

Optionally, determining the target channel model according to tra _cur includes: determining tra _ref , tra _ref being the trace of the spatial correlation matrix corresponding to the second channel model; if the ratio of tra _cur to tra _ref is greater than a third trace threshold, determining the target channel model to be the first channel model; if tra _cur is The ratio of tra _ref is less than the fourth trace threshold, and the target channel model is determined to be the second channel model; wherein the third trace threshold is greater than or equal to the fourth trace threshold.

If the ratio of tra _cur to tra _ref is greater than the third trace threshold, it means that the distance between the terminal device and the antenna array is relatively close, the distances between the various oscillators in the antenna array and the terminal device vary greatly, and the actual position of the terminal device is more consistent with the first channel model. If the ratio of tra _cur to tra _ref is less than the fourth trace threshold, it means that the distance between the terminal device and the antenna array is relatively far, the distances between the various oscillators in the antenna array and the terminal device vary slightly and can be considered equal, and the actual position of the terminal device is more consistent with the second channel model. Based on the ratio of tra _cur to tra _ref , the currently applicable channel model can be accurately determined to improve the accuracy of channel estimation.

Optionally, tra _ref is a preset value, or tra _ref is an average value of traces of spatial correlation matrices of multiple terminal devices to which the second channel model is applied.

Tra _Ref may be a value pre-configured by the network device, a value defined by the protocol, an empirical value, or a value measured when the communication network is established. By presetting Tra _Ref , the frequency of receiving Tra _Ref from the network device by the terminal device is reduced, or the terminal device does not need to receive Tra _Ref from the network device, thereby reducing the power consumption of the terminal device in determining Tra _Ref . By determining Tra _Ref by the average value of the traces of the spatial correlation matrix of multiple terminal devices, the error of Tra _Ref can be reduced, and the target channel model determined based on Tra _Ref is more accurate.

Optionally, before determining tra _ref , the communication method further includes: receiving second indication information, where the second indication information is used to indicate tra _ref ; and determining tra _ref includes: determining tra _ref according to the second indication information.

In this embodiment, the terminal device may obtain the latest tra _ref through the second indication information. The latest tra _ref is more consistent with the current channel condition. Therefore, the target channel model determined based on the latest tra _ref is more accurate.

Optionally, _trace is the average of the traces of the spatial correlation matrix of multiple time units.

By determining tra _cur by taking an average value of the traces of the spatial correlation matrix of a plurality of time units, the error of tra _cur can be reduced, and the target channel model determined based on the tra _cur is more accurate.

Optionally, the communication method further includes: sending third indication information, where the third indication information is used to indicate a target channel model.

After the terminal device determines the target channel model, it can inform the network device of the target channel model through the third indication information, so that the network device can reconstruct a more accurate precoding matrix based on the target channel model.

Optionally, before determining the first spatial domain basis, the communication method also includes: receiving fourth indication information, the fourth indication information is used to indicate a target channel model, the target channel model is a first channel model or a second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determining the target channel model according to the fourth indication information; determining the first spatial domain basis, including: determining the first spatial domain basis when the target channel model is the first channel model.

In this embodiment, the terminal device obtains the target channel model from the network device through the fourth indication information, and there is no need to determine the target channel model through local calculation, thereby reducing the power consumption of the terminal device in determining the target channel model.

In the second aspect, the embodiment of the present application provides a communication method, the execution subject of the method can be a network device or a chip applied to the network device, and the following description is taken as an example that the execution subject is a network device. The method includes: receiving a PMI, the PMI includes an identifier and a combination coefficient of a first spatial basis; determining the first spatial basis from a spatial basis set according to the identifier of the first spatial basis, the spatial basis set includes multiple spatial basis, each of the multiple spatial basis is determined by the angle and distance of a multipath between the antenna array of the network device and the first object; determining a precoding matrix according to the first spatial basis and the combination coefficient.

As the Rayleigh distance increases, the terminal device is more likely to be in an area that conforms to the law of spherical waves. Due to the existence of the spherical wavefront, the signal phase at different positions is distorted. Therefore, the distance from the antenna element to the scatterer needs to be considered when performing precoding, that is, the multipath distance needs to be considered. In this embodiment, each spatial basis in the spatial basis set considers the angle and distance of the multipath at the same time, and the codebook set based on the spatial basis set is more in line with the law of spherical waves. Therefore, the PMI sent by the terminal device, which includes the identifier of the first spatial basis and the combination coefficient, can match the spatial position determined by the network device with the actual position of the terminal device, thereby improving the accuracy of channel estimation.

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the communication method further includes: determining a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a number of quantization bits Δd of the distance between the terminal device and the antenna array; determining a distance candidate value set according to r _max , r _min and Δd; determining an angle candidate value set; and determining a spatial basis set according to the distance candidate value set and the angle candidate value set.

The spatial basis set is determined based on the maximum value r _max and the minimum value r _min of the distance between the terminal device and the antenna array. When the distance between the terminal device and the antenna array changes, the spatial basis set also changes accordingly. Therefore, the spatial basis set determined in this embodiment is more adapted to the actual position of the terminal device.

Optionally, determining a distance candidate value set according to r _max , r _min and Δd includes: determining a distance interval according to r _max , r _min and Δd d _gap ; determine the distance candidate value set according to r _max , r _min and d _gap , the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , and the difference between any two distance candidate values in the distance candidate value set is an integer multiple of d _gap .

Optionally,

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the communication method also includes: determining a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a distance interval d _gap ; determining a distance candidate value set according to r _max , r _min and d _gap , the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , the difference between two adjacent distance candidate values in the distance candidate value set is d _gap , and d _gap is associated with the distance between the terminal device and the antenna array; determining an angle candidate value set; and determining a spatial basis set according to the distance candidate value set and the angle candidate value set.

The correlation relationship is, for example, that d _gap is positively correlated with the distance between the terminal device and the antenna array, that is, the greater the distance between the terminal device and the antenna array, the greater the d _gap ; and the smaller the distance between the terminal device and the antenna array, the smaller the d _gap .

Optionally, r _max and r _min are determined based on the TA of the signal between the antenna array and the terminal device.

The multiplexing TA determines r _max and r _min , and there is no need to send a special ranging signal, which can save signaling overhead.

Optionally, the identifier of the first spatial basis includes: the identifier of the angle basis corresponding to the first spatial basis, and the identifier of the distance basis corresponding to the first spatial basis; the PMI also includes: a bitmap of non-zero coefficients, the number of bits of the bitmap is 2*L*D*M, L is the number of angle basis corresponding to multiple spatial basis, D is the number of distance basis corresponding to multiple spatial basis, and M is the number of frequency domain basis; the oversampling rate of the distance basis corresponding to the first spatial basis.

A non-zero coefficient is a combination coefficient that is not equal to 0. A bitmap with a bit number of 2*L*D*M can adapt to scenarios including angle basis, distance basis, and frequency domain basis. The oversampling rate can be used to expand the number of distance basis, thereby expanding the number of spatial basis in the spatial basis set. A larger spatial basis set is conducive to the network device to recover a precoding matrix that is closer to the precoding matrix determined by the terminal device, thereby improving the accuracy of channel estimation.

Optionally, the antenna array includes a first subarray and a second subarray, and the first spatial basis includes: an angle basis of the first subarray, and a distance basis of the first subarray; and/or an angle basis of the second subarray, and a distance basis of the second subarray.

Different subarrays can share some parameters. For example, the first subarray and the second subarray can share the frequency domain basis and the combined system. In the first subarray and the second subarray, the spatial domain basis of one subarray can also be derived based on the spatial domain set of the other subarray and the geometric relationship between the two subarrays. Therefore, when sending PMI, the terminal device can send the identifier of the frequency domain basis, the identifier of the spatial domain basis and the coefficient of one subarray in the first subarray and the second subarray, thereby reducing the feedback overhead.

Optionally, the first spatial basis includes: an angle basis of the first subarray, and a distance basis of the first subarray; determining the precoding matrix according to the first spatial basis and the combination coefficient includes: determining the angle basis of the second subarray and the distance basis of the second subarray according to the angle basis of the first subarray, the distance basis of the first subarray, and the spacing between the first subarray and the second subarray; determining the precoding matrix according to the angle basis of the first subarray, the distance basis of the first subarray, the angle basis of the second subarray, the distance basis of the second subarray and the combination coefficient.

Since the codebook of the embodiment of the present application adds the distance dimension, the complexity of the channel estimation of the terminal device increases, the feedback overhead increases, and the power consumption increases. After the antenna array is divided into multiple subarrays, the terminal device can estimate the basis of different subarrays respectively, and finally jointly feed back the PMI of multiple subarrays. The network device can reconstruct the channel according to the geometric relationship between the multiple subarrays and the PMI of the multiple subarrays. Since the amount of received data that the terminal device needs to process when estimating the basis of a subarray is reduced, the number of times the dictionary learning process performs loop nesting of distance and angle is reduced, thereby reducing the complexity and power consumption of the channel estimation of the terminal device.

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the communication method also includes: determining the distance d _TA between the terminal device and the antenna array; determining the target channel model according to d _TA , the target channel model is the first channel model or the second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis includes: when the target channel model is the first channel model, determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis.

Different distances are suitable for different target channel models. The target channel model determined based on the distance between the terminal device and the antenna array can match the actual position of the terminal device and improve the accuracy of channel estimation.

Optionally, determining the target channel model according to d _TA includes: determining d _FF , where d _FF is the distance from each vibrator in the antenna array to the first object in the second channel model; if the absolute value of the difference between d _TA and d _FF is less than a first distance threshold, determining the target channel model to be the first channel model; if the absolute value of the difference between d _TA and d _FF is greater than a second distance threshold, determining the target channel model to be the second channel model; wherein the first distance The distance threshold is less than or equal to the second distance threshold.

If the absolute value of the difference between d _TA and d _FF is less than the first distance threshold, it means that the distance between the terminal device and the antenna array is relatively close, the distances between the vibrators in the antenna array and the terminal device are relatively different, and the actual position of the terminal device is more consistent with the first channel model. If the absolute value of the difference between d _TA and d _FF is greater than the second distance threshold, it means that the distance between the terminal device and the antenna array is relatively far, the distances between the vibrators in the antenna array and the terminal device are relatively different and can be considered equal, and the actual position of the terminal device is more consistent with the second channel model. Based on the difference between d _TA and d _FF , the currently applicable channel model can be accurately determined to improve the accuracy of channel estimation.

Optionally, determining the target channel model according to d _TA includes: determining d _FF , where d _FF is the distance from each vibrator in the antenna array in the second channel model to the first object; if the ratio of d _TA to d _FF is less than a third distance threshold, determining that the target channel model is the first channel model; if the ratio of d _TA to d _FF is greater than a fourth distance threshold, determining that the target channel model is the second channel model; wherein the third distance threshold is less than or equal to the fourth distance threshold.

If the ratio of d _TA to d _FF is less than the third distance threshold, it means that the distance between the terminal device and the antenna array is relatively close, the distances between the various vibrators in the antenna array and the terminal device are relatively different, and the actual position of the terminal device is more consistent with the first channel model. If the ratio of d _TA to d _FF is greater than the fourth distance threshold, it means that the distance between the terminal device and the antenna array is relatively far, the distances between the various vibrators in the antenna array and the terminal device are relatively different and can be considered equal, and the actual position of the terminal device is more consistent with the second channel model. Based on the ratio of d _TA to d _FF , the currently applicable channel model can be accurately determined to improve the accuracy of channel estimation.

Optionally, determining the distance d _TA between the terminal device and the antenna array includes: determining a TA of the first signal; and determining d _TA according to the TA of the first signal.

The multiplexing TA determines d _TA , and there is no need to send a special ranging signal, which can save signaling overhead.

Optionally, the first signal is one of multiple signals; the multiple signals include a random access preamble, an SRS and a DMRS, and the first signal is the SRS; or, the multiple signals include a random access preamble and a DMRS, and the first signal is the DMRS.

The TA measured by SRS is more accurate than the TA measured by DMRS or random access preamble code, and the TA measured by DMRS is more accurate than the TA measured by random access preamble code. Therefore, by selecting the first signal based on the above priority, a more accurate TA can be obtained, thereby making the target channel model determined based on TA more accurate.

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the communication method also includes: determining the trace tra _cur of the spatial correlation matrix of the antenna array; determining the target channel model according to tra _cur , the target channel model is the first channel model or the second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis includes: when the target channel model is the first channel model, determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis.

There is a correlation between tra _cur and the target channel model. Different tra _cur are suitable for different target channel models. The target channel model determined based on tra _cur can match the actual position of the terminal device and improve the accuracy of channel estimation.

Optionally, determining the target channel model according to tra _cur includes: determining tra _ref , tra _ref being the trace of the spatial correlation matrix corresponding to the second channel model; if the absolute value of the difference between tra _cur and tra _ref is greater than a first trace threshold, determining that the target channel model is the first channel model; if the absolute value of the difference between tra _cur and tra _ref is less than a second trace threshold, determining that the target channel model is the second channel model; wherein the first trace threshold is greater than or equal to the second trace threshold.

If the absolute value of the difference between tra _cur and tra _ref is greater than the first trace threshold, it means that the distance between the terminal device and the antenna array is relatively close, the distances between the various oscillators in the antenna array and the terminal device are quite different, and the actual position of the terminal device is more consistent with the first channel model. If the absolute value of the difference between tra _cur and tra _ref is less than the second trace threshold, it means that the distance between the terminal device and the antenna array is relatively far, the distances between the various oscillators in the antenna array and the terminal device are relatively different and can be considered equal, and the actual position of the terminal device is more consistent with the second channel model. Based on the difference between d _TA and d _FF , the currently applicable channel model can be accurately determined to improve the accuracy of channel estimation.

Optionally, determining the target channel model according to tra _cur includes: determining tra _ref , where tra _ref is the trace of the spatial correlation matrix corresponding to the second channel model; if the ratio of tra _cur to tra _ref is greater than a third trace threshold, determining that the target channel model is the first channel model; if the ratio of tra _cur to tra _ref is less than a fourth trace threshold, determining that the target channel model is the second channel model; wherein the third trace threshold is greater than or equal to the fourth trace threshold.

If the ratio of tra _cur to tra _ref is greater than the third trace threshold, it means that the distance between the terminal device and the antenna array is relatively close, and the distances from each vibrator in the antenna array to the terminal device vary greatly, so the actual position of the terminal device is more consistent with the first channel model. If the ratio of tra _cur to tra _ref is less than the fourth trace threshold, it means that the distance between the terminal device and the antenna array is relatively far, and the distances from each vibrator in the antenna array to the terminal device vary slightly and can be considered equal, so the actual position of the terminal _device is more consistent with the second _channel model. The currently applicable channel model can be accurately determined, thereby improving the accuracy of channel estimation.

Optionally, _trace is the average of the traces of the spatial correlation matrix of multiple time units.

By determining tra _cur by taking an average value of the traces of the spatial correlation matrix of a plurality of time units, the error of tra _cur can be reduced, and the target channel model determined based on the tra _cur is more accurate.

Optionally, tra _ref is a preset value, or tra _ref is an average value of traces of spatial correlation matrices of multiple terminal devices to which the second channel model is applied.

Tra _Ref can be a value defined by a protocol, a value defined by a protocol, an empirical value, or a value measured when a communication network is established. By presetting Tra _Ref , the network device does not need to calculate Tra _Ref , thereby reducing the power consumption of the network device in determining Tra _Ref . By determining Tra _Ref by the average value of the trace of the spatial correlation matrix of multiple terminal devices, the error of Tra _Ref can be reduced, and the target channel model determined based on Tra _Ref is more accurate.

Optionally, the communication method further includes: sending fourth indication information, where the fourth indication information is used to indicate a target channel model.

After the network device determines the target channel model, it indicates the target channel model to the terminal device through the fourth indication information. The terminal device does not need to determine the target channel model through local calculation, thereby reducing the power consumption of the terminal device in determining the target channel model.

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the communication method also includes: receiving third indication information, the third indication information is used to indicate a target channel model, the target channel model is a first channel model or a second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determining the target channel model according to the third indication information; determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, including: when the target channel model is the first channel model, determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis.

After the terminal device determines the target channel model, it can inform the network device of the target channel model through the third indication information, so that the network device can reconstruct a more accurate precoding matrix based on the target channel model.

Optionally, before receiving the third indication information, the communication method further includes: sending first indication information, where the first indication information is used to indicate TA, and TA is used to determine a target channel model.

The network device can determine TA based on the first signal and inform the terminal device of TA. The terminal device can determine d _TA based on TA, and then determine the target channel model according to d _TA . Therefore, this embodiment can reuse the existing process (the process of the terminal device obtaining TA) to determine the target channel model, thereby reducing the overhead of determining the target channel model.

Optionally, before receiving the third indication information, the communication method also includes: sending second indication information, the second indication information is used to indicate the trace tra _ref of the spatial correlation matrix corresponding to the second channel model, tra _ref is the average value of the trace of the spatial correlation matrix of multiple terminal devices applying the second channel model, and tra _ref is used to determine the target channel model.

In this embodiment, the terminal device may obtain the latest tra _ref through the second indication information. The latest tra _ref is more consistent with the current channel condition. Therefore, the target channel model determined based on the latest tra _ref is more accurate.

In a third aspect, an embodiment of the present application provides a communication device. The communication device may include a processing unit and a transceiver unit, configured to execute: any one of the methods in the first aspect and its optional embodiments described above. The transceiver unit is a sending unit when executing the sending step, and is a receiving unit when executing the receiving step.

In a fourth aspect, an embodiment of the present application provides a communication device. The communication device may include a processing unit and a transceiver unit, configured to execute: any method in the second aspect and its optional implementations described above. The transceiver unit is a sending unit when executing the sending step, and is a receiving unit when executing the receiving step.

In a fifth aspect, an embodiment of the present application provides a communication device, which may be a terminal device or a chip applied to a terminal device. The communication device may include a processor, configured to execute: any method in the above first aspect and its optional implementation manner.

Optionally, when the communication device is a terminal device, the processor is, for example, a system on chip (SoC) or a central processor unit (CPU); when the communication device is a chip, the processor is, for example, a core, which may include at least one execution unit (execution unit), such as an arithmetic and logic unit (ALU).

Optionally, the communication device may further include a transceiver. When the communication device is a terminal device, the transceiver may be a transceiver circuit, an antenna, etc.; when the communication device is a chip applied to a terminal device, the transceiver may be an input/output interface, a pin, a circuit, etc.

Optionally, the communication device may further include a memory, the memory being used to store a computer program or instruction, and the processor executing the computer program or instruction stored in the memory so that the communication device performs any one of the above-mentioned first aspect and its optional implementation modes. When the communication device is a terminal device, the memory may be a read-only memory, a random access memory, etc.; when the communication device is a chip applied to a terminal device, the memory may be a register, a cache, etc.

In a sixth aspect, an embodiment of the present application provides a communication device, which may be a network device or a chip applied to a network device. The communication device may include a processor, configured to execute: any method in the second aspect and its optional implementation manners described above.

Optionally, when the communication device is a network device, the processor is, for example, a CPU, an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA); when the communication device is a chip, the processor is, for example, a core, which may include at least one execution unit, such as an ALU.

Optionally, the communication device may further include a transceiver. When the communication device is a network device, the transceiver may be a transceiver circuit, an antenna, etc.; when the communication device is a chip applied to a network device, the transceiver may be an input/output interface, a pin, a circuit, etc.

Optionally, the communication device may further include a memory, the memory being used to store a computer program or instruction, and the processor executing the computer program or instruction stored in the memory so that the communication device performs any one of the methods in the above-mentioned second aspect and its optional implementations. When the communication device is a network device, the memory may be a read-only memory, a random access memory, etc.; when the communication device is a chip applied to a network device, the memory may be a register, a cache, etc.

In the seventh aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed on a computer, the computer executes any method in the first aspect and its optional embodiments.

In an eighth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed on a computer, the computer executes any method in the second aspect and its optional implementation methods.

In the ninth aspect, an embodiment of the present application provides a computer program product, which includes: a computer program code or a computer program instruction. When the computer program code or the computer program instruction is executed by a communication device, the communication device executes any one of the methods in the first aspect and its optional embodiments.

In the tenth aspect, an embodiment of the present application provides a computer program product, which includes: a computer program code or a computer program instruction. When the computer program code or the computer program instruction is executed by a communication device, the communication device executes any one of the methods in the second aspect and its optional embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a communication system applicable to the present application;

FIG2 is a schematic diagram of a protocol stack applicable to the present application;

FIG3 is a schematic diagram of a far-field channel model provided in an embodiment of the present application;

FIG4 is a schematic diagram of a near-field channel model provided in an embodiment of the present application;

FIG5 is a schematic diagram of a communication method provided in an embodiment of the present application;

FIG6 is a schematic diagram of a geometric relationship provided in an embodiment of the present application;

FIG7 is a signaling interaction flow chart of a feedback PMI provided in an embodiment of the present application;

FIG8 is a flowchart of another signaling interaction for feeding back PMI provided in an embodiment of the present application;

9 is a signaling interaction flow chart for determining a target channel model provided by an embodiment of the present application;

10 is another signaling interaction flow chart for determining a target channel model provided in an embodiment of the present application;

11 is a flowchart of signaling interaction for determining a target channel model according to another embodiment of the present application;

FIG12 is a schematic diagram of a communication device provided in an embodiment of the present application;

FIG13 is a schematic diagram of another communication device provided in an embodiment of the present application;

FIG14 is a schematic diagram of a terminal device provided in an embodiment of the present application;

FIG15 is a schematic diagram of a network device provided in an embodiment of the present application.

DETAILED DESCRIPTION

The technical solution in this application will be described below in conjunction with the accompanying drawings.

Fig. 1 is a schematic diagram of a communication system applicable to the present application. The communication system includes a terminal device 110 and a network device 120. The following describes each part of the communication system.

Ⅰ. Terminal device 110.

In the embodiment of the present application, the terminal device 110 may be a device that provides voice and/or data to a user, for example, a handheld device or a vehicle-mounted device with a wireless connection function. The terminal device 110 may also be referred to as user equipment (UE), a terminal, an access station, a UE station, a remote station, a wireless communication device, or a user device.

For example, the terminal device 110 can be a mobile phone, a tablet computer, a computer with wireless transceiver function, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a whole vehicle, a wireless communication module in the whole vehicle, a telematics box (T-box), a road side unit (RSU), a wireless terminal in unmanned driving, a smart speaker in the Internet of Things (IoT), a wireless terminal device in remote medical, a wireless terminal device in a smart grid, a wireless terminal device in transportation safety, a wireless terminal device in a smart city, or a wireless terminal device in a smart home. The embodiments of the present application do not limit the specific technology and specific form adopted by the terminal device 110.

As an example but not limitation, in the embodiment of the present application, the terminal device 110 may also be a wearable device. Wearable devices may also be referred to as wearable smart devices, which are a general term for wearable devices that are intelligently designed and developed using wearable technology for daily wear, such as glasses, gloves, watches, clothing, and shoes. A wearable device is a portable device that is worn directly on the body or integrated into the user's clothes or accessories. Wearable devices are not only hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. Broadly speaking, wearable smart devices include electronic devices that are fully functional, large in size, and can achieve full or partial functions without relying on smartphones, such as smart watches or smart glasses, or electronic devices that only focus on a certain type of application function and need to be used in conjunction with other devices such as smartphones, such as various types of smart bracelets and smart jewelry for measuring vital signs.

The terminal device 110 may also be a vehicle-to-everything (V2X) device, such as a smart car (or intelligent car), a digital car, an unmanned car (or driverless car, or pilotless car, or automobile), a self-driving car (or autonomous car), a pure electric vehicle (or battery EV), a hybrid electric vehicle (or HEV), a range extended EV (or REEV), a plug-in hybrid electric vehicle (or PHEV), or a new energy vehicle (or new energy vehicle). The various terminal devices described above, if located on a vehicle (e.g., placed in or installed in a vehicle), can be considered as vehicle-mounted terminal devices, which are also referred to as on-board units (or OBUs).

The terminal device 110 of the present application may also be a vehicle-mounted module, vehicle-mounted module, vehicle-mounted component, vehicle-mounted chip or vehicle-mounted unit built into the vehicle as one or more components or units. The vehicle may implement the method of the present application through the built-in vehicle-mounted module, vehicle-mounted module, vehicle-mounted component, vehicle-mounted chip or vehicle-mounted unit.

In addition, in the embodiment of the present application, the terminal device 110 may also be a device in a future-evolved public land mobile network (PLMN), for example, the terminal device 110 may be a terminal device in a sixth generation mobile communication technology (6G) system. The embodiment of the present application does not limit the specific type of the terminal device 110.

Ⅱ. Network equipment 120.

The network device 120 is a device that provides wireless communication functions for terminal devices and is responsible for functions related to the air interface (abbreviated as "air interface").

The network equipment 120 can also be called a network device or a radio access network (RAN) device. The network equipment 120 includes but is not limited to: a base station (BS), an evolved base station (eNodeB), a transmission reception point (TRP), a next generation base station (next generation nodeB, gNB) in the fifth generation (5th generation, 5G) mobile communication system, a next generation base station in a 6G mobile communication system, a base station in a future mobile communication system, a wireless fidelity (WiFi) system, a long range radio (LoRa) system or an access node in a vehicle networking system.

The RAN device can be a module or unit that completes part of the functions of the base station, for example, it can be a centralized unit (CU), a distributed unit (DU), or a radio unit (RU). The CU here completes the functions of the radio resource control protocol and the packet data convergence protocol (PDCP) of the base station, and can also complete the function of the service data adaptation protocol (SDAP); the DU completes the functions of the radio link control layer and the medium access control (MAC) layer of the base station, and can also complete the functions of part of the physical layer or all of the physical layer. For the specific description of the above-mentioned protocol layers, please refer to the relevant technical specifications of the 3rd generation partnership project (3GPP). The CU and DU can be set separately, or they can be included in the same network element, such as the baseband unit (BBU). The RU can be included in the radio frequency device or radio frequency unit, for example, in the radio remote unit The antenna is located in a remote radio unit (RRU), an active antenna unit (AAU) or a remote radio head (RRH).

In different systems, CU, DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in an open radio access network (ORAN) system, CU may also be called an open CU (open CU, O-CU), DU may also be called an open DU (open DU, O-DU), and RU may also be called an open RU (open RU, O-RU). Any unit in the CU, DU and RU in this application may be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

The RAN device may be a macro base station, a micro base station, an indoor station, a relay node or a donor node, etc. The RAN device may also be a base station corresponding to a small cell, where the small cell may include: a metro cell, a micro cell, a pico cell or a femto cell. The network device 120 in the embodiment of the present application may be any of the above devices or devices in the device, and the embodiment of the present application does not limit the specific technology and specific device form adopted by the network device 120. For the convenience of description, the RAN device may be used as an abbreviation for the network device 120, and the base station is used as an example of the RAN device.

Base stations and terminals can be fixed or movable. Base stations and terminals can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on the water surface; they can also be deployed on airplanes, balloons, and artificial satellites. The embodiments of this application do not limit the application scenarios of base stations and terminals.

The roles of the base station and the terminal can be relative. For example, a drone (or a helicopter) can be configured as a mobile base station. For those terminals that access the network device 120 through the drone, the drone is a base station; but for the network device 120, the drone is a terminal, that is, the network device 120 and the drone communicate through the wireless air interface protocol. Of course, the network device 120 and the drone can also communicate through the interface protocol between base stations. In this case, relative to the network device 120, the drone is also a base station. Therefore, both the base station and the terminal can be collectively referred to as a communication device. The network device 120 in Figure 1 can be referred to as a communication device with a base station function, and the terminal device 110 in Figure 1 can be referred to as a communication device with a terminal function.

Base stations and terminals, base stations and base stations, and terminals and terminals can communicate through authorized spectrum, unauthorized spectrum, or both; they can communicate through spectrum below 6 gigahertz (GHz), spectrum above 6 GHz, or spectrum below 6 GHz and spectrum above 6 GHz. The embodiments of the present application do not limit the spectrum resources used for wireless communication.

In the embodiments of the present application, the functions of the base station may also be performed by a module (such as a chip) in the base station, or by a control subsystem including the base station function. The control subsystem including the base station function here may be a control center in the above-mentioned application scenarios such as smart grid, industrial control, smart transportation, and smart city. The functions of the terminal may also be performed by a module (such as a chip or a modem) in the terminal, or by a device including the terminal function.

In this application, the base station sends a downlink signal or downlink information to the terminal, and the downlink information is carried on the downlink channel; the terminal sends an uplink signal or uplink information to the base station, and the uplink information is carried on the uplink channel. In order to communicate with the base station, the terminal needs to establish a wireless connection on the cell controlled by the base station. The cell with which the terminal has established a wireless connection is called the service cell of the terminal. When the terminal communicates with the service cell, it will also be interfered by signals from neighboring cells.

The following describes a protocol stack applicable to this application.

The protocol stack of the terminal device 110 and the network device 120 is shown in Figure 2. The protocol stack is mainly the protocol stack of the access layer, wherein the access layer can be divided into a radio resource control (RRC) layer, a PDCP layer, a radio link control (RLC) layer, a MAC layer and a physical (PHY) layer.

The following describes the workflow of the protocol stack using uplink transmission as an example.

(1) The main functions of the RRC layer include system messages, admission control, security management, measurement and reporting, as well as switching and mobility. The control plane data related to these functions is generated in the non-access stratum (NAS). The RRC layer is also responsible for the radio resource management of the transmission of NAS protocol data units (PDUs). After the NAS PDU reaches the RRC layer, it is processed as an RRC service data unit (SDU) to generate an RRC PDU. The control plane data generated by the RRC layer (such as RRC reconfiguration messages) will also be packaged into RRC PDUs.

(2) The main functions of the PDCP layer include transmitting user plane and control plane data, maintaining PDCP sequence numbers, routing and repetition, encryption/decryption and integrity protection, reordering, supporting out-of-order delivery, and duplicate discard. After the RRC PDU reaches the PDCP layer, it is processed as a PDCP SDU to generate a PDCP PDU.

(3) The main functions of the RLC layer include error detection and correction, segmentation and reassembly, resegmentation, and duplicate packet detection. After the PDCP PDU reaches the RLC layer, it is processed as an RLC SDU to generate an RLC PDU.

(4) The main functions of the MAC layer include mapping between logical channels and transport channels, multiplexing/demultiplexing, scheduling, hybrid automatic repeat request (HARQ), and logical channel priority setting. After the RLC PDU reaches the MAC layer, it is processed as a MAC SDU to generate a MAC subPDU. Multiple MAC subPDUs are cascaded to generate a MAC PDU.

(5) The main functions of the PHY layer include coding, modulation, and multiple-input multiple-output (MIMO). After the MAC PDU reaches the PHY layer, it is sent out on the corresponding time-frequency resources.

As can be seen from the above, data transmitted between the same protocol layers can be called SDU, and data transmitted between adjacent protocol layers can be called PDU. For a certain protocol layer, the data it processes can be called SDU, and the data it outputs can be called PDU.

For example, the data processed by the RRC layer of the terminal device 110 is RRC SDU. The RRC layer adds protocol control information (PCI) to the RRC SDU and encapsulates it into RRC PDU. The RRC PDU is processed by the PDCP layer, the RLC layer, the MAC layer, and the PHY layer, and then transmitted to the network device 120 via a wireless signal. The information carried by the wireless signal reaching the network device 120 is processed by the PHY layer, the MAC layer, the RLC layer, and the PDCP layer in sequence, and reaches the RRC layer in the form of RRC PDU. The RRC layer decapsulates the RRC PDU, removes the PCI, and restores the RRC SDU.

If the data volume of an SDU is large, the terminal device 110 can divide the SDU into multiple segments, encapsulate them into multiple PDUs and send them out, and the network device 120 decapsulates the multiple PDUs and reassembles them into SDUs. If the data volume of multiple SDUs is small, the terminal device 110 can splice the multiple SDUs together, encapsulate them into one PDU and send them out, and the network device 120 decapsulates the PDU and separates the multiple SDUs.

To facilitate understanding of the embodiments of the present application, the following is a brief introduction to the technologies involved in the embodiments of the present application.

1. Precoding technology.

When the channel state is known, the transmitting device (such as a network device) can process the signal to be transmitted with the help of a precoding matrix that matches the channel state, so that the precoded signal to be transmitted is adapted to the channel, thereby reducing the complexity of the receiving device (such as a terminal device) in eliminating the influence between channels. Therefore, by precoding the signal to be transmitted, the quality of the received signal (such as the signal to interference plus noise ratio (SINR)) is improved. Therefore, the use of precoding technology can realize the transmission of the transmitting device and multiple receiving devices on the same time-frequency resources, that is, multiple user multiple input multiple output (MU-MIMO) is realized.

It should be understood that the relevant description of the precoding technology is only for ease of understanding and is not intended to limit the scope of protection of the embodiments of the present application. In the specific implementation process, the sending device can also perform precoding in other ways. For example, when channel information (e.g., channel matrix) cannot be obtained, precoding is performed using a pre-set precoding matrix or weighted processing method. For the sake of brevity, it will not be repeated.

2. Channel state information (CSI).

In a wireless communication system, information used to describe the channel properties of a communication link reported by a receiving device to a transmitting device. For example, a CSI report may include: PMI, rank indication (RI), channel quality indicator (CQI), channel state information reference signal (CSI-RS), resource indicator (CSI-RS resource indicator, CRI), and layer indicator (LI), etc. It should be understood that the specific contents of the CSI listed above are only exemplary and do not constitute any limitation to this application. CSI may include one or more of the items listed above, and may also include other information used to characterize CSI in addition to the above items, and this application does not limit this.

3. PMI.

PMI can be used to indicate a precoding matrix, which can be, for example, a precoding matrix determined by the terminal device based on a channel matrix of each frequency domain unit, which can be determined by the terminal device through channel estimation or based on channel reciprocity.

For example, the precoding matrix can be obtained by performing singular value decomposition (SVD) on the channel matrix or the covariance matrix of the channel matrix, or by performing eigenvalue decomposition (EVD) on the covariance matrix of the channel matrix. It should be understood that the determination methods of the precoding matrix listed above are only examples and should not constitute any limitation to this application. For the sake of brevity, they are not listed here one by one.

The precoding matrix determined by the terminal device may be referred to as the precoding matrix to be fed back, or the precoding matrix to be reported. The terminal device may indicate the precoding matrix to be fed back through the PMI, so that the network device can recover the precoding matrix based on the PMI. The precoding matrix recovered by the network device based on the PMI may be the same as or similar to the precoding matrix to be fed back.

The network device can determine the precoding matrix corresponding to one or more frequency domain units based on the feedback of the terminal device. The precoding matrix thus determined by the network device can be directly used for downlink data transmission; or it can be processed to obtain the precoding matrix finally used for downlink data transmission. The beamforming method is, for example: zero forcing (ZF), regularized zero-forcing (RZF), minimum mean-squared error (MMSE), or maximum signal-to-leakage-and-noise ratio (SLR) SLNR) etc. This application does not limit this.

In downlink channel measurement, the higher the degree of similarity between the precoding matrix recovered by the network device based on the PMI and the precoding matrix determined by the terminal device, the more the precoding matrix determined by the network device for data transmission can be adapted to the downlink channel, thereby improving the transmission quality of the signal.

It should be understood that PMI is only an exemplary name and should not constitute any limitation to the present application. The present application does not exclude the possibility of defining signaling with other names in future protocols to represent the same or similar functions.

4. Spatial layer (layer).

A spatial layer may also be referred to as a transport layer, layer, transport stream, spatial stream, or stream. In an embodiment of the present application, the number of spatial layers may be determined by the rank fed back by the terminal device based on channel measurement. For example, the number of spatial layers may be equal to the rank fed back by the terminal device based on channel measurement.

In MIMO, a spatial layer can be regarded as an independently transmittable data stream. In order to improve the utilization of spectrum resources and the data transmission capacity of the communication system, network equipment can transmit data to terminal equipment through multiple spatial layers.

The number of spatial layers is the rank of the channel matrix. The terminal device can determine the number of spatial layers R according to the channel matrix obtained by channel estimation, and further determine the precoding matrix. For example, the precoding matrix can be determined by performing SVD on the channel matrix or the covariance matrix of the channel matrix. In the SVD process, different spatial layers can be distinguished according to the size of the eigenvalue. For example, the precoding vector determined by the eigenvector corresponding to the largest eigenvalue can be corresponded to the first spatial layer, and the precoding vector determined by the eigenvector corresponding to the smallest eigenvalue can be corresponded to the Rth spatial layer. That is, the eigenvalues corresponding to the first spatial layer to the Rth spatial layer decrease successively. Simply put, the strength of the R spatial layers decreases from the first spatial layer to the Rth spatial layer.

It should be understood that distinguishing different spatial layers based on characteristic values is only a possible implementation method and does not constitute any limitation to the present application. For example, the protocol may also predefine other criteria for distinguishing spatial layers, which is not limited in the present application.

5. Precoding vector.

A precoding matrix may include one or more vectors, such as column vectors. A precoding matrix may be used to determine one or more precoding vectors.

When the number of spatial layers is 1 and the number of polarization directions of the transmitting antenna is also 1, the precoding matrix is the precoding vector. When the number of spatial layers is multiple and the number of polarization directions of the transmitting antenna is 1, the precoding vector may refer to the component of the precoding matrix on one spatial layer. When the number of spatial layers is 1 and the number of polarization directions of the transmitting antenna is multiple, the precoding vector may refer to the component of the precoding matrix in one polarization direction. When the number of spatial layers is multiple and the number of polarization directions of the transmitting antenna is also multiple, the precoding vector may refer to the component of the precoding matrix in one spatial layer and one polarization direction.

It should be understood that the precoding vector may also be determined by a vector in a precoding matrix, for example, obtained by mathematically transforming the vector in the precoding matrix. The present application does not limit the mathematical transformation relationship between the precoding matrix and the precoding vector.

6. Antenna port.

The antenna port can be referred to as a port for short. It can be understood as a transmitting antenna recognized by the receiving device, or a transmitting antenna that can be distinguished in space. An antenna port can be preconfigured for each virtual antenna, and each virtual antenna can be a weighted combination of multiple physical antennas. Each antenna port can correspond to a reference signal. Therefore, each antenna port can be called a reference signal port, for example, a CSI-RS port, an SRS port, etc. In an embodiment of the present application, the reference signal can be a non-precoded reference signal or a precoded reference signal, and the present application does not limit this. When the reference signal is a precoded reference signal, the reference signal port can be a transmitting antenna port, and the transmitting antenna port can refer to an independent transceiver unit (transceiver unit).

7. Airspace base.

The spatial basis can also be called a spatial domain vector, a spatial component vector, a beam vector, a spatial beam basis vector, or a spatial basis vector. Each element in the spatial vector can represent the weight of each antenna port. Based on the weight of each antenna port represented by each element in the spatial vector, the signals of each antenna port are linearly superimposed to form an area with a strong signal in a certain direction in space.

The length of the spatial domain vector may be the number of transmit antenna ports in one polarization direction, N _s , where N _s ≥ 1 and is an integer. The spatial domain vector may be, for example, a column vector or a row vector of length N _s . This application does not limit this.

Optionally, the spatial domain vector is a discrete Fourier transform (DFT) vector. The DFT vector may refer to a vector in a DFT matrix.

Optionally, the spatial domain vector is a conjugate transposed vector of the DFT vector. The DFT conjugate transposed vector may refer to a column vector in a conjugate transposed matrix of the DFT matrix.

Optionally, the spatial domain vector is an oversampled DFT vector. The oversampled DFT vector may refer to a vector in an oversampled DFT matrix.

In the embodiment of the present application, the spatial domain vector is one of the vectors used to construct the precoding matrix.

8. Spatial basis set.

The spatial basis set may also be referred to as a candidate spatial vector set, a candidate spatial component vector set, a spatial component vector set, a candidate spatial basis vector set, a spatial basis vector set, a candidate beam vector set, a beam vector set, a candidate spatial beam basis vector set, a spatial beam basis vector set, etc. A plurality of spatial vectors (or candidate spatial vectors) of different lengths may be included to correspond to different numbers of antenna ports. In an embodiment of the present application, the spatial vector used to construct the precoding vector may be determined from the candidate spatial vector set. In other words, the candidate spatial vector set includes a plurality of candidate spatial vectors that can be used to construct the precoding vector.

In one possible design, the candidate spatial vector set may include _Ns candidate spatial vectors, and the _Ns candidate spatial vectors may be mutually orthogonal. Each candidate spatial vector in the candidate spatial vector set may be a vector in a 2D-DFT matrix, where 2D may represent two different directions, for example, a horizontal direction and a vertical direction. If the number of antenna ports in the horizontal direction and the vertical direction are _N1 and _N2 , respectively, then _Ns = _N1 × _N2 . _Ns , _N1 , and _N2 are all positive integers.

_Ns candidate spatial vectors can be recorded as The N _s candidate spatial vectors can construct the matrix B _s , The matrix _Bs can be used for the spatial compression described below to select one or more candidate spatial vectors for constructing a precoding matrix. If each candidate spatial vector in the set of candidate spatial vectors is taken from a 2D-DFT matrix, then Where D _N represents an N×N orthogonal DFT matrix, and the element in the mth row and nth column of the orthogonal DFT matrix is

In another possible design, the candidate spatial domain vector set can be expanded to _Os × _Ns candidate spatial domain vectors by an oversampling factor _Os . In this case, the candidate spatial domain vector set can include _Os subsets, and each subset can include _Ns candidate spatial domain vectors. The _Ns candidate spatial domain vectors in each subset can be mutually orthogonal. Each candidate spatial domain vector in the candidate spatial domain vector set can be taken from an oversampled 2D-DFT matrix. For example, the oversampling factor _Os is a positive integer, _Os = _O1 × _O2 , _O1 can be an oversampling factor in the horizontal direction, and _O2 can be an oversampling factor in the vertical direction. _O1 ≥1, _O2 ≥1, _O1 and _O2 are not 1 at the same time, and both are positive integers.

The N _s candidate spatial domain vectors in the o _s th subset (0≤o _s ≤O _s -1, and o _s is an integer) of the candidate spatial domain vector set can be respectively recorded as Then based on the N _s candidate spatial vectors in the o _sth subset, the matrix can be constructed A matrix consisting of one or more subsets of the O _s subsets may be used to perform the spatial domain compression described below to select one or more spatial domain vectors for constructing a precoding matrix.

It should be understood that the present application does not limit the specific form of the candidate spatial domain vector set and the specific form of the candidate spatial domain vector.

9. Frequency domain unit.

The frequency domain unit is a unit of frequency domain resources, which can represent different frequency domain resource granularities. The frequency domain unit may include, for example, a subband, a resource block (RB), a subcarrier, a resource block group (RBG), or a precoding resource block group (PRG). In addition, the frequency domain length of a frequency domain unit may also be R times the CQI subband, where R is less than or equal to 1, and the value of R may be, for example, 1, or the value of R may be pre-configured to the terminal device by the network device through signaling. In addition, the frequency domain length of a frequency domain unit may also be RB.

In an embodiment of the present application, the precoding matrix corresponding to the frequency domain unit may refer to a precoding matrix determined by channel measurement and feedback based on a reference signal on the frequency domain unit. The precoding matrix corresponding to the frequency domain unit may be used to precode data subsequently transmitted through the frequency domain unit. Hereinafter, the precoding matrix corresponding to the frequency domain unit may also be referred to as the precoding matrix of the frequency domain unit.

10. Frequency domain basis.

The frequency domain basis can also be called a frequency domain vector, a frequency domain component vector, or a frequency domain basis vector, etc., which can be used to represent the changing pattern of the channel in the frequency domain. Each frequency domain vector can represent a changing pattern. When a signal is transmitted through a wireless channel, it can reach the receiving antenna from the transmitting antenna through multiple paths. Multipath delay causes frequency selective fading, which is the change of the frequency domain channel. Therefore, different frequency domain vectors can be used to represent the changing pattern of the channel in the frequency domain caused by the delay on different transmission paths.

The length of the frequency domain vector can be denoted as _Nf , where _Nf is a positive integer. The frequency domain vector can be, for example, a column vector or a row vector of length _Nf . The length of the frequency domain vector can be determined by the number of frequency domain units to be reported preconfigured in the reporting bandwidth, or by the length of the reporting bandwidth, or by a protocol predefined value. This application does not limit the length of the frequency domain vector. Among them, the reporting bandwidth can, for example, refer to the CSI reporting bandwidth (csi-ReportingBand) carried in the CSI reporting preconfiguration in the high-level signaling.

The frequency domain vectors corresponding to all spatial domain vectors corresponding to each spatial layer may be referred to as the frequency domain vectors corresponding to the spatial layer. The frequency domain vectors corresponding to each spatial layer may be the same or different.

11. Frequency domain basis set.

The frequency domain basis set may also be referred to as a candidate frequency domain vector set, a candidate frequency domain component vector set, a frequency domain component vector set, a frequency domain basis vector set, or a frequency domain vector set, etc., and may include candidate frequency domain vectors of multiple different lengths. In an embodiment of the present application, the frequency domain vector used to construct the precoding vector may be determined from the candidate frequency domain vector set. In other words, the candidate frequency domain vector set includes multiple candidate frequency domain vectors that can be used to construct the precoding vector.

In one possible design, the candidate frequency domain vector set may include N _f candidate frequency domain vectors. The N _f candidate frequency domain vectors may be mutually orthogonal. Each candidate frequency domain vector in the candidate frequency domain vector set may be a vector in a DFT matrix or an inverse discrete Fourier transform (IDFT) matrix, wherein the IDFT matrix is a conjugate transposed matrix of the DFT matrix.

The N _f candidate frequency domain vectors can be expressed as The N _f candidate frequency domain vectors can construct the matrix B _f , This matrix may be used to perform frequency domain compression as described below to select one or more frequency domain vectors used to construct a precoding matrix.

In another possible design, the candidate frequency domain vector set can be expanded to _Of × _Nf candidate frequency domain basis vectors by an oversampling factor _Of . In this case, the candidate frequency domain vector set can include _Of subsets, each of which can include _Nf candidate frequency domain basis vectors. The _Nf candidate frequency domain basis vectors in each subset can be mutually orthogonal. Each candidate frequency domain vector in the candidate frequency domain vector set can be taken from an oversampled DFT matrix or a conjugate transposed matrix of an oversampled DFT matrix. Wherein, the oversampling factor _Of is a positive integer.

Therefore, each candidate frequency domain vector in the candidate frequency domain vector set can be taken from a DFT matrix or an oversampled DFT matrix, or from a conjugate transposed matrix of a DFT matrix or a conjugate transposed matrix of an oversampled DFT matrix. Each column vector in the candidate frequency domain vector set can be called a DFT vector or an oversampled DFT vector. In other words, the candidate frequency domain vector can be a DFT vector or an oversampled DFT vector.

12. Space-frequency vector pair.

A space-frequency vector pair can also be called a space-frequency component vector. A space-domain vector and a frequency-domain vector can be combined to obtain a space-frequency vector pair. In other words, a space-frequency vector pair can include a space-domain vector and a frequency-domain vector. A space-frequency component matrix can be obtained by the space-domain vector and the frequency-domain vector in a space-frequency vector pair. For example, a space-frequency component matrix can be obtained by multiplying a space-domain vector with the conjugate transpose of a frequency-domain vector. The space-frequency component matrix described here is relative to the space-frequency matrix described below. Since a space-frequency matrix can be obtained by weighted summation of multiple space-frequency component matrices, each item used for weighting can be called a component of a space-frequency matrix, i.e., the space-frequency component matrix mentioned here.

13. Space-frequency matrix.

In the embodiment of the present application, the space-frequency matrix can be understood as an intermediate quantity used to determine the precoding matrix or channel matrix corresponding to each frequency domain unit. For a terminal device, the space-frequency matrix can be determined by the precoding matrix or channel matrix corresponding to each frequency domain unit. For a network device, the space-frequency matrix can be obtained by the weighted sum of multiple space-frequency component matrices to restore the channel matrix or precoding matrix.

For example, the space-frequency matrix can be denoted as W, Among them, w ₀ to There are N _f column vectors corresponding to N _f frequency domain units, and each column vector may be a precoding matrix corresponding to each frequency domain unit. The N _f column vectors correspond to the precoding vectors of the N _f frequency domain units, respectively. That is, the space-frequency matrix can be regarded as a joint matrix composed of the precoding vectors corresponding to the N _f frequency domain units.

In a possible design, the space-frequency matrix may correspond to the spatial layer. The space-frequency matrix is said to correspond to the spatial layer because the terminal device can feedback the frequency domain vector and the space-frequency combining coefficient based on each spatial layer. The space-frequency matrix determined by the network device based on the feedback of the terminal device is the space-frequency matrix corresponding to the spatial layer. The space-frequency matrix corresponding to the spatial layer can be directly used to determine the precoding matrix corresponding to each frequency domain unit. The precoding matrix corresponding to a certain frequency domain unit can be constructed by, for example, the column vector corresponding to the same frequency domain unit in the space-frequency matrix corresponding to each spatial layer. For example, the nth (0≤n≤N ₃ -1, and n is an integer) column vector in the space-frequency matrix corresponding to each spatial layer is extracted and arranged from left to right in the order of the spatial layer to obtain a matrix of dimension N _s ×Z, where Z represents the number of spatial layers, and Z≥1 is an integer. The matrix is normalized, for example, multiplied by a power normalization coefficient, to obtain the precoding matrix of the nth frequency domain unit.

It should be understood that normalizing the matrix by multiplying the power normalization coefficient is only one possible implementation method and should not constitute any limitation to the present application. The present application does not limit the specific method of normalization.

It should be understood that the space-frequency matrix is only a form of expression for determining an intermediate quantity of a precoding matrix or a channel matrix, and should not constitute any limitation to the present application. For example, by connecting the column vectors in the space-frequency matrix in order from left to right, or arranging them according to other predefined rules, a vector with a length of _Ns × _Nf can also be obtained, which can be called a space-frequency vector.

It should also be understood that the dimensions of the space-frequency matrix and the space-frequency vector shown above are only examples and should not constitute any limitation to the present application. For example, the space-frequency matrix may also be a matrix with a dimension of _Nf × _Ns . Each row vector may correspond to a frequency domain unit, which is used to determine the corresponding The precoding vector of the frequency domain unit.

In addition, when the transmitting antenna is configured with multiple polarization directions, the dimension of the space-frequency matrix can be further expanded. For example, for a dual-polarization antenna, the dimension of the space-frequency matrix can be _2Ns × _Nf or _Nf × _2Ns . It should be understood that the present application does not limit the number of polarization directions of the transmitting antenna.

14. Combination coefficient.

The combination coefficient may also be referred to as a space-frequency combining coefficient, a space-frequency coefficient, a combining coefficient, or a weighted coefficient, etc. Each space-frequency combining coefficient may correspond to a space-domain vector and a frequency-domain vector, or in other words, each space-frequency combining coefficient may correspond to a space-frequency vector pair. Each space-frequency combining coefficient is a weighted coefficient (or, weight) of the space-frequency component matrix constructed by the space-frequency vector pair to which it corresponds. The space-frequency combining coefficient corresponds to a space-domain vector and a frequency-domain vector. Specifically, the element in the i-th row and j-th column of the space-frequency combining coefficient matrix is the space-frequency combining coefficient corresponding to the space-frequency vector pair formed by the i-th space-domain vector and the j-th frequency-domain vector. For dual-polarization directional antennas, the above i∈{1,2,...,2L}, and the length of each space-domain vector is 2N _s .

In one implementation, in order to control the reporting overhead, the terminal device may only report the space-frequency combining coefficient matrix For example, the network device may configure the maximum number of space-frequency combining coefficients K ₀ that can be reported by the terminal device corresponding to each spatial layer, where K ₀ ≤ 2LM. K ₀ is The total number of space-frequency combining coefficients 2LM included in may have a proportional relationship, for example, K ₀ =β·2LM, and the value of β may be In addition, the terminal device may report only K ₁ space-frequency combining coefficients with non-zero amplitudes, where K ₁ ≤K ₀ .

Each space-frequency combining coefficient may include an amplitude and a phase. For example, in the space-frequency combining coefficients ae ^jθ , a is the amplitude and θ is the phase.

In one implementation, for the K ₁ reported space-frequency combining coefficients, their amplitude values and phase values can be independently quantized. The quantization method for the amplitude includes the following steps:

1) For K ₁ space-frequency combining coefficients, the space-frequency combining coefficient with the largest amplitude value is used as a reference to normalize the K ₁ space-frequency combining coefficients. If the i-th space-frequency combining coefficient before normalization is c _i , then after normalization, c _i ′＝c _i /c _i ·, where c _i · is the space-frequency combining coefficient with the largest amplitude value. After normalization, the space-frequency combining coefficient with the largest quantized reference amplitude value is 1.

2) The terminal device reports the index of the space-frequency combining coefficient with the largest amplitude value. The indication information indicating the index of the space-frequency combining coefficient with the largest amplitude value may include: Bit.

3) For the polarization direction where the space-frequency combination coefficient with the largest amplitude value is located, the quantization reference amplitude value is 1. For another polarization direction, the amplitude of the space-frequency combination coefficient with the largest amplitude in this polarization direction can be used as the quantization reference amplitude value of this polarization direction. The quantization reference amplitude value is quantized and reported using 4 bits. The candidate quantization reference amplitude values include

4) For each polarization direction, the quantization reference amplitude value corresponding to the polarization direction is used as a reference, and the differential amplitude value of each space-frequency combining coefficient is quantized by 3 bits. The candidate differential amplitude values include The differential amplitude value represents the difference value relative to the quantization reference amplitude value corresponding to the polarization direction. If the quantization reference amplitude value corresponding to the polarization direction of a space-frequency combining coefficient is A, and the differential amplitude value of the space-frequency combining coefficient after quantization is B, then the amplitude value of the space-frequency combining coefficient after quantization is A*B.

5) The phase of each normalized space-frequency combining coefficient is quantized by 3 bits or 4 bits, where 3 bits can be used for 8-phase shift keying (PSK) scenarios and 4 bits can be used for 16PSK scenarios.

Among the multiple space-frequency vector pairs selected by the terminal device for constructing the precoding matrix, each space-frequency vector pair may correspond to a space-frequency combining coefficient. Among the multiple space-frequency combining coefficients corresponding to the multiple space-frequency vector pairs, the amplitude values of some space-frequency combining coefficients may be zero, or close to zero, and the corresponding quantization value may be zero. The space-frequency combining coefficients whose amplitude is quantized by the quantization value zero can be called the space-frequency combining coefficients with zero amplitude. Correspondingly, the amplitude values of some space-frequency combining coefficients are large, and the corresponding quantization values are not zero. The space-frequency combining coefficients whose amplitude is quantized by a non-zero quantization value can be called the space-frequency combining coefficients with non-zero amplitude. In other words, the multiple space-frequency combining coefficients corresponding to the multiple space-frequency vector pairs can be composed of one or more space-frequency combining coefficients with non-zero amplitude and one or more space-frequency combining coefficients with zero amplitude.

It should be understood that the space-frequency combining coefficient can be indicated by a quantized value, by an index of a quantized value, or by a non-quantized value. The present application does not limit the indication method of the space-frequency combining coefficient, as long as the receiving end can obtain the space-frequency combining coefficient. Hereinafter, for the convenience of explanation, the information used to indicate the space-frequency combining coefficient is referred to as the quantization information of the space-frequency combining coefficient. The quantization information may be, for example, a quantization value, an index or any other information that may be used to indicate the space-frequency combining coefficient.

15. Dual domain compression.

Dual-domain compression may include compression in two dimensions: spatial domain compression and frequency domain compression. Spatial domain compression may specifically refer to selecting one or more spatial domain vectors from a set of spatial domain vectors as vectors for constructing a precoding matrix. Frequency domain compression may refer to selecting one or more frequency domain vectors from a set of frequency domain vectors as vectors for constructing a precoding matrix. As previously mentioned, a matrix constructed by a spatial domain vector and a frequency domain vector may be referred to as a space-frequency component matrix. The selected one or more spatial domain vectors and one or more frequency domain vectors may construct one or more space-frequency component matrices. The weighted sum of the one or more space-frequency component matrices may be used to construct a space-frequency matrix corresponding to a spatial layer. In other words, the space-frequency matrix may be approximated as the weighted sum of the space-frequency component matrices constructed by the above-selected one or more spatial domain vectors and one or more frequency domain vectors. Based on the space-frequency matrix corresponding to a spatial layer, the precoding vector corresponding to each frequency domain unit on the spatial layer may be determined.

For example, the selected one or more spatial domain vectors may constitute a matrix W ₁ , where each column vector in W ₁ corresponds to a selected spatial domain vector. The selected one or more frequency domain vectors may constitute a matrix W ₃ , where each column vector in W ₃ corresponds to a selected frequency domain vector. The space-frequency matrix W may be represented as a result of linearly combining the selected one or more spatial domain vectors and the selected one or more frequency domain vectors. Taking the space-frequency matrix corresponding to the spatial layer as an example, the space-frequency matrix corresponding to a spatial layer may be represented as

When the rank R is greater than 1, the spatial domain vectors used by each spatial layer may not be exactly the same, that is, each spatial layer uses an independent spatial domain vector; the spatial domain vectors used by each spatial layer may also be the same, that is, multiple spatial layers share L spatial domain vectors.

When the rank R is greater than 1, the frequency domain vectors used by each spatial layer may not be exactly the same, that is, each spatial layer uses an independent frequency domain vector; the frequency domain vectors used by each spatial layer may also be the same, that is, multiple spatial layers share M frequency domain vectors. Assume that each spatial layer uses its own independent frequency domain vector. For example, the i-th (0≤i≤R-1, i is an integer) spatial layer among the R spatial layers corresponds to ^Mi frequency domain vectors, that is, the frequency domain vectors corresponding to the i-th spatial layer reported by the terminal device are ^Mi. Where ^Mi ≥1, and ^Mi is an integer.

In this case, the precoding vector corresponding to each frequency domain unit on the i-th spatial layer may be constructed based on the above L spatial domain vectors and M ⁱ frequency domain vectors.

If dual-polarization transmitting antennas are used, L spatial vectors can be selected for each polarization direction. Then the dimension of _W1 can be _2Ns × 2L. In a possible implementation, the same L spatial vectors can be used for the two polarization directions. in, For example, it can be L spatial vectors selected from the spatial vector set mentioned above. In this case, _W1 can be expressed as:

in, Represents the i-th spatial domain vector among the selected L spatial domain vectors, i=0, 1,…, L-1.

For the i-th spatial layer, the dimension of W ₃ ^H may be ^Mi ×N _f . Each column vector in W ₃ may be a frequency domain vector. At this time, each spatial domain vector in W ₁ and each frequency domain vector in W ₃ may constitute a space-frequency vector pair, and each space-frequency vector pair may correspond to a space-frequency combining coefficient. Then, there are 2L×M ⁱ space-frequency vector pairs constructed by 2L spatial domain vectors and Mi frequency domain vectors, and the 2L× ^{M i space} -frequency combining coefficients correspond one to one.

For the i-th spatial layer, It may be a coefficient matrix composed of the above 2L×M ⁱ space-frequency combining coefficients, and its dimension may be 2L×M ⁱ . The lth row in can correspond to the lth spatial vector in the first polarization direction among the 2L spatial vectors. The L+lth row in can correspond to the lth spatial domain vector in the second polarization direction among the 2L spatial domain vectors. The m-th (0≤m≤M ⁱ -1, and m is an integer) column in can correspond to the m-th frequency domain vector among the M ⁱ frequency domain vectors.

Therefore, in the dual-domain compressed feedback method, the frequency domain vector and the spatial domain vector corresponding to each of the R spatial layers are selected to construct the position of the space-frequency vector pair of the precoding matrix and the space-frequency combining coefficients of each space-frequency vector pair.

The position of the space-frequency vector pair used to construct the precoding matrix specifically refers to the position of the space-domain vector of the precoding matrix used to construct the space-domain vector reported by the terminal device and the position of the frequency-domain vector of the precoding matrix used to construct the space-domain vector reported by the terminal device. Since each space-frequency vector pair corresponds to a non-zero space-frequency combining coefficient (referred to as a non-zero coefficient), the position of the space-frequency vector pair used to construct the precoding matrix is also the position of the non-zero coefficient.

It should be understood that the relationships between the various spatial layers and the spatial domain vectors and frequency domain vectors listed above are only examples and should not constitute any limitation to the present application.

It should also be understood that the relationship between the space-frequency matrix W and W ₁ , W ₃ shown above is only an example and should not constitute any limitation to the present application. Based on the same concept, those skilled in the art can perform mathematical transformation on the above relationship to obtain other equations for characterizing the space-frequency matrix W and W ₁ , For example, the space- _frequency matrix W can also be expressed as In this case, each row vector in W ₃ may correspond to a selected frequency domain vector.

Since dual-domain compression compresses both the spatial domain and the frequency domain, the terminal device can feed back one or more selected spatial domain vectors and one or more frequency domain vectors to the network device when giving feedback, and no longer needs to feed back the spatial-frequency combining coefficients based on each frequency domain unit. Therefore, dual-domain compression can reduce feedback overhead. At the same time, since the frequency domain vector can represent the frequency variation law of the channel, the linear superposition of one or more frequency domain vectors is used to simulate the variation of the channel in the frequency domain, which can maintain a high feedback accuracy, so that the precoding matrix recovered by the network device based on the feedback of the terminal device can still be well adapted to the channel.

It should be understood that in order to facilitate the understanding of dual-domain compression, the above text introduces the terms space-frequency matrix, space-frequency vector, etc., but this should not constitute any limitation to this application. The specific process of the terminal device determining the PMI is the internal implementation behavior of the terminal device, and this application does not limit the specific process of the terminal device determining the PMI. The specific process of the network device determining the precoding matrix based on the PMI is the internal implementation behavior of the network device, and this application does not limit the specific process of the network device determining the precoding matrix based on the PMI.

As an optional example, the terminal device may report the following information to the network device through the PMI:

The index of the spatial domain vector contained in the _W1 matrix corresponding to each spatial layer;

The _W3 matrix corresponding to each spatial layer contains the indices of the frequency domain vectors.

The index of the spatial domain vector and the index of the frequency domain vector may be referred to as a codebook index. The network device determines the corresponding spatial domain vector and frequency domain vector from the codebook based on the codebook index to restore the channel matrix or the precoding matrix.

16. Far-field channel model and near-field channel model.

Fig. 3 is a schematic diagram of a far-field channel model provided by an embodiment of the present application. In the far-field channel model, the distances from each antenna element in the antenna array to the nearest scatterer are approximately the same, and the propagation of electromagnetic waves satisfies the plane wave law. Therefore, the far-field channel model needs to consider the multipath angle parameter, but does not need to consider the distance from the antenna element to the scatterer.

Fig. 4 is a schematic diagram of a near-field channel model provided in an embodiment of the present application. In the near-field channel model, the distances from each antenna element in the antenna array to the nearest scatterer vary greatly, and the propagation of electromagnetic waves satisfies the law of spherical waves. Therefore, in addition to considering the multipath angle parameter, the near-field channel model also needs to consider the distance from the antenna element to the scatterer.

With the development of large-scale antenna arrays, the area of antenna arrays of network equipment has further increased. When the carrier frequency remains unchanged, the Rayleigh distance will increase exponentially with the increase of the area of the antenna array.

The Rayleigh distance is defined as

Where r is the Rayleigh distance, D is the area of the antenna array, and λ is the wavelength of the electromagnetic wave.

As the Rayleigh distance increases, the terminal device is more likely to be in an area that conforms to the law of spherical waves. Due to the existence of the spherical wavefront, the signal phase at different locations is distorted, which increases the mismatch risk of the traditional codebook.

For example, traditional codebooks include frequency-domain-angle dual-domain compression codebooks, frequency-domain-angle reciprocity codebooks, and frequency-domain-angle dual-domain compression codebooks that are further compressed in time. These codebooks do not consider the distance dimension. The spatial position determined based on the traditional codebook does not match the actual position of the terminal device, resulting in a decrease in the accuracy of channel estimation.

The following describes a communication method provided by an embodiment of the present application. As shown in FIG5 , the method 500 includes:

S510, the terminal device 110 determines a first spatial basis, the first spatial basis belongs to a spatial basis set, the spatial basis set includes multiple spatial basis, each of the multiple spatial basis is determined by the angle and distance of a multipath between the antenna array of the network device 120 and the first object.

Some features of the first spatial basis and the spatial basis set can be found in the relevant description above and will not be repeated here.

In the antenna array of the network device 120, each antenna may be an antenna that supports switching between left-hand circular polarization or right-hand circular polarization, or an antenna that supports both left-hand circular polarization and right-hand circular polarization, or an antenna that supports linear polarization. The embodiments of the present application do not limit the specific type of the antenna array. For example, the antenna in the antenna array may be an end-fire circular polarization antenna, an end-ray polarization antenna, an edge-fire circular polarization antenna, or an edge-ray polarization antenna. The antennas in the antenna array may be the same or different.

The first object is the scatterer closest to the antenna array. If the multipath between the terminal device 110 and the network device 120 is a line-of-sight (LoS) path, the first object is the terminal device 110. If the multipath between the terminal device 110 and the network device 120 is a non-line-of-sight (non-LoS) path, the first object is the scatterer closest to the antenna array. Scatterers can refer to any object in the real world, such as buildings, terrain, and vegetation in the environment.

In the spatial basis set, different spatial basis correspond to different multipaths.

Before determining the first spatial domain basis, the terminal device 110 needs to determine a distance candidate value set, and then determine the spatial domain according to the distance candidate value set. Basis set. The following describes an example of a method for the terminal device 110 to determine a distance candidate value set.

Method 1 for determining a set of candidate distance values.

The terminal device 110 determines a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a quantization bit number Δd of the distance between the terminal device 110 and the antenna array; and determines a distance candidate value set according to r _max , r _min and Δd.

r _max and r _min may be determined based on the TA of the signal between the antenna array and the terminal device 110 . The terminal device 110 may calculate the TA itself or receive the TA from the network device 120 . The terminal device 110 may also directly receive r _max and r _min from the network device 120 .

For example, the terminal device 110 receives a first signal from the network device 120 and determines the TA of the first signal. The TA of the first signal has an error range, and r _max and r _min can be determined based on the upper limit and the lower limit of the error range.

For example, the network device 120 receives a first signal from the terminal device 110 and determines the TA of the first signal. The TA of the first signal has an error range. The network device 120 informs the terminal device 110 of the error range. The terminal device 110 can determine r _max and r _min based on the upper and lower limits of the error range.

For example, the network device 120 receives a first signal from the terminal device 110 and determines the TA of the first signal. The TA of the first signal has an error range. r _max and r _min can be determined based on the upper and lower limits of the error range. Then, the network device 120 informs the terminal device 110 of r _max and r _min .

Optionally, when the terminal device 110 determines the distance candidate value set according to r _max , r _min and Δd, the distance interval d _gap may be determined according to r _max , r _min and Δd; the distance candidate value set is determined according to r _max , r _min and d _gap , wherein the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , and the difference between any two distance candidate values in the distance candidate value set is an integer multiple of d _gap .

Optionally, The d _gap may be obtained from the network device 120 .

The difference between any two distance candidate values in the distance candidate value set is an integer multiple of d _gap , which means that the intervals between two adjacent distance candidate values in the distance candidate value set are equal.

For example, the distance candidate value set r may be {r _min , r _min +d _gap , r _min +2d _gap , . . . , r _max }, where r _min and r _min +d _gap are two adjacent distance candidate values, and r _min +d _gap and r _min +2d _gap are two adjacent distance candidate values.

Method 2 for determining a set of distance candidate values.

Determine a maximum value r _max and a minimum value r _min of the distance between the terminal device 110 and the antenna array, and a distance interval d _gap ; determine a distance candidate value set according to r _max , r _min and d _gap , wherein the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , the difference between two adjacent distance candidate values in the distance candidate value set is d _gap , and d _gap is associated with the distance between the terminal device 110 and the antenna array.

In the second method for determining the distance candidate value set, the method for the terminal device 110 to determine r _max and r _min is the same as the method for determining r _max and r _min in the first method for determining the distance candidate value set, and will not be repeated herein.

The terminal device 110 may obtain d _gap from the network device 120 .

For example, the network device 120 may send d _gaps corresponding to different distances to the terminal device 110. After receiving the d _gaps corresponding to different distances, the terminal device 110 determines the corresponding interval d _gap1 according to r _min , and then calculates the sum of r _min and d _gap1 to obtain r _min + d _gap1 ; then the terminal device 110 calculates the sum of r _min + d _gap1 and d _gap2 according to the interval d _gap2 corresponding to r _min + d _gap1 , and obtains r _min + d _gap1 + d _gap2 ; and so on, until the distance candidate value r _min + d _gap1 + d _gap2 +…+ d _gapn closest to r _max is calculated, and a distance candidate value set r is obtained, where r may be {r _min , r _min + d _gap1 , r _min + d _gap1 + d _gap2 ,…, r _min + d _gap1 + d _gap2 +…+ d _gapn , r _max }.

For another example, the network device 120 may send a function (or "variation relationship") of d _gap varying with distance to the terminal device 110. After receiving the function, the terminal device 110 determines the corresponding interval d _gap1 according to r _min and the function, and then calculates the sum of r _min and d _gap1 to obtain r _min + d _gap1 ; then the terminal device 110 determines the corresponding interval d _gap2 according to r _min + d _gap1 and the function, and then calculates the sum of r _min + d _gap1 and d _gap2 to obtain r _min + d _gap1 + d _gap2 ; and so on, until the calculated distance candidate value r _min + d _gap1 + d _gap2 + ... + d _gapn closest to r _max is obtained, and a distance candidate value set r is obtained, where r may be {r _min , r _min + d _gap1 , r _min + d _gap1 + d _gap2 , ..., r _min + d _gap1 + d _gap2 + ... + d _gapn , r _max }.

In the distance candidate value set r obtained based on the second method for determining the distance candidate value set, the intervals between two adjacent distance candidate values are different, that is, d _gap1 is different from d _gap2 .

After determining the distance candidate value set, the terminal device 110 may determine the angle candidate value set, and determine the spatial basis set according to the distance candidate value set and the angle candidate value set.

For example, the terminal device 110 may determine the angle candidate value set according to 3GPP TS 38.214 V16.4.0 (2020-12). When the antenna array is a planar array, the terminal device 110 may determine the spatial basis set according to formula (1) and formula (2).

In formula (1), Ω _i is the angle distance fusion parameter of the i-th vibrator in the antenna array, d is the multipath distance from the reference vibrator in the antenna array to the nearest scatterer (i.e., the value in the distance candidate value set), is the multipath angle (i.e., the value in the angle candidate value set), _ri is the position of the i-th element in the antenna array, is the position of the reference vibrator, where the i-th vibrator is any vibrator in the antenna array, the reference vibrator can be the vibrator with the shortest distance to the nearest scatterer among the vibrators in the antenna array, and i is a positive integer.

In formula (2), a _i is the spatial basis (also called the steering vector) of the i-th oscillator in the antenna array, e is a natural constant, j is the imaginary part, f is the carrier frequency, c is the speed of light, n is the number of columns of the i-th oscillator, m is the number of rows of the i-th oscillator, d _x is the spacing of the oscillators in the antenna array in the horizontal dimension, _dy is the spacing of the oscillators in the antenna array in the vertical dimension, Ω _x is the component of Ω _i in the horizontal dimension, and Ω _y is the component of Ω _i in the vertical dimension. _{d x} and d _y can be obtained from the network device 120, or can be equal to half a wavelength by default.

The terminal device 110 can obtain the number of vibrators _N1 in the horizontal dimension and the number of vibrators _N2 in the vertical dimension of the antenna array from the network device 120, calculate the _Ωi and _ai of each vibrator, the set consisting of the _Ωi of all vibrators is the angle basis set, and the set consisting of the _ai of all vibrators is the spatial basis set.

It should be understood that the above method for determining the spatial basis set is an example rather than a limitation. After the terminal device 110 determines the spatial basis set, it can determine the first spatial basis from the spatial basis set.

Optionally, the antenna array may be divided into a plurality of sub-arrays, and the terminal device 110 may determine the first spatial basis based on the sub-arrays.

For example, the antenna array may be divided into a first subarray and a second subarray, and the terminal device 110 determines first received data, second received data, r _max , r _min and δ, wherein the first received data is data from the first subarray, the second received data is data from the second subarray, r _min is the maximum value of the distance between the terminal device 110 and the antenna array, r _min is the minimum value of the distance between the terminal device 110 and the antenna array, and δ is the spacing between the first subarray and the second subarray; the terminal device 110 processes the first received data, the second received data, r _min , r _min and δ through dictionary learning to obtain the angle basis of the first subarray, the distance basis of the first subarray, the angle basis of the second subarray and the distance basis of the second subarray.

The dictionary learning algorithm is as follows.

The relationship between channels, dictionaries, and sent signals is as follows:
h(x,y)＝W(r)s；

Among them, h(x, y) represents the channel, W(r) represents the dictionary used for channel estimation _, that is, the angle basis set and the distance basis set, and s represents the transmitted signal.

The dimension of the dictionary can be defined as N*N, then,
W(r)=[b _N (θ ₁ ,r ₁ ), b _N (θ ₂ ,r ₂ ),…, b _N (θ _N ,r _N )];

Wherein, _bN represents the steering vector, _θ1 to _θN represent the candidate values of the multipath angles from the N subarrays to the nearest scatterer, and _r1 to _rN represent the candidate values of the multipath distances from the N subarrays to the nearest scatterer. As shown in FIG6, _θ1 represents the candidate value of the multipath angle from the first subarray to the nearest scatterer, _θ2 represents the candidate value of the multipath angle from the second subarray to the nearest scatterer, _r1 represents the candidate value of the multipath distance from the first subarray to the nearest scatterer, _r2 represents the candidate value of the multipath distance from the second subarray to the nearest scatterer, and δ represents the spacing between the first subarray and the second subarray.

After the antenna array is divided into the first subarray and the second subarray, the transmitted signal s can also be divided into two parts. Accordingly, the two signals received by the terminal device 110 are _y1 and _y2 , where _y1 is the first received data and _y2 is the second received data.

For each iteration of each multipath, the following process occurs:

The terminal device 110 calculates initial dictionaries W ₁ (r) and W ₂ (r) using r _max and all angles;

Estimate θ ₁ based on W ₁ (r), where is the estimated value of θ ₁ ;

according to Determine d ₁ and d ₂ , determine θ _min based on d ₁ , and determine θ _max based on d ₂ ; select some elements from W ₂ (r) based on θ _min and θ _max The element is used as a sub-dictionary W _2,sub (r), where

Estimate θ ₂ based on W _2,sub (r), where is the estimated value of θ ₂ ;

According to the geometric relationship shown in Figure 6, r ₁ and r ₂ are calculated, where

is the estimated value of r ₁ , is the estimated value of r ₂ ;

according to Update the columns of W ₁ (r) according to Update the columns of W ₂ (r).

Repeat the above steps until the iteration is terminated to obtain updated W ₁ (r) and updated W ₂ (r), and calculate multipath parameters such as delay, angle, and distance based on the updated W ₁ (r) and updated W ₂ (r).

Through dictionary learning, the multipath delay, multipath angle, multipath distance, and combination coefficient estimated by the first subarray, as well as the multipath delay, multipath angle, multipath distance, and combination coefficient estimated by the second subarray can be obtained. Based on the multipath angle and multipath distance, the spatial domain basis (including the distance basis and the angle basis) and the frequency domain basis can be calculated.

It should be noted that each sub-array includes at least one vibrator, and the number of vibrators included in each sub-array may be the same or different.

After the terminal device 110 determines the angle basis and the distance basis of the first subarray, and the angle basis and the distance basis of the second subarray, it can report them in the following ways:

Reporting method 1: τ, r ₁ , θ ₁ and α ₁ .

Reporting method 2: τ, r ₂ , θ ₂ and α ₂ .

Reporting method three: τ, r ₁ , θ ₁ , α ₁ and α ₂ .

Reporting method four: τ, r ₂ , θ ₂ , α ₁ and α ₂ .

Reporting method five: τ, r ₁ , θ ₁ , r ₂ , θ ₂ , α ₁ and α ₂ .

τ is the index of the frequency domain basis shared by the first subarray and the second subarray, _r1 is the index of the distance basis of the first subarray, _r2 is the index of the distance basis of the second subarray, _θ1 is the index of the angle basis of the first subarray, _θ2 is the index of the angle basis of the second subarray, _α1 is the combination coefficient of the first subarray, and _α2 is the combination coefficient of the second subarray.

The network device 120 can derive the angle basis and distance basis of the second subarray based on the geometric relationship shown in FIG6 and the angle basis and distance basis of the first subarray, or the network device 120 can derive the angle basis and distance basis of the first subarray based on the geometric relationship shown in FIG6 and the angle basis and distance basis of the second subarray. Therefore, the terminal device 110 can reduce the feedback overhead through reporting mode 1 to reporting mode 4. In addition, if it is believed that the combination coefficients of the same multipath are the same, α ₁ is equal to α ₂ , and the terminal device 110 can further reduce the feedback overhead through reporting mode 1 and reporting mode 2; if it is believed that the combination coefficients of the same multipath are different, α ₁ is not equal to α ₂ , and the terminal device 110 can adopt reporting mode 3 to reporting mode 5.

In the example of determining a spatial basis based on dictionary learning, the first spatial basis includes: an angle basis of the first subarray, and a distance basis of the first subarray; and/or an angle basis of the second subarray, and a distance basis of the second subarray.

After the antenna array is divided into multiple sub-arrays, the terminal device 110 can estimate the basis of different sub-arrays respectively, and finally jointly feed back the PMIs of the multiple sub-arrays to the network device 120, and the network device 120 can reconstruct the channel according to the geometric relationship between the multiple sub-arrays and the PMIs of the multiple sub-arrays. Since the amount of received data that the terminal device 110 needs to process when estimating the basis of a sub-array is reduced, the number of loop nestings of distance and angle in the dictionary learning process is reduced, thereby reducing the complexity and power consumption of the channel estimation of the terminal device 110.

After the terminal device 110 determines the first spatial basis, it can perform the following steps.

S520: Determine a combination coefficient according to the first spatial basis.

The terminal device 110 may determine the combination coefficient based on steps 1 and 2 described below.

Step 1: The terminal device 110 performs space-frequency joint covariance matrix statistics on the downlink channel and performs inter-polarization averaging to obtain right Perform SVD or eigendecomposition to obtain the matrix of eigenvectors Pair Matrix Cut off and select the one with larger energy The corresponding eigenvalues The columns constitute the statistical feature matrix Contains most of the energy of the channel (P can be determined by the terminal device 110 itself, or the network device 120 specifies an optional range and the terminal device 110 selects P from the range).

Step 2: The terminal device 110 uses the DFT codebook to construct a statistical feature matrix of the statistical feature vector Make an approximation, that is, find W _f , W _s and W ₂ such that or Wherein, _Wf and _Ws are sub-matrices composed of some columns of the oversampled DFT matrix, _Wf represents the frequency domain basis, _Ws represents the spatial domain basis (such as the first spatial domain basis described above); _W2 represents the combination coefficient matrix, which is The projection on the spatial compression matrix W ₁ , therefore, the process of determining W ₂ is to find a matrix that can correct W ₁ to The process of the matrix.

Step 1 and step 2 are examples rather than limitations, and the present application does not limit the method for determining the combination coefficient according to the first spatial basis. After determining the combination coefficient, the terminal device 110 may perform the following steps.

S530, sending PMI, where the PMI includes an identifier and a combination coefficient of the first spatial basis.

Accordingly, network device 120 receives the PMI.

Each spatial basis in the spatial basis set has a corresponding identifier (also called an "index"). The terminal device 110 can report the index of one or more selected spatial basis to the network device 120 through the PMI. The one or more spatial basis includes the first spatial basis.

Optionally, the index of the first spatial basis may include an identifier of an angle basis corresponding to the first spatial basis, and an identifier of a distance basis corresponding to the first spatial basis. Optionally, the PMI also includes an oversampling rate of the angle basis corresponding to the first spatial basis and an oversampling rate of the distance basis corresponding to the first spatial basis.

The elements in _W2 are the combination coefficients corresponding to all spatial bases, and the terminal device 110 can select all or part of the combination coefficients to report to the network device 120. For example, the terminal device 110 can report the non-zero coefficients and the strongest coefficients of all the combination coefficients to the network device 120 through the PMI, wherein the non-zero coefficients can be indicated by a bitmap, and the number of bits of the bitmap is 2*L*D*M, where L is the number of angle bases corresponding to all spatial bases in the spatial base set, D is the number of distance bases corresponding to all spatial bases in the spatial base set, and M is the number of all frequency domain bases.

A bitmap with a bit number of 2*L*D*M can adapt to scenarios including angle basis, distance basis and frequency domain basis. The oversampling rate of the distance basis can be used to expand the number of distance basis, thereby expanding the number of spatial basis in the spatial basis set. A larger spatial basis set is conducive to the network device to recover a precoding matrix that is closer to the precoding matrix determined by the terminal device, thereby improving the accuracy of channel estimation.

Optionally, the PMI also includes other information, such as the number of non-zero coefficients, RI, CQI, the index of the frequency domain basis, and the oversampling rate of the frequency domain basis, etc. The embodiment of the present application does not limit the information included in the PMI.

After receiving the PMI, the network device 120 may perform the following steps.

S540: Determine the first spatial basis from the spatial basis set according to the identifier of the first spatial basis.

S550: Determine a precoding matrix according to the first spatial basis and the combination coefficients.

The network device 120 determines one or more spatial basis from a spatial basis set based on the spatial basis index in the PMI, the one or more spatial basis includes a first spatial basis, and the one or more spatial basis constitutes a spatial compression matrix W ₁ . The network device 120 determines one or more combination coefficients based on the PMI, and the one or more combination coefficients constitute a combination coefficient matrix W ₂ . The network device 120 determines one or more frequency domain basis from a frequency domain basis set based on the frequency domain basis index in the PMI, and the one or more frequency domain basis constitutes a frequency domain compression matrix W ₃ .

Subsequently, the network device 120 may determine the precoding matrix W according to W ₁ , W ₂ , W ₃ and the near-field codebook structure shown in formula (3).

In formula (3), Where P is the number of antenna ports, L is the number of spatial basis, D is the number of distance basis, M is the number of frequency domain basis, N ₃ is the number of frequency domain units, and the dimension of the precoding matrix W is P×N ₃ .

It should be noted that the network device 120 has determined the spatial basis set before executing S540. The method for the network device 120 to determine the spatial basis set can refer to the method for the terminal device 110 to determine the spatial basis set, which will not be repeated here.

As the Rayleigh distance increases, the terminal device 110 is more likely to be in an area that conforms to the law of spherical waves. Due to the existence of the spherical wavefront, the signal phase at different positions is distorted. Therefore, when performing precoding, it is necessary to consider the distance from the antenna vibrator to the scatterer, that is, the multipath distance. In method 500, each spatial basis in the spatial basis set considers the angle and distance of the multipath at the same time, and the codebook set based on the spatial basis set is more in line with the law of spherical waves. Therefore, the identifier and the combination system of the first spatial basis sent by the terminal device 110 The PMI of the number can match the spatial location determined by the network device 120 with the actual location of the terminal device, thereby improving the accuracy of channel estimation.

The above describes the process of method 500 .

Optionally, in method 500, the signaling interaction process of the terminal device 110 feeding back the PMI based on formula (1) and formula (2) is shown in FIG. 7 .

S710 , the network device 120 sends parameters required for feedback of the PMI to the terminal device 110 .

The parameters required for PMI feedback include, for example, r _max , r _min , Δd, N ₁ and N ₂ . The parameters required for PMI feedback may also include other parameters, such as the horizontal spacing of the elements in the antenna array and the vertical spacing of the elements in the antenna array, which are not limited here.

S720, the terminal device 110 determines a spatial domain basis, a frequency domain basis and a combination coefficient according to the parameters required for feedback of the PMI.

The method for determining the spatial domain basis and the combination coefficient according to r _max , r _min , Δd, N ₁ and N ₂ is as described above, and the method for determining the frequency domain basis can refer to the relevant method in the prior art, which will not be described again here.

S730 , the terminal device 110 sends the PMI to the network device 120 .

The PMI includes the index of the spatial domain basis, the index of the frequency domain basis and the combination coefficient. The PMI may also include the number of non-zero coefficients, RI, CQI, and the oversampling rate of the frequency domain basis, etc. The embodiment of the present application does not limit the information contained in the PMI.

S740: The network device 120 determines a precoding matrix according to the PMI.

The method for determining the precoding matrix according to the PMI is as described in S550 and will not be repeated here.

Optionally, in method 500, a signaling interaction process of the terminal device 110 feeding back PMI based on multiple sub-arrays is as shown in FIG8 .

S810 , the network device 120 sends parameters required for feedback of the PMI to the terminal device 110 .

The parameters required for feeding back the PMI include, for example, r _max , r _min , and the spacing of each subarray (eg, δ). The parameters required for feeding back the PMI may also include other parameters, for example, the number of transducers of each subarray, which is not limited here.

S820, the terminal device 110 determines a spatial domain basis, a frequency domain basis and a combination coefficient according to the parameters required for feedback of the PMI.

The terminal device 110 may determine the spatial domain basis, the frequency domain basis and the combination coefficient according to the dictionary learning algorithm described above and the parameters required for feeding back the PMI.

For example, the terminal device 110 processes the first received data, the second received data, r _min , r _min and δ through dictionary learning to obtain the angle basis of the first subarray, the distance basis of the first subarray, the angle basis of the second subarray and the distance basis of the second subarray.

S830 , the terminal device 110 sends the PMI to the network device 120 .

The PMI includes the index of the spatial basis of one or more subarrays, the index of the frequency basis and the combination coefficient. The PMI may also include the number of non-zero coefficients, RI, CQI, and the oversampling rate of the frequency basis, etc. The embodiment of the present application does not limit the information contained in the PMI.

S840: The network device 120 determines a precoding matrix according to the PMI.

The method for determining the precoding matrix according to the PMI is as described in S550 and will not be repeated here.

The above describes in detail the method for determining the precoding matrix in the scenario of the near-field channel model. Optionally, the terminal device 110 and the network device 120 may determine whether the near-field channel model or the far-field channel model is applicable to the current scenario before executing the method 500. The terminal device 110 may determine the channel model applicable to the current scenario by the following two methods.

Method 1 for determining a target channel model.

Determine a distance d _TA between the terminal device 110 and the antenna array; determine a target channel model according to d _TA , where the target channel model is a first channel model or a second channel model, wherein, in the first channel model, distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, distances from each vibrator in the antenna array to the first object are equal; determine a first spatial basis, including: when the target channel model is the first channel model, determine the first spatial basis.

The first channel model is a near-field channel model, and the second channel model is a far-field channel model. The terminal device 110 may determine the TA of the first signal, and determine d _TA according to the TA of the first signal.

TA is a parameter used to maintain uplink time synchronization. For the terminal device 110 to communicate with the network device 120, uplink time synchronization and downlink time synchronization are required. After the terminal device 110 is turned on, it will search for a cell and obtain downlink time synchronization through the primary synchronization signal and the secondary synchronization signal broadcast by the cell. Any uplink signal can be used as an input for the physical layer to perform uplink timing measurement. For example, the uplink signal used by the physical layer for uplink timing measurement can be: random access (RA) preamble, SRS, DMRS and physical uplink control channel (PUCCH).

When the terminal device 110 performs random access, the physical layer will obtain the uplink timing value based on the RA preamble code measurement, and report the measured TA to L2; the timing maintenance after the terminal device 110 successfully performs random access can be performed through SRS or PUCCH, and when there is uplink data transmission, DMRS can also be used to obtain the uplink timing measurement offset value.

TA can reflect the distance between the network device 120 and the terminal device 110. The method for calculating the distance d _TA according to TA is as follows: _dTA =TA*c/2, c is the speed of light.

The network device 120 may obtain the TA by measuring the first signal, and send the TA to the terminal device 110 through the first indication information. Optionally, when the multiple signals between the terminal device 110 and the network device 120 include a random access preamble, an SRS, and a DMRS, the first signal may be an SRS; or, when the multiple signals between the terminal device 110 and the network device 120 include a random access preamble and a DMRS, the first signal may be a DMRS.

The TA measured by SRS is more accurate than the TA measured by DMRS or random access preamble code, and the TA measured by DMRS is more accurate than the TA measured by random access preamble code. Therefore, by selecting the first signal based on the above priority, a more accurate TA can be obtained, thereby making the target channel model determined based on TA more accurate.

The network device 120 may also measure multiple signals to obtain multiple TAs, send the multiple TAs to the terminal device 110, and use one of the TAs in the first indication information. The terminal device 110 calculates d _TA according to the TA indicated by the first indication information.

The network device 120 may also calculate d _TA and send d _TA to the terminal device 110 .

Before determining the target channel model according to d _TA , the terminal device 110 may also determine d _FF , where d _FF is the distance from each vibrator in the antenna array to the first object in the second channel model, wherein d _FF = 2D ² /λ, D is the area of the antenna array, and λ is the wavelength of the electromagnetic wave. After calculating d _FF , the network device 120 sends d _FF to the terminal device 110. Subsequently, the terminal device 110 may determine the target channel model according to the absolute value of the difference between d _TA and d _FF , or the terminal device 110 may determine the target channel model according to the ratio of d _TA to d _FF .

For another example, if |d _TA -d _FF |<first distance threshold, the terminal device 110 determines that the target channel model is the first channel model; if |d _TA -d _FF |＞second distance threshold, the terminal device 110 determines that the target channel model is the second channel model; wherein the first distance threshold is less than or equal to the second distance threshold, and the first distance threshold and the second distance threshold can be obtained from the network device 120.

For example, if d _TA /d _FF < the third distance threshold, the terminal device 110 determines that the target channel model is the first channel model; if d _TA /d _FF > the fourth distance threshold, the terminal device 110 determines that the target channel model is the second channel model; wherein the third distance threshold is less than or equal to the fourth distance threshold, and the third distance threshold and the fourth distance threshold can be obtained from the network device 120.

After the terminal device 110 determines the target channel model, it can inform the network device 120 of the target channel model through the third indication information, so that the network device 120 can reconstruct a more accurate precoding matrix based on the target channel model.

Optionally, the network device 120 may determine the target channel model according to the absolute value of the difference between d _TA and d _FF or according to the ratio of d _TA to d _FF , and then the network device 120 informs the terminal device 110 of the target channel model through fourth indication information. The terminal device 110 does not need to determine the target channel model through local calculation, thereby reducing the power consumption of the terminal device 110 in determining the target channel model.

The above describes the method for the terminal device 110 and the network device 120 to determine the target channel model.

Optionally, the signaling interaction process of the method in which the terminal device 110 determines the target channel model according to _dTA is shown in FIG9 .

S910, the terminal device 110 sends a first signal to the network device 120.

The first signal may be at least one of the random access preamble, SRS and DMRS mentioned above. The first signal may also be other uplink signals capable of measuring TA, such as PUCCH.

S920, the network device 120 measures TA through the first signal.

S930 , the network device 120 sends a TA to the terminal device 110 .

If the network device 120 measures the TAs of multiple signals, the network device 120 may send the priorities of the TAs of the multiple signals to the terminal device 110 when sending the TAs. Optionally, the priority may also be a preset priority. Optionally, the network device 120 may not send the priority, but directly instruct the terminal device 110 to use one of the TAs of the multiple signals, for example, by indicating the TA of the first signal through the first indication information, wherein the first indication information may be a 2-bit field; the first indication information of 00 may indicate the TA of the random access preamble, the first indication information of 01 may indicate the TA of the SRS, the first indication information of 10 may indicate the TA of the DMRS, and the first indication information of 11 may indicate the TA of the PUCCH.

S940, the terminal device 110 determines d _TA according to the TA.

The terminal device 110 may determine a TA according to the priority or the instruction of the network device 120 , and calculate d _TA according to the TA.

S950 , the network device 120 sends d _FF and a distance threshold to the terminal device 110 .

The distance threshold can be:

a first distance threshold, and a second distance threshold; and/or

a third distance threshold, and, a fourth distance threshold.

If the first distance threshold is equal to the second distance threshold, the network device 120 may send only one of them; if the third distance _threshold is equal to the fourth distance threshold, the network device 120 may send only one of them. The embodiment of the present application does not limit the specific message that carries the d _FF and the distance threshold.

S950 may be executed at any time before S960, for example, before S930, after S930, or simultaneously with S930, that is, the network device 120 sends TA, d _FF , and distance threshold to the terminal device 110 through one message.

Optionally, the distance threshold may be preset, such as a value specified by a protocol, or a value configured by a manufacturer. In this case, the network device 120 no longer sends the distance threshold.

S960: The terminal device 110 determines a target channel model according to d _TA , d _FF and a distance threshold.

If the distance threshold includes a first distance threshold and a second distance threshold, the terminal device 110 may determine the target channel model according to the absolute value of the difference between d _TA and d _FF and the first distance threshold and the second distance threshold.

If the distance threshold includes a third distance threshold and a fourth distance threshold, the terminal device 110 may determine the target channel model according to the ratio of d _TA to d _FF , and the third distance threshold and the fourth distance threshold.

If the distance threshold includes a first distance threshold, a second distance threshold, a third distance threshold and a fourth distance threshold, the terminal device 110 can decide which distance thresholds to use to determine the target channel model.

S970 , the terminal device 110 indicates the target channel model to the network device 120 .

For example, the terminal device 110 can indicate the target channel model to the network device 120 through the third indication information, wherein the third indication information can be a 1-bit field; the third indication information being 0 can indicate that the target channel model is the first channel model, and the third indication information being 1 can indicate that the target channel model is the second channel model.

Optionally, the signaling interaction flow of the method in which the network device 120 determines the target channel model according to _dTA is shown in FIG10 .

S1010, the terminal device 110 sends a first signal to the network device 120.

The first signal may be at least one of the random access preamble, SRS and DMRS mentioned above. The first signal may also be other uplink signals capable of measuring TA, such as PUCCH.

S1020, the network device 120 measures TA through the first signal.

S1030: The network device 120 determines d _TA according to the TA.

If the first signal includes multiple signals, the network device 120 may determine which signal's TA to use to determine d _TA . For example, the network device 120 may determine the TA to use the SRS to determine d _TA according to the priorities of the random access preamble, SRS, and DMRS.

S1040: The network device 120 determines a target channel model according to d _TA , d _FF and a distance threshold.

If the distance threshold includes a first distance threshold and a second distance threshold, the network device 120 may determine the target channel model according to the absolute value of the difference between d _TA and d _FF and the first distance threshold and the second distance threshold.

If the distance threshold includes a third distance threshold and a fourth distance threshold, the network device 120 may determine the target channel model according to the ratio of d _TA to d _FF , and the third distance threshold and the fourth distance threshold.

If the distance threshold includes a first distance threshold, a second distance threshold, a third distance threshold, and a fourth distance threshold, the network device 120 may decide by itself which distance thresholds to use to determine the target channel model.

S1050 , the network device 120 indicates the target channel model to the terminal device 110 .

For example, the network device 120 can indicate the target channel model to the terminal device 110 through the fourth indication information, wherein the fourth indication information can be a 1-bit field; the fourth indication information being 0 can indicate that the target channel model is the first channel model, and the fourth indication information being 1 can indicate that the target channel model is the second channel model.

Method 2 for determining the target channel model.

Determine the trace tra _cur of the spatial correlation matrix of the antenna array; determine the target channel model according to tra _cur , the target channel model is a first channel model or a second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determine the first spatial basis, including: when the target channel model is the first channel model, determine the first spatial basis.

tra _cur is the trace of the spatial correlation matrix of the current antenna array. The terminal device 110 can calculate the average value of the trace of the spatial correlation matrix of multiple time units, and use the average value as tra _cur to reduce the error of tra _cur . The time unit is, for example, a transmission time interval (TTI) or a time slot. The embodiment of the present application does not limit the specific type of the time unit.

Before determining the target channel model according to tra _cur , the terminal device 110 may also determine tra _ref , where tra _ref is the trace of the spatial correlation matrix corresponding to the second channel model. The network device 120 may calculate tra _ref and inform the terminal device 110 of tra _ref through the second indication information.

Optionally, tra _ref is a preset value, or tra _ref is an average value of traces of spatial correlation matrices of multiple terminal devices to which the second channel model is applied. The embodiment of the present application does not limit the method for determining tra _ref .

After determining tra _cur and tra _ref , the terminal device 110 may determine the target channel model according to the absolute value of the difference between tra _cur and tra _ref , or Alternatively, the terminal device 110 may determine the target channel model according to the ratio of tra _cur to tra _ref .

For example, if |tra _cur -tra _ref |＞first trace threshold, the terminal device 110 determines that the target channel model is the first channel model; if |tra _cur -tra _ref |<second trace threshold, the terminal device 110 determines that the target channel model is the second channel model; wherein the first trace threshold is greater than or equal to the second trace threshold, and the first trace threshold and the second trace threshold can be obtained from the network device 120.

For another example, if tra _cur /tra _ref ＞the third trace threshold, the terminal device 110 determines that the target channel model is the first channel model; if tra _cur /tra _ref <the fourth trace threshold, the terminal device 110 determines that the target channel model is the second channel model; wherein the third trace threshold is greater than or equal to the fourth trace threshold, and the third trace threshold and the fourth trace threshold can be obtained from the network device 120.

After the terminal device 110 determines the target channel model, it can inform the network device 120 of the target channel model through the third indication information, so that the network device 120 can reconstruct a more accurate precoding matrix based on the target channel model.

Optionally, the network device 120 may determine the target channel model according to the absolute value of the difference between tra _cur and tra _ref or according to the ratio of tra _cur to tra _ref , and then the network device 120 informs the terminal device 110 of the target channel model through the fourth indication information. The terminal device 110 does not need to determine the target channel model through local calculation, thereby reducing the power consumption of the terminal device 110 in determining the target channel model.

Different bandwidth parts (BWP) can share the above-mentioned judgment of the target channel model and various indication information. In the carrier aggregation (CA) scenario, similar frequency bands can also share the above-mentioned judgment of the target channel model and various indication information.

For example, after the terminal device 110 determines the target channel model of BWP1, it can determine that the target channel model of BWP2 is the target channel model of BWP1; after the terminal device 110 informs the network device 120 of the target channel model of BWP1 through the third indication information, the network device 120 can determine that the target channel model of BWP2 is the target channel model of BWP1 according to the third indication information.

For another example, after the network device 120 determines the target channel model of frequency band 1, it can determine that the target channel model of frequency band 2 is the target channel model of frequency band 1; after the terminal device 110 informs the terminal device 110 of the target channel model of frequency band 1 through the fourth indication information, the terminal device 110 can determine that the target channel model of frequency band 2 is the target channel model of frequency band 1 according to the third indication information. Among them, frequency band 1 and frequency band 2 are frequency bands corresponding to two aggregated carriers, and the frequencies of frequency band 1 and frequency band 2 are similar.

Optionally, the signaling interaction process of the method in which the terminal device 110 determines the target channel model according to the tra _cur is shown in FIG. 11 .

S1110 , the network device 120 sends tra _ref and a trace threshold to the terminal device 110 .

The trace threshold can be:

a first trace threshold, and a second trace threshold; and/or

The third trace threshold, and, the fourth trace threshold.

If the first trace threshold is equal to the second trace threshold, the network device 120 may send only one of them; if the third trace threshold is equal to the fourth trace threshold, the network device 120 may send only one of them. The tra _ref and the trace threshold may be carried in one message or in multiple messages. The embodiment of the present application does not limit the specific message carrying the tra _ref and the trace threshold.

After calculating tra _ref , the network device 120 may inform the terminal device 110 of tra _ref through the second indication information.

S1120, the terminal device 110 determines tra _cur .

The terminal device 110 can calculate the average value of the trace of the spatial correlation matrix of multiple time units, and use the average value as the tra _cur to reduce the error of the tra _cur . The time unit is, for example, TTI or time slot. The embodiment of the present application does not limit the specific type of the time unit.

S1130: The terminal device 110 determines a target channel model according to tra _cur , tra _ref and a trace threshold.

If the trace threshold includes a first trace threshold and a second trace threshold, the terminal device 110 may determine the target channel model according to the absolute value of the difference between tra _cur and tra _cur , and the first trace threshold and the second trace threshold.

If the trace threshold includes a third trace threshold and a fourth trace threshold, the terminal device 110 may determine the target channel model according to the ratio of tra _cur to tra _cur and the third trace threshold and the fourth trace threshold.

If the trace thresholds include a first trace threshold, a second trace threshold, a third trace threshold, and a fourth trace threshold, the terminal device 110 may decide which trace thresholds to use to determine the target channel model.

S1140 , the terminal device 110 indicates the target channel model to the network device 120 .

For example, the terminal device 110 can indicate the target channel model to the network device 120 through the third indication information, wherein the third indication information can be a 1-bit field; the third indication information being 0 can indicate that the target channel model is the first channel model, and the third indication information being 1 can indicate that the target channel model is the second channel model.

The above describes in detail the method examples provided by the embodiments of the present application. It is understandable that in order to implement the above functions, the corresponding device includes a hardware structure and/or software module corresponding to each function. The units and algorithm steps of each example described in the disclosed embodiments can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

Figures 12 and 13 are schematic diagrams of the structures of two possible communication devices provided in the embodiments of the present application. These communication devices can be used to implement the functions of the terminal device 110 or the network device 120 in the above method embodiments, and therefore also have the beneficial effects of the above method embodiments. In the embodiments of the present application, these communication devices can be the terminal device 110 shown in Figure 1, can be the network device 120 described in Figure 1, and can also be a model (such as a chip) applied to the terminal device 110 or the network device 120.

As shown in Fig. 12, the communication device 1200 includes a processing unit 1210 and a transceiver unit 1220. The transceiver unit 1220 performs a receiving step and/or a sending step under the control of the processing unit 1210, wherein the transceiver unit 1220 is a sending unit when performing the sending step, and is a receiving unit when performing the receiving step.

The communication device 1200 is used to implement the functions of the terminal device 110 or the network device 120 in the method embodiments described in Figures 5, 7, 8, 9, 10 or 11 above.

When the communication device 1200 is used to implement the function of the terminal device 110, the processing unit 1210 is used to: determine a first spatial basis, the first spatial basis belongs to a spatial basis set, the spatial basis set includes multiple spatial basis, each of the multiple spatial basis is determined by the angle and distance of a multipath between the antenna array of the network device and the first object; determine the combination coefficient according to the first spatial basis; the transceiver unit 1220 is used to: send PMI, the PMI includes the identifier of the first spatial basis and the combination coefficient.

Optionally, before determining the first spatial basis, the processing unit 1210 is further used to: determine a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a quantization bit number Δd of the distance between the terminal device and the antenna array; determine a distance candidate value set according to r _max , r _min and Δd; determine an angle candidate value set; and determine a spatial basis set according to the distance candidate value set and the angle candidate value set.

Optionally, the processing unit 1210 is specifically configured to: determine a distance gap d _gap according to r _max , r _min and Δd; determine a distance candidate value set according to r _max , r _min and d _gap , the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , and the difference between any two distance candidate values in the distance candidate value set is an integer multiple of d _gap .

Optionally, before determining the first spatial basis, the processing unit 1210 is further used to: determine a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a distance interval d _gap ; determine a distance candidate value set according to r _max , r _min and d _gap , the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , the difference between two adjacent distance candidate values in the distance candidate value set is d _gap , and d _gap is associated with the distance between the terminal device and the antenna array; determine an angle candidate value set; and determine a spatial basis set according to the distance candidate value set and the angle candidate value set.

Optionally, the antenna array includes a first subarray and a second subarray, and the processing unit 1210 is specifically used to: determine first received data, second received data, r _max , r _min and δ, wherein the first received data is data from the first subarray, the second received data is data from the second subarray, r _min is the maximum value of the distance between the terminal device and the antenna array, r _min is the minimum value of the distance between the terminal device and the antenna array, and δ is the spacing between the first subarray and the second subarray; process the first received data, the second received data, r _min , r _min and δ through dictionary learning to obtain the angle basis of the first subarray, the distance basis of the first subarray, the angle basis of the second subarray and the distance basis of the second subarray; wherein the first spatial domain basis includes: the angle basis of the first subarray, and, the distance basis of the first subarray; and/or, the angle basis of the second subarray, and, the distance basis of the second subarray.

Optionally, before determining the first spatial basis, the processing unit 1210 is further used to: determine a distance d _TA between the terminal device and the antenna array; determine a target channel model based on d _TA , the target channel model being a first channel model or a second channel model, wherein, in the first channel model, distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, distances from each vibrator in the antenna array to the first object are equal; determining the first spatial basis includes: determining the first spatial basis when the target channel model is the first channel model.

Optionally, the processing unit 1210 is specifically used to: determine d _FF , where d _FF is the distance from each vibrator in the antenna array to the first object in the second channel model; if the absolute value of the difference between d _TA and d _FF is less than a first distance threshold, determine that the target channel model is the first channel model; if the absolute value of the difference between d _TA and d _FF is greater than a second distance threshold, determine that the target channel model is the second channel model; wherein the first distance threshold is less than or equal to the second distance threshold.

Optionally, the processing unit 1210 is specifically used to: determine d _FF , where d _FF is the distance from each vibrator in the antenna array to the first object in the second channel model; if the ratio of d _FF to d _FF is less than a third distance threshold, determine that the target channel model is the first channel model; if the ratio of d _FF to d _FF is greater than a fourth distance threshold, determine that the target channel model is the second channel model; wherein the third distance threshold is less than or equal to the fourth distance threshold.

Optionally, the processing unit 1210 is specifically configured to: determine a TA of the first signal; and determine d _TA according to the TA of the first signal.

Optionally, before determining the TA of the first signal, the transceiver unit 1220 is further used to: receive first indication information, where the first indication information is used to indicate the TA of the first signal; and the processing unit 1210 is specifically used to: determine the TA of the first signal according to the first indication information.

Optionally, before determining the first spatial basis, the processing unit 1210 is further used to: determine the trace tra _cur of the spatial correlation matrix of the antenna array; determine a target channel model according to tra _cur , the target channel model is a first channel model or a second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determining the first spatial basis includes: determining the first spatial basis when the target channel model is the first channel model.

Optionally, the processing unit 1210 is specifically used to: determine tra _ref , where tra _ref is the trace of the spatial correlation matrix corresponding to the second channel model; if the absolute value of the difference between tra _cur and tra _ref is greater than a first trace threshold, determine that the target channel model is the first channel model; if the absolute value of the difference between tra _cur and tra _ref is less than a second trace threshold, determine that the target channel model is the second channel model; wherein the first trace threshold is greater than or equal to the second trace threshold.

Optionally, the processing unit 1210 is specifically used to: determine tra _ref , where tra _ref is the trace of the spatial correlation matrix corresponding to the second channel model; if the ratio of tra _cur to tra _ref is greater than a third trace threshold, determine that the target channel model is the first channel model; if the ratio of tra _cur to tra _ref is less than a fourth trace threshold, determine that the target channel model is the second channel model; wherein the third trace threshold is greater than or equal to the fourth trace threshold.

Optionally, before determining tra _ref , the transceiver unit 1220 is further configured to: receive second indication information, where the second indication information is used to indicate tra _ref ; and the processing unit 1210 is specifically configured to: determine tra _ref according to the second indication information.

Optionally, the transceiver unit 1220 is further used to: send third indication information, where the third indication information is used to indicate a target channel model.

Optionally, before determining the first spatial basis, the transceiver unit 1220 is also used to: receive fourth indication information, the fourth indication information is used to indicate a target channel model, the target channel model is a first channel model or a second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; the processing unit 1210 is also used to: determine the target channel model according to the fourth indication information; the processing unit 1210 is specifically used to: determine the first spatial basis when the target channel model is the first channel model.

Those skilled in the art can clearly understand that when the communication device 1200 is used to implement the functions of the terminal device 110, the specific working process of the communication device 1200 and the technical effects produced by the execution steps can refer to the description in the corresponding method embodiment mentioned above. For the sake of brevity, they will not be repeated here.

The communication device 1200 may be a terminal device or a chip. The processing unit 1210 may be implemented by hardware or software. When implemented by hardware, the processing unit 1210 may be a logic circuit, an integrated circuit, etc.; when implemented by software, the processing unit 1210 may be a general-purpose processor, which is implemented by reading software codes stored in a storage unit. The storage unit may be integrated in the processing unit 1210 or located outside the processing unit 1210 and exists independently.

When the communication device 1200 is used to implement the function of the network device 120, the transceiver unit 1220 is used to: receive PMI, the PMI includes an identifier and a combination coefficient of a first spatial basis; the processing unit 1210 is used to: determine the first spatial basis from a spatial basis set according to the identifier of the first spatial basis, the spatial basis set includes multiple spatial basis, each of the multiple spatial basis is determined by the angle and distance of a multipath between the antenna array of the network device and the first object; determine the precoding matrix according to the first spatial basis and the combination coefficient.

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the processing unit 1210 is further used to: determine a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a number of quantization bits Δd of the distance between the terminal device and the antenna array; determine a distance candidate value set according to r _max , r _min and Δd; determine an angle candidate value set; and determine a spatial basis set according to the distance candidate value set and the angle candidate value set.

Optionally, the processing unit 1210 is specifically configured to: determine a distance gap d _gap according to r _max , r _min and Δd; determine a distance candidate value set according to r _max , r _min and d _gap , the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , and the difference between any two distance candidate values in the distance candidate value set is an integer multiple of d _gap .

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the processing unit 1210 is further used to: determine a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a distance interval d _gap ; determine a distance candidate value set according to r _max , r _min and d _gap , the maximum distance candidate value of the distance candidate value set is r _max , the minimum distance candidate value of the distance candidate value set is r _min , the difference between two adjacent distance candidate values in the distance candidate value set is d _gap , and d _gap is associated with the distance between the terminal device and the antenna array; determine an angle candidate value set; and determine a spatial basis set according to the distance candidate value set and the angle candidate value set.

Optionally, the first spatial basis includes: an angle basis of the first subarray, and a distance basis of the first subarray; the processing unit 1210 is specifically used to: determine the angle basis of the second subarray and the distance basis of the second subarray according to the angle basis of the first subarray, the distance basis of the first subarray, and the spacing between the first subarray and the second subarray; and determine the angle basis of the second subarray and the distance basis of the second subarray according to the angle basis of the first subarray, the distance basis of the first subarray The basis, the angle basis of the second subarray, the distance basis of the second subarray, and the combining coefficients determine a precoding matrix.

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the processing unit 1210 is further used to: determine the distance d _TA between the terminal device and the antenna array; determine the target channel model according to d _TA , the target channel model is the first channel model or the second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determine the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, including: when the target channel model is the first channel model, determine the first spatial basis from the spatial basis set according to the identifier of the first spatial basis.

Optionally, the processing unit 1210 is specifically used to: determine d _FF , where d _FF is the distance from each vibrator in the antenna array to the first object in the second channel model; if the absolute value of the difference between d _TA and d _FF is less than a first distance threshold, determine that the target channel model is the first channel model; if the absolute value of the difference between d _TA and d _FF is greater than a second distance threshold, determine that the target channel model is the second channel model; wherein the first distance threshold is less than or equal to the second distance threshold.

Optionally, the processing unit 1210 is specifically used to: determine d _FF , where d _FF is the distance from each vibrator in the antenna array to the first object in the second channel model; if the ratio of d _TA to d _FF is less than a third distance threshold, determine that the target channel model is the first channel model; if the ratio of d _TA to d _FF is greater than a fourth distance threshold, determine that the target channel model is the second channel model; wherein the third distance threshold is less than or equal to the fourth distance threshold.

Optionally, the processing unit 1210 is specifically configured to: determine a TA of the first signal; and determine d _TA according to the TA of the first signal.

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the processing unit 1210 is further used to: determine the trace tra _cur of the spatial correlation matrix of the antenna array; determine the target channel model according to tra _cur , the target channel model is the first channel model or the second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; determine the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, including: when the target channel model is the first channel model, determine the first spatial basis from the spatial basis set according to the identifier of the first spatial basis.

Optionally, the processing unit 1210 is specifically used to: determine tra _ref , where tra _ref is the trace of the spatial correlation matrix corresponding to the second channel model; if the absolute value of the difference between tra _cur and tra _ref is greater than a first trace threshold, determine that the target channel model is the first channel model; if the absolute value of the difference between tra _cur and tra _ref is less than a second trace threshold, determine that the target channel model is the second channel model; wherein the first trace threshold is greater than or equal to the second trace threshold.

Optionally, the processing unit 1210 is specifically used to: determine tra _ref , where tra _ref is the trace of the spatial correlation matrix corresponding to the second channel model; if the ratio of tra _cur to tra _ref is greater than a third trace threshold, determine that the target channel model is the first channel model; if the ratio of tra _cur to tra _ref is less than a fourth trace threshold, determine that the target channel model is the second channel model; wherein the third trace threshold is greater than or equal to the fourth trace threshold.

Optionally, the transceiver unit 1220 is further used to: send fourth indication information, where the fourth indication information is used to indicate a target channel model.

Optionally, before determining the first spatial basis from the spatial basis set according to the identifier of the first spatial basis, the transceiver unit 1220 is also used to: receive third indication information, the third indication information is used to indicate a target channel model, the target channel model is a first channel model or a second channel model, wherein, in the first channel model, the distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, the distances from each vibrator in the antenna array to the first object are equal; the processing unit 1210 is also used to: determine the target channel model according to the third indication information; the processing unit 1210 is specifically used to: when the target channel model is the first channel model, determine the first spatial basis from the spatial basis set according to the identifier of the first spatial basis.

Optionally, before receiving the third indication information, the transceiver unit 1220 is further used to: send first indication information, where the first indication information is used to indicate TA, and TA is used to determine a target channel model.

Optionally, before receiving the third indication information, the transceiver unit 1220 is further used to: send second indication information, the second indication information is used to indicate the trace tra _ref of the spatial correlation matrix corresponding to the second channel model, tra _ref is the average value of the traces of the spatial correlation matrices of multiple terminal devices applying the second channel model, and tra _ref is used to determine the target channel model.

Those skilled in the art can clearly understand that when the communication device 1200 is used to implement the functions of the network device 120, the specific working process of the communication device 1200 and the technical effects produced by the execution steps can refer to the description in the corresponding method embodiment mentioned above. For the sake of brevity, they will not be repeated here.

The communication device 1200 may be a network device or a chip. The processing unit 1210 may be implemented by hardware or software. When implemented by hardware, the processing unit 1210 may be a logic circuit, an integrated circuit, etc.; when implemented by software, the processing unit 1210 may be a general-purpose processor, which is implemented by reading software codes stored in a storage unit. The storage unit may be integrated in the processing unit 1210 or located outside the processing unit 1210 and exists independently.

As shown in FIG13 , the communication device 1300 includes a processor 1310 and an interface circuit 1320. The processor 1310 and the interface circuit 1320 are coupled to each other. It is understood that the interface circuit 1320 may be a transceiver or an input/output interface. Optionally, the communication device 1300 may further include a memory 1330 for storing instructions executed by the processor 1310 or storing input data required by the processor 1310 to execute instructions or storing data generated after the processor 1310 executes instructions.

When the communication device 1300 is used to implement the method shown in FIG. 5 , the processor 1310 is used to implement the function of the processing unit 1210 , and the interface circuit 1320 is used to implement the function of the transceiver unit 1220 .

When the communication device 1300 is a terminal chip (i.e., a chip applied to a terminal device), the terminal chip implements the functions of the terminal device 110 in the above method embodiment. The terminal chip receives information from the base station, which can be understood as the information is first received by other modules in the terminal (such as a radio frequency module or an antenna), and then sent to the terminal chip by these modules. The terminal chip sends information to the base station, which can be understood as the information is first sent to other modules in the terminal (such as a radio frequency module or an antenna), and then sent to the base station by these modules.

When the communication device 1300 is a base station chip (i.e., a chip applied to a base station), the base station chip implements the functions of the network device 120 in the above method embodiment. The base station chip receives information from the terminal, which can be understood as the information is first received by other modules in the base station (such as a radio frequency module or an antenna), and then sent to the base station chip by these modules. The base station chip sends information to the terminal, which can be understood as the information is sent to other modules in the base station (such as a radio frequency module or an antenna), and then sent to the terminal by these modules.

In the present application, when entity A sends information to entity B, it can be that A sends it directly to B, or that A sends it to B indirectly through other entities. Similarly, when entity B receives information from entity A, it can be that entity B directly receives the information sent by entity A, or that entity B indirectly receives the information sent by entity A through other entities. Entities A and B here can be RAN nodes or terminals, or modules inside the RAN nodes or terminals. The sending and receiving of information can be information interaction between a RAN node and a terminal, for example, information interaction between a base station and a terminal; the sending and receiving of information can also be information interaction between two RAN nodes, for example, information interaction between a CU and a DU; the sending and receiving of information can also be information interaction between different modules inside a device, for example, information interaction between a terminal chip and other modules of the terminal, or information interaction between a base station chip and other modules in the base station.

FIG14 is a schematic diagram of the structure of a terminal device provided in an embodiment of the present application. For ease of explanation, FIG14 only shows the main components of the terminal device 1400. The terminal device 1400 can be applied to the system shown in FIG1 to implement the functions of the terminal device in the above method embodiment. As shown in the device, the terminal device 1400 includes a processor, a memory, a control circuit, an antenna, and an input-output device. The processor is mainly used to process the communication protocol and the communication data, and to control the entire terminal device, execute the software program, and process the data of the software program, for example, to support the terminal device to perform the actions described in the above method embodiment. The memory is mainly used to store software programs and data. The control circuit is mainly used for the conversion of digital signals and radio frequency signals and the processing of radio frequency signals. The control circuit and the antenna together can also be called a transceiver, which is mainly used to send and receive radio frequency signals in the form of electromagnetic waves. The input-output device is, for example, a touch screen, a display screen, a keyboard, etc., which is mainly used to receive data input by the user and output data to the user.

When the terminal device is turned on, the processor can read the software program in the memory, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be sent wirelessly, the processor processes the data to be sent and outputs a digital signal to the RF circuit. The RF circuit processes the digital signal and then sends the RF signal outward in the form of electromagnetic waves through the antenna. When data is sent to the terminal device, the RF circuit receives the RF signal through the antenna, converts the RF signal into a digital signal, and outputs the digital signal to the processor. The processor converts the digital signal into data and processes the data.

Those skilled in the art will appreciate that, for ease of explanation, FIG. 14 shows only one memory and one processor. In an actual terminal device, there may be multiple processors and multiple memories. The memory may also be referred to as a storage medium or a storage device, etc., which is not limited in this application.

As an optional implementation, the processor may include a baseband processor and/or a central processing unit. The baseband processor is mainly used to process the communication protocol and communication data, and the central processing unit is mainly used to control the entire terminal device, execute the software program, and process the data of the software program. The processor in Figure 14 may integrate the functions of the baseband processor and the central processing unit. Those skilled in the art may understand that the baseband processor and the central processing unit may also be independent processors, interconnected by technologies such as buses. Those skilled in the art may understand that the terminal device may include multiple baseband processors to adapt to different network formats, the terminal device may include multiple central processing units to enhance its processing capabilities, and the various components of the terminal device may be connected through various buses. The baseband processor may also be described as a baseband processing circuit or a baseband processing chip. The central processing unit may also be described as a central processing circuit or a central processing chip. The function of processing the communication protocol and communication data may be built into the processor, or may be stored in the memory in the form of a software program, and the processor executes the software program to implement the baseband processing function.

In the embodiment of the present application, the antenna and the control circuit having the transceiver function can be regarded as the transceiver unit 1401 of the terminal device 1400. For example, it is used to support the receiving function and sending function described in the embodiment of the method for implementing the terminal device. The processor with processing function is regarded as the processor 1402 of the terminal device 1400. The terminal device 1400 includes a transceiver unit 1401 and a processor 1402. The transceiver unit 1401 may also be referred to as a transceiver, a transceiver, a transceiver device, etc. Exemplarily, the device used to implement the receiving function in the transceiver unit 1401 may be regarded as a receiving unit, and the device used to implement the sending function in the transceiver unit 1401 may be regarded as a sending unit, that is, the transceiver unit 1401 includes a receiving unit and a sending unit, and the receiving unit may also be referred to as a receiver, an input port, a receiving circuit, etc., and the sending unit may be referred to as a transmitter, a transmitter, or a transmitting circuit, etc. Exemplarily, the transceiver unit 1401 may not include an antenna, but only include a circuit part, so that the antenna is external to the transceiver unit.

The processor 1402 can be used to execute the instructions stored in the memory to control the transceiver unit 1401 to receive signals and/or send signals, and complete the functions of the terminal device in the above method embodiment. As an implementation method, the function of the transceiver unit 1401 can be considered to be implemented by a transceiver circuit or a dedicated chip for transceiver. When executing the transceiver of various types of signals, the processor 1402 controls the transceiver unit 1401 to implement the reception. Therefore, the processor 1402 is the signal transceiver decider and initiates the data transceiver operation, and the transceiver unit 1401 is the executor of the signal transceiver.

Figure 15 is a schematic diagram of the structure of a network device provided in an embodiment of the present application. For ease of explanation, Figure 15 only shows the main components of the network device 1500. The network device 1500 can be applied to the system shown in Figure 1 to implement the functions of the network device in the above method embodiment. As shown in Figure 15, the network device 1500 may include one or more DU1510, and one or more CU1520. DU1510 may include at least one antenna 1511, at least one radio frequency unit 1512, at least one processor 1513 and at least one memory 1514. CU1520 can communicate with the core network, and CU1520 may include at least one processor 1522 and at least one memory 1521.

DU1510 is mainly used for receiving and transmitting RF signals and converting RF signals to baseband signals, and completing some baseband processing functions. CU1520 may include at least one processor 1522 and at least one memory 1521. CU1520 and DU1510 may communicate through interfaces, wherein the control plane (CP) interface may be Fs-C, such as F1-C, and the user plane (UP) interface may be Fs-U, such as F1-U.

CU1520 is the control center of the network device 1500, which can also be called a processing unit, and is mainly used to complete baseband processing functions, such as channel coding, multiplexing, modulation, spread spectrum, etc. For example, CU1520 can be used to control the network device 1500 to execute the operation process of the network device in the above method embodiment. DU1510 and CU1520 can be physically set together or physically separated, that is, a distributed base station.

The baseband processing functions on DU1510 and CU1520 can be divided according to the protocol layers of the wireless network. For example, the functions of the PDCP layer and above protocol layers are set in CU1520, and the functions of the protocol layers below PDCP are set in DU1510.

In an optional embodiment, DU1510 may be composed of one or more boards, and the multiple boards may jointly support a wireless access network with a single access indication (such as a new radio (NR) network), or may respectively support wireless access networks with different access standards (such as a long-term evolution (LTE) network and a NR network). The memory 1514 is used to store necessary instructions and data, and the processor 1513 is used to control the network device 1500 to perform necessary actions. The memory 1514 and the processor 1513 may serve one or more boards. In other words, a memory and a processor may be separately set on each board. A shared memory and a processor may also be set for multiple boards. In addition, necessary circuits may also be set on each board.

In an optional embodiment, CU1520 may be composed of one or more single boards, and multiple single boards may jointly support a wireless access network with a single access indication (such as an NR network), or may respectively support wireless access networks with different access standards (such as an LTE network and an NR network). The memory 1521 is used to store necessary instructions and data, and the processor 1522 is used to control the network device 1500 to perform necessary actions, for example, to control the network device 1500 to execute the operation flow of the network device in the above method embodiment. The memory 1521 and the processor 1522 may serve one or more single boards. In other words, a memory and a processor may be separately set on each single board. A shared memory and a processor may also be set for multiple single boards. In addition, necessary circuits may also be set on each single board.

It should be understood that the network device 1500 shown in FIG15 can implement various processes related to the network device in the method embodiment. The operations and/or functions of each module in the network device 1500 are respectively to implement the corresponding processes in the above method embodiment. For details, please refer to the description in the above method embodiment, which will not be repeated here.

It should be understood that the network device 1500 shown in FIG. 15 is only a possible architecture of the network device and does not constitute any limitation to the present application. The method provided in the present application may be applicable to network devices of other architectures. For example, a network device including a CU, a DU, and an AAU, or a network device including a BBU and an RRU. The present application does not limit the specific architecture of the network device.

It is understandable that the processor in the embodiments of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

The method steps in the embodiments of the present application can be implemented in hardware or in software instructions that can be executed by a processor. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, register, hard disk, mobile hard disk, CD-ROM or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. The storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a base station or a terminal. The processor and the storage medium can also be present in a base station or a terminal as discrete components.

In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instruction is loaded and executed on a computer, the process or function described in the embodiment of the present application is executed in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device or other programmable device. The computer program or instruction may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer program or instruction may be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired or wireless means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server, data center, etc. that integrates one or more available media. The available medium may be a magnetic medium, for example, a floppy disk, a hard disk, a tape; it may also be an optical medium, for example, a digital video disc; it may also be a semiconductor medium, for example, a solid-state hard disk. The computer-readable storage medium may be a volatile or nonvolatile storage medium, or may include both volatile and nonvolatile types of storage media.

In the various embodiments of the present application, unless otherwise specified or provided for in any logical conflict, the terms and/or descriptions between the different embodiments are consistent and may be referenced to each other, and the technical features in the different embodiments may be combined to form new embodiments according to their inherent logical relationships.

In the present application, "at least one" means one or more, and "more than one" means two or more. "And/or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and/or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of the present application, the character "/" generally indicates that the previous and next associated objects are in an "or" relationship; in the formula of the present application, the character "/" indicates that the previous and next associated objects are in a "division" relationship. "Including at least one of A, B and C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B and C.

It is understood that the various numbers involved in the embodiments of the present application are only for the convenience of description and are not used to limit the scope of the embodiments of the present application. The size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic.

It should also be understood that in the present application, "when", "if" and "if" all mean that the UE or base station will take corresponding actions under certain objective circumstances. It is not a time limit, and it does not require the UE or base station to make judgments when implementing it, nor does it mean that there are other limitations.

Claims (26)

A communication method, characterized by comprising: Determine a first spatial basis, where the first spatial basis belongs to a spatial basis set, where the spatial basis set includes multiple spatial basis, and each of the multiple spatial basis is determined by an angle and a distance of a multipath between an antenna array of a network device and a first object; Determine a combination coefficient according to the first spatial domain basis; A precoding matrix indication PMI is sent, where the PMI includes an identifier of the first spatial basis and the combination coefficient. The method according to claim 1, characterized in that before determining the first spatial basis, the method further comprises: Determine a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a number of quantization bits Δd of the distance between the terminal device and the antenna array; Determine a distance candidate value set according to the r _max , the r _min and the Δd; Determine a set of candidate angle values; The spatial basis set is determined according to the distance candidate value set and the angle candidate value set. The method according to claim 2, characterized in that the determining of a distance candidate value set according to the r _max , the r _min and the Δd comprises: Determine a distance gap d _gap according to the r _max , the r _min and the Δd; The distance candidate value set is determined according to the r _max , the r _min and the d _gap , wherein the maximum distance candidate value of the distance candidate value set is the r _max , the minimum distance candidate value of the distance candidate value set is the r _min , and the difference between any two distance candidate values in the distance candidate value set is an integer multiple of the d _gap . The method according to claim 3, characterized in that The method according to claim 2, characterized in that before determining the first spatial basis, the method further comprises: Determine a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a distance interval d _gap ; determining a distance candidate value set according to the r _max , the r _min and the d _gap , wherein a maximum distance candidate value of the distance candidate value set is the r _max , a minimum distance candidate value of the distance candidate value set is the r _min , a difference between two adjacent distance candidate values in the distance candidate value set is d _gap , and the d _gap is associated with a distance between the terminal device and the antenna array; Determine a set of candidate angle values; The spatial basis set is determined according to the distance candidate value set and the angle candidate value set. The method according to any one of claims 2 to 5, characterized in that the r _max and the r _min are determined based on a timing advance TA of a signal between the antenna array and the terminal device. The method according to any one of claims 1 to 6, characterized in that The identifier of the first airspace basis includes: an identifier of an angle basis corresponding to the first spatial domain basis, and an identifier of a distance basis corresponding to the first spatial domain basis; The PMI also includes: A bitmap of non-zero coefficients, wherein the number of bits of the bitmap is 2*L*D*M, wherein L is the number of angle bases corresponding to the multiple spatial bases, D is the number of distance bases corresponding to the multiple spatial bases, and M is the number of frequency domain bases; An oversampling rate of a distance basis corresponding to the first spatial domain basis. The method according to any one of claims 1 to 7, characterized in that before determining the first spatial basis, the method further comprises: Determine a distance d _TA between a terminal device and the antenna array; determining a target channel model according to the _dTA , where the target channel model is a first channel model or a second channel model, wherein in the first channel model, distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, distances from each vibrator in the antenna array to the first object are equal; The determining of the first spatial domain basis comprises: When the target channel model is the first channel model, the first spatial basis is determined. The method according to claim 8, characterized in that the determining the target channel model according to the _dTA comprises: Determine d _FF , where d _FF is the distance from each vibrator in the antenna array in the second channel model to the first object; If the absolute value of the difference between the d _TA and the d _FF is less than a first distance threshold, determining that the target channel model is the first channel model; If the absolute value of the difference between the d _TA and the d _FF is greater than a second distance threshold, determining that the target channel model is the second channel model; The first distance threshold is less than or equal to the second distance threshold. The method according to claim 8, characterized in that the determining the target channel model according to the _dTA comprises: Determine d _FF , where d _FF is the distance from each vibrator in the antenna array in the second channel model to the first object; If the ratio of the d _TA to the d _FF is less than a third distance threshold, determining that the target channel model is the first channel model; If the ratio of the d _TA to the d _FF is greater than a fourth distance threshold, determining that the target channel model is the second channel model; The third distance threshold is less than or equal to the fourth distance threshold. The method according to any one of claims 8 to 10, characterized in that the method further comprises: Send third indication information, where the third indication information is used to indicate the target channel model. The method according to any one of claims 1 to 7, characterized in that before determining the first spatial basis, the method further comprises: receiving fourth indication information, where the fourth indication information is used to indicate a target channel model, where the target channel model is a first channel model or a second channel model, wherein in the first channel model, distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, distances from each vibrator in the antenna array to the first object are equal; Determine the target channel model according to fourth indication information; The determining of the first spatial domain basis comprises: When the target channel model is the first channel model, the first spatial basis is determined. A communication method, characterized by comprising: Receiving a precoding matrix indication PMI, wherein the PMI includes an identifier and a combination coefficient of a first spatial basis; Determine the first spatial basis from a spatial basis set according to the identifier of the first spatial basis, where the spatial basis set includes multiple spatial basis, and each of the multiple spatial basis is determined by an angle and a distance of a multipath between an antenna array of a network device and a first object; A precoding matrix is determined according to the first spatial basis and the combining coefficients. The method according to claim 13, characterized in that before determining the first spatial basis from the set of spatial basis according to the identifier of the first spatial basis, the method further comprises: Determine a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a number of quantization bits Δd of the distance between the terminal device and the antenna array; Determine a distance candidate value set according to the r _max , the r _min and the Δd; Determine a set of candidate angle values; The spatial basis set is determined according to the distance candidate value set and the angle candidate value set. The method according to claim 14, characterized in that the determining of a distance candidate value set according to the r _max , the r _min and the Δd comprises: Determine a distance gap d _gap according to the r _max , the r _min and the Δd; The distance candidate value set is determined according to the r _max , the r _min and the d _gap , wherein the maximum distance candidate value of the distance candidate value set is the r _max , the minimum distance candidate value of the distance candidate value set is the r _min , and the difference between any two distance candidate values in the distance candidate value set is an integer multiple of the d _gap . The method according to claim 15, characterized in that The method according to claim 14, characterized in that before determining the first spatial basis from the set of spatial basis according to the identifier of the first spatial basis, the method further comprises: Determine a maximum value r _max and a minimum value r _min of the distance between the terminal device and the antenna array, and a distance interval d _gap ; determining a distance candidate value set according to the r _max , the r _min and the d _gap , wherein a maximum distance candidate value of the distance candidate value set is the r _max , a minimum distance candidate value of the distance candidate value set is the r _min , a difference between two adjacent distance candidate values in the distance candidate value set is d _gap , and the d _gap is associated with a distance between the terminal device and the antenna array; Determine a set of candidate angle values; The spatial basis set is determined according to the distance candidate value set and the angle candidate value set. The method according to any one of claims 14 to 17, characterized in that the r _max and the r _min are determined based on a timing advance TA of a signal between the antenna array and the terminal device. The method according to any one of claims 13 to 18, characterized in that The identifier of the first airspace basis includes: an identifier of an angle basis corresponding to the first spatial domain basis, and an identifier of a distance basis corresponding to the first spatial domain basis; The PMI also includes: A bitmap of non-zero coefficients, wherein the number of bits of the bitmap is 2*L*D*M, wherein L is the number of angle bases corresponding to the multiple spatial bases, D is the number of distance bases corresponding to the multiple spatial bases, and M is the number of frequency domain bases; An oversampling rate of a distance basis corresponding to the first spatial domain basis. The method according to any one of claims 13 to 19, characterized in that before determining the first spatial basis from a set of spatial basis according to the identifier of the first spatial basis, the method further comprises: Determine a distance d _TA between a terminal device and the antenna array; Determining a target channel model according to the _dTA , the target channel model is a first channel model or a second channel model, wherein in the first channel model, distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, distances from each vibrator in the antenna array to the first object are equal; The determining the first spatial basis from a set of spatial basis according to the identifier of the first spatial basis includes: When the target channel model is the first channel model, the first spatial basis is determined from the spatial basis set according to an identifier of the first spatial basis. The method according to claim 20, characterized in that the determining the target channel model according to the d _TA comprises: Determine d _FF , where d _FF is the distance from each vibrator in the antenna array in the second channel model to the first object; If the absolute value of the difference between the d _TA and the d _FF is less than a first distance threshold, determining that the target channel model is the first channel model; If the absolute value of the difference between the d _TA and the d _FF is greater than a second distance threshold, determining that the target channel model is the second channel model; The first distance threshold is less than or equal to the second distance threshold. The method according to claim 20, characterized in that the determining the target channel model according to the d _TA comprises: Determine d _FF , where d _FF is the distance from each vibrator in the antenna array in the second channel model to the first object; If the ratio of the d _TA to the d _FF is less than a third distance threshold, determining that the target channel model is the first channel model; If the ratio of the d _TA to the d _FF is greater than a fourth distance threshold, determining that the target channel model is the second channel model; The third distance threshold is less than or equal to the fourth distance threshold. The method according to any one of claims 20 to 22, characterized in that the method further comprises: Send fourth indication information, where the fourth indication information is used to indicate the target channel model. The method according to any one of claims 13 to 19, characterized in that before determining the first spatial basis from a set of spatial basis according to the identifier of the first spatial basis, the method further comprises: receiving third indication information, where the third indication information is used to indicate a target channel model, where the target channel model is a first channel model or a second channel model, wherein in the first channel model, distances from each vibrator of the antenna array to the first object are not equal, and in the second channel model, distances from each vibrator in the antenna array to the first object are equal; Determine the target channel model according to the third indication information; The determining the first spatial basis from a set of spatial basis according to the identifier of the first spatial basis includes: When the target channel model is the first channel model, the first spatial basis is determined from the spatial basis set according to an identifier of the first spatial basis. A communication device, characterized in that it includes: a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices and transmit them to the processor or send signals from the processor to other communication devices, and the processor is used to implement the method as described in any one of claims 1 to 12 through a logic circuit or by executing code instructions, or the processor is used to implement the method as described in any one of claims 13 to 24 through a logic circuit or by executing code instructions. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program or instruction, and when the computer program or instruction is executed by a communication device, the method according to any one of claims 1 to 12 is implemented, or The method according to any one of claims 13 to 24.