A method and device for identifying a wireless signal line-of-sight propagation environment

Abstract

The present invention provides a method and device for identifying a line-of-sight propagation environment for wireless signals. During the movement of a terminal, CSI data is read at set time intervals, and the speed information of the terminal movement is collected; the positioning area of ​​the terminal is determined, and a hologram of the positioning area is constructed using the read CSI data and the collected speed information; the peak-to-average ratio of the hologram is calculated; and according to the peak-to-average ratio, whether the current propagation environment is a line-of-sight propagation type is determined. The present invention utilizes channel state information during wireless communication to realize the identification of the line-of-sight propagation environment for wireless signals without the need for dedicated measuring equipment, and is suitable for the identification of line-of-sight propagation environments when the terminal is moving.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a method and device for identifying a wireless signal line-of-sight propagation environment suitable for OFDM communication. Background Art

[0002] Wireless signal line-of-sight propagation environment recognition has a wide range of uses in indoor positioning and other fields, and is crucial for achieving robust and accurate positioning. At present, although some theoretical models can be used to describe wireless channel parameters such as the Rice factor, and then distinguish the line-of-sight propagation environment of wireless signals, it requires the use of special channel listening equipment or long-term channel measurement to achieve; and in many cases, such as WiFi communication, the channel bandwidth is limited, and it is difficult to use the channel impulse response (CIR) to achieve the recognition of the line-of-sight propagation environment. In addition, the existing wireless signal line-of-sight propagation environment recognition methods are mostly for the recognition of the terminal in a stationary state, and there is still a lack of effective methods for the recognition of the wireless signal line-of-sight propagation environment when the terminal is moving. Summary of the invention

[0003] The purpose of the present invention is to provide a method and device for identifying a wireless signal line-of-sight propagation environment based on channel state information (CSI) to solve the problem of identifying a wireless signal line-of-sight propagation environment when a terminal is moving.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] On the one hand, a method for identifying a wireless signal line-of-sight propagation environment includes:

[0006] When the terminal is moving, the CSI data is read at set time intervals and the speed information of the terminal is collected;

[0007] Determine the positioning area of ​​the terminal, and construct a hologram of the positioning area using the read CSI data and the collected speed information;

[0008] calculating a peak-to-average ratio of the hologram;

[0009] According to the peak-to-average ratio, it is determined whether the current propagation environment is line-of-sight propagation.

[0010] Furthermore, the method of constructing a hologram of the positioning area by using the read CSI data and the collected speed information includes:

[0011] Taking a certain position in the positioning area as the initial point, performing iterative search in the positioning area along different coordinate axis directions at a predetermined position sampling granularity to obtain multiple position points;

[0012] Each position point is assumed to be the current position of the terminal. Based on the current position, combined with the speed information of the terminal and the CSI reading time interval, the position of the position trajectory points corresponding to all CSI data collections before the current position point is calculated;

[0013] According to the calculated positions of the current position point and all the previous position trajectory points, combined with the base station position and the communication frequency point, the phase theoretical value of the direct signal at the current position point and all the previous position trajectory points is calculated respectively;

[0014] According to the theoretical phase value of the direct signal at the current position and all previous position trajectory points, combined with the phase measurement value of the signal at the actual position trajectory point, the target search function of the current position point is calculated, and the target search functions of all position points constitute the hologram of the positioning area; wherein the phase measurement value is obtained from the read CSI data.

[0015] Furthermore, the positions of all position trajectory points before the current position point are calculated according to the following formula:

[0016] p i =p N -v·Δt·(Ni), i=1,2,…,N

[0017] In the formula, p i represents the position of the terminal at the i-th position trajectory point, p N represents the current location of the terminal, N represents the number of location points, v represents the speed of the terminal movement, and Δt represents the CSI reading time interval.

[0018] Furthermore, the theoretical phase value of the direct signal at the current position point and all previous position trajectory points is calculated according to the following formula:

[0019] ∠CSI i,d =(2π|p BS -p i |f i / c)mod2π

[0020] Where, ∠CSI i,d represents the theoretical phase value of the direct signal at the i-th position trajectory point; p BS represents the base station location; p i represents the position of the i-th trajectory point; |p BS -p i | represents the distance between the mobile terminal and the base station at the i-th trajectory point; f i is the communication signal frequency at the i-th position trajectory point; c represents the wireless signal propagation rate.

[0021] Furthermore, the target search function is calculated according to the following formula:

[0022]

[0023] In the formula, p(x,y) represents a point in the positioning area, OSF p(x,y) represents the target search function at position p(x,y), ∠CSI i Represents the phase measurement value at the i-th position trajectory point, which is obtained from the read CSI data, ∠CSI i,d Represents the theoretical phase value of the direct signal at the i-th position trajectory point.

[0024] Furthermore, the peak-to-average ratio is calculated according to the following formula:

[0025]

[0026] In the formula, I represents the hologram, ρ represents the peak-to-average ratio of hologram I, max(I) represents the maximum value of each element in hologram I, and mean(I) represents the average value of each element in hologram I.

[0027] Further, judging whether the current propagation environment is line-of-sight propagation according to the peak-to-average ratio includes:

[0028] Determine whether the peak-to-average ratio is greater than the set peak-to-average ratio threshold. If it is greater than the peak-to-average ratio threshold, determine that the current propagation environment is line-of-sight (LOS) propagation; if it is less than the peak-to-average ratio threshold, determine that the current propagation environment is non-line-of-sight (NLOS) propagation.

[0029] Furthermore, the peak-to-average ratio threshold is determined by the following method:

[0030] Measure the peak-to-average ratio in an actual line-of-sight propagation environment, and take the average or median value to obtain the mean peak-to-average ratio in the actual line-of-sight propagation environment;

[0031] Measure the peak-to-average ratio in an actual non-line-of-sight propagation environment, and take the average or median value to obtain the mean peak-to-average ratio in the actual non-line-of-sight propagation environment;

[0032] The peak-to-average ratio threshold of the hologram is obtained by taking the average or median of the peak-to-average ratio mean value in the actual line-of-sight propagation environment and the peak-to-average ratio mean value in the actual non-line-of-sight propagation environment.

[0033] On the other hand, a wireless signal line-of-sight propagation environment recognition device includes:

[0034] The acquisition module is configured to read the CSI data at a set time interval during the movement of the terminal and to collect the speed information of the terminal movement;

[0035] A hologram construction module is configured to determine a positioning area of ​​the terminal and construct a hologram of the positioning area using the read CSI data and the collected speed information;

[0036] a peak-to-average ratio calculation module, configured to calculate the peak-to-average ratio of the hologram;

[0037] A judgment module is configured to judge whether the current propagation environment is line-of-sight propagation according to the peak-to-average ratio

[0038] Furthermore, the hologram construction module comprises:

[0039] A position search module is configured to take a position in the positioning area as an initial point, perform iterative search in the positioning area along different coordinate axis directions at a predetermined position sampling granularity, and obtain multiple position points;

[0040] The trajectory point estimation module is configured to assume each position point as the current position of the terminal, and estimate the position of the position trajectory points corresponding to all CSI data collections before the current position point according to the current position, combined with the speed information of the terminal and the CSI reading time interval;

[0041] The phase theoretical value calculation module is configured to calculate the phase theoretical values ​​of the direct signals at the current position point and all the previous position trajectory points according to the calculated positions of the current position point and all the previous position trajectory points, combined with the base station position and the communication frequency point;

[0042] The target search function calculation module is configured to calculate the target search function of the current position point based on the theoretical phase value of the direct signal at the current position and all previous position trajectory points, combined with the phase measurement value of the signal at the actual position trajectory point; wherein the phase measurement value is obtained from the read CSI data.

[0043] Compared with the prior art, the beneficial technical effect of the present invention is that the present invention utilizes the channel state information in the wireless communication process to realize the identification of the line-of-sight propagation environment of the wireless signal without the need for special measurement equipment, and is suitable for the identification of the line-of-sight propagation environment when the terminal is moving. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a flow chart of a method for identifying a wireless signal line-of-sight propagation environment according to an embodiment of the present invention;

[0045] Figure 2 is a flow chart of constructing a hologram according to an embodiment of the present invention;

[0046] Figure 3 It is a structural diagram of a wireless signal line-of-sight propagation environment identification device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with specific examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention.

[0048] like Figure 1 As shown, a method for identifying a wireless signal line-of-sight propagation environment includes:

[0049] Step 1: During the movement of the terminal, the CSI data is read at a set time interval and the speed information of the terminal movement is collected;

[0050] During the movement, the mobile terminal P reads the speed information v from the equipped inertial measurement unit and periodically reads the CSI data from the communication signal. The CSI reading time interval Δt is known. Each CSI data corresponds to a position trajectory point, and each CSI data includes information such as the phase measurement value and amplitude value at the corresponding position trajectory point.

[0051] Step 2, determining the positioning area of ​​the terminal, and constructing a hologram of the positioning area using the read CSI data and the collected speed information;

[0052] Determine the possible location area of ​​the terminal P to be located. The range of the location area in the x-axis direction is [x min ,x max ], and the range in the y-axis direction is [y min ,y max ].

[0053] Combination Figure 2 As shown, the method for constructing the positioning area hologram specifically includes:

[0054] S201, taking a position in the positioning area as an initial point, performing an iterative search in the positioning area along different coordinate axis directions at a predetermined position sampling granularity to obtain a plurality of position points;

[0055] In one embodiment, if Figure 2 As shown, the position p(x min ,y min ), is the initial position, keep the y value unchanged, slide along the x-axis with the position sampling granularity ΔL, and obtain the position points p(x min ,y min )、p(x min +ΔL,y min )、p(x min +2ΔL,y min ), ..., until x min +m·ΔL>x max; Then, for each position point obtained, keep the x value unchanged and slide along the y-axis direction with the position sampling granularity ΔL, thereby obtaining a series of new position points respectively.

[0056] Among them, the position in the positioning area can be expressed by p(x,y):

[0057]

[0058] Wherein, ΔL represents the position sampling granularity, m=0, 1, 2…, n=0, 1, 2….

[0059] S202, assuming each position point as the current position of the terminal, and calculating the positions of all position trajectory points corresponding to the channel state information collection before the current position point according to the current position, combined with the speed information of the terminal and the channel state information reading time interval;

[0060] Assume that the current position of the terminal P to be located is p N According to the velocity information v, the position {p1,…,p N}. The specific calculation formula is as follows:

[0061] p i =p N -v·Δt·(Ni), i=1,2,…,N

[0062] In the formula, p i represents the position of the i-th position trajectory point, p N represents the current location of the terminal, N represents the number of location points, v represents the speed of the terminal movement, and Δt represents the CSI reading time interval.

[0063] S203, calculating the phase theoretical values ​​of the direct signals at the current position point and all the previous position trajectory points respectively according to the calculated positions of the current position point and all the previous position trajectory points, in combination with the base station position and the communication frequency point;

[0064] The specific calculation formula is as follows:

[0065] ∠CSI i,d =(2π|p BS -p i |f i / c)mod 2π

[0066] Where, ∠CSI i,d represents the theoretical phase value of the direct signal at the i-th position trajectory point; p BS represents the base station location; p i represents the position of the i-th trajectory point; |p BS-p i | represents the distance between the mobile terminal and the base station at the i-th trajectory point; f i is the communication signal frequency at the i-th position trajectory point, which is a known quantity; c represents the wireless signal propagation rate.

[0067] S204, calculating the target search function of the current position point according to the phase theoretical value of the direct signal at the current position and all previous position trajectory points, combined with the phase measurement value of the signal at the actual position trajectory point;

[0068] The target search function is calculated according to the following formula:

[0069]

[0070] In the formula, OSF p(x,y) represents the target search function at position p(x,y); ∠CSI i represents the CSI phase measurement value at the i-th position trajectory point, which is obtained from the read CSI data; ∠CSI i,d Represents the theoretical phase value of the direct signal at the i-th position trajectory point.

[0071] The target search function is calculated for all position points in the positioning area I, and the hologram of the positioning area I is constructed as follows:

[0072]

[0073] The two-dimensional case is given here, which can be easily extended to the three-dimensional case.

[0074] Step 3, calculating the peak-to-average ratio of the hologram;

[0075] The peak-to-average ratio of hologram I is calculated according to the following formula:

[0076]

[0077] Wherein, ρ represents the peak-to-average ratio of hologram I, max(I) represents the maximum value of each element in hologram I, and mean(I) represents the average value of each element in hologram I.

[0078] Step 4: determine whether the current propagation environment is line-of-sight propagation according to the peak-to-average ratio.

[0079] According to whether the peak-to-average ratio is greater than a preset peak-to-average ratio threshold, it is determined that the current propagation environment is LOS propagation or NLOS propagation.

[0080] Among them, the hologram peak-to-average ratio threshold ρ th It is set according to the actual test data of the indoor environment. The hologram peak-to-average ratio threshold can be determined by various methods such as actual measurement and self-learning.

[0081] In one embodiment, the method for determining the hologram peak-to-average ratio threshold is:

[0082] Measure the peak-to-average ratio in the actual line-of-sight propagation environment and obtain its average value Measure the peak-to-average ratio in an actual non-line-of-sight propagation environment and obtain its average value Set the hologram peak-to-average ratio threshold to the average of the above two values, that is,

[0083] In other embodiments, it can also be determined according to the following method:

[0084] Measure the peak-to-average ratio in the actual line-of-sight propagation environment, and take the value to obtain the average peak-to-average ratio in the actual line-of-sight propagation environment;

[0085] The peak-to-average ratio is measured in an actual non-line-of-sight propagation environment, and the value is taken to obtain the average peak-to-average ratio in the actual non-line-of-sight propagation environment;

[0086] The median of the peak-to-average ratio average value in the actual line-of-sight propagation environment and the peak-to-average ratio average value in the actual non-line-of-sight propagation environment is taken to obtain the hologram peak-to-average ratio threshold value.

[0087] Perform a double-select test on the hologram peak-to-average ratio:

[0088]

[0089] Among them, H0 represents LOS environment, and H1 represents NLOS environment.

[0090] When the hologram peak-to-average ratio ρ is greater than the set threshold ρ th When , the current environment is determined to be LOS propagation environment; when the hologram peak-to-average ratio ρ is less than the set threshold ρ th , it is determined that the current propagation environment is NLOS.

[0091] In another embodiment, a wireless signal line-of-sight propagation environment recognition device, such as Figure 3 As shown, including:

[0092] The acquisition module 301 is configured to read the CSI data at a set time interval during the movement of the terminal and to collect the speed information of the terminal movement;

[0093] A hologram construction module 302 is configured to determine a location area of ​​the terminal and construct a hologram of the location area using the acquired CSI data and speed information;

[0094] A peak-to-average ratio calculation module 303, configured to calculate the peak-to-average ratio of the hologram;

[0095] The judgment module 304 is configured to judge whether the current propagation environment is line-of-sight propagation according to the peak-to-average ratio.

[0096] Among them, the hologram building module includes:

[0097] A position search module is configured to take a position in the positioning area as an initial point, perform iterative search in the positioning area along different coordinate axis directions at a predetermined position sampling granularity, and obtain multiple position points;

[0098] The trajectory point estimation module is configured to assume each position point as the current position of the terminal, and estimate the position of the position trajectory points corresponding to all CSI data collections before the current position point according to the current position, combined with the speed information of the terminal and the CSI reading time interval;

[0099] The phase theoretical value calculation module is configured to calculate the phase theoretical values ​​of the direct signal at the current position point and all the previous position trajectory points according to the calculated positions of the current position point and all the previous position trajectory points, combined with the base station position and the communication frequency point;

[0100] The target search function calculation module is configured to calculate the target search function of the current position point based on the phase theoretical value of the direct signal at the current position and all previous position trajectory points combined with the phase measurement value of the signal at the actual position trajectory point, and the target search functions of all position points constitute a hologram of the positioning area; wherein the phase measurement value is obtained from the read CSI data.

[0101] The present invention reads the channel state information during the terminal movement process; constructs a hologram in combination with the speed information provided by the inertial measurement unit; calculates the peak-to-average ratio of the hologram; and performs a double-selection test on the peak-to-average ratio of the hologram to determine whether the current environment is a line-of-sight propagation environment for wireless signals. The method uses the channel state information during wireless communication to realize the identification of the line-of-sight propagation environment for wireless signals, does not require special measurement equipment, and is suitable for identifying the line-of-sight propagation environment when the terminal is moving.

[0102] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0103] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0104] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0105] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0106] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for identifying a wireless signal line-of-sight propagation environment, characterized in that: include: When the terminal is moving, the CSI data is read at set time intervals and the speed information of the terminal is collected; Determine the positioning area of ​​the terminal, and construct a hologram of the positioning area using the read CSI data and the collected speed information; calculating a peak-to-average ratio of the hologram; According to the peak-to-average ratio, determining whether the current propagation environment is line-of-sight propagation; The method of constructing a hologram of the positioning area by using the read CSI data and the collected speed information includes: Taking a certain position in the positioning area as the initial point, performing iterative search in the positioning area along different coordinate axis directions at a predetermined position sampling granularity to obtain multiple position points; Each position point is assumed to be the current position of the terminal. Based on the current position, combined with the speed information of the terminal and the CSI reading time interval, the position of the position trajectory points corresponding to all CSI data collections before the current position point is calculated; According to the calculated positions of the current position point and all the previous position trajectory points, combined with the base station position and the communication frequency point, the phase theoretical value of the direct signal at the current position point and all the previous position trajectory points is calculated respectively; According to the phase theoretical value of the direct signal at the current position and all previous position trajectory points, combined with the phase measurement value of the signal at the real position trajectory point, the target search function of the current position point is calculated, and the target search functions of all position points constitute the hologram of the positioning area; wherein the phase measurement value is obtained from the read CSI data; The determining, according to the peak-to-average ratio, whether the current propagation environment is line-of-sight propagation includes: Determine whether the peak-to-average ratio is greater than a set peak-to-average ratio threshold. If it is greater than the peak-to-average ratio threshold, determine that the current propagation environment is line-of-sight propagation. If it is less than the peak-to-average ratio threshold, determine that the current propagation environment is non-line-of-sight propagation.

2. A method for identifying a wireless signal line-of-sight propagation environment according to claim 1, characterized in that: The positions of all position trajectory points before the current position point are calculated according to the following formula: ， ； In the formula, p i represents the position of the terminal at the i-th position trajectory point, p N represents the current location of the terminal, N represents the number of location points, v represents the moving speed of the terminal, and Δt represents the CSI reading time interval.

3. The method for identifying a wireless signal line-of-sight propagation environment according to claim 1, characterized in that: The theoretical phase value of the direct signal at the current position point and all previous position trajectory points is calculated according to the following formula: ； In the formula, represents the theoretical phase value of the direct signal at the i-th position trajectory point; p BS represents the base station location; p i represents the position of the i-th trajectory point; represents the distance between the mobile terminal and the base station at the i-th trajectory point; f i represents the communication signal frequency at the i-th position trajectory point; c represents the wireless signal propagation rate.

4. The method for identifying a wireless signal line-of-sight propagation environment according to claim 1, characterized in that: The target search function is calculated according to the following formula: ； In the formula, p(x, y) represents a point in the positioning area. represents the target search function at position p(x, y), Represents the phase measurement value at the i-th position trajectory point, which is obtained from the read CSI data. Represents the theoretical phase value of the direct signal at the i-th position trajectory point.

5. The method for identifying a wireless signal line-of-sight propagation environment according to claim 1, characterized in that: The peak-to-average ratio is calculated according to the following formula: ； Where I represents the hologram, represents the peak-to-average ratio of hologram I, represents the maximum value of each element in hologram I, Represents the average value of each element in hologram I.

6. The method for identifying a wireless signal line-of-sight propagation environment according to claim 1, characterized in that: The peak-to-average ratio threshold is determined by the following method: Measure the peak-to-average ratio in an actual line-of-sight propagation environment, and take the average or median value to obtain the mean peak-to-average ratio in the actual line-of-sight propagation environment; Measure the peak-to-average ratio in an actual non-line-of-sight propagation environment, and take the average or median value to obtain the mean peak-to-average ratio in the actual non-line-of-sight propagation environment; The peak-to-average ratio threshold of the hologram is obtained by taking the average or median of the peak-to-average ratio mean value in the actual line-of-sight propagation environment and the peak-to-average ratio mean value in the actual non-line-of-sight propagation environment.

7. A wireless signal line-of-sight propagation environment recognition device, characterized in that: include: The acquisition module is configured to read the CSI data at a set time interval during the movement of the terminal and to collect the speed information of the terminal movement; A hologram construction module is configured to determine the positioning area of ​​the terminal, and to construct a hologram of the positioning area using the read CSI data and the collected speed information; it includes: a position search module, configured to take a certain position in the positioning area as the initial point, and to perform iterative search in the positioning area along different coordinate axis directions at a predetermined position sampling granularity to obtain multiple position points; a trajectory point calculation module, configured to assume each position point as the current position of the terminal, and to calculate the position of the position trajectory point corresponding to all CSI data collections before the current position point according to the current position, combined with the speed information of the terminal and the CSI reading time interval; a phase theoretical value calculation module, configured to calculate the phase theoretical value of the direct signal at the current position point and all the previous position trajectory points according to the calculated positions of the current position point and all the previous position trajectory points, combined with the base station position and the communication frequency; a target search function calculation module, configured to calculate the target search function of the current position point according to the phase theoretical value of the direct signal at the current position and all the previous position trajectory points, combined with the phase measurement value of the signal at the real position trajectory point; wherein the phase measurement value is obtained from the read CSI data; a peak-to-average ratio calculation module, configured to calculate the peak-to-average ratio of the hologram; The judgment module is configured to judge whether the current propagation environment is line-of-sight propagation according to the peak-to-average ratio, including: judging whether the peak-to-average ratio is greater than a set peak-to-average ratio threshold; if it is greater than the peak-to-average ratio threshold, judging that the current propagation environment is line-of-sight propagation; if it is less than the peak-to-average ratio threshold, judging that the current propagation environment is non-line-of-sight propagation.

Images