WO2024255234A1 - Wireless sensing method and apparatus for environment depth and computer readable storage medium - Google Patents

Abstract

The present application relates to the technical field of communications, and discloses a wireless sensing method and apparatus for an environment depth and a computer readable storage medium, capable of realizing ubiquitous communication sensing. The method comprises: receiving an echo signal, the echo signal being a signal obtained after a sensing signal sent by a sensing transmitting base station is reflected by a sensing object in the environment, and the sensing object in the environment comprising a dynamic sensing object and a static sensing object; and determining sensing information of the static sensing object according to the echo signal.

Description

Wireless perception method, device and computer-readable storage medium for environmental depth

This disclosure claims priority to Chinese patent application No. 202310710392.X filed on June 14, 2023, the entire contents of which are incorporated by reference into this application.

Technical Field

The present application relates to the field of communication technology, and in particular to a method, device and computer-readable storage medium for wirelessly sensing environmental depth.

Background Art

At present, in wireless communication systems, full-duplex base stations can send perception signals in various directions in the environment through radars additionally deployed in the full-duplex base stations, and receive the perception signals reflected by the environment (i.e., echo signals). The full-duplex base station can analyze the echo signals to obtain perception information of each perception object in the environment.

However, full-duplex base stations have great limitations and have not been widely used in current wireless communication systems, resulting in the above communication perception method being unable to achieve ubiquitous communication perception.

Summary of the invention

The embodiments of the present application provide a method, device and computer-readable storage medium for wireless perception of environmental depth, which can realize ubiquitous communication perception.

On the one hand, a method for wireless sensing of environmental depth is provided, comprising:

receiving an echo signal, where the echo signal is a signal generated after a sensing signal sent by a sensing transmitting base station is reflected by a sensing object in the environment; the sensing object in the environment includes a dynamic sensing object and a stationary sensing object;

According to the echo signal, the perception information of the stationary perception object is determined.

In yet another aspect, a communication device is provided, comprising: a communication unit and a processing unit;

A communication unit, configured to receive an echo signal, wherein the echo signal is a signal generated after a sensing signal sent by a sensing transmitting base station is reflected by a sensing object in the environment; the sensing object in the environment includes a dynamic sensing object and a stationary sensing object;

The processing unit is used to determine the perception information of the stationary perception object according to the echo signal.

On the other hand, a communication node is provided, comprising: a memory and a processor; the memory and the processor are coupled; the memory is used to store a computer program; and when the processor executes the computer program, the wireless perception method of the environment depth of any of the above embodiments is implemented.

On the other hand, a computer-readable storage medium is provided, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the method for wirelessly sensing the environment depth of any of the above embodiments is implemented.

On the other hand, a computer program product is provided, which includes computer program instructions, and when the computer program instructions are executed by a processor, the method for wirelessly sensing the depth of an environment of any of the above embodiments is implemented.

In the embodiment of the present application, the wireless perception method of the depth of the environment provided divides the subject of transmitting the perception signal from the subject of receiving the echo signal, so that the base stations in the embodiment of the present application are all non-full-duplex base stations, that is, the perception signal is sent by the non-full-duplex base station (i.e., the perception transmitting base station), and the echo signal is received by the non-full-duplex base station (i.e., the perception receiving base station), and the perception information of the stationary perception object in the environment is determined based on the above echo signal. Since the limitations of non-full-duplex base stations are relatively small, non-full-duplex base stations are widely used in current wireless communication systems, so that a wide range of communication perception of stationary perception objects in the environment can be achieved.

Secondly, non-full-duplex base stations can send perception signals and receive echo signals through general communication functions without the need for additional deployment of devices, thereby achieving ubiquitous communication perception of stationary perception objects in the environment while ensuring deployment costs.

Thirdly, the perception receiving base station only determines the perception information of the stationary perception objects in the environment based on the echo signal, so as to avoid the interference of the dynamic perception objects on the communication perception of the above-mentioned overall environment, thereby improving the quality of the communication perception of the overall environment.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solution in the present application, the drawings required for use in some embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only drawings of some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

FIG1 is a schematic diagram of the structure of a wireless communication system provided by some embodiments of the present application;

FIG2 is a flow chart of a wireless sensing method for environmental depth provided by some embodiments of the present application;

FIG3 is a flow chart of another wireless sensing method for environmental depth provided by some embodiments of the present application;

FIG4 is a schematic diagram of a delay Doppler spectrum provided by some embodiments of the present application;

FIG5 is a schematic diagram of an impulse response sequence provided in some embodiments of the present application;

FIG6 is a flow chart of another wireless sensing method for environmental depth provided by some embodiments of the present application;

FIG7 is a schematic diagram of multiple reflections provided by some embodiments of the present application;

FIG8 is a flow chart of another wireless sensing method for environmental depth provided by some embodiments of the present application;

FIG9 is a schematic diagram of a reflection point to be selected provided in some embodiments of the present application;

FIG10 is a schematic diagram of the structure of a communication device provided in some embodiments of the present application;

FIG11 is a schematic diagram of the structure of another communication device provided in some embodiments of the present application.

DETAILED DESCRIPTION

The following will be combined with the drawings in this application to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

It should be noted that, in this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

In the description of this application, unless otherwise specified, "/" means "or", for example, A/B can mean A or B. "And/or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and/or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, "at least one" means one or more, and "multiple" means two or more.

The industrial revolution era is divided based on different stages of industrial development. The first industrial revolution era was the steam engine stage, the second industrial revolution era was the electrification stage, the third industrial revolution era was the information stage, and the fourth industrial revolution era (the current era) is the intelligent stage. In the fourth industrial revolution era, intelligent technology can not only penetrate into people's lives, bringing great convenience and new experiences to people's lives, but also penetrate into all walks of life, and realize industrial upgrading through intelligent technology. Improving industrial efficiency can greatly liberate human hands and get rid of the constraints of low-level production.

The current industrial development is in the era of the fourth work revolution (i.e., the intelligent stage). At present, intelligent technologies mainly include ubiquitous sensing technology, ubiquitous computing technology, and intelligent product research and development technology. Among them, ubiquitous sensing technology is of great significance to the development of the fourth work revolution era. For example, in the scenario of autonomous driving, ubiquitous sensing technology can be used to determine the distance and position information of the perceived objects in the environment in order to provide accurate environmental information. The above-mentioned ubiquitous sensing technology needs to be applied to ubiquitous systems. In the current system, only wireless communication systems can carry the above-mentioned ubiquitous sensing technology. In view of this, it is an important demand of the intelligent era to realize ubiquitous sensing using widely existing wireless networks, and realizing ubiquitous sensing through wireless communication systems has become the main feasible technical route. In addition, wireless communication systems can also carry the above-mentioned ubiquitous computing technology.

At present, in wireless communication systems, communication perception of the environment can be achieved through the following methods 1 and 2. Method 1: Communication perception of the environment is achieved based on vision. Method 2: Communication perception of the environment is achieved based on radar. The following describes the above methods 1 and 2 respectively:

Method 1: Realize communication perception of the environment based on vision.

The process of realizing communication perception of the environment based on vision can be as follows: deploying and starting an image acquisition device on a base station so that the image acquisition device can acquire environmental images. The base station performs operations such as segmentation and recognition on the environmental images acquired by the image acquisition device to obtain environmental data.

Problems with method 1: If communication perception of the environment is achieved based on vision, it is necessary to deploy additional image acquisition devices, which increases the deployment cost. In addition, the image acquisition devices have limitations in capturing environmental images and are not easy to deploy, which makes it impossible to capture environmental images more comprehensively, and thus, ubiquitous perception cannot be achieved. In addition, the image acquisition device cannot distinguish between dynamic perception objects and static perception objects in the environment, so it is impossible to achieve targeted communication perception of static perception objects in the environment. In addition, the current communication perception can only perceive the overall environment, and cannot distinguish between dynamic perception objects and static perception objects in the environment. Dynamic perception objects will interfere with the above-mentioned overall environmental perception, thereby affecting the perception effect of the environment.

Method 2: Realize communication perception of the environment based on radar.

The implementation process of ubiquitous perception based on radar can be as follows: deploy and start the radar on the base station, so that the base station can send radar perception signals in all directions of space through the radar, and collect and receive radar perception signals (i.e. radar echo signals) reflected by the environment or perception objects to form a point cloud. The base station processes the above point cloud to obtain environmental data.

Problems with method 2: If perception is achieved based on radar, additional radars need to be deployed, which increases the deployment cost. Moreover, radars can only be deployed in full-duplex base stations, and each still has interference problems, which has great limitations, resulting in full-duplex base stations being unable to be used on a larger scale, and thus, ubiquitous perception cannot be achieved. Current wireless communication systems mainly include non-full-duplex base stations (for example, transmitting base stations, time-division multiplexing receiving base stations, and frequency-division multiplexing receiving base stations), but radars cannot be applied to non-full-duplex base stations, resulting in the inability of non-full-duplex base stations to achieve ubiquitous perception. In addition, current communication perception can only perceive the overall environment, and cannot distinguish between dynamic perception objects and static perception objects in the environment. Dynamic perception objects will interfere with the communication perception of the above-mentioned overall environment, thereby affecting the perception of the environment. Effect.

The wireless perception method of the depth of the environment provided in the embodiment of the present application separates the subject of transmitting the perception signal from the subject of receiving the echo signal, so that the base stations in the embodiment of the present application are all non-full-duplex base stations, that is, the perception signal is sent by the non-full-duplex base station (i.e., the perception transmitting base station), and the echo signal is received by the non-full-duplex base station (i.e., the perception receiving base station), and the perception information of the stationary perception object in the environment is determined based on the above echo signal. Since the limitations of non-full-duplex base stations are relatively small, non-full-duplex base stations are widely used in current wireless communication systems, so that a wide range of communication perception of stationary perception objects in the environment can be achieved.

Secondly, non-full-duplex base stations can send perception signals and receive echo signals through general communication functions without the need for additional deployment of devices, thereby achieving ubiquitous communication perception of stationary perception objects in the environment while ensuring deployment costs.

Thirdly, the perception receiving base station only determines the perception information of the stationary perception objects in the environment based on the echo signal, so as to avoid the interference of the dynamic perception objects on the communication perception of the above-mentioned overall environment, thereby improving the quality of the communication perception of the overall environment.

The technical solution provided in the embodiments of the present application can be applied to various wireless communication systems, for example, a new radio (NR) wireless communication system using the fifth generation mobile communication technology (5G), a future evolution system, or a multi-communication fusion system.

Exemplarily, a schematic diagram of the structure of a wireless communication system 10 provided in an embodiment of the present application is shown in Fig. 1. The wireless communication system 10 may include a sensing transmitting base station 101 and at least one sensing receiving base station 102. Fig. 1 only shows one sensing transmitting base station 101 and two sensing receiving base stations 102.

The perception receiving base station 102 is used to receive the echo signal and determine the perception information of the stationary perception object according to the echo signal.

The echo signal is a signal generated after the sensing signal sent by the sensing transmitting base station 101 is reflected by a sensing object in the environment. The sensing object in the environment includes a dynamic sensing object and a stationary sensing object.

In some implementations, the sensing transmitting base station 101 may send sensing signals in different preset transmitting directions. As shown in FIG1 , the five sensing signals in FIG1 correspond to different preset transmitting directions respectively. The direction includes an azimuth and an elevation. For example, the preset transmitting azimuths of the five sensing signals in FIG1 are dp, d0, dn, dm, and dl, respectively, and the preset transmitting elevation angles of the five sensing signals in FIG1 are θp, θ0, θn, θm, and θl, respectively.

It should be noted that a series of synchronizations such as time synchronization and configuration information synchronization are required between the sensing transmitting base station 101 and the sensing receiving base station 102, so as to lay a foundation for the subsequent assisted communication perception between the sensing transmitting base station 101 and the sensing receiving base station 102.

The sensing transmitting base station 101 and the sensing receiving base station 102 may also be referred to as a radio access network node (RAN node) or access network equipment. The radio access network node is used to implement wireless physical layer functions, resource scheduling and wireless resource management, wireless access control and mobility management functions, service quality management, data compression and encryption and other functions. Among them, the access network equipment is used to provide communication coverage for a specific geographical area and communicate with terminal devices in the covered area (cell). The sensing transmitting base station 101 and the sensing receiving base station 102 may specifically be various forms of control nodes (for example, network controllers, wireless controllers (for example, wireless controllers in cloud radio access network (CRAN) scenarios)), etc. Among them, The sensing transmitting base station 101 and the sensing receiving base station 102 include various forms of macro base stations, micro base stations (also called small stations), relay stations, and access points (APs).

In systems using different wireless access technologies, the names of devices with the functions of sensing transmitting base station 101 and sensing receiving base station 102 may be different. For example, in an LTE system, it may be an evolved NodeB (eNB or eNodeB), in a heterogeneous network (HetNet) scenario, it may be a micro base station eNB, in a distributed base station scenario, it may be a baseband unit (BBU) and a remote radio unit (RRU), in a CRAN scenario, it may be a baseband pool (BBU pool) and RRU, and in a 5G system or NR system, it may be a next generation node base station (gNB). This application does not limit the specific names of the sensing transmitting base station 101 and the sensing receiving base station 102. The access network device may also be an access network device in a future evolved public land mobile network (PLMN), etc.

It should be noted that Figure 1 is only an exemplary framework diagram. The number of nodes and the names of each device included in Figure 1 are not limited. In addition to the functional nodes shown in Figure 1, the wireless communication system 10 may also include other nodes (for example, application servers), and this application does not impose any restrictions on this.

The application scenarios of the embodiments of the present application are not limited. The system architecture and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. It is known to those skilled in the art that with the evolution of the network architecture and the emergence of new business scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

FIG2 is a flow chart of a wireless sensing method for environment depth provided in an embodiment of the present application. As shown in FIG2 , the method may include:

S201: A sensing transmitting base station sends a sensing signal, and correspondingly, a sensing receiving base station receives an echo signal.

The echo signal is a signal generated after the sensing signal sent by the sensing transmitting base station is reflected by a sensing object in the environment. The sensing objects in the environment include dynamic sensing objects and stationary sensing objects.

In some embodiments, the application server may send configuration information to the sensing transmitting base station and the sensing receiving base station respectively. The configuration information includes: time information, period information, time-frequency resource information, and direction sending rules for the first transmission of the sensing signal. The period information includes the sensing signal transmission period and the number of moments in the sensing signal transmission period. The direction sending rules include: initial direction and direction step size.

Exemplarily, the above-mentioned direction may include an azimuth angle and/or an elevation angle. In the case where the direction includes an azimuth angle and an elevation angle, the direction sending rule may include (α1, α1+i*dα) and (β1, β1+k*dβ). Among them, α1 is the initial azimuth angle. dα is the step size of the azimuth angle. β1 is the initial pitch angle. dβ is the step size of the pitch angle. i and k are both positive integers.

Combined with the above example, taking the maximum value of i as 50 and the maximum value of k as 60 as an example: the sensing transmitting base station can record (α1+50dα) as α2, and record (β1+60dβ) as β2. In this example, the sensing transmitting base station can be within the azimuth range (i.e. (α 1, α2)) and the pitch angle range (i.e., (β1, β2)) to traverse and send perception signals.

As an implementation manner, the implementation process of the above S201 may be: the sensing transmitting base station may send a sensing signal in a transmission direction in the nth cycle. The sensing receiving base station receives an echo signal in the nth cycle. The echo signal includes a signal after the sensing signal sent by the sensing transmitting base station in the transmission direction in the nth cycle is reflected by a sensing object in the environment. n is a positive integer.

In some examples, the stationary perceived object includes at least one of the following: ground, sky, building, stool. The above are only some exemplary descriptions of stationary perceived objects, and the stationary perceived objects may also include other objects (eg, trees), and this application does not impose any limitation on this.

It should be noted that the reflections described in the embodiments of the present application may also be scattering, and the present application does not impose any limitation on this.

In some examples, the echo signal may be a single-path signal or a multi-path signal, and the present application does not impose any limitation on this.

S202. The perception receiving base station determines perception information of the stationary perception object according to the echo signal.

In some embodiments, the implementation process of the above S202 may be: the perception receiving base station may analyze the echo signal to obtain the perception data about all the perception objects in the environment, and extract the perception data about the stationary perception objects in the environment from the perception data about all the perception objects in the environment. The perception receiving base station determines the perception information of the stationary perception objects based on the perception data about the stationary perception objects in the environment.

In some examples, the perception information may include the position and/or the signal strength of the echo signal. The above are only some exemplary descriptions of the perception information, and the perception information may also include other information (eg, length, width, height, and direction), and this application does not impose any limitation on this.

In some embodiments, the perception receiving base station can directly draw a perception environment map based on the perception information of the stationary perception object, and can also send the perception information of the stationary perception object to the application server so that the application server can draw a perception environment map based on the perception information of the stationary perception object.

It should be noted that, when there is only one perception receiving base station, the perception receiving base station can directly draw the perception environment map based on the perception information of the stationary perception object, which can reduce the calculation pressure of the application server. When there are multiple perception receiving base stations, each perception receiving base station can send the perception information of the stationary perception object to the application server, and the application server summarizes the perception information of the stationary perception object perceived by each perception receiving base station, and draws the perception environment map based on the above-summarized information, which can ensure the comprehensiveness of the perception environment map.

In some examples, the above-mentioned perceived environment map may be a grayscale image, an image in a raw format, or an image in a red, green, blue (RGB) format. The above is only an exemplary description of the perceived environment map, and the perceived environment map may also be other images, and this application does not impose any limitation on this.

The wireless sensing method for the depth of environment provided in the embodiment of the present application separates the subject of transmitting the sensing signal from the subject of receiving the echo signal, so that the base stations in the embodiment of the present application are all non-full-duplex base stations, that is, the sensing signal is sent by the non-full-duplex base station (i.e., the sensing transmitting base station), and the echo signal is received by the non-full-duplex base station (i.e., the sensing receiving base station), and the environment is determined based on the above echo signal. The non-full-duplex base station is widely used in the current wireless communication system because of the small limitation of the non-full-duplex base station. Therefore, it can realize the extensive communication perception of the stationary sensing objects in the environment.

Secondly, non-full-duplex base stations can send perception signals and receive echo signals through general communication functions without the need for additional deployment of devices, thereby achieving ubiquitous communication perception of stationary perception objects in the environment while ensuring deployment costs.

Thirdly, the perception receiving base station only determines the perception information of the stationary perception objects in the environment based on the echo signal, so as to avoid the interference of the dynamic perception objects on the communication perception of the above-mentioned overall environment, thereby improving the quality of the communication perception of the overall environment.

In some embodiments, as shown in FIG3, when the echo signal includes echo signals received at multiple times in the nth cycle based on multiple antenna channels, the embodiment of the present application further provides a wireless perception method of environmental depth, the method comprising the following steps:

S301. The sensing receiving base station performs Doppler analysis on the echo signal to obtain environmental sensing data.

The environmental sensing data is used to represent the impulse response sequence of the echo signal reflected by the stationary sensing object. The impulse response sequence is used to represent the phase information and amplitude information of the echo signal under different time delays.

In some embodiments, the implementation process of the above S301 may be: the sensing receiving base station performs Doppler analysis on the echo signal to obtain a delay Doppler spectrum, and determines the data in the delay Doppler spectrum that is within a preset frequency range as the environmental sensing data.

In combination with the above embodiment, in the case where the echo signal includes echo signals received at multiple moments in the nth cycle based on multiple antenna channels, the implementation process of the above S301 may specifically be: the perception receiving base station may analyze the echo signals received at multiple moments in the nth cycle by each antenna channel to obtain the delay Doppler spectrum of the echo signal received by each antenna channel, and extract data within a preset frequency range from the delay Doppler spectrum of the echo signal received by each antenna channel to obtain the environmental perception data of the echo signal received by each antenna channel. The perception receiving base station determines the environmental perception data of the echo signals received by the multiple antenna channels as the above environmental perception data.

It is understandable that, since the data within the preset frequency range in the delay Doppler spectrum can represent the perception data about the perception object that has not undergone frequency shift or the perception data about the perception object with a smaller frequency shift, the data within the preset frequency range in the above delay Doppler spectrum can be used to represent the perception data about the stationary perception object (i.e., the impulse response sequence of the echo signal reflected by the stationary perception object). In view of this, the perception receiving base station screens the data in the delay Doppler spectrum and determines the data within the preset frequency range in the delay Doppler spectrum as environmental perception data, so that the perception data about the dynamic perception object and the perception data about the static perception object can be distinguished, and the perception data about the dynamic perception object can be eliminated, thereby avoiding the interference caused by the dynamic perception object to the above overall environmental perception, so as to achieve the purpose of eliminating interference.

In some embodiments, the sensing receiving base station performs Doppler analysis on the echo signal to obtain the delay Doppler spectrum as follows: the sensing receiving base station calculates the time domain impulse response of the echo signal at multiple moments based on the echo signal received at the nth period, and analyzes the time domain impulse response of the echo signal at the multiple moments to obtain the delay Doppler spectrum. The sensing receiving base station can determine the delay Doppler spectrum of the echo signal received by each antenna channel based on the above method.

In some examples, FIG4 shows an example of a delay-Doppler spectrum of an echo signal obtained after the perception signal #1 (i.e., the perception signal transmitted at an azimuth angle of 44° and a pitch angle of -20°) is reflected by a perception object in the environment. As shown in FIG4, the X-axis of the delay-Doppler spectrum is used to characterize the frequency, the Y-axis of the delay-Doppler spectrum is used to characterize the time, and the Z-axis of the delay-Doppler spectrum is used to characterize the phase information and amplitude information of the echo signal. The perception receiving base station extracts data within a preset frequency range from the above-mentioned delay-Doppler spectrum as environmental perception data, and can display the environmental perception data in the form of an impulse response sequence. FIG5 shows an example of an impulse response sequence. As shown in FIG5, the X-axis of the impulse response sequence is used to characterize the time, and the Y-axis of the impulse response sequence is used to characterize the phase information and amplitude information of the echo signal.

As an example, the preset frequency range may be [-threshold 1, threshold 1]. The threshold 1 may be 5 Hz. The above is only an exemplary description of threshold 1, and threshold 1 may also be other values (for example, 10 Hz), and the present application does not impose any limitation on this.

S302: The perception receiving base station determines perception information of the stationary perception object based on the environmental perception data.

In some embodiments, the implementation process of the above S302 may be: the perception receiving base station may analyze the environmental perception data of the echo signals received by multiple antenna channels included in the above environmental perception data to obtain the perception information of a point, and when the point is a primary reflection point, determine the perception information of the point as the perception information of a stationary perception object.

In an embodiment of the present application, the perception receiving base station can perform Doppler analysis on the echo signal to obtain perception data about the stationary perception object, and determine the perception information of the stationary perception object based on the perception data about the stationary perception object, thereby providing an implementation method for the perception receiving base station to determine the perception information of the stationary perception object.

In some embodiments, as shown in FIG6 , the embodiment of the present application further provides a method for wirelessly sensing an environment depth, the method comprising the following steps:

S601. The perception receiving base station determines perception information of a primary reflection point based on environmental perception data.

The primary reflection point is the point where the sensing signal is reflected by the stationary sensing object for the first time.

In some examples, the perception signal may be reflected multiple times by multiple parts of a stationary perception object. FIG7 shows an example of multiple reflections. As shown in FIG7, the perception signal 1 transmitted by the perception transmitting base station is reflected for the first time on the a-surface of the stationary perception object 1. In this case, the perception receiving base station may use point a' on the a-surface of the stationary perception object 1 as a primary reflection point. If the above-mentioned perception signal needs to be reflected again, the perception receiving base station may receive the echo signal after the perception signal is reflected by the above-mentioned primary reflection point, and the energy corresponding to the echo signal is the scattered energy.

After the above-mentioned perception signal 1 is reflected for the first time on the a-surface of the stationary perception object 1, it is reflected again on the b-surface of the stationary perception object 1. In this case, the perception receiving base station can use point b' on the b-surface of the stationary perception object 1 as the secondary reflection point.

The perception signal may also be reflected multiple times by multiple stationary perception objects. For another example, the perception signal 2 transmitted by the perception transmitting base station is reflected for the first time by the stationary perception object 2. In this case, the perception receiving base station may use the point c' of the stationary perception object 2 as the first reflection point. After the perception signal 2 is reflected for the first time by the stationary perception object 2, it is reflected again by the stationary perception object 3. In this case, the sensing receiving base station can use the point d' of the stationary sensing object 3 as the secondary reflection point. If the sensing signal does not need to be reflected again, the sensing receiving base station can receive the echo signal after the sensing signal is reflected by the secondary reflection point, and the energy corresponding to the echo signal is the reflection energy.

S602. The perception receiving base station determines the perception information of the primary reflection point as the perception information of the stationary perception object.

In combination with the above example, the perception receiving base station may determine the perception information at point a' of surface a of the stationary perception object 1 as the perception information of the stationary perception object. Alternatively, the perception receiving base station may determine the perception information at point c' of the stationary perception object 2 as the perception information of the stationary perception object.

In the embodiment of the present application, since the transmission path and transmission time of the echo signal obtained after multiple reflections are difficult to estimate, it is difficult for the perception receiving base station to determine the accuracy of the perception information of multiple reflection points. In view of this, the perception receiving base station determines the perception information of a single reflection point based on the environmental perception data, and determines the perception information of the single reflection point as the perception information of the stationary perception object, which can improve the accuracy of the perception information of the determined stationary perception object.

In some embodiments, as shown in FIG8 , the embodiment of the present application further provides a method for wirelessly sensing an environment depth, the method comprising the following steps:

S801. The perception receiving base station determines perception information of a candidate reflection point based on environmental perception data.

The selected reflection point is the midpoint of the shortest line segment between the transmitting direction and the receiving direction. The transmitting direction is the direction in which the sensing transmitting base station sends the sensing signal. The receiving direction is the direction in which the sensing receiving base station receives the echo signal.

Based on the description of the above perception information, it can be known that the perception information may include the position and the strength of the echo signal. The following describes the implementation process of the perception receiving base station determining the position of the candidate reflection point and the strength of the echo signal based on the environmental perception data.

In some embodiments, the sensing receiving base station determines the position of the selected reflection point based on the environmental sensing data as follows: the sensing receiving base station determines the peak value of the first path from the impulse response sequence, and analyzes the peak values of the first paths of multiple antenna channels to obtain the angle of arrival of the first path. The sensing receiving base station determines the position of the selected reflection point based on the sensing receiving base station position, the sensing signal transmission angle, the sensing transmitting base station position, and the angle of arrival of the first path. The first path is the first path in the impulse response sequence of the sensing signal with a peak value greater than the second preset threshold.

It should be noted that the sensing receiving base station can set the second preset threshold based on experience. For example, the sensing receiving base station can set the second preset threshold to a noise value. The above is only an exemplary description of the second preset threshold. The second preset threshold can also be other values, and this application does not impose any restrictions on this.

In some implementations, the above-mentioned perception receiving base station analyzes the peak value of the first path of multiple antenna channels to obtain the angle of arrival of the first path, which can be determined by the following method 1 and method 2. Among them, method 1 is that the perception receiving base station analyzes the peak value of the first path of multiple antenna channels based on spatial filtering to obtain the angle of arrival of the first path. Method 2 is that the perception receiving base station analyzes the peak value of the first path of multiple antenna channels based on multiple signal classification (MUSIC) to obtain the angle of arrival of the first path. The above-mentioned method 1 and method 2 are respectively explained below.

The implementation process of method 1 may be as follows: the sensing receiving base station may determine the product of the peak value of the first path of each antenna channel and the phase as the beamforming value of each antenna channel, and add the beamforming values of each antenna channel to obtain the target value of the phase. Based on the above method, the sensing receiving base station determines the target values of multiple phases, and determines the arrival angle of the first path based on the phase with the largest target value.

The implementation process of method 2 may be: the perceptual receiving base station may form a matrix based on the peak value of the first path of each antenna channel, and perform eigendecomposition on the matrix to obtain an echo signal subspace corresponding to the echo signal component and a noise subspace orthogonal to the echo signal component. The perceptual receiving base station estimates the arrival angle of the first path using the orthogonality of the echo signal subspace and the noise subspace.

It should be noted that the above-mentioned method 1 and method 2 are only exemplary descriptions of the implementation process of the perception receiving base station analyzing the peak value of the first path of multiple antenna channels to obtain the arrival angle of the first path. The perception receiving base station can also analyze the peak value of the first path of multiple antenna channels by other methods to obtain the arrival angle of the first path, and the present application does not impose any restrictions on this.

In some examples, the above-mentioned arrival angle includes a pitch angle and/or an azimuth angle. The above is only an exemplary description of the arrival angle, and the arrival angle can also be other angles, and the present application does not impose any limitation on this.

In some implementations, the sensing receiving base station determines the position of the candidate reflection point based on the sensing receiving base station position, the sensing signal transmission angle, the sensing transmitting base station position, and the arrival angle of the first path by the following method 3 and method 4. Among them, method 3 is that the sensing receiving base station directly determines the position of the candidate reflection point. Method 4 is that the sensing receiving base station determines the position of the candidate reflection point when the length of the shortest line segment between the transmitting direction and the receiving direction is less than or equal to the third preset threshold. The above methods 3 and 4 are described below.

The implementation process of method 3 may be: the sensing receiving base station constructs a straight line equation of the transmitting direction based on the sensing transmitting base station position and the transmitting angle of the sensing signal, and constructs a straight line equation of the receiving direction based on the sensing receiving base station position and the arrival angle of the first path. The sensing receiving base station may determine the shortest line segment between the transmitting direction and the receiving direction through the straight line equation of the transmitting direction and the straight line equation of the receiving direction, and determine the position of the midpoint of the shortest line segment as the position of the selected reflection point.

The implementation process of method 4 may be: the sensing receiving base station may determine whether the length of the shortest line segment is less than or equal to a third preset threshold. When the length of the shortest line segment is less than or equal to the third preset threshold, the sensing receiving base station may determine the position of the selected reflection point based on method 3.

It should be noted that the sensing receiving base station can set the third preset threshold based on experience. For example, the sensing receiving base station can set the third preset threshold to 50 meters. The above is only an exemplary description of the third preset threshold. The third preset threshold can also be other values (for example, 45 meters). This application does not impose any limitation on this.

It can be understood that if the length of the shortest line segment is longer, it can be shown that the transmission direction of the perception signal and the receiving direction are unlikely to intersect, while the transmission direction of the normal perception signal and the receiving direction of the normal echo signal will intersect. Based on the above, when the length of the shortest line segment is greater than the third preset threshold, the perception receiving base station can determine that there is an estimated difference in the receiving direction. The problem of estimation error is solved, so there is no need to estimate the position of the candidate reflection point based on the erroneous first path arrival angle, thereby saving redundant calculations.

It should be noted that the above-mentioned method 3 and method 4 are only exemplary descriptions of the implementation process of the perception receiving base station determining the position of the selected reflection point based on the perception receiving base station position, the perception signal transmission angle, the perception transmitting base station position, and the first path arrival angle. The perception receiving base station can also determine the position of the selected reflection point based on the perception receiving base station position, the perception signal transmission angle, the perception transmitting base station position, and the first path arrival angle by other methods. The present application does not impose any restrictions on this.

Exemplarily, in conjunction with FIG5, the impulse response sequence shown in FIG5 includes five peak values. The first peak value and the second peak value of the above five peak values are both less than or equal to the second preset threshold. The third peak value of the above five paths is greater than the second preset threshold. In this example, the perceptual receiving base station can determine the path corresponding to the third peak value as the first path. In addition, the perceptual receiving base station can determine the path corresponding to the fourth peak value as the second path.

In some embodiments, the implementation process of the perception receiving base station determining the signal strength of the echo signal obtained after being reflected by the selected reflection point based on the environmental perception data can be as follows: the perception receiving base station determines the modulus value in the peak value of the first path as the signal strength of the echo signal obtained after being reflected by the selected reflection point.

Exemplarily, an example of a reflection point to be selected is shown in Fig. 9. As shown in Fig. 9, the shortest line segment between the transmitting direction and the receiving direction is line segment d, and point O is the midpoint of line segment d. In this example, the reflection point to be selected is point O.

S802: When the difference between the sum of the first distance and the second distance and the transmission distance of the perception signal is less than or equal to a first preset threshold, the perception receiving base station determines the perception information of the candidate reflection point as the perception information of the primary reflection point.

Among them, the first distance is the distance between the selected reflection point and the sensing receiving base station, and the second distance is the distance between the selected reflection point and the sensing transmitting base station.

For example, take the first distance D1 as 500 meters, the second distance D2 as 800 meters, the transmission distance D3 as 1250 meters, and the first preset threshold as 80 meters: since the difference between the sum of the first distance and the second distance and the transmission distance of the perception signal is 50 meters, and the first preset threshold is 80 meters, the perception receiving base station can determine that |D1+D2-D3| is less than the first preset threshold, and then determine the perception information of the selected reflection point as the perception information of the primary reflection point.

It should be noted that the sensing receiving base station can set the first preset threshold based on experience. For example, the sensing receiving base station can set the first preset threshold to 80 meters. The above is only an exemplary description of the first preset threshold. The first preset threshold can also be other values (for example, 70 meters). This application does not impose any restrictions on this.

In some embodiments, the implementation process of the sensing receiving base station determining the transmission distance may be: the sensing receiving base station determines the time of the peak of the first path from the impulse response sequence, and determines the product of the time of the peak of the first path and the transmission speed as the transmission distance.

In the embodiment of the present application, the sensing receiving base station obtains the sensing information of the candidate reflection point based on the environmental sensing data analysis, and determines whether the candidate reflection point is accurate based on the sum of the distances between the candidate reflection point and each base station and the transmission distance. If the difference between the sum of the first distance and the second distance and the transmission distance is less than or equal to the first preset threshold, it can be indicated that the estimated transmission distance is consistent with the actual transmission distance. The difference between the actual transmission distance and the selected reflection point is small, so that the perception receiving base station can determine the selected reflection point more accurately. In view of this, when the difference between the sum of the first distance and the second distance and the transmission distance of the perception signal is less than or equal to the first preset threshold, the perception receiving base station can determine the perception information of the selected reflection point as the perception information of the primary reflection point, which can improve the accuracy of the determined primary reflection point, and then improve the accuracy of the perception information of the determined stationary perception object.

It is understandable that, in order to realize the above functions, the communication device includes a hardware structure and/or software module corresponding to each function. It should be easily appreciated by those skilled in the art that, in conjunction with the algorithm steps of each example described in the embodiments of the present application, the present application 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 the present application.

The embodiment of the present application can divide the functional modules of the communication device according to the above method embodiment. For example, each functional module can be divided corresponding to each function, or two or more functions can be integrated into one functional module. The above integrated module can be implemented in the form of hardware or software. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. The following is an example of dividing each functional module corresponding to each function.

FIG10 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application, and the communication device can execute the wireless sensing method of the environment depth provided in the above method embodiment. As shown in FIG10 , the communication device 100 includes: a communication unit 1001 and a processing unit 1002 .

The communication unit 1001 is used to receive an echo signal, where the echo signal is a signal after the perception signal sent by the perception transmitting base station is reflected by a perception object in the environment; the perception object in the environment includes a dynamic perception object and a stationary perception object;

The processing unit 1002 is used to determine the perception information of the stationary perception object according to the echo signal.

In some embodiments, the echo signal includes a signal after the perception signal sent by the perception transmitting base station in the transmission direction in the nth cycle is reflected by the perception object in the environment; n is a positive integer; and the communication unit 1001 is also used for receiving in the nth cycle.

In some embodiments, the echo signal includes echo signals received at multiple times in the nth cycle based on multiple antenna channels; the processing unit 1002 is also used to perform Doppler analysis on the echo signal to obtain environmental perception data, and the environmental perception data is used to represent the impulse response sequence of the echo signal reflected by the stationary perception object; the impulse response sequence is used to represent the phase information and amplitude information of the echo signal under different time delays; the processing unit 1002 is also used to determine the perception information of the stationary perception object based on the environmental perception data.

In some embodiments, the processing unit 1002 is further used to determine the perception information of a primary reflection point based on the environmental perception data, where the primary reflection point is the point where the perception signal is first reflected by a stationary perception object; the processing unit 1002 is further used to determine the perception information of the primary reflection point as the perception information of the stationary perception object.

In some embodiments, the processing unit 1002 is further configured to determine the perception information of the candidate reflection point based on the environmental perception data. The selected reflection point is the midpoint of the shortest line segment between the transmitting direction and the receiving direction, the transmitting direction is the direction in which the perception transmitting base station sends the perception signal, and the receiving direction is the direction in which the perception receiving base station receives the echo signal; when the difference between the sum of the first distance and the second distance and the transmission distance of the perception signal is less than or equal to the first preset threshold, the processing unit 1002 is also used to determine the perception information of the selected reflection point as the perception information of the primary reflection point, the first distance is the distance between the selected reflection point and the perception receiving base station, and the second distance is the distance between the selected reflection point and the perception transmitting base station.

In some embodiments, the sensing information includes the position and/or the signal strength of the echo signal obtained after being reflected by the stationary sensing object.

In some embodiments, the processing unit 1002 is also used to determine the peak value of the first path from the impulse response sequence; the first path is the first path in the impulse response sequence of the perception signal whose peak value is greater than a second preset threshold; the processing unit 1002 is also used to analyze the peak value of the first path of multiple antenna channels to obtain the arrival angle of the first path; the processing unit 1002 is also used to determine the position of the selected reflection point based on the position of the perceived receiving base station, the transmission angle of the perceived signal, the position of the perceived transmitting base station, and the arrival angle of the first path.

In some embodiments, when the length of the shortest line segment is less than or equal to a third preset threshold, the processing unit 1002 is further used to determine the position of the selected reflection point based on the position of the perceived receiving base station, the transmission angle of the perceived signal, the position of the perceived transmitting base station, and the arrival angle of the first path.

In some embodiments, the processing unit 1002 is further used to perform Doppler analysis on the echo signal to obtain a delay Doppler spectrum; the processing unit 1002 is further used to determine the data in the delay Doppler spectrum that is within a preset frequency range as environmental perception data.

In some embodiments, the processing unit 1002 is further configured to determine the modulus value in the peak value of the first path as the signal strength of the echo signal obtained after being reflected by the to-be-selected reflection point.

In some embodiments, the processing unit 1002 is further used to determine the time of the peak of the first path from the impulse response sequence; the processing unit 1002 is further used to determine the product of the time of the peak of the first path and the transmission speed as the transmission distance.

In some embodiments, the communication processing unit is also used to receive configuration information from the application server; the configuration information includes: time information, period information, time-frequency resource information, and direction sending rules for the first transmission of the perception signal; the period information includes the perception signal transmission period and the number of moments in the perception signal transmission period; the direction sending rules include: initial direction and direction step.

In some embodiments, the processing unit 1002 is further configured to draw a perception environment map based on the perception information of the stationary perception object.

In some embodiments, the communication unit 1001 is further used to send the perception information of the stationary perception object to the application server.

In specific implementation, the devices in Figure 1 can all adopt the composition structure shown in Figure 11, or include the components shown in Figure 11. Figure 11 is a schematic diagram of the composition of a communication device 110 provided in an embodiment of the present application. As shown in Figure 11, the communication device 110 may include a processor 1101, a communication line 1102, a communication interface 1103, and a memory 1104. Among them, the processor 1101, the memory 1104 and the communication interface 1103 can be connected through the communication line 1102.

The processor 1101 is a CPU, a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device (PLD), or a microcontroller. The processor 1101 may also be other devices with processing functions, such as circuits, devices or software modules, without limitation.

The communication line 1102 is used to transmit information between the components included in the communication device 110 .

The communication interface 1103 is used to communicate with other devices or other communication networks. The other communication networks may be Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc. The communication interface 1103 may be a module, a circuit, a communication interface or any device capable of achieving communication.

The memory 1104 is used to store instructions, where the instructions may be computer programs.

Among them, the memory 1104 can be a read-only memory (ROM) or other types of static storage devices that can store static information and/or instructions, or a random access memory (RAM) or other types of dynamic storage devices that can store information and/or instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), magnetic disk storage media or other magnetic storage devices, etc., without limitation.

It should be noted that the memory 1104 can exist independently of the processor 1101, or can be integrated with the processor 1101. The memory 1104 can be used to store instructions or program codes or some data, etc. The memory 1104 can be located in the communication device 110, or can be located outside the communication device 110, without limitation. The processor 1101 is used to execute the instructions stored in the memory 1104 to implement the wireless perception method of the environment depth provided in the following embodiments of the present application.

In one example, the processor 1101 may include one or more CPUs, for example, CPU0 and CPU1.

As an implementation, the communication device 110 includes multiple processors.

As an implementation, the communication device 110 further includes an output device and an input device. Exemplarily, the input device is a keyboard, a mouse, a microphone, a joystick, and the like, and the output device is a display screen, a speaker, and the like.

It should be noted that the communication device 110 may be a desktop computer, a portable computer, a network server, a mobile phone, a tablet computer, a wireless terminal, an embedded device, a chip system, or a device having a similar structure as shown in FIG11. In addition, the composition structure shown in FIG11 does not constitute a limitation on the devices in FIG1 and FIG11. In addition to the components shown in FIG11, the devices in FIG1 and FIG11 may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

In the embodiments of the present application, the chip system may be composed of a chip, or may include a chip and other discrete devices. Some embodiments of the present application provide a computer-readable storage medium (e.g., a non-transitory computer-readable storage medium), which stores computer program instructions. When the computer program instructions are executed on a computer, the computer executes the wireless sensing method of the environment depth in any of the above embodiments.

Exemplarily, the computer-readable storage medium may include, but is not limited to: a magnetic storage device (e.g., a hard disk, a floppy disk, or a magnetic tape), an optical disk (e.g., a compact disk (CD), a digital versatile disk (DVD), The various computer-readable storage media described herein may represent one or more devices and/or other machine-readable storage media for storing information. The term "machine-readable storage medium" may include, but is not limited to, wireless channels and various other media capable of storing, containing and/or carrying instructions and/or data.

An embodiment of the present application provides a computer program product comprising instructions. When the computer program product is run on a computer, the computer is enabled to execute the wireless perception method of environmental depth described in any of the above embodiments.

The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims (16)

A method for wireless perception of environmental depth, characterized in that it is applied to perceive a receiving base station, and the method comprises: receiving an echo signal, wherein the echo signal is a signal after a perception signal sent by a perception transmitting base station is reflected by a perception object in an environment; the perception object in the environment includes a dynamic perception object and a stationary perception object; The perception information of the stationary perception object is determined according to the echo signal. The method according to claim 1 is characterized in that the echo signal comprises a signal after the perception signal sent by the perception transmitting base station in the transmission direction of the nth cycle is reflected by the perception object in the environment; n is a positive integer; The receiving echo signal comprises: The echo signal is received in the nth period. The method according to claim 2, characterized in that the echo signal comprises echo signals received at multiple times in the nth period based on multiple antenna channels; The determining, according to the echo signal, the perception information of the stationary perception object comprises: Performing Doppler analysis on the echo signal to obtain environmental perception data, wherein the environmental perception data is used to represent an impulse response sequence of the echo signal reflected by the stationary perception object; the impulse response sequence is used to represent phase information and amplitude information of the echo signal under different time delays; Based on the environmental perception data, perception information of the stationary perception object is determined. The method according to claim 3, characterized in that the determining the perception information of the stationary perception object based on the environmental perception data comprises: Determine, based on the environmental perception data, perception information of a primary reflection point, where the primary reflection point is a point where the perception signal is reflected by the stationary perception object for the first time; The perception information of the primary reflection point is determined as the perception information of the stationary perception object. The method according to claim 4, characterized in that the step of determining the perception information of a primary reflection point based on the environmental perception data comprises: Based on the environmental perception data, determining perception information of a candidate reflection point, the candidate reflection point being the midpoint of the shortest line segment between a transmitting direction and a receiving direction, the transmitting direction being the direction in which the perception transmitting base station sends the perception signal, and the receiving direction being the direction in which the perception receiving base station receives the echo signal; When the difference between the sum of the first distance and the second distance and the transmission distance of the perception signal is less than or equal to a first preset threshold, the perception information of the selected reflection point is determined as the perception information of the primary reflection point, the first distance is the distance between the selected reflection point and the perception receiving base station, and the second distance is the distance between the selected reflection point and the perception transmitting base station. The method according to claim 5 is characterized in that the perception information includes the position and/or the signal strength of the echo signal obtained after being reflected by the stationary perception object. The method according to claim 6, characterized in that the method further comprises: Determine the peak value of the first path from the impulse response sequence; the first path is the first path in the impulse response sequence of the perception signal, the peak value of which is greater than a second preset threshold; Analyze the peak values of the first paths of the multiple antenna channels to obtain the arrival angles of the first paths; The position of the candidate reflection point is determined based on the position of the sensing receiving base station, the transmission angle of the sensing signal, the position of the sensing transmitting base station, and the arrival angle of the first path. The method according to claim 7 is characterized in that the determining the position of the candidate reflection point based on the position of the sensing receiving base station, the transmission angle of the sensing signal, the position of the sensing transmitting base station, and the arrival angle of the first path comprises: When the length of the shortest line segment is less than or equal to a third preset threshold, the position of the selected reflection point is determined based on the position of the perception receiving base station, the transmission angle of the perception signal, the position of the perception transmitting base station, and the arrival angle of the first path. The method according to claim 3, characterized in that the step of performing Doppler analysis on the echo signal to obtain environmental perception data comprises: Performing Doppler analysis on the echo signal to obtain a delay Doppler spectrum; The data in the delay Doppler spectrum that is within a preset frequency range is determined as the environmental sensing data. The method according to claim 8, characterized in that the method further comprises: The modulus value in the peak value of the first path is determined as the signal strength of the echo signal obtained after being reflected by the to-be-selected reflection point. The method according to claim 8, characterized in that the method further comprises: Determining the time of the peak of the first path from the impulse response sequence; The product of the time of the peak of the first path and the transmission speed is determined as the transmission distance. The method according to any one of claims 1 to 11, characterized in that the method further comprises: Receive configuration information from an application server; the configuration information includes: time information, period information, time-frequency resource information, and direction sending rules for the first transmission of the perception signal; the period information includes the perception signal transmission period and the number of moments in the perception signal transmission period; the direction sending rules include: initial direction and direction step. The method according to any one of claims 1 to 11, characterized in that the method further comprises: Based on the perception information of the stationary perception object, a perception environment map is drawn. The method according to any one of claims 1 to 11, characterized in that the method further comprises Send the perception information of the stationary perception object to the application server. A communication device, comprising: a processor and a memory; The memory stores instructions executable by the processor; When the processor is configured to execute the instructions, the communication device implements the wireless perception method of environment depth according to any one of claims 1 to 14. A computer-readable storage medium, characterized in that computer instructions are stored on the computer-readable storage medium, and when the computer instructions are executed on a communication device, the communication device executes the wireless perception method of environmental depth as described in any one of claims 1 to 14.