CN106612133A - Method and device for MIMO (multiple-input-multiple-output) communication - Google Patents

Abstract

Embodiments of the present disclosure provide methods for multiple-input multiple-output (MIMO) communications. The method includes receiving information for long-term precoding from a device indicating a first beam group for a first dimension and a second beam group for a second dimension, the first beam group and the second beam group forming a 2-dimensional beam network In the grid, the beams in the beam grid or the beams in the subset of the beam grid are mapped to the beam set according to the mapping rule; the short-term precoding information is received from the device, which includes a one-dimensional index, which is used to indicate from the beam beams selected in the set; and transmitting MIMO-precoded data to the device according to the long-term precoding information and the short-term precoding information. The present disclosure also provides corresponding devices. According to the embodiments of the present disclosure, the feedback of precoding information can be simplified and more efficient.

Description

Method and apparatus for multiple input multiple output communication

technical field

Embodiments of the present disclosure relate to wireless communications, and more particularly multiple-input multiple-output (MIMO) communications.

Background technique

With the development of wireless communication, the demand for data rate continues to increase, and frequency resources become more scarce at the same time. In order to improve resource utilization efficiency, MIMO technology has been proposed. MIMO technology can utilize air space to transmit multiple data streams simultaneously on the same time-frequency resource, thereby effectively improving system throughput.

Two-dimensional (2D) MIMO transmission has been studied and adopted by some wireless communication systems, such as the Long Term Evolution (LTE) system specified by the 3rd Generation Partnership Project (3GPP). For 2D-MIMO, conventional antenna arrays are arranged horizontally to form beams on the horizontal plane. In order to exploit the potential gain from three-dimensional (3D) wireless channels, 3D MIMO has been discussed in the field of wireless communication, e.g. at 3GPP meetings (see e.g. 3GPP document TR 36.873), e.g. modeling of 3D MIMO channel propagation is discussed .

To obtain more potential gains from 3D wireless channels, planar (2D) active antenna arrays have been used to form 3D beams in the horizontal and vertical domains. This antenna arrangement leads to an increase in the number of antenna ports and a change in the antenna structure, which will affect the statistical characteristics of the wireless channel. Therefore, a new codebook needs to be designed for this 2D active antenna array. In particular, in order to support multi-stream MIMO transmission, it is necessary to design a codebook to support a transmission rank greater than 1.

Contents of the invention

A brief overview of the various embodiments is given below to provide a basic understanding of some aspects of the various embodiments. This summary is not intended to identify key elements or delineate the scope of various embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

A first aspect of the present disclosure provides a method for multiple-input multiple-output MIMO communication, the method includes: receiving long-term precoding information for the MIMO communication from a device, the long-term precoding information indicating the first A first beam group for a dimension, and a second beam group for a second dimension, the second dimension being different from the first dimension; wherein the first beam group and the second beam group constitute a 2-dimensional a beam grid, and beams in the beam grid or beams in a subset of the beam grid are mapped to a beam set according to a mapping rule; short-term precoding information for the MIMO communication is received from the device, The short-term precoding information includes a one-dimensional index, and the index is used to indicate a beam selected from the beam set; and according to the long-term precoding information and the short-term precoding information, send the MIMO precoded data.

In an embodiment, the mapping rules may comprise at least one of the following mapping rules: mapping beams in a beam grid or beams in said subset of said beam grid to said beams in order of first dimension priority set; map the beams in the beam grid or the beams in the subset of the beam grid to the beam set in the order of second dimension priority; map the beams in the beam grid in a random order mapping beams or beams in the subset of the beam grid to the set of beams; and mapping beams in the beam grid or beams in the subset of the beam grid to the set of beams in a predetermined order The set of beams.

In another embodiment, the method may further include: sending long-term precoding configuration information to the device, where the long-term precoding configuration information is used to perform beam selection from the first beam group to obtain the compressed first beam group, and beam selection from the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the sub-groups of the beam grid set.

In yet another embodiment, the method may further include: sending mapping configuration information to the device, where the mapping configuration information indicates a mapping rule.

In an embodiment, the short-term precoding information further includes phase adjustment information for indicating phase adjustment between different antenna polarizations, and the length of the phase adjustment information depends on the number of beams included in the beam set.

In one embodiment, when the beam set includes only a single beam, the length of the phase adjustment information is greater than that when the beam set includes multiple beams.

In one embodiment, when the beam set only includes a single beam, at least some bits of the one-dimensional index are used for the phase adjustment information.

In another embodiment, at least N beams in the first beam group are orthogonal to each other, and at least N beams in the second beam group are orthogonal to each other, where N is a positive integer, And N is the minimum number of beams in the beam group determined by the transmission rank that need to be kept orthogonal.

A second aspect of the present disclosure provides a method for MIMO communication, including: sending long-term precoding information for the MIMO communication to a device, the long-term precoding information indicating a first beam group for a first dimension , and the second beam group for the second dimension, the second dimension is different from the first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and the The beams in the beam grid or the beams in the subset of the beam grid are mapped to the beam set according to the mapping rule; the short-term precoding information used for the MIMO communication is sent to the device, and the short-term precoding information includes a an index of a dimension indicating a beam selected from the set of beams; and receiving MIMO-precoded data from the device.

In an embodiment, the mapping rules comprise at least one of the following mapping rules: mapping beams in a beam grid or beams in said subset of said beam grid to said set of beams in order of first dimension priority ; map the beams in the beam grid or the beams in the subset of the beam grid to the beam set according to the second dimension priority order; map the beams in the beam grid in a random order Or the beams in the subset of the beam grid are mapped to the beam set; and the beams in the beam grid or the beams in the subset of the beam grid are mapped to the set of beams in a predetermined order set of beams.

In another embodiment, the method may further include: receiving long-term precoding configuration information from the device, and the long-term precoding configuration information is used to perform beam selection from the first beam group to obtain the compressed first beam group, and beam selection from the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the sub-groups of the beam grid set.

In yet another embodiment, the method may further include: receiving mapping configuration information from the device, the mapping configuration information indicating a mapping rule.

In an embodiment, the short-term precoding information further includes phase adjustment information for indicating phase adjustment between different antenna polarizations, and the length of the phase adjustment information depends on the number of beams included in the beam set.

In one embodiment, when the beam set includes only a single beam, the length of the phase adjustment information is greater than that when the beam set includes multiple beams.

In one embodiment, when the beam set only includes a single beam, at least some bits of the one-dimensional index are used for the phase adjustment information.

In another embodiment, at least N beams of the first beam set in the method are orthogonal to each other, and at least N beams of the second beam set are orthogonal to each other, where N is orthogonal Integer, and N is the minimum number of beams in the beamset that need to remain orthogonal as determined by the transmission rank.

A third aspect of the present disclosure provides an apparatus for MIMO communication, including: a first receiver configured to receive long-term precoding information for the MIMO communication from a device, the long-term precoding information indicating A first beam group for a first dimension, and a second beam group for a second dimension, the second dimension being different from the first dimension; wherein the first beam group and the second beam group constitute 2 Dimensional beam grid, and the beams in the beam grid or the beams in the subset of the beam grid are mapped to the beam set according to the mapping rule; the second receiver is configured to receive from the device for the Short-term precoding information for MIMO communication, where the short-term precoding information includes a one-dimensional index, and the index is used to indicate a beam selected from the beam set; the first transmitter is configured to, according to the long-term precoding information and the short-term precoding information, and transmit MIMO-precoded data to the device.

In an embodiment, the apparatus may further include: a second transmitter configured to send long-term precoding configuration information to the device, and the long-term precoding configuration information is used to perform beam processing from the first beam group selecting a compressed first beam group, and performing beam selection from the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the The subset of the beam grid.

In another embodiment, the apparatus may further include: a third sender configured to send mapping configuration information to the device, where the mapping configuration information indicates a mapping rule.

A fourth aspect of the present disclosure provides an apparatus for MIMO communication, including: a first transmitter configured to send long-term precoding information for the MIMO communication to a device, the long-term precoding information indicating A first beam group for a first dimension, and a second beam group for a second dimension, the second dimension being different from the first dimension; wherein the first beam group and the second beam group constitute 2 dimensional beam grid, and the beams in the beam grid or the beams in the subset of the beam grid are mapped to the beam set according to the mapping rule; the second transmitter is configured to send to the device the The short-term precoding information of the MIMO communication, the short-term precoding information includes a one-dimensional index, the index is used to indicate the beam selected from the beam set; and the first receiver is configured to receive from the A device receives MIMO precoded data.

In an embodiment, the apparatus may further include: a second receiver configured to receive long-term precoding configuration information from the device, and the long-term precoding configuration information is used to perform beam processing from the first beam group selecting a compressed first beam group, and performing beam selection from the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the The subset of the beam grid.

In another embodiment, the apparatus may further include: a third receiver configured to receive mapping configuration information from the device, where the mapping configuration information indicates a mapping rule.

According to the method or device of the embodiments of the present disclosure, the feedback of short-term precoding information can be simplified; and in some embodiments, for high transmission rank, the performance of 3D MIMO can be improved by providing beam groups with orthogonal beams.

Although specific embodiments are shown by way of example in the drawings, it should be understood that the description herein of specific embodiments is not intended to limit the embodiments to the specific forms disclosed.

Description of drawings

The objects, advantages and other features of the present disclosure will become more apparent from the following disclosure and claims. Here, for purposes of example only, a non-limiting description of a preferred embodiment is given with reference to the accompanying drawings, in which:

Fig. 1a shows a schematic diagram of an exemplary wireless communication system in which the method of the embodiments of the present disclosure can be implemented;

Figure 1b shows a schematic diagram of an exemplary, 2D antenna array;

Figures 2a-2d show schematic diagrams of various configurations for long-term column selection, according to embodiments of the present disclosure;

FIG. 3 shows a flow chart of a method implemented at a MIMO sender according to an embodiment of the present disclosure;

FIG. 4 shows a flowchart of a method implemented at a receiver of MIMO according to an embodiment of the present disclosure;

FIG. 5 shows a structural diagram of an apparatus implemented at a MIMO sender according to an embodiment of the present disclosure; and

FIG. 6 shows a structural diagram of an apparatus implemented at a receiver of MIMO according to an embodiment of the present disclosure.

detailed description

In the following description, numerous details are set forth for purposes of explanation. However, one of ordinary skill in the art will recognize that embodiments of the disclosure may be practiced without the use of these specific details. Thus, the present disclosure is not intended to be limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and features described herein.

It should be understood that the terms "first", "second", etc. are only used to distinguish one element from another element. In fact, the first element can also be called the second element, and vice versa. In addition, it should also be understood that "comprising", "comprising" is only used to describe the existence of stated features, elements, functions or components, but does not exclude the existence of one or more other features, elements, functions or components.

For ease of explanation, embodiments of the present disclosure will be introduced herein in the context of 3GPP LTE/LTE-Advanced (LTE-A), and LTE/LTE-A (eg, TS36.211v.c70, TS36.212v.c60, TS36.212v.c60, TS36.213vc70), however, as those skilled in the art can understand, the embodiments of the present disclosure are by no means limited to the application environment of 3GPP LTE/LTE-A, on the contrary, but can be applied to any In wireless communication systems such as WLAN, device-to-device communication, or other communication systems developed in the future, such as 5G, etc. Likewise, the devices in the embodiments of the present disclosure may be user equipment (UE), or any terminal with wireless communication functions, including but not limited to mobile phones, computers, personal digital assistants, game consoles, wearable devices, and sensors Wait. The term UE is used interchangeably with mobile station, subscriber station, mobile terminal, user terminal or wireless device. Additionally, a base station in embodiments of the present disclosure may be, for example, a Node B (NodeB, or NB), a base transceiver station (BTS), a base station (BS), or a base station subsystem (BSS), a relay, a remote radio head terminal (RRH) and so on.

A schematic diagram of an exemplary wireless communication system 100 in which the methods of embodiments of the present disclosure can be implemented is given in FIG. 1a. The wireless communication system 100 may include one or more network nodes 101, for example, in this example, the network nodes 101 may be embodied as base stations, such as evolved Node Bs (eNodeBs, or eNBs). It should be understood that the network node 101 may also be embodied in other forms, such as a Node B (Node B, or NB), a basic transceiver station (BTS), a repeater, and the like. A network node 101 may provide radio connectivity for a plurality of wireless devices (eg, UEs 102-104) within its coverage area.

The network node 101 may be equipped with a 2D antenna array, such as _an active antenna array with N1 rows and _N2 columns and cross-polarization shown in FIG. 1b , so as to provide 3D MIMO communication with the UE. This MIMO communication can be applied in the downlink (forward link) direction from the base station to the UE, and can also be applied in the uplink (reverse link) direction from the UE to the base station. For downlink MIMO, considering that the transmitter uses a 2D active antenna array, and the transmitted signal is denoted as s, the signal Y received by the receiver before combining can be expressed as:

Y=HWs+n (1)

where H denotes a wireless MIMO channel with a 3D radio propagation model, n denotes noise and interference, W denotes a MIMO precoder, and W can be represented as follows:

W＝W ₁ W ₂ (2)

Among them, W ₁ is the long-term and wideband precoding matrix (or codebook) feedback, which indicates a group of beams according to the long-term and wideband channel state information (CSI), and W ₂ is the short-term and sub-band feedback, which is derived from One or more beams are further selected from the beam group defined by W ₁ , that is, one or more columns are selected from the beam group of the long-term codebook, and phases between different antenna polarizations are adjusted.

The UE may estimate channel state information based on, for example, downlink pilot signals, and feed back the long-term codebook W ₁ and the short-term codebook W ₂ to the MIMO base station respectively. _The structure of W1 can be expressed as follows:

in represents the Kronecker multiplication operation, with Denote the beam group of the first dimension (for example, the vertical dimension) and the beam group of the second dimension (for example, the horizontal dimension) respectively. i, j respectively represent the index of the wave array. with This may include, but is not limited to, beams selected from a discrete Fourier transform (DFT) matrix. with Each column of represents a beam, e.g. The m _1th column of and The _m2th column of can be expressed as:

Where N ₁ and N ₂ represent the number of antenna ports of the first dimension and the second dimension of the antenna array respectively, and o ₁ and o ₂ represent the oversampling factors of the first dimension and the second dimension of the antenna array respectively.

The channel conditions at the sender and receiver determine the supported transmission rank. For rank- ₁ transmission, X1 and X2 in the long-term codebook shown in ( ₃ ) can be expressed as follows:

where L ₁ ' and L ₂ ' respectively represent the size of the beam group of the first dimension and the second dimension of the antenna array, that is, the number of beams in the beam group; s ₁ and s ₂ represent the first dimension and the second dimension of the antenna array, respectively Intergroup spacing of beamgroups in 2D. In some embodiments, when the total number of antenna ports (2.N ₁ .N ₂ ) is 12 and 16, both L ₁ ' and L ₂ ' can be set as L ₁ '=4, L ₂ '= 2.

Since the short-term codebook is used to further select beams from the beamgroup indicated by the long-term codebook, a larger beam group size means that more load is required for short-term codebook feedback. To reduce the feedback overhead of short-term codebooks, long-term column selection can be applied to long-term beamgroups (see document R1-156217 of 3GPP RAN1 #82bis). For example, long-term column selection can adopt four configurations as shown in Figure 2a-2d, where it is assumed that L ₁ '=4 and L ₂ '=2, each block in the figure represents a beam, and the black block represents the selected beam . Assuming that L ₁ and L ₂ are used to represent the number of beams in the beam group after long-term column selection, then in configuration 1 shown in Figure 2a, (L ₁ ,L ₂ )=(1,1),(s ₁ ,s ₂ ) = (1,1), ie, only one beam is selected from the beam grid. In configuration 2 shown in Figure 2b, (L ₁ ,L ₂ )=(2,2), (s ₁ ,s ₂ )=(2,2); this configuration selects adjacent Square four beams. In configuration 3 shown in Fig. 2c, (L ₁ ,L ₂ )=(2,2), (s ₁ ,s ₂ )=(2,2); adjacent 2D beams. In configuration 4 shown in Fig. 2c, (L ₁ ,L ₂ )=(2,2), (s ₁ ,s ₂ )=(2,2); and only horizontal beams are selected.

For the transmission of rank 1, the short-term codebook W ₂ only selects beams in the horizontal dimension, and then according to formula (2), the short-term codebook is further applied to the long-term codebook after long-term column selection, and can be obtained, for example:

where Q represents the total number of antenna ports; the superscript ⁽¹⁾ of W represents rank 1; m ₁ and m ₂ are the indices of the beams selected from the long-term column selected beam group (or, in other words, the compressed beam group) ; φ _n represents the phase adjustment factor between different antenna polarizations, and φ _n =e ^jπn/2 , n∈{0,1,2,3}.

For transmission ranks greater than 1, more than one beam will be selected. In this case, the short-term codebook feedback will not be able to directly Existing designs are applied because existing designs only allow short-term codebooks for beam selection in the horizontal domain.

In order to realize simple and effective short-term codebook design while supporting a transmission rank greater than one, the present disclosure proposes an improved method and device.

A flowchart of a method 300 for MIMO communication in a wireless communication network (eg, network 100 ) according to an embodiment of the present disclosure is shown in FIG. 3 . The method 300 can be performed by a MIMO sender, for example, by eNB 101 in FIG. 1a in case of downlink MIMO, or by any one of UEs 102-104 in FIG. 1a in case of uplink MIMO. As an example only, in the following description, the method is performed by the eNB.

As shown in FIG. 3, the method 300 includes: at block S301, the eNB receives long-term precoding information for MIMO communication from a device (such as UE 102), the long-term precoding information indicates the first beam for the first dimension group, and a second beam group for a second dimension, the second dimension being different from the first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and the beam grid The beams in or the beams in the subset of the beam grid are mapped to the beam set according to the mapping rule; at block S302, the eNB receives short-term precoding information for MIMO communication from the device, and the short-term precoding information includes A one-dimensional index, the index is used to indicate the beam selected from the beam set; in block S303, the eNB sends the MIMO precoded information to the device according to the long-term precoding information and the short-term precoding information encoded data.

In one embodiment, the long-term precoding information received at block S301 may indicate a long-term codebook W1 as shown in equation (3), which consists of a beam group X ₁ in the first dimension (such as the vertical dimension) and a beam group X in the second dimension (for example, the horizontal dimension) beam group X ₂ is represented, and each column of X ₁ and X ₂ can be represented, for example, in the form shown in formula (4). However, as those skilled in the art can understand, the specific forms _of X1 and X2 are given only as examples, and embodiments of the present disclosure are by no means limited _thereto .

In an embodiment, the long-term precoding information may be embodied in the form of a long-term precoding index (PMI).

In one embodiment, the receiving of S301 may be performed through a physical uplink control channel, but embodiments of the present disclosure are not limited thereto. For example, in other embodiments, the receiving of S301 may also be performed through a physical uplink shared channel.

In the current 3GPP specifications for LTE (such as Rel-10), the short-term codebook is only used for column selection in the horizontal dimension. Therefore, it is not suitable for selecting beams from the above-mentioned long-term codebook for 3D MIMO communication. Especially for transmission ranks greater than 1.

In order to obtain effective short-term codebook feedback, for example, enabling the reuse of the existing short-term codebook design in LTEl-10 to support 3D MIMO (especially 3D MIMO with a transmission rank greater than 1), in the embodiments of the present disclosure, The concept of beam mapping is proposed. Map the beams in the 2-dimensional beam grid composed of the first beam group and the second beam group into a beam set, so that the short-term codebook feedback can only use the 1-dimensional index to select beams from it, as in LTE Rel- Selecting beams from the horizontal domain in 10 is the same.

In another embodiment, long-term column selection can also be performed on the long-term codebook first to obtain the compressed first beam group and the compressed second beam group, and then the compressed first beam group and the compressed second beam group The beams in the beam grid formed by the beam group are mapped to the beam set, and the beams are selected from them using the short-term codebook. For example, the compressed first beam set and the compressed second beam set may be obtained according to any of the example configurations in Figures 2a-2d.

Therefore, according to an embodiment of the present disclosure, the short-term precoding information received in S302 indicates the beam selected from the mapped beam set.

In an embodiment, according to the received long-term precoding information and short-term precoding information, the following final precoder can be determined:

Among them, in one embodiment, may be W ₁ indicated by the long-term precoding information; and in another embodiment, It can be W ₁ after long-term column selection, that is, a subset of W ₁ , for example, It can be expressed as:

W2 is designed to select beams in the long _- term precoder and apply phase adjustments for different antenna polarizations. According to an embodiment of the present disclosure, since the first beam group of the first dimension (or a subset thereof in the case of long-term column selection) and the second beam group of the second dimension (or a subset thereof in the case of long-term column selection) in the long-term precoder have been combined Beams in a 2-dimensional beam grid formed by a subset of its long-term column selection) are mapped to a beam set, so W ₂ can indicate the beam selected for each rank by a 1-dimensional index, e.g., The existing W ₂ design in LTE Rel-10 can be reused, i.e.

where k and k' indicate the one-dimensional index of the beam (or column) selected for the first rank and the second rank respectively, 0≤k, k'≤L ₁ L ₂ -1; e _k represents the kth A vector whose elements are 1 and the rest are 0, which indicates The k-th column of is selected by the short-term feedback; n indicates the index of the phase adjustment factor.

According to an embodiment of the present disclosure, the mapping rule for mapping the beams in the 2-dimensional beam grid or the beams in the subset of the beam grid to the beam set includes: in order of first dimension priority The beams in the beam grid or the subset of the beam grid are mapped to the set of beams. For example, the mapping rule can be expressed as:

According to this mapping rule, the selected beams (black blocks in the figure) in the beam grid obtained by long-term column selection in Figure 2b (configuration 2) are mapped to the beam set {b0,b1,b2,b3} can get:

b0=(0,0), b1=(1,0), b2=(0,1), b3=(1,1) (12)

Wherein (i, j) represents the index of the first dimension beam and the second dimension beam to which each element in the beam set is mapped.

In another embodiment, the mapping rule may further include mapping the beams in the beam grid or the beams in the subset of the beam grid to the beam set in order of second dimension priority. The mapping rule can be expressed, for example, as:

According to the mapping rule, the beam represented by the black block in Fig. 2b is mapped to the beam set {b0, b1, b2, b3} to obtain: b0=(0,0), b1=(0,1), b2=( 1,0), b3=(1,1).

In yet another embodiment, the mapping rule may further comprise mapping beams in a beam grid or beams in said subset of said beam grid to said set of beams in a predetermined/random order. The predetermined/random order may vary over time in one embodiment.

Similarly, the above mapping rules can also be applied to configuration 3 in FIG. 2c. In this case, the first-dimension-first mapping rule can be expressed as, for example:

where q=L ₁ '/L ₁ . According to the mapping rule, the beam represented by the black block in Fig. 2c is mapped to the beam set {b0, b1, b2, b3} to obtain: b0=(0,0), b1=(2,0), b2=( 1,1), b3=(3,1).

If you refer to the second-dimension-first mapping rule for configuration 3, for example:

Then b0=(0,0), b1=(1,1), b2=(2,0), b3=(3,1) can be obtained.

For configuration 4 shown in Figure 2d, for example, the following mapping rules can be applied:

This results in b0=(0,0), b1=(1,0), b2=(2,0), b3=(3,0).

In another embodiment, the subset of beam grids after the column selection is performed by configuration 3 or configuration 4 may also be mapped in a predetermined or random order.

As can be understood by those skilled in the art, the embodiments of the present disclosure are not limited to any specific mapping rules and sequences.

In an embodiment, the method may further include: at block S311, sending long-term precoding configuration information to the device, the long-term precoding configuration information is used to perform beam selection from the first beam group to obtain the compressed first a beam group, and performing beam selection from the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the beam grid. Subset.

In another embodiment, the subset of the beam grid used for mapping to the beam set may not depend on the long-term precoding configuration information sent in block S311, but may be obtained in other ways. For example selected from a grid of beams by predetermined selection rules.

In yet another embodiment, the method may further include: at block S312, sending mapping configuration information to the device, the mapping configuration information indicating that the beams in the beam grid or the beam grid A mapping rule for mapping beams in the subset to the set of beams. For example, the mapping configuration information may indicate to apply one of the mapping rules of first dimension priority, second dimension priority, and predetermined order/random order mapping, and/or, the mapping configuration information may also indicate the method used to determine the predetermined/random mapping The parameters of the mapping order.

In another embodiment, the mapping rule may be predetermined, so that signaling does not need to be transmitted between devices.

In some embodiments, the short-term precoding information received in block S302 further includes phase adjustment information, which is used to indicate phase adjustment between different antenna polarizations, as described in conjunction with formula (10).

The inventors of the present disclosure recognized that the size of the set of beams from which beams are selected may be different in different configurations. For example, when applying different long-term column selection configurations as in Fig. 2a-2d, the number of beams in the selected 2D beam grid is different, resulting in different sizes of beam sets mapped to. Therefore, the present disclosure proposes that, for different beam set sizes, indexes of different lengths may be used to indicate the selected beams, so as to save signaling overhead. For example, when performing long-term column selection for configuration 1 shown in Fig. 2a, only one beam is selected. In this case, no bits would be needed for the indication of the beam, but only the phase adjustment between different antenna polarizations. Therefore, in one embodiment, the short-term codebook may have the following form:

Therefore, in an embodiment, when a shorter index is not needed or needs to indicate beam selection, the bits used to indicate the phase adjustment information can be increased, that is, the length of the phase adjustment information can depend on the number of bits included in the beam set. number of beams. This enables better performance without increasing the overall feedback load.

In an embodiment, when the beam set includes only a single beam, the length of the phase adjustment information may be greater than that when the beam set includes multiple beams. In another embodiment, when the set of beams includes only a single beam (for example, when applying configuration 1 of Fig. 2a), at least a part of the bits of the one-dimensional index used to indicate the beam selection may be used for the phase Adjustment information. This example embodiment enables reuse of the beam indicating bits to indicate phase adjustments, resulting in more efficient utilization of the feedback load. For example, in the existing design of short-term codebook feedback, 1 bit can be used to indicate phase adjustment, that is, n in formula (10) can take the value of 0 or 1; and according to an embodiment, the original indicator k can be used bits to further indicate n, so that n can be extended to, for example, 2 bits, ie, n∈{0,1,2,3}, ie, the phase adjustment can be selected from 4 alternatives.

When applying configurations 2-4 shown in Figures 2b-2d for long-term column selection, the bit indicating k may not be reused, for example, W ₂ still has the form shown in (10). Therefore, the meaning of the bit used to indicate k can vary with different configurations, ensuring flexible utilization of the feedback load.

In one embodiment, it is assumed that the short-term codebook can be constructed by reusing the existing design of W ₂ in LTE Rel-10. The inventors of the present disclosure realized that the phase adjustment factor in W2 can only guarantee that the _two beams are orthogonal, that is, for transmission ranks greater than 2, when more than two beams need to be selected, the selected Some of the beams themselves should be mutually orthogonal to ensure good MIMO performance. For example, for the case of transmission rank 3 or 4, at least 2 of the selected beams need to be orthogonal; and for the case of rank 5 or 6, at least 3 of the selected beams should be mutually orthogonal Orthogonal; for rank 7 or 8, at least 4 of the selected beams should be mutually orthogonal. Since the beam selected by W ₂ depends on the long-term codebook design, in some embodiments of the present disclosure, a criterion for long-term codebook design is also proposed.

In one embodiment, at least N beams in the first beam group indicated by the long-term precoding information received in block S301 are orthogonal to each other, and at least N beams in the second beam group are orthogonal to each other. Orthogonal, where N is a positive integer, and N is the minimum number of beams in the beam group determined by the transmission rank that need to be kept orthogonal. For example, N can be set as where R represents the transmission rank.

In one embodiment, a specific long-term codebook can be designed for each long-term column selection configuration (such as shown in FIGS. 2a-2d ) to ensure a minimum number of orthogonal beams (orthogonal column ). For example, for a codebook design with a transmission rank of 3 or 4, the The restrictions are as follows:

In this case, any W ₂ design column choice for different ranks across the second dimension can guarantee orthogonality (eg for configurations 2,3,4). Alternatively, or additionally, the The design is as follows:

In this case, any W ₂ design column selection for different ranks across the first dimension can guarantee orthogonality with 2 beam spacings (eg for configurations 3,4). This design can be used, for example, when the transmission rank is 3 or 4.

In another embodiment, it may be set so that all beams in Xi ^,j are orthogonal. For example, the first beam group and the second beam group indicated by the long-term precoding information received in block S301 may be designed as follows:

For the case of N ₁ =4, N ₂ =2, o ₁ =8, o ₂ =4, L ₁ '=4, L ₂ '=2, L ₁ =2, L ₂ =2, it can be obtained:

In this case, no matter which long-term column selection configuration is used, the beams selected by W ₂ can be guaranteed to be orthogonal.

As those skilled in the art can understand, the beam orthogonal design of the long-term codebook given above is only exemplary, and the present disclosure is not limited to any specific beam orthogonal design.

In addition, it should be noted that in some embodiments, the beam-orthogonal design of the long-term codebook of the present disclosure can be implemented independently of the simplified feedback method of the short-term codebook. This means that the beam-orthogonal design of the long-term codebook can be used even with beam mapping and short-term precoding information feedback methods different from those described above.

Reference is now made to FIG. 4 , which shows a flowchart of a method 400 for MIMO communication in a wireless communication network (eg, network 100 ), according to an embodiment of the present disclosure. The method 400 corresponds to the method 300 and can be performed by a MIMO receiver. For example, in the case of downlink MIMO, it may be performed by UE 102 in FIG. 1a, or in the case of uplink MIMO, by eNB 101 in FIG. 1a. And the method can also be used in non-cellular networks, such as device-to-device communication, where both the MIMO sender and receiver can be user equipment. As an example only, in the following description, the method is performed by the UE.

As shown in FIG. 4 , the method 400 includes: at block S401, sending long-term precoding information for the MIMO communication to a device (such as the base station 101), the long-term precoding information indicating the first A beam group, and a second beam group for a second dimension, the second dimension is different from the first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and the beam grid The beams in the grid or the beams in the subset of the beam grid are mapped to a beam set according to a mapping rule; at block S402, short-term precoding information for MIMO communication is sent to the device, and the short-term precoding information includes a one-dimensional index used to indicate a beam selected from the set of beams; and at block S403, MIMO precoded data is received from the device.

Since method 400 is a method at the MIMO receiving end corresponding to method 300, the long-term precoding information and short-term precoding information sent at block S401 and block S402 are the same as the long-term precoding information received at block S301 and block S302 in method 300 The coding information and the short-term precoding information may be the same, so details will not be repeated here. For example, the short-term precoding information sent at block S402 may indicate a beam selected from the set of mapped beams. This mapping enables reuse of the existing short-term codebook design in LTE Rel-10, simplifying the feedback of short-term precoding information. Regarding the mapping rules, it has been described above in conjunction with the method 300, and will not be repeated here.

In an embodiment, the method 400 may further include: at block S411, receiving long-term precoding configuration information from the device, the long-term precoding configuration information is used to perform beam selection from the first beam group to obtain compressed the first beam group, and beam selection from the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the beam grid The subset of .

In another embodiment, the method 400 may further include: at block S412, receiving mapping configuration information from the device, the mapping configuration information indicating the beams in the beam grid or the beam grid A mapping rule for mapping the beams in the subset to the beam set. In yet another embodiment, the mapping rule may be predetermined, so that it does not need to be indicated through signaling between devices.

In some embodiments, the short-term precoding information sent in block S402 further includes phase adjustment information, which is used to indicate phase adjustment between different antenna polarizations. Considering that the size of the beam set from which the beam is selected may be different in different configurations, the present disclosure proposes that, for different beam set sizes, indexes of different lengths may be used to indicate the selected beam to save signaling overhead. Alternatively or additionally, in one embodiment, when a shorter index is not required or required to indicate beam selection, bits used to indicate phase adjustment information may be added, that is, the length of phase adjustment information may depend on the beam selection The number of beams included in the set. This enables better performance without increasing the overall feedback load.

In an embodiment, when the beam set includes only a single beam, the length of the phase adjustment information may be greater than that when the beam set includes multiple beams. In another embodiment, when the set of beams only includes a single beam (for example, when configuration 1 of FIG. 2a is applied), the one-dimensional index sent in block S402 for indicating the beam selected from the set of beams In , at least some of the bits may be used to indicate phase adjustment between different antenna polarizations. In this embodiment, when it is not necessary to perform beam indication, the indication bit or a part thereof is used for indicating phase adjustment, thereby improving the utilization efficiency of the feedback load.

In another embodiment, the first beam group and the second beam group indicated by the long-term precoding information sent in block S401 may be further configured so that the beams selected through the short-term codebook are orthogonal. For example, at least N beams in the first beam group may be set to be orthogonal to each other, and at least N beams in the second beam set may be set to be orthogonal to each other, where N is a positive integer, and N is the minimum number of beams in the beam set that need to be kept orthogonal as determined by the transmission rank. In one example, there may be a minimum number of orthogonal beams in each beam group; in another embodiment, all beams in each beam group may be made orthogonal. As can be appreciated by those skilled in the art, the present disclosure is not limited to any particular beam orthogonal design.

Fig. 5 shows an exemplary structural diagram of an apparatus 500 for MIMO communication in a wireless communication network according to an embodiment of the present disclosure. In one embodiment, the apparatus 500 may be implemented as a sender (eg, eNB 101 or UE 102 ) or a part thereof in MIMO communication. The apparatus 500 is operable to perform the method 300 described with reference to FIG. 3 , as well as any other processes and methods. It should be understood that the method 300 is not limited to be executed by the apparatus 500, and at least some blocks of the method 300 may also be executed by other apparatuses or entities.

As shown in FIG. 5 , the apparatus 500 includes a first receiver 501 configured to receive long-term precoding information for the MIMO communication from another device, the long-term precoding information indicating a first beam for a first dimension group, and a second beam group for a second dimension, the second dimension being different from the first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and the beam grid The beams in or the beams in the subset of the beam grid are mapped to a beam set according to a mapping rule; the second receiver 502 is configured to receive short-term precoding information for MIMO communication from the device, the short-term The precoding information includes a one-dimensional index, where the index is used to indicate a beam selected from the beam set; and the first transmitter 503 is configured to, according to the long-term precoding information and the short-term precoding information, MIMO-precoded data is sent to the device.

The rules for mapping long-term precoding information, short-term precoding information, beam grids or subsets of beam grids to beam sets have been described above with respect to Figures 3-4 and will not be repeated here.

In an embodiment, the apparatus 500 may further include a second transmitter 511, configured to send long-term precoding configuration information to the device, and the long-term precoding configuration information is used for beam selection from the first beam group obtaining a compressed first beam group, and performing beam selection from the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the beam The subset of the grid.

In another embodiment, the apparatus 500 may further include a third transmitter 512, configured to send mapping configuration information to the device, the mapping configuration information indicating that the beam in the beam grid or the beam A mapping rule for mapping beams in said subset of grids to said set of beams.

As described above in connection with methods 300 and 400, in some embodiments, the short-term precoding information received by the second receiver may further include phase adjustment information, which is used to indicate phase adjustment between different antenna polarizations, and, The length of the phase adjustment information depends on the number of beams included in the beam set. In one embodiment, when the beam set includes only a single beam, the length of the phase adjustment information is greater than that when the beam set includes multiple beams.

In another embodiment, when the beam set includes only a single beam, at least a part of bits of the one-dimensional index in the short-term precoding information received by the second receiver are used for phase adjustment information.

Additionally, or alternatively, in one embodiment, the first beam group indicated by the long-term precoding information received by the first receiver 501 may be set such that at least N beams therein are orthogonal to each other, and The second beam group may be configured such that at least N beams therein are orthogonal to each other, where N is a positive integer, and N is the minimum number of beams in the beam group determined by the transmission rank that need to be kept orthogonal.

Furthermore, in some embodiments, the above-mentioned orthogonal design of the first beam set and the second beam set can be implemented independently of any specific short-term precoding information feedback method.

As those skilled in the art can understand, the device 500 may also include other units not shown in FIG. 5 .

Fig. 6 shows an exemplary structural diagram of an apparatus 600 for MIMO communication in a wireless communication network according to an embodiment of the present disclosure. In one embodiment, the apparatus 600 may be implemented as a receiver (eg, eNB 101 or UE 102 ) or a part thereof in MIMO communication, and may perform MIMO communication with the apparatus 500 . The apparatus 600 is operable to perform the method 400 described with reference to FIG. 4 , as well as any other processes and methods. It should be understood that the method 400 is not limited to be performed by the device 600, and at least some blocks of the method 400 may also be performed by other devices or entities.

As shown in FIG. 6 , the apparatus 600 includes a first transmitter 601 configured to send long-term precoding information for the MIMO communication to the device, the long-term precoding information indicating the first beam group for the first dimension , and for the second beam group of the second dimension, the second dimension is different from the first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and in the beam grid The beams in the beam or the beams in the subset of the beam grid are mapped to the beam set according to the mapping rule; the second transmitter 602 is configured to send short-term precoding information for MIMO communication to the device, the short-term precoding The coding information includes a one-dimensional index used to indicate a beam selected from the beam set; and a first receiver 603 configured to receive MIMO precoded data from the device.

Since the apparatus 600 is operable to execute the method 400 described with reference to FIG. The description of the mapping rules from sets to sets of beams is also applicable here and will not be repeated here.

In an embodiment, the apparatus 600 may further include a second receiver 611 configured to receive long-term precoding configuration information from the device, and the long-term precoding configuration information is used to perform beam selection to obtain a compressed first beam group, and performing beam selection from the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the The subset of the beam grid.

Alternatively or additionally, in an embodiment, the apparatus 600 may further include a third receiver 612 configured to receive mapping configuration information from the device, the mapping configuration information indicating the beam grid A mapping rule for mapping beams in or beams in the subset of the beam grid to the set of beams.

As can be understood by those skilled in the art, the devices 500 and 600 may further include other units not shown in Figs. 5 and 6 respectively.

The advantages of the method and device proposed by the embodiments of the present disclosure include at least one of the following:

- Enables simplified feedback of short-term precoding information for 3D MIMO;

- Improve the utilization efficiency of feedback information;

- Guarantee the orthogonality of the selected beams;

-Achieving performance improvements in 3D-MIMO systems.

A person skilled in the art will readily recognize that blocks or steps in various above-described methods can be performed by programmed computers. In this disclosure, some embodiments are also intended to cover program storage devices, e.g., digital data storage media, which are machine- or computer-readable and encode a program of machine-executable or computer-executable instructions, wherein the instructions execute Some or all of the steps of the methods described above. The program storage devices may be, for example, digital memories, magnetic storage media such as a magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. The embodiments are also intended to cover computers programmed to perform the steps of the above described methods. Some embodiments are also intended to cover an apparatus comprising at least one processor; and at least one memory comprising computer program code, wherein the at least one memory and the computer program code are configured to communicate with the at least one Together, the processor causes the apparatus to perform the method 300 or 400 .

The functions of the various elements of the apparatus shown in the figures may be provided through the use of software, dedicated hardware and hardware capable of executing the software associated with appropriate software, or firmware, or a combination thereof. When provided by a processor, the functionality may be provided by a single dedicated processor, by a single shared processor, or by multiple separate processors. Additionally, the term "processor" may include, but is not limited to, digital signal processor (DSP) hardware, network processors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), read-only memory for storing software (ROM), random access memory (RAM), and non-volatile storage devices. Other conventional and/or custom hardware may also be included.

Those skilled in the art should understand that the description and drawings merely illustrate the principles of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its spirit and scope. Furthermore, all examples set forth herein are primarily intended to be expressly for teaching purposes only, to assist the reader in understanding the principles of the disclosure and concepts contributed by the inventors to advance the art, and should be construed as not limited to such specifically illustrated examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof.

Claims (32)

1. A method for multiple-input multiple-output MIMO communication, comprising: Long-term precoding information for the MIMO communication is received from the device, the long-term precoding information indicates a first beam group for a first dimension, and a second beam group for a second dimension, the second dimension being different from The first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and beams in the beam grid or beams in a subset of the beam grid are Map to the beam set according to the mapping rules; receiving short-term precoding information for the MIMO communication from the device, the short-term precoding information including a one-dimensional index, the index being used to indicate a beam selected from the beam set; sending MIMO-precoded data to the device according to the long-term precoding information and the short-term precoding information. 2. The method of claim 1, wherein the mapping rules include at least one of: mapping beams in a beam grid or beams in said subset of said beam grid to said set of beams in order of first dimension first; mapping beams in the beam grid or beams in the subset of the beam grid to the set of beams in order of second dimension preference; mapping the beams in the beam grid or the subset of the beam grid to the set of beams in a random order; and The beams in the beam grid or the beams in the subset of the beam grid are mapped to the set of beams in a predetermined order. 3. The method of claim 1, further comprising: Sending long-term precoding configuration information to the device, the long-term precoding configuration information is used to perform beam selection from the first beam group to obtain a compressed first beam group, and perform beam selection from the second beam group A compressed second beam set is selected; wherein said compressed first beam set and said compressed second beam set form said subset of said beam grid. 4. The method of claim 1, further comprising: sending mapping configuration information to the device, where the mapping configuration information indicates the mapping rule. 5. The method of any one of claims 1 to 4, wherein: The short-term precoding information further includes phase adjustment information for indicating phase adjustment between different antenna polarizations, and, The length of the phase adjustment information depends on the number of beams included in the beam set. 6. The method of claim 5, wherein when the beam set includes only a single beam, the length of the phase adjustment information is greater than when the beam set includes a plurality of beams. 7. The method of claim 5, wherein: When the beam set only includes a single beam, at least some bits of the one-dimensional index are used for the phase adjustment information. 8. The method of any one of claims 1 to 4, wherein: at least N beams in the first set of beams are orthogonal to each other, and at least N beams in the second set of beams are orthogonal to each other, where N is a positive integer, and N is the minimum number of beams in the beam group determined by the transmission rank that need to be kept orthogonal. 9. A method for multiple-input multiple-output MIMO communication, comprising: sending long-term precoding information for the MIMO communication to the device, the long-term precoding information indicating a first beam group for a first dimension, and a second beam group for a second dimension, the second dimension being different from The first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and beams in the beam grid or beams in a subset of the beam grid are Map to the beam set according to the mapping rules; sending short-term precoding information used for the MIMO communication to the device, where the short-term precoding information includes a one-dimensional index, and the index is used to indicate a beam selected from the beam set; MIMO precoded data is received from the device. 10. The method of claim 9, wherein the mapping rules include at least one of: mapping beams in a beam grid or beams in said subset of said beam grid to said set of beams in order of first dimension first; mapping beams in the beam grid or beams in the subset of the beam grid to the set of beams in order of second dimension preference; mapping the beams in the beam grid or the subset of the beam grid to the set of beams in a random order; and The beams in the beam grid or the beams in the subset of the beam grid are mapped to the set of beams in a predetermined order. 11. The method of claim 9, further comprising: receiving long-term precoding configuration information from the device, the long-term precoding configuration information being used to perform beam selection from the first beam group to obtain a compressed first beam group, and to perform beam selection from the second beam group A compressed second beam set is selected; wherein said compressed first beam set and said compressed second beam set form said subset of said beam grid. 12. The method of claim 9, further comprising: Mapping configuration information is received from the device, the mapping configuration information indicating the mapping rules. 13. The method of any one of claims 9 to 12, wherein: The short-term precoding information further includes phase adjustment information for indicating phase adjustment between different antenna polarizations, and, The length of the phase adjustment information depends on the number of beams included in the beam set. 14. The method of claim 13, wherein the length of the phase adjustment information is greater when the beam set includes only a single beam than when the beam set includes a plurality of beams. 15. The method of claim 13, wherein: When the beam set only includes a single beam, at least some bits of the one-dimensional index are used for the phase adjustment information. 16. The method of any one of claims 9 to 12, wherein: at least N beams in the first set of beams are orthogonal to each other, and at least N beams in the second set of beams are orthogonal to each other, where N is a positive integer, and N is the minimum number of beams in the beam group determined by the transmission rank that need to be kept orthogonal. 17. An apparatus for multiple-input multiple-output MIMO communication, comprising: A first receiver configured to receive long-term precoding information for the MIMO communication from a device, the long-term precoding information indicating a first beam set for a first dimension and a second beam set for a second dimension , the second dimension is different from the first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and the beams in the beam grid or the beams The beams in the subset of the grid are mapped to the set of beams according to the mapping rule; The second receiver is configured to receive short-term precoding information for the MIMO communication from the device, the short-term precoding information includes a one-dimensional index, and the index is used to indicate selection from the beam set the beam; The first transmitter is configured to send MIMO precoded data to the device according to the long-term precoding information and the short-term precoding information. 18. The apparatus of claim 17, wherein the mapping rules comprise at least one of: mapping beams in a beam grid or beams in said subset of said beam grid to said set of beams in order of first dimension first; mapping beams in the beam grid or beams in the subset of the beam grid to the set of beams in order of second dimension preference; mapping the beams in the beam grid or the subset of the beam grid to the set of beams in a random order; and The beams in the beam grid or the beams in the subset of the beam grid are mapped to the set of beams in a predetermined order. 19. The apparatus of claim 17, further comprising: The second transmitter is configured to send long-term precoding configuration information to the device, where the long-term precoding configuration information is used to perform beam selection from the first beam group to obtain a compressed first beam group, and from the first beam group performing beam selection in the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the subset of the beam grid. 20. The apparatus of claim 17, further comprising: A third sender configured to send mapping configuration information to the device, where the mapping configuration information indicates the mapping rule. 21. The apparatus of any one of claims 17 to 20, wherein: The short-term precoding information further includes phase adjustment information for indicating phase adjustment between different antenna polarizations, and, The length of the phase adjustment information depends on the number of beams included in the beam set. 22. The apparatus of claim 21, wherein the length of the phase adjustment information is greater when the set of beams includes only a single beam than when the set of beams includes a plurality of beams. 23. The apparatus of claim 21, wherein: When the beam set only includes a single beam, at least some bits of the one-dimensional index are used for the phase adjustment information. 24. The apparatus of any one of claims 17 to 20, wherein: at least N beams in the first set of beams are orthogonal to each other, and at least N beams in the second set of beams are orthogonal to each other, where N is a positive integer, and N is the minimum number of beams in the beam group determined by the transmission rank that need to be kept orthogonal. 25. An apparatus for multiple-input multiple-output MIMO communication, comprising: A first transmitter configured to send long-term precoding information for the MIMO communication to a device, the long-term precoding information indicating a first beam group for a first dimension and a second beam group for a second dimension , the second dimension is different from the first dimension; wherein, the first beam group and the second beam group form a 2-dimensional beam grid, and the beams in the beam grid or the beams The beams in the subset of the grid are mapped to the set of beams according to the mapping rule; The second transmitter is configured to send short-term precoding information used for the MIMO communication to the device, where the short-term precoding information includes a one-dimensional index, and the index is used to indicate to select from the beam set the beam; A first receiver configured to receive MIMO-precoded data from the device. 26. The apparatus of claim 25, wherein the mapping rules comprise at least one of: mapping beams in a beam grid or beams in said subset of said beam grid to said set of beams in order of first dimension first; mapping beams in the beam grid or beams in the subset of the beam grid to the set of beams in order of second dimension preference; mapping the beams in the beam grid or the subset of the beam grid to the set of beams in a random order; and The beams in the beam grid or the beams in the subset of the beam grid are mapped to the set of beams in a predetermined order. 27. The apparatus of claim 25, further comprising: The second receiver is configured to receive long-term precoding configuration information from the device, the long-term precoding configuration information is used to perform beam selection from the first beam group to obtain a compressed first beam group, and from the first beam group performing beam selection in the second beam group to obtain a compressed second beam group; wherein the compressed first beam group and the compressed second beam group constitute the subset of the beam grid. 28. The apparatus of claim 25, further comprising: A third receiver configured to receive mapping configuration information from the device, the mapping configuration information indicating the mapping rule. 29. Apparatus according to any one of claims 25 to 28, wherein: The short-term precoding information further includes phase adjustment information for indicating phase adjustment between different antenna polarizations, and, The length of the phase adjustment information depends on the number of beams included in the beam set. 30. The apparatus of claim 29, wherein the length of the phase adjustment information is greater when the set of beams includes only a single beam than when the set of beams includes multiple beams. 31. The device of claim 29, wherein: When the beam set only includes a single beam, at least some bits of the one-dimensional index are used for the phase adjustment information. 32. Apparatus according to any one of claims 25 to 28, wherein: at least N beams in the first set of beams are orthogonal to each other, and at least N beams in the second set of beams are orthogonal to each other, where N is a positive integer, and N is the minimum number of beams in the beam group determined by the transmission rank that need to be kept orthogonal.