Wireless device and wireless communication system

Abstract

The present invention comprises: a communication unit that transmits a sensing signal and receives a reflected sensing signal obtained by reflection of the sensing signal, and a reference signal transmitted by a second wireless device; and a control unit that compares the reflected sensing signal with the reference signal and determines the likelihood that the sensing signal was reflected by the second wireless device.

Description

Wireless device and wireless communication system

[0001] The present invention relates to wireless devices and wireless communication systems.

[0002] ISAC (Integrated Sensing and Communication) is one of the technologies that has attracted attention as part of the 6th generation (6G) communications standard. ISAC integrates wireless communication and wireless sensing functions, enabling wireless communication and wireless sensing to be performed within the same frequency range using the same wireless transceiver circuit.

[0003] Wireless sensing is a technology that uses radio waves to search for targets. In wireless sensing, for example, a communication device transmits a sensing signal and receives the sensing signal that is physically reflected (hereinafter referred to as "reflection") by the target, thereby estimating the target's position, speed, etc. Furthermore, by combining it with AI technology, it is also possible to estimate the target's material.

[0004] Techniques relating to wireless sensing are described in the following prior art documents.

[0005] JP 2017-46027 A JP 2008-96198 A

[0006] However, in wireless sensing, there are cases where the sensing signal is reflected by an obstacle other than the target, and in such cases, the communication device may erroneously determine the position of the obstacle as the position of the target.

[0007] It is difficult for the communication device to determine whether the received sensing signal has been reflected by the target or by another obstacle.

[0008] Therefore, one disclosure provides a wireless device and a wireless communication system that improve the accuracy of detecting a target using a received sensing signal.

[0009] The wireless communication device includes a communication unit that transmits a sensing signal and receives a reflected sensing signal that is the reflected sensing signal and a reference signal that is transmitted by a second wireless device, and a control unit that compares the reflected sensing signal with the reference signal and determines the likelihood that the sensing signal has been reflected by the second wireless device.

[0010] One aspect of the present invention is to improve the accuracy of detecting a target using a received sensing signal.

[0011] Fig. 1 is a diagram showing an example of the configuration of a wireless communication system 10. Fig. 2 is a diagram showing an example of the configuration of a first wireless device 100. Fig. 3 is a diagram showing an example of the configuration of a second wireless device 200. Fig. 4 is a diagram showing an example of a sequence in the detection process when a sensing signal is reflected by the second wireless device 200. Fig. 5 is a diagram showing an example of a sequence in the detection process when a sensing signal is reflected by an obstacle. Fig. 6 is a diagram showing an example of a processing flowchart of the likelihood determination process S100.

[0012] [First Embodiment] A first embodiment will be described.

[0013] 1 is a diagram showing an example of the configuration of a wireless communication system 10. The wireless communication system 10 includes a first wireless device 100 and a second wireless device 200. The wireless communication system 10 is a system in which the first wireless device 100 detects the second wireless device 200. The detection includes calculating (estimating) the position, speed (including the relative speed with respect to the first wireless device 100), moving direction, etc. of the second wireless device 200.

[0014] The first radio device 100 is a device that is wirelessly connected to the second radio device 200 and performs wireless communication (communication T2), and is, for example, a base station device such as an eNodeB or gNodeB, a radio device such as an RU (Radio Unit), or a terminal device such as an in-vehicle terminal device or a smartphone in vehicle-to-everything (V2X) communication or device-to-device (D2D) communication. The first radio device 100 transmits a sensing signal T1 to the second radio device 200 and receives the reflected sensing signal T1 (reflected sensing signal). The first radio device 100 further instructs the second radio device 200 to transmit a reference signal using the communication T2. ​​The reference signal is, for example, a signal that can be recognized by the communication device that transmits the sensing signal.

[0015] The second wireless device 200 is a device that is wirelessly connected to the first wireless device 100 and performs wireless communication (communication T2), and is, for example, a terminal device such as a smartphone. The second wireless device 200 reflects the sensing signal T1 transmitted by the first wireless device 100. The second wireless device 200 further transmits a reference signal to the first wireless device 100 using communication T2 in accordance with an instruction from the first wireless device 100.

[0016] The first radio device 100 uses the difference in reception time between the sensing signal T1 and the reference signal to determine the likelihood that the sensing signal T1 has been reflected by the second radio device 200 or not.

[0017] 2 is a diagram showing an example of the configuration of the first radio device 100. The first radio device 100 has a CPU (Central Processing Unit) 110, a storage 120, a memory 130, and a wireless communication circuit 150.

[0018] The storage 120 is an auxiliary storage device that stores programs and data, such as a flash memory, a hard disk drive (HDD), or a solid state drive (SSD). The storage 120 stores a wireless communication program 121 and a detection program 122.

[0019] The memory 130 is an area into which the programs stored in the storage 120 are loaded. The memory 130 may also be used as an area in which the programs store data.

[0020] The wireless communication circuit 150 is a device that performs wireless communication with the second wireless device 200. The first wireless device 100 transmits and receives signals (messages) to and from the second wireless device 200 via the wireless communication circuit 150. The wireless communication circuit 150 also transmits sensing signals and receives reflected sensing signals. Note that the first wireless device 100 may have a wireless communication circuit that transmits and receives sensing signals and a wireless communication circuit that performs wireless communication with the second wireless device 200, each of which is provided as a separate wireless communication circuit.

[0021] The CPU 110 is a processor that loads programs stored in the storage 120 into the memory 130, executes the loaded programs, configures each unit, and realizes each process.

[0022] The CPU 110 establishes a communication unit and performs wireless communication processing by executing the wireless communication program 121. The wireless communication processing is processing for establishing a wireless connection with the second wireless device 200 and transmitting and receiving signals via the wireless connection.

[0023] The CPU 110 executes the detection program 122 to construct a control unit and perform detection processing. The detection processing is processing for calculating the position and speed of the second wireless device 200. In the detection processing, the first wireless device 100 transmits and receives a sensing signal, instructs the second wireless device 200 to transmit a reference signal, and receives the reference signal. The first wireless device 100 determines the likelihood that the sensing signal has been reflected by the first wireless device based on the difference between the reception timing of the reference signal and the reception timing of the sensing signal.

[0024] The CPU 110 executes the sensing signal control module 1221 included in the detection program 122 to establish a control unit and perform sensing signal control processing. The sensing signal control processing is processing for transmitting a sensing signal to (in the direction of) the second wireless device 200 and receiving the reflected sensing signal.

[0025] The CPU 110 executes the reference signal control module 1222 included in the detection program 122 to establish a control unit and perform reference signal control processing. The reference signal control processing is processing for instructing the second wireless device 200 to transmit a reference signal and receiving the reference signal.

[0026] The CPU 110 constructs a control unit and performs a likelihood determination process by executing a likelihood determination module 1223 included in the detection program 122. The likelihood determination process is a process of determining whether or not a received sensing signal is a signal reflected by the second wireless device 200, and determining whether the received sensing signal has been reflected by the second wireless device 200 or by a device other than the second wireless device 200.

[0027] 3 is a diagram showing an example of the configuration of the second wireless device 200. The second wireless device 200 includes a CPU 210, a storage 220, a memory 230, and a wireless communication circuit 250.

[0028] The storage 220 is an auxiliary storage device such as a flash memory, HDD, or SSD that stores programs and data. The storage 220 stores a wireless communication program 221 and a reference signal transmission program 222.

[0029] The memory 230 is an area into which the programs stored in the storage 220 are loaded. The memory 230 may also be used as an area in which the programs store data.

[0030] The wireless communication circuit 250 is a device that performs wireless communication with the first wireless device 100. The second wireless device 200 transmits and receives signals to and from the first wireless device 100 via the wireless communication circuit 250.

[0031] The CPU 210 is a processor that loads programs stored in the storage 220 into the memory 230, executes the loaded programs, configures each unit, and realizes each process.

[0032] The CPU 210 establishes a second communication unit and performs wireless communication processing by executing the wireless communication program 221. The wireless communication processing is processing for establishing a wireless connection with the first wireless device 100 and transmitting and receiving signals via the wireless connection.

[0033] The CPU 210 executes the reference signal transmission program 222 to establish a second control unit and perform a reference signal transmission process. The reference signal transmission process is a process of transmitting a reference signal to the first radio device 100 at a predetermined timing in accordance with an instruction from the first radio device 100.

[0034] <Detection Process> The detection process will be described below using sequences for two patterns: when the sensing signal is reflected by the second wireless device 200, and when it is reflected by another obstacle.

[0035] 4 is a diagram showing an example of a sequence in the detection process when a sensing signal is reflected by the second wireless device 200. The first wireless device 100 and the second wireless device 200 are in a wireless connection state (S10) and are capable of wireless communication.

[0036] In the detection process, the first radio device 100 transmits a reference signal configuration to the second radio device 200 (S11). The reference signal configuration includes information about the reference signal. The information about the reference signal includes, for example, transmission power, parameters for transmission power configuration, a transmission frequency range, and transmission signal generation parameters. The second radio device 200 stores the information about the reference signal.

[0037] The first radio apparatus 100 transmits a reference signal transmission instruction to the second radio apparatus 200 at a predetermined timing (S12). The reference signal transmission instruction may include, for example, the transmission timing (for example, the transmission time) of the reference signal. The reference signal configuration may be transmitted, for example, by Radio Resource Control (RRC) signaling or by a Physical Downlink Control Channel (PDCCH).

[0038] If the reference signal transmission instruction does not include a transmission timing, upon receiving the reference signal transmission instruction (S12), the second radio device 200 immediately transmits a reference signal to the first radio device 100 (S13). The first radio device 100, assuming that the reference signal will be transmitted immediately, transmits a reference signal transmission instruction to the first radio device 100 so that the reference signal, the sensing signal reflected by the second radio device 200, and the reference signal arrive simultaneously (S12). The first radio device 100 calculates (estimates) the time it takes for the reference signal to arrive from the second radio device 200, the time it takes for the sensing signal to arrive at the first radio device 100 after being transmitted from the first radio device 100 and reflected by the second radio device 200, and the time it takes for the reference signal transmission instruction to arrive at the second radio device 200, and calculates the timing at which they will arrive simultaneously. Each of these times is calculated taking into consideration, for example, the frequency, phase, and transmission power of the signal, the position of the second radio device 200 (including the direction, distance, estimated position, etc.), and radio conditions. The reference signal transmission instruction may be transmitted, for example, on the PDCCH.

[0039] When the reference signal transmission instruction includes a transmission timing, upon receiving the reference signal transmission instruction (S12), the second radio apparatus 200 transmits the reference signal to the first radio apparatus 100 in accordance with the transmission timing (S13). The transmission timing may be, for example, the transmission time or a delay interval, such as a number of milliseconds after receiving the reference signal transmission instruction. The first radio apparatus 100 calculates the timing of simultaneous arrival, taking the transmission timing into consideration. The calculation method for the signal arrival time and the information to be considered are the same as when the reference signal transmission instruction does not include a transmission timing.

[0040] In the above, "simultaneous" means arriving (receiving) at exactly the same time, but also includes, for example, the case where one signal arrives within a predetermined time after the other signal arrives. In this case, it is preferable that the predetermined time be as small as possible.

[0041] The first radio device 100 transmits the sensing signal to the first radio device 100 (S14). Transmitting to the first radio device 100 includes transmitting in the direction where the first radio device 100 is likely to be located. As described above, the first radio device 100 transmits the sensing signal at a timing when the sensing signal reflected by the first radio device 100 and the reference signal arrive at the first radio device 100 at the same time (S14).

[0042] The sensing signal is reflected by the second wireless device 200 (S15) and reaches the first wireless device 100 (S16).

[0043] The first wireless device 100 calculates the time difference (P1) between the reception of the reference signal (S13) and the reception of the sensing signal (S16), and executes the likelihood determination process S100, which will be described later.

[0044] 5 is a diagram showing an example of a sequence in which a sensing signal is reflected by an obstacle during detection processing. The first wireless device 100 and the second wireless device 200 are in a wireless connection state (S20) and are capable of wireless communication.

[0045] In the detection process, the first radio apparatus 100 transmits a reference signal configuration to the second radio apparatus 200 (S21).

[0046] The first radio apparatus 100 transmits a reference signal transmission instruction to the second radio apparatus 200 at a predetermined timing (S22). The control when the reference signal transmission instruction does not include a transmission timing and when it includes a transmission timing are the same as the sequence in FIG. 4 .

[0047] When the second radio apparatus 200 receives the reference signal transmission instruction (S22), it transmits a reference signal to the first radio apparatus 100 in accordance with the reference signal transmission instruction (S23).

[0048] The first radio device 100 transmits the sensing signal to the first radio device 100 (S24). The first radio device 100 transmits the sensing signal at a timing when the sensing signal reflected by the first radio device 100 and the reference signal arrive at the first radio device 100 at the same time (S24).

[0049] The sensing signal is reflected by an obstacle present between the first wireless device 100 and the second wireless device 200 (S25) and reaches the first wireless device 100 (S26).

[0050] The first wireless device 100 calculates the time difference (P2) between the reception of the reference signal (S23) and the reception of the sensing signal (S26), and executes the likelihood determination process S100.

[0051] Here, if the sensing signal is reflected by an obstacle, it takes a short time for the sensing signal to return to the first wireless device 100. That is, the difference P2 becomes larger than the difference P1.

[0052] For example, if the sensing signal is not reflected by the second wireless device 200 for some reason but is reflected by an obstacle located farther away than the second wireless device 200, the reflected wave of the sensing signal will be delayed in reaching the first wireless device 100, and it is possible that a difference greater than difference P1 will occur.

[0053] In this way, the difference in arrival time becomes large when the sensing signal is reflected by an area other than the second wireless device 200. The first wireless device 100 uses this assumption to execute the likelihood determination process S100.

[0054] 6 is a diagram showing an example of a processing flowchart of the likelihood determination process S100. The first wireless device 100 calculates the difference between the reception time of the sensing signal and the reception time of the reference signal (S100-1). The difference is difference P1 in FIG. 4 and difference P2 in FIG. 5.

[0055] The first wireless device 100 compares the calculated difference with a first threshold value (S100-2). If the difference is smaller than the first threshold value (No in S100-2), the first wireless device 100 determines that the sensing signal has been reflected by the second wireless device 200 (S100-3), and ends the process.

[0056] On the other hand, if the difference is greater than or equal to the first threshold (Yes in S100-2), the first wireless device 100 determines that the sensing signal was reflected by something other than the second wireless device 200 (S100-4), performs the detection process again (S100-5), and ends the process.

[0057] When performing the detection process again, if the reference signal setting is the same as the previously transmitted reference signal setting, transmission of the reference signal setting may be omitted. Furthermore, an upper limit may be set for the number of times the detection process is re-executed. Furthermore, the value of the first threshold may be increased depending on the number of times the detection process is re-executed.

[0058] The first threshold may be set depending on the type and situation of the service to be applied. From the viewpoint of the type of service, for example, a stricter setting value may be used for services that involve human life or for which accidents must be avoided. Furthermore, when a mobile robot in a factory or warehouse is controlled via wireless signals, the first threshold may be set depending on the presence and density of obstacles around the robot.

[0059] The first threshold may be set to a value based on the time length of one OFDM symbol (for example, half the time of one OFDM symbol).

[0060] This makes it possible to discard sensing signals reflected by sources other than the second wireless device 200, thereby improving the accuracy of sensing (detection).

[0061] [Other Embodiments] In the first embodiment, the sensing signal and the reference signal are controlled so that they arrive at the first wireless device 100 at the same time, but, for example, the arrival times of the sensing signal and the reference signal may be controlled so that they are N milliseconds (N is a number greater than 0). In this case, the likelihood is determined based on the difference from N milliseconds.

[0062] In the first embodiment, the likelihood is determined based on the difference in reception time between the sensing signal and the reference signal. However, the likelihood may also be determined based on the following criteria, for example: Difference between the arrival angle of the sensing signal and the arrival angle of the reference signal. In this case, the smaller the difference, the higher the likelihood is determined. Average difference between the received power of the sensing signal and the received power of the reference signal at the first wireless device 100, when converted so that the transmission power of the sensing signal and the transmission power of the reference signal are the same. In this case, the closer this difference is to 3 dB, the higher the likelihood is determined. The amount of frequency Doppler shift between the received sensing signal and the reference signal. In this case, the smaller the amount of frequency Doppler shift, the higher the likelihood is determined.

[0063] Furthermore, since the first wireless device 100 receives the sensing signal and the reference signal at approximately the same time, mutual interference may occur between the received sensing signal and the reference signal. Therefore, in order to minimize performance degradation, the sensing signal may be orthogonal to the reference signal, or may be transmitted in a different subband and orthogonalized in a frequency domain.

[0064] Furthermore, if the likelihood is low (for example, if S100-2 in FIG. 6 returns Yes), the following processing may be performed. If the amount of frequency Doppler shift is large, the relative movement speed of the second wireless device 200 is fast, and sensing signals are repeatedly transmitted at shorter time intervals in the time domain so that sensing can be performed to track the movement. If a large number of reflected signals are received and are quite close to each other in the time domain, the frequency width of the sensing signal is widened (i.e., the time length is shortened) and the signal is transmitted in order to increase the resolution in the time domain. If it is determined that the wireless propagation characteristics in the wireless space have strong frequency selectivity, multiple sensing signals are simultaneously transmitted at different center frequencies in the frequency domain.

[0065] Furthermore, the reference signal may be, for example, a conventional signal, such as a pilot signal, a reference signal, or a random access signal.

[0066] 10: Wireless communication system 100: First wireless device 110: CPU 120: Storage 121: Wireless communication program 122: Detection program 1221: Sensing signal control module 1222: Reference signal control module 1223: Determination module 130: Memory 150: Wireless communication circuit 200: Second wireless device 210: CPU 220: Storage 221: Wireless communication program 222: Reference signal transmission program 230: Memory 250: Wireless communication circuit

Claims

1. A wireless device having: a communication unit that transmits a sensing signal and receives a reflected sensing signal that is the sensing signal reflected back, and a reference signal that is transmitted by a second wireless device; and a control unit that compares the reflected sensing signal with the reference signal and determines the likelihood that the sensing signal has been reflected by the second wireless device.

2. The radio device according to claim 1, wherein the control unit instructs the second radio device to transmit a reference signal so that the first reception timing of the reflected sensing signal when the sensing signal is reflected by the second radio device and the second reception timing of the reference signal are within a predetermined time.

3. The wireless device according to claim 2, wherein the control unit determines that the closer the difference between the first reception timing and the second reception timing is to within the specified time, the higher the likelihood that the sensing signal has been reflected by the second wireless device.

4. The wireless device according to claim 1, wherein the frequencies of the sensing signal and the reference signal are orthogonal to each other.

5. The radio device according to claim 1, wherein the communication unit transmits configuration information including information related to the reference signal to the second radio device.

6. The wireless device according to claim 2, wherein the communication unit transmits an instruction signal including the transmission instruction to the second wireless device.

7. The radio device according to claim 6, wherein the transmission instruction includes information regarding the timing of transmitting the reference signal.

8. A wireless communication system comprising: a wireless device that transmits a sensing signal, receives a reflected sensing signal of the sensing signal and a reference signal transmitted by a second wireless device, compares the reflected sensing signal with the reference signal, and determines the likelihood that the sensing signal has been reflected by the second wireless device; and the second wireless device that transmits the reference signal to the wireless device.

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