Wireless communication system, wireless capture device, wireless communication method, and wireless communication program

Abstract

To provide a wireless communication system capable of measuring propagation channel information at a time when there is movement of objects in a target area.SOLUTION: A wireless communication system includes a base station, a wireless terminal, a sound detection device, and a wireless capture device that captures wireless frames. The sound detection device detects sounds occurring in a target area of wireless communication. The wireless capture device extracts propagation channel information from the wireless frames while targeting wireless frames captured at the time when the sound is detected by the sound detection device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to techniques for measuring propagation channel information. [Background technology]

[0002] A technique has been disclosed for estimating the location of a wireless terminal whose installation location is unknown by utilizing propagation channel information (Channel State Information, hereinafter referred to as CSI) exchanged between a wireless base station and a plurality of wireless terminals whose installation locations are known and a wireless terminal whose installation location is unknown (see, for example, Patent Document 1). The location of the wireless terminal whose installation location is unknown can be estimated from the correlation between the CSI derived from each wireless terminal whose installation location is known and the CSI derived from the wireless terminal whose installation location is unknown. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-019158 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned method, the CSI is measured even during times when the movement of objects in the target area is small or when there is no movement of objects. The CSI measured during such times has small fluctuations, and it can be said that the estimation accuracy is low even if it is used to estimate the position of a wireless terminal.

[0005] In order to solve the above-mentioned problems, a first object of the present disclosure is to provide a wireless communication system capable of measuring CSI at a time when there is movement of an object in a target area.

[0006] A second object of the present disclosure is to provide a wireless capture device capable of measuring CSI at a time when there is movement of an object in a target area.

[0007] A third object of the present disclosure is to provide a wireless communication method capable of measuring CSI at a time when there is movement of an object in a target area.

[0008] A fourth object of the present disclosure is to provide a wireless communication program capable of measuring CSI at a time when there is movement of an object in a target area. [Means for solving the problem]

[0009] The first aspect of the present disclosure is A wireless communication system that measures propagation channel information included in a wireless frame transmitted and received in wireless communication between a base station and a wireless terminal, The base station; The wireless terminal; A sound detection device; a wireless capture device for capturing the wireless frames; Equipped with The sound detection device is configured to execute a process of detecting a sound generated in a target area of ​​the wireless communication, The wireless capture device is preferably configured to perform an extraction process for extracting propagation channel information from the wireless frames captured at the time when a sound is detected by the sound detection device.

[0010] The second aspect is as follows: A wireless capture device that captures wireless frames transmitted and received in wireless communication between a base station and a wireless terminal and measures propagation channel information included in the wireless frames, comprising: It is preferable that the apparatus is configured to perform an extraction process for extracting propagation channel information from the radio frames captured at the time when the sound is detected by a sound detection device that detects sound generated in a target area of ​​the wireless communication.

[0011] The third aspect is as follows: A wireless communication method for measuring propagation channel information included in a wireless frame transmitted and received in wireless communication between a base station and a wireless terminal, comprising: A sound detection device detects a sound generated in a target area of ​​the wireless communication; a wireless capture device that captures the wireless frames extracts propagation channel information from the wireless frames captured at a time when the sound is detected by the sound detection device; It is preferred that the compound contains

[0012] The fourth aspect is as follows: A wireless communication program to be executed by a wireless capture device that captures wireless frames transmitted and received in wireless communication between a base station and a wireless terminal and measures propagation channel information included in the wireless frames, the program comprising: For wireless capture devices, It is preferable that the information processing device includes a program for executing an extraction process to extract propagation channel information from the wireless frames captured at the time when the sound is detected by a sound detection device that detects sound generated in the target area of ​​the wireless communication. Effect of the Invention

[0013] In the present disclosure, the movement of an object in a target area is detected as sound, and CSI is extracted from a wireless frame captured during the time when the sound is detected. This makes it possible to provide a wireless communication system, a wireless capture device, a wireless communication method, and a wireless communication program capable of measuring CSI during the time when an object in a target area moves. [Brief description of the drawings]

[0014] [Figure 1] 1 is a configuration example of a wireless communication system according to a first embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating a configuration of a conventional wireless communication system. [Diagram 3] FIG. 1 is a diagram illustrating an example of CSI measured in a conventional wireless communication system. [Figure 4] FIG. 1 is a diagram illustrating a problem in a conventional wireless communication system. [Diagram 5]FIG. 2 is a diagram illustrating a method for extracting CSI in a wireless communication system according to a first embodiment of the present disclosure. [Figure 6] 1 is a block diagram showing an example configuration of a wireless capturing device in accordance with a first embodiment of the present disclosure. [Figure 7] 4 is an example of data stored in a storage unit according to the first embodiment of the present disclosure. [Figure 8] FIG. 2 is a diagram illustrating an example of compressed CSI according to the first embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0016] First embodiment 1 is a configuration example of a wireless communication system 100 according to a first embodiment of the present disclosure. The wireless communication system 100 includes a wireless LAN base station (hereinafter referred to as a base station) 110, a plurality of wireless LAN terminals (hereinafter referred to as wireless terminals) 120, and a plurality of sound detection devices 130. However, the plurality of wireless terminals 120 includes known terminals 121(1), 121(2), ... 121(6) whose installation positions are known, and an unknown terminal 122 whose installation position is unknown. The known terminal 121 and the unknown terminal 122 may have the same configuration or different configurations. Also, although the number of unknown terminals 122 is assumed to be one here, there may be a plurality of unknown terminals.

[0017] The base station 110 performs wireless LAN communication based on the wireless LAN standard IEEE802.11ac / ax. The base station 110 has one or more antennas. The base station 110 uses these antennas simultaneously to perform communication with multiple wireless terminals 120.

[0018] Base station 110 transmits a radio signal including a known frame to wireless terminal 120. The radio signal transmitted from base station 110 to wireless terminal 120 fluctuates due to the influence of the movement of objects present in the propagation path.

[0019] The wireless terminal 120 receives a wireless signal from the base station 110 using one or more antennas. Furthermore, the wireless terminal 120 calculates a difference from a known frame based on the received wireless signal, and derives compressed CSI. The compressed CSI is information on a wireless propagation path. The information on the wireless propagation path includes amplitude information and phase information for each OFDM subcarrier on the propagation path between the antenna of the base station 110 and the antenna of the wireless terminal 120, as well as information on relative values ​​between each antenna.

[0020] Furthermore, the wireless terminal 120 stores the compressed CSI in a radio frame of Compressed Beamforming Report (CBFR) and feeds it back to the antenna of the base station 110.

[0021] The above description of the wireless terminal 120 is common to both the known terminal 121 and the unknown terminal 122. Hereinafter, when there is no need to distinguish between the known terminal 121 and the unknown terminal 122, they will simply be referred to as the wireless terminal 120.

[0022] The wireless capture device 140 captures wireless frames fed back from the multiple wireless terminals 120 to the base station 110. Furthermore, the wireless capture device 140 executes a process (hereinafter referred to as an extraction process) of extracting compressed CSI from wireless frames captured at the time when sound is detected by the sound detection device 130 described later. The extraction of compressed CSI is based on the IEEE802.11ac / ax standard. Since the compressed CSI shows a time variation according to the movement of objects existing in the target area 10, it is possible to estimate the position of the unknown terminal 122 by determining the correlation between the CSI originating from the known terminal 121 and the CSI originating from the unknown terminal 122.

[0023] The sound detection device 130 is a device such as a smart speaker that detects sounds generated in the target area 10 where the base station 110 and the wireless terminal 120 perform wireless communication. The sound detection device 130 transmits a notification of the detection of the sound to the wireless capture device 140. Note that, although multiple sound detection devices 130 are arranged in the example of FIG. 1, if a single device can detect sounds generated in the target area 10, multiple sound detection devices 130 may not be required. The sound detection device 130 may also be built into the wireless terminal 120. For example, if the wireless terminal 120 is a smartphone, it can be used as the sound detection device 130 by utilizing a microphone function.

[0024] In this manner, in the wireless communication system 100 of the present disclosure, for a wireless frame captured at the time when a sound is detected by the sound detection device 130, the wireless capture device 140 extracts compressed CSI from the wireless frame.

[0025] Comparative Example Here, as a comparative example of the present disclosure, a method for estimating the position of an unknown terminal 122 in the prior art will be described. Fig. 2 is a diagram illustrating a configuration of a conventional wireless communication system 200. Here, a case is shown in which the conventional wireless communication system 200 includes six known terminals 121(1), 121(2), ... 121(6) and one unknown terminal 122.

[0026] 3 is a diagram for explaining an example of CSI measured in conventional wireless communication system 200. In the conventional technology, CSI originating from each of known terminals 121 and CSI originating from unknown terminal 122 are also measured as a function of time. In location estimation, CSI of known terminal 121(6), which changes over time in the same manner as CSI originating from unknown terminal 122, is determined to have the highest correlation with CSI originating from unknown terminal 122. Therefore, unknown terminal 122 is estimated to be present in the vicinity of known terminal 121(6).

[0027] 4 is a diagram illustrating a problem with the conventional wireless communication system 200. In the conventional wireless communication system 200, the CSI is measured even during a time A (hereinafter referred to as a non-active time) when there is little or no movement of objects in the target area 10. The CSI measured during the non-active time A has smaller fluctuations than the CSI measured during a time B (hereinafter referred to as an active time) when there is movement of objects.

[0028] In conventional wireless communication system 200, correlation between known terminal 121 and unknown terminal 122 is determined using CSI including CSI during inactive time A, so that the estimation accuracy of the position of unknown terminal 122 is low.

[0029] FIG. 5 is a diagram for explaining a method of extracting CSI in the wireless communication system 100 according to the first embodiment of the present disclosure. In the wireless communication system 100 of the present disclosure, the sound detection device 130 monitors sounds generated in the target area 10. This makes it possible to detect sounds generated by the movement of an object. Since the wireless capture device 140 extracts compressed CSI from wireless frames captured at the time when the sound is detected by the sound detection device 130, it becomes possible to measure only the CSI in the active time B. By using only the CSI in the active time B for estimating the position of the unknown terminal 122, it is expected that the accuracy of the position estimation will be improved. Furthermore, it is also possible to reduce the power consumption related to the measurement of the CSI in the inactive time A.

[0030] 6 is a block diagram showing a configuration example of a wireless capture device 140 according to the first embodiment of the present disclosure. The wireless interface unit 41 includes an antenna and captures wireless frames in accordance with the IEEE802.11ac / ax (Wi-Fi5 / Wi-Fi6) standard specifications. The reception unit 42 receives notifications informing of sound detection from the multiple sound detection devices 130. In response to receiving the notifications, the reception unit 42 instructs the capture unit 43 to acquire wireless frames.

[0031] The capture unit 43 stops acquiring wireless frames while there is no instruction from the reception unit 42. However, when an instruction is issued from the reception unit 42, the capture unit 43 acquires wireless frames captured by the wireless interface unit 41 and outputs them to the filtering unit 44. This makes it possible to output to the filtering unit 44 only wireless frames that were captured at the time when sound was detected, from among the wireless frames captured by the wireless interface unit 41.

[0032] The filtering unit 44 outputs only the wireless frames that meet a predetermined condition among the wireless frames received from the capture unit 43 to the extraction unit 45. The predetermined condition includes that the type of the wireless frame is a frame that includes the target CSI, i.e., a CBFR frame, and the like.

[0033] The extraction unit 45 extracts the compressed CSI from the CBFR frame output from the filtering unit 44. The preprocessing unit 46 performs preprocessing on the compressed CSI, such as converting the CSI from polar coordinate display to rectangular coordinate display. The preprocessing unit 46 further outputs the compressed CSI and its acquisition time to the storage unit 47.

[0034] The location estimation unit 48 refers to the storage unit 47, determines the correlation between the CSI derived from the known terminal 121 and the CSI derived from the unknown terminal 122, and estimates the location of the unknown terminal 122. The processing performed by the location estimation unit 48 includes statistical processing and comparison processing. In the statistical processing, a statistical value indicating the fluctuation of the CSI over a predetermined time period is calculated for the CSI derived from the known terminal 121 and the CSI derived from the unknown terminal 122. The statistical value is, for example, a variance value. In the orthogonal coordinate display, a variance value exists for each of the x component and the y component of the CSI. In addition, a variance value exists for each subcarrier of OFDM.

[0035] In the comparison process, the similarity between the statistical value obtained by the statistical process on the CSI originating from the known terminal 121 and the statistical value obtained by the statistical process on the CSI originating from the unknown terminal 122 is calculated for each known terminal 121. For example, if the statistical value is a variance value, a portion where the variance value is greater than a specified value is extracted on the frequency axis and the time axis. Furthermore, the number of components (hereinafter referred to as fluctuation components) whose variance value at a specified time and frequency exceeds a specified threshold value is calculated.

[0036] If the difference in the number of fluctuation components between two CSIs is small, it can be considered that the fluctuation conditions of the CSIs are similar. Therefore, the location estimation unit 48 calculates the difference between the number of fluctuation components included in the CSI derived from the known terminal 121 and the number of fluctuation components included in the CSI derived from the unknown terminal 122 for each known terminal 121. Furthermore, the location estimation unit 48 identifies the known terminal 121 that is the source of the CSI with the smallest difference in the number of fluctuation components in comparison with the CSI derived from the unknown terminal 122. Furthermore, the location estimation unit 48 estimates that the unknown terminal 122 is present in the vicinity of the identified known terminal 121.

[0037] The processing performed by the wireless capturing device 140 may be executed by a communication program using a computer having a CPU and memory and storing a program in the memory. Alternatively, the processing may be executed by a communication program using an integrated circuit such as an FPGA (Field Programmable Gate Array). The communication program may be provided by being recorded on a storage medium, or may be provided through a network. This point is common to all the following embodiments.

[0038] 7 illustrates an example of data stored in storage unit 47 according to the first embodiment of the present disclosure. Storage unit 47 stores compressed CSI and its acquisition time for each pair of base station 110 and wireless terminal 120 that transmits or receives the CSI.

[0039] 8 is a diagram showing an example of compressed CSI according to the first embodiment of the present disclosure. Shown are combinations of the number of transmitter antennas (denoted as i) and the number of receiver antennas (denoted as j), and the number and type of compressed CSI obtained according to the combination. Here, φij is the phase difference of the radio signal between the transmitter antenna and the receiver antenna. Also, Ψij is a value expressed as the arctangent of the absolute value of the amplitude ratio of the radio signal between the transmitter antenna and the receiver antenna. φij and Ψij are angles, and their domains are φij∈[0,2π) and Ψij∈[0,π / 2), respectively.

[0040] As described above, the present disclosure can provide a wireless communication system, a wireless acquisition device, a wireless communication method, and a wireless communication program capable of measuring CSI at a time when an object is moving in a target area.

[0041] <Variation 1> In the above description, the wireless capture device 140 captures wireless frames transmitted from the unknown terminal 122 and the multiple known terminals 121 to the base station 110, respectively, and estimates the position of the unknown terminal 122. However, if there is one base station 110 and one wireless terminal 120, it is possible to obtain the above-mentioned effect of measuring the CSI at a time when an object is moving in the target area 10. In this case, it is not necessary to estimate the position.

[0042] <Variation 2> Also, in the above description, it has been explained that the wireless capturing device 140 extracts compressed CSI from wireless frames captured at the time when sound is detected by the sound detection device 130. However, when there are multiple sound detection devices 130, CSI may be extracted from wireless frames captured at the time when sound is simultaneously detected by a predetermined number of sound detection devices 130. This makes it possible to prevent the wireless capturing device 140 from immediately starting CSI measurement when noise unrelated to the movement of an object in the target area 10 is detected by one sound detection device 130.

[0043] <Variation 3> 6, it has been described that the wireless interface unit 41 captures wireless frames even while there is no notification of sound detection from the sound detection device 130. However, the wireless interface unit 41 may capture wireless frames for the time when sound is detected by the sound detection device 130. This makes it possible to capture only wireless frames including CSI during the activity time B, which has the effect of further reducing power consumption.

[0044] Variation 4 6, in the comparison process performed by the location estimation unit 48, the similarity of the statistical values ​​obtained by the statistical process is calculated based on the difference in the number of fluctuation components. However, the method of calculating the similarity of the statistical values ​​is not limited to this. For example, a cross-correlation value between the statistical value obtained by the statistical process for the CSI derived from the known terminal 121 and the statistical value obtained by the statistical process for the CSI derived from the unknown terminal 122 may be calculated. The location of the unknown terminal 122 can be estimated by this method as well.

[0045] The present disclosure is not limited to the above-described embodiment, and various modifications can be made in the implementation stage without departing from the spirit of the present disclosure. In addition, the embodiments may be implemented in appropriate combination, and in that case, the combined effects can be obtained.

[0046] <Correspondence to terms used in claims> The known terminal 121 is referred to as a first terminal in the claims, and the unknown terminal 122 is referred to as a second terminal in the claims. [Explanation of symbols]

[0047] 10 target area, 41 wireless interface unit, 42 reception unit, 43 capture unit, 44 filtering unit, 45 extraction unit, 46 preprocessing unit, 47 storage unit, 48 position estimation unit, 100 wireless communication system, 110 base station, 120 wireless terminal, 121 known terminal, 122 unknown terminal, 130 sound detection device, 140 wireless capture device, 200 conventional wireless communication system, A non-active time, B active time

Claims

1. A wireless communication system that measures propagation channel information included in a wireless frame transmitted and received in wireless communication between a base station and a wireless terminal, The base station; The wireless terminal; A sound detection device; a wireless capture device for capturing the wireless frames; Equipped with The sound detection device is configured to execute a process of detecting a sound generated in a target area of ​​the wireless communication, a wireless communication device configured to perform an extraction process for extracting propagation channel information from the wireless frames captured at a time when a sound is detected by the sound detection device, the wireless capture device being configured to extract propagation channel information from the wireless frames captured at a time when a sound is detected by the sound detection device.

2. The wireless communication system according to claim 1 , wherein the wireless capture device further performs a process of capturing the wireless frame at a time when a sound is detected by the sound detection device.

3. A plurality of the sound detection devices are provided, In the extraction process, the wireless capture device The wireless communication system according to claim 1 , wherein propagation channel information is extracted from the wireless frames captured during a time when a sound is detected simultaneously by a predetermined number of sound detection devices.

4. A plurality of the wireless terminals are provided, The wireless terminals include a plurality of first terminals each having a known installation position and a second terminal each having an unknown installation position; The wireless capture device includes: performing the extraction process on radio frames transmitted from the second terminal and the plurality of first terminals to the base station, determining a correlation between a plurality of pieces of propagation channel information originating from the plurality of first terminals and a piece of propagation channel information originating from the second terminal for each first terminal; A process of identifying a first terminal that is a source of propagation channel information having the highest correlation with propagation channel information originating from the second terminal; A process of estimating that the second terminal is present in the vicinity of the identified first terminal; The wireless communication system of claim 1 , further configured to:

5. A wireless capture device that captures wireless frames transmitted and received in wireless communication between a base station and a wireless terminal and measures propagation channel information included in the wireless frames, comprising: and a wireless capture device configured to perform an extraction process for extracting propagation channel information from the wireless frames captured at a time when a sound is detected by a sound detection device that detects sound generated in a target area of ​​the wireless communication.

6. The wireless terminals include a plurality of first terminals each having a known installation position and a second terminal each having an unknown installation position; the extraction process is performed on radio frames transmitted from the second terminal and the plurality of first terminals to the base station, determining a correlation between a plurality of pieces of propagation channel information originating from the plurality of first terminals and a piece of propagation channel information originating from the second terminal for each first terminal; A process of identifying a first terminal that is a source of propagation channel information having the highest correlation with propagation channel information originating from the second terminal; A process of estimating that the second terminal is present in the vicinity of the identified first terminal; The wireless capture device of claim 5 further configured to perform the following:

7. A wireless communication method for measuring propagation channel information included in a wireless frame transmitted and received in wireless communication between a base station and a wireless terminal, comprising: A sound detection device detects a sound generated in a target area of ​​the wireless communication; a wireless capture device that captures the wireless frames extracts propagation channel information from the wireless frames captured at a time when the sound is detected by the sound detection device; A wireless communication method comprising:

8. A wireless communication program to be executed by a wireless capture device that captures wireless frames transmitted and received in wireless communication between a base station and a wireless terminal and measures propagation channel information included in the wireless frames, the program comprising: For wireless capture devices, A program for wireless communication, comprising a program for executing an extraction process for extracting propagation channel information from a wireless frame captured at a time when sound is detected by a sound detection device that detects sound generated in a target area of ​​the wireless communication.

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