WIFI radar control method and WIFI radar communication circuit

Abstract

A WiFi radar control method includes the following steps: In a first radar transceiver time slot, a plurality of first radar frames are sequentially transmitted, and a plurality of first reflected echoes corresponding to the first radar frames are received. The waveform of the first reflected echoes is used to determine whether the first radar frame is subject to interference. When interference is determined to be present in the first radar frame, a retry count is incremented. When the retry count is not zero, at least one retry radar frame is transmitted in the first radar transceiver time slot or in a second radar transceiver time slot following the first radar transceiver time slot.

Description

[Technical Field]

[0001] This disclosure relates to a WiFi radar control method and a WiFi radar communication circuit, and in particular to a control method for sending a retry frame when WiFi radar signal interference occurs. [Previous Technology]

[0002] WiFi radar technology utilizes the reflection, scattering, and diffraction characteristics of transmitted wireless signals for sensing, similar to traditional radar systems. However, it does not require additional dedicated hardware to transmit radar signals; instead, it can utilize existing WiFi transceiver circuits to transmit radar signals, thereby detecting environmental changes and target movement. WiFi radar technology primarily utilizes the existing WiFi transceiver circuit hardware to implement radar functionality. The transmitted radar frames may be affected by interference from the surrounding environment (e.g., competition with other nearby WiFi signals, surrounding Bluetooth communication circuits, and the multipath effect). Therefore, how to avoid the impact of signal interference and maintain an effective number of frames in each sensing cycle is one of the challenges of WiFi radar technology. [Summary of the Invention]

[0003] One embodiment of this disclosure discloses a WiFi radar control method comprising the following steps: In a first radar transceiver time slot, a plurality of first radar frames are sequentially transmitted, and a plurality of first reflected echoes corresponding to the first radar frames are received. The waveform of the first reflected echoes is used to determine whether the first radar frame is interfered with. When interference is determined to be present in the first radar frame, a retry count is incremented. When the retry count is not zero, at least one retry radar frame is transmitted in the first radar transceiver time slot or in a second radar transceiver time slot following the first radar transceiver time slot.

[0004] One embodiment of this disclosure discloses a WiFi radar control method comprising the following steps: In a radar transceiver slot, a radar frame is transmitted and a corresponding reflected echo is received. The waveform of the reflected echo is used to determine whether the radar frame is interfered with. If the radar frame is determined not to be interfered with, the target frame count is decremented. If the target frame count is not zero, another radar frame is transmitted in the radar transceiver slot.

[0005] One embodiment of this disclosure discloses a WiFi radar communication circuit including an analog front-end circuit and a control unit. The analog front-end circuit is coupled to a transmitting antenna and a receiving antenna, and is used to control the transmitting antenna and the receiving antenna to operate in a WiFi communication frequency band or a radar transceiver frequency band. The control unit is coupled to the analog front-end circuit. The control unit is used to sequentially transmit a plurality of first radar frames to the transmitting antenna through the analog front-end circuit in a first radar transceiver time slot, and to receive a plurality of first reflected echoes corresponding to the plurality of first radar frames from the receiving antenna. The control unit is used to determine whether the plurality of first radar frames are interfered with based on the waveforms of the plurality of first reflected echoes. When it is determined that the first radar frame is interfered with, the control unit is used to increment the retry count. When the retry count is not zero, at least one retry radar frame is transmitted in the first radar transceiver time slot or in the second radar transceiver time slot following the first radar transceiver time slot.

Implementation Method

[0007] Please refer to Figure 1, which illustrates a schematic diagram of a WiFi radar communication circuit 100 according to some embodiments of the present disclosure. In one embodiment, the WiFi radar communication circuit 100 has hardware components similar to those of a WiFi transceiver circuit. Furthermore, the WiFi radar communication circuit 100 can utilize the WiFi transceiver circuit to implement scanning signals required by an antenna. In addition to transmitting and receiving WiFi communication packets, the WiFi radar communication circuit 100 can also transmit radar frames and receive radar reflections. For example, the WiFi radar communication circuit 100 can share a portion of its front-end circuitry for transmitting and receiving WiFi communication packets and radar frames, and can process WiFi communication packets and radar frames separately through their respective digital terminal circuits.

[0008] The WiFi radar communication circuit 100 can be applied to scenarios such as human body sensing and motion detection (e.g., smart home, detecting whether there is someone in the house through Wi-Fi signal), health monitoring, gesture control (e.g., non-contact control, operating smart devices with gestures) or smart monitoring system (e.g., home security, to detect abnormal movement or intruders).

[0009] As shown in Figure 1, the WiFi radar communication circuit 100 includes an analog front-end (AFE) circuit 120, a digital-to-analog converter (DAC) 140, an analog-to-digital converter (ADC) 150, a digital signal processor (DSP) 160, and a control unit 180. It should be noted that various hardware structures can be used to implement the WiFi radar communication circuit 100. Figure 1 illustrates one implementation of the circuit architecture, but this disclosure is not limited to the hardware architecture shown in Figure 1.

[0010] The analog front-end circuit 120 is coupled to the transmitting antenna ATX and the receiving antenna ARX. In this embodiment, the analog front-end circuit 120 may include a signal coupler 122, a power amplifier 124, a low noise amplifier (LNA) 126, a mixer 128, and a filter 129. The analog front-end circuit 120 is used to control the operation of the transmitting antenna ATX and the receiving antenna ARX in the WiFi communication band or the radar transceiver band. The power amplifier 124 is used to provide gain for the antenna's transmitted signal. The low noise amplifier 126 is used to enhance the antenna's received signal and improve sensitivity. The mixer 128 is used to convert the received antenna signal. The filter 129 is used to adjust or select the passing signal frequency band.

[0011] For example, the WiFi communication frequency band can cover wireless communication bands such as those around 2.4 GHz, 5 GHz, and 6 GHz; the radar transceiver frequency band can cover wireless communication bands such as those from 5.725 GHz to 5.875 GHz. In some embodiments, the radar transceiver frequency band used by the WiFi radar communication circuit 100 may overlap with the general WiFi communication frequency band to a certain extent. Therefore, when the WiFi radar communication circuit 100 transmits and receives radar frames, it may be subject to interference from other WiFi signal sources or the surrounding environment.

[0012] A digital-to-analog converter 140 is coupled between a digital signal processor 160 and an analog front-end circuit 120 to convert digital signals provided by the digital signal processor 160 into analog signals. An analog-to-digital converter 150 is coupled between the analog front-end circuit 120 and the digital signal processor 160 to convert analog signals provided by the analog front-end circuit 120 into digital signals.

[0013] The digital signal processor 160 is used to perform digital processing of transmitted or received signals, such as processing Channel State Information (CSI), Time of Flight (ToF), and Phase Difference information. In some embodiments, the digital signal processor 160 includes an Orthogonal Frequency-Division Multiplexing (OFDM) unit 162 for digital processing of WiFi communication packets, and the digital signal processor 160 further includes a Frequency Modulated Continuous Wave (FMCW) unit 164 for digital processing of radar frames.

[0014] The control unit 180 can be used to execute software instructions (such as algorithms, control methods, etc.) of the application layer 182. The control unit 180 can be implemented by a processor, a microcontroller (MCU), an application-specific integrated circuit (ASIC), or a field-programmable gate array (FPGA).

[0015] In order to ensure the correctness of the WiFi radar communication circuit 100 when performing radar detection function, and to avoid excessive power consumption, the WiFi radar communication circuit 100 is pre-set to send and receive a certain number of valid radar frames within a certain working cycle.

[0016] For example, each working cycle can be 1 second. The WiFi radar communication circuit 100 is preset to send and receive 6 valid radar frames every 1 second, that is, the number of target frames per second is 6. In this disclosure, after the WiFi radar communication circuit 100 sends a radar frame, it can distinguish whether the radar frame is interfered with, and automatically send additional radar frames (e.g., retry radar frames) according to the interference situation to make up for the number of target frames.

[0017] Please refer to Figures 2A and 2B together. Figures 2A and 2B illustrate a flowchart of a WiFi radar control method 200 according to some embodiments of this disclosure. When a radar frame is determined to be interfered with, the WiFi radar control method 200 can automatically send a retry radar frame in one or more radar transceiver slots according to the interference situation, thereby trying to replenish the number of target frames as much as possible.

[0018] Please also refer to Figure 3A, which is a schematic diagram of the first embodiment when the radar frames of the first radar transceiver slot TR1 and the second radar transceiver slot TR2 do not encounter interference.

[0019] As shown in Figure 3A, assuming that each working cycle (TPD) of the WiFi radar communication circuit 100 is 1 second, each working cycle (TPD) includes a first WiFi communication time slot (TW1), a first radar transceiver time slot (TR1), a second WiFi communication time slot (TW2), and a second radar transceiver time slot (TR2). In this example, the sum of the first WiFi communication time slot (TW1) and the first radar transceiver time slot (TR1) is 500 milliseconds (ms), and the sum of the second WiFi communication time slot (TW2) and the second radar transceiver time slot (TR2) is also 500 milliseconds (ms). The length of the working cycle (TPD) is greater than the length of the first radar transceiver time slot (TR1) and also greater than the length of the second radar transceiver time slot (TR2).

[0020] It should be further noted that the embodiment illustrated in Figure 3A is a timing diagram of the WiFi radar communication circuit 100 operating alternately in two modes: WiFi communication function and radar detection function. However, this disclosure is not limited to this. If the WiFi radar communication circuit 100 operates the radar detection function alone, the first WiFi communication time slot TW1 and the second WiFi communication time slot TW2 can be omitted. In this case, the first radar transceiver time slot TR1 is 500 milliseconds (ms), and the second radar transceiver time slot TR2 is 500 milliseconds (ms). Furthermore, if the WiFi radar communication circuit 100 operates the radar detection function alone, steps S202, S204, S231, S232, S234, and S261 in the WiFi radar control method 200 in Figures 2A and 2B can be omitted.

[0021] As shown in Figures 1, 2A, and 3A, the WiFi radar communication circuit 100 first executes step S202, transmitting and receiving WiFi communication packets PW1 on the WiFi communication frequency band BWF in the first WiFi communication time slot TW1. Then, when the first WiFi communication time slot TW1 ends and the first radar transceiver time slot TR1 begins, step S204 is executed, switching the operation of the WiFi radar communication circuit 100 from the WiFi communication frequency band BWF to the radar transceiver frequency band BRAD.

[0022] Next, in the first radar transceiver slot TR1, step S206 is executed to send the first radar frame F1A and receive the first reflected echo corresponding to the first radar frame F1A.

[0023] Next, step S208 is executed, in which the control unit 180 of the WiFi radar communication circuit 100 decrements the target frame count CTARGET.

[0024] In this embodiment, since it is assumed that the number of target frames per work cycle (e.g., per second) is 6, the initial value of the target frame count CTARGET of the first radar frame F1A is set to 3 in this example. When the transmission of the first radar frame F1A is completed, the target frame count CTARGET will be decremented from 3 to 2 through step S208.

[0025] Next, step S210 is executed to determine whether the first radar frame F1A is interfered with based on the waveform of the first reflected echo received after the first radar frame F1A is transmitted.

[0026] In some embodiments, the plurality of first radar frames F1A, F1B, and F1C shown in Figure 3A are plurality of frequency modulated continuous wave (FMCW) radar frames, each of which contains a plurality of linear sweep signals (e.g., chirp sweep signals). As shown in Figure 3A, the first radar frame F1A contains a plurality of linear sweep signals CRP.

[0027] In some embodiments, the determination of whether the first radar frame F1A is interfered with in step S210 above is based on the difference between the waveform of the first reflected echo corresponding to the first radar frame F1A and the linear sweep signal CRP.

[0028] Generally speaking, if the first radar frame F1A is not interfered with by other signals, the waveform of the first reflected echo (which will have a certain delay or phase difference compared to the linear sweep signal CRP of the first radar frame F1A) will retain a waveform similar to the linear sweep signal CRP.

[0029] On the other hand, if the first radar frame F1A is interfered with by other signals, the waveform of the first reflected echo will deviate significantly from the waveform of the original linear sweep signal CRP in the first radar frame F1A, for example, there may be jitter or noise at different frequencies. Therefore, when the difference between the waveform of the first reflected echo corresponding to the first radar frame F1A and the waveform of the linear sweep signal CRP is too large (e.g., greater than 20%), it can be determined that the first radar frame F1A is interfered with.

[0030] The above example regarding whether the first radar frame F1A is interfered with is based on the difference between the waveform of the first reflected echo and the waveform of the linear sweep signal CRP, but this disclosure is not limited thereto. In other embodiments, the control unit 180 of the WiFi radar communication circuit 100 may also determine whether the radar frame is interfered with based on spectrum analysis (if there are additional spectrum components, it may indicate interference), beat frequency analysis (if there are additional beat frequencies, it may indicate interference), channel state information (CSI) detection, or autocorrelation function detection.

[0031] In the example shown in Figure 3A, it is assumed that the first radar frames F1A, F1B, and F1C are not interfered with. In this case, step S212 will not be executed, and the retry count CRETRY will remain at its initial value of zero.

[0032] Next, step S214 is executed to determine whether the target frame count CTARGET has been returned to zero (at this time, only the first radar frame F1A has been sent, and the target frame count CTARGET is equal to 2 and has not yet been returned to zero), so it will return to step S206.

[0033] Therefore, steps S206 to S214 will be repeated to send the subsequent first radar frame F1B. The detailed process is as described above and will not be repeated here. When the execution reaches step S214 for the second time (at this time, two first radar frames F1A and F1B have been sent, and the target frame count CTARGET is equal to 1 and has not yet returned to zero), it will return to step S206 again.

[0034] Therefore, steps S206 to S214 will be repeated, and another first radar frame F1C will be sent. The detailed process is as described above and will not be repeated here. When step S214 is executed for the third time (at this time, three first radar frames F1A, F1B and F1C have been sent. The target frame count CTARGET has been reduced to zero), step S216 will be entered.

[0035] In the above steps, since it is assumed that the first radar frames F1A, F1B, and F1C are not interfered with in the example shown in Figure 3A, the retry count CRETRY remains zero. In this embodiment, the control unit 180 of the WiFi radar communication circuit 100 executes step S216 to determine whether the retry count CRETRY has returned to zero. If the retry count CRETRY is determined to have returned to zero, then step S218 can be executed. After the transmission of the first radar frame F1C and the reception of its first reflected echo are completed, at least a portion of the circuit elements in the WiFi radar communication circuit 100 are turned off early until the second WiFi communication time slot TW2 is entered, at which point the relevant circuit elements are woken up again.

[0036] Step S218 can turn off one or more circuit elements in the analog front-end circuit 120, digital-to-analog converter 140, analog-to-digital converter 150 and digital signal processor 160 in the WiFi radar communication circuit 100 shown in Figure 1, thereby saving the power consumption caused by these circuit elements.

[0037] Next, when the first radar transceiver time slot TR1 ends and the second WiFi communication time slot TW2 begins, step S231 is executed to switch the operation of the WiFi radar communication circuit 100 from the radar transceiver frequency band BRAD to the WiFi communication frequency band BWF. Then, step S232 can be executed to send the WiFi communication packet PW2.

[0038] Next, we enter the second WiFi communication time slot TW2. Please refer to Figure 1, Figure 2B and Figure 3A. Steps S234 to S261 shown in Figure 2B are similar to steps S204 to S231 shown in Figure 2A. The only difference is that the steps shown in Figure 2B are mainly for the operation of the second radar transceiver time slot TR2, which is located after the first radar transceiver time slot TR1.

[0039] Step S234 is executed, switching the WiFi radar communication circuit 100 from the WiFi communication band BWF to the radar transceiver band BRAD. Next, in the second radar transceiver time slot TR2, step S236 is executed, transmitting the second radar frame F2A and receiving the corresponding second reflected echo. Next, step S238 is executed, decrementing the target frame count CTARGET (from the initial value of 3 to 2) by the control unit 180 of the WiFi radar communication circuit 100. Next, step S240 is executed, determining whether the second radar frame F2A is interfered with based on the waveform of the second reflected echo received after the transmission of the second radar frame F2A.

[0040] In some embodiments, the plurality of second radar frames F2A, F2B and F2C shown in Figure 3A are a plurality of frequency modulated continuous wave radar frames, each of which contains a plurality of linear sweep signals CRP (e.g., chirp scan signals).

[0041] In some embodiments, the determination of whether the second radar frame F2A is interfered with in step S240 above is based on the difference between the waveform of the second reflected echo corresponding to the second radar frame F2A and the linear sweep signal CRP.

[0042] In the example shown in Figure 3A, it is assumed that the second radar frames F2A, F2B, and F2C are not interfered with. In this case, step S242 will not be executed, and the retry count CRETRY will remain at its initial value of zero.

[0043] Next, step S244 is executed to determine whether the target frame count CTARGET has been returned to zero (at this time, the target frame count CTARGET is equal to 2 and has not been returned to zero), so it will return to step S236.

[0044] Therefore, steps S236 to S244 will be repeated to send subsequent second radar frames F2B and F2C. The detailed process is as described above and will not be repeated here. When the execution reaches step S244 for the third time (at this time, three second radar frames F2A, F2B and F2C have been sent. The target frame count CTARGET has been returned to zero), step S246 will be entered to determine whether the retry count CRETRY has been returned to zero.

[0045] At this point, the CRETRY retry count has been determined to be zero, so step S248 can be executed. After the transmission of the second radar frame F2C and the reception of its second reflected echo are completed, at least a portion of the circuit elements in the WiFi radar communication circuit 100 are turned off early, and the relevant circuit elements are woken up again when the next WiFi communication time slot is entered. When the second radar transceiver time slot TR2 ends, step S261 is executed to switch the operation of the WiFi radar communication circuit 100 from the radar transceiver frequency band BRAD to the WiFi communication frequency band BWF.

[0046] In the first embodiment of Figure 3A above, when the radar frames that have reached the target frame number are completed and are not interfered with, some circuit elements in the WiFi radar communication circuit 100 can be turned off in advance to save energy.

[0047] Please also refer to Figure 3B, which is a schematic diagram of the second embodiment when some radar frames in the first radar transceiver slot TR1 are interfered with while the radar frames in the second radar transceiver slot TR2 are not interfered with.

[0048] Compared to the example in Figure 3A above (where the first radar frames F1A, F1B and F1C and the second radar frames F2A, F2B and F2C do not encounter interference), in the second embodiment of Figure 3B, it is assumed that the two first radar frames F1A and F1C in the first radar transceiver slot TR1 encounter interference.

[0049] Referring to Figures 1, 2A, and 3B, in the step of sequentially transmitting three first radar frames F1A, F1B, and F1C in the first radar transceiver slot TR1, step S212 is executed twice in both first radar frames F1A and F1C, causing the retry count CRETRY to increment from an initial value of 0 to 1, and then from 1 to 2. Therefore, in the example of Figure 3B, when the first radar frames F1A, F1B, and F1C are completed, the target frame count CTARGET is 0 and the retry count CRETRY is 2.

[0050] Next, step S216 is executed to determine whether the retry count CRETRY is zero. Since the retry count CRETRY is 2, step S220 is executed to determine whether the first remaining time of the first radar transceiver slot TR1 is sufficient. At this time, the first remaining time of the first radar transceiver slot TR1 is still sufficient to accommodate one radar frame. Therefore, step S222 is executed, the first retry radar frame F1D is transmitted in the first radar transceiver slot TR1, and the first retry reflected echo corresponding to the first retry radar frame F1D is received.

[0051] Step S224 is executed to determine whether the first retry radar frame F1D is interfered with based on the waveform of the first retry reflected echo. At this time, in the embodiment of Figure 3B, it is assumed that the first retry radar frame F1D is not interfered with, so step S226 is executed to decrease the retry count CRETRY from 2 to 1.

[0052] Then, returning to step S216, it is determined that the retry count CRETRY has not yet reached zero. Step S220 is then executed again to determine if the first remaining time of the first radar transceiver slot TR1 is sufficient. Since the first remaining time of the first radar transceiver slot TR1 is insufficient to accommodate another retry radar frame, step S228 is executed to determine if the duty cycle TPD has expired. At this point, as shown in Figure 3B, when the first retry radar frame F1D is completed, the duty cycle TPD has not yet expired, so step S231 is executed to switch the WiFi radar communication circuit 100 (operation) from the radar transceiver band BRAD to the WiFi communication band BWF. Next, step S232 can be executed to send the WiFi communication packet PW2.

[0053] On the other hand, if it is determined that the working cycle TPD has expired, step S230 can be executed to make appropriate adjustments to the settings of the WiFi radar communication circuit 100 and reset the retry count CRETRY to zero.

[0054] Next, referring to Figures 1, 2B and 3B, three second radar frames F2A, F2B and F2C are sequentially transmitted in the second radar transceiver slot TR2 (repeating steps S236, S238, S240 and S244). At this time, since the second radar frames F2A, F2B and F2C are not interfered with, the retry count CRETRY remains at 1 (accumulated in the first radar transceiver slot TR1 and carried into the second radar transceiver slot TR2).

[0055] Next, after step S246, it is determined that the retry count CRETRY has not yet reached zero, and step S250 is entered to determine whether the second remaining time of the second radar transceiver slot TR2 is sufficient. At this time, the second remaining time of the second radar transceiver slot TR2 is still sufficient to accommodate one radar frame. Therefore, step S252 is entered, and the second retry radar frame F2D is transmitted in the second radar transceiver slot TR2, and the second retry reflected echo corresponding to the second retry radar frame F2D is received. Next, in step S254, it is determined whether the second retry radar frame F2D is interfered with based on the waveform of the second reflected echo. At this time, since it is determined that the second retry radar frame F2D is not interfered with, step S256 is executed to decrease the retry count CRETRY from 1 to 0. Conversely, if it is determined that the second retry radar frame F2D is interfered with, the retry count CRETRY will be maintained.

[0056] At this point, return to step S246. Since the retry count CRETRY has reached zero, proceed to step S248 and shut down some circuit components in the WiFi radar communication circuit 100. When the second radar transceiver slot TR2 ends, execute step S261 to switch the operation of the WiFi radar communication circuit 100 from the radar transceiver band BRAD to the WiFi communication band BWF.

[0057] In the second embodiment of Figure 3B above, the first radar transceiver time slot TR1 and the second radar transceiver time slot TR2 jointly refer to the retry count CRETRY to control whether to transmit at least one retry radar frame (e.g., the first retry radar frame F1D and the second retry radar frame F2D). In this case, if two radar frames encounter interference in the first radar transceiver time slot TR1, compensation for only one retry radar frame (e.g., the first retry radar frame F1D) is completed in the first remaining time of the first radar transceiver time slot TR1. In this case, the retry radar frame (e.g., the second retry radar frame F2D) can be continued to be transmitted using the second radar transceiver time slot TR2 after the first radar transceiver time slot TR1. Through the above-described WiFi radar control method 200, it can be ensured that a total of 6 valid (uninterrupted) target frames are completed in one working cycle TPD. In this way, the stability and accuracy of radar detection in each working cycle TPD can be improved.

[0058] It should be added that the number of radar transceiver time slots included in each working cycle TPD in this disclosure document (2 in the embodiment), the number of target frames in each radar transceiver time slot (3 in the embodiment), and the remaining time length of each radar transceiver time slot (enough to accommodate 1 retry radar frame in the embodiment) are not limited to the above embodiments. The above embodiments are for illustrative purposes and can be adjusted according to actual applications.

[0059] Please also refer to Figure 3C, which shows a schematic diagram of the third embodiment where some radar frames in the first radar transceiver slot TR1 and the second radar transceiver slot TR2 encounter interference.

[0060] In the third embodiment of Figure 3C, it is assumed that two first radar frames F1A and F1C in the first radar transceiver slot TR1 are interfered with, and a second radar frame F2A in the second radar transceiver slot TR2 is also interfered with.

[0061] As shown in Figure 3C, when the first radar transceiver slot TR1 is completed (corresponding to steps S202 to S231 shown in Figure 2A), the retry count CRETRY is 1.

[0062] Please refer to Figures 1, 2B, and 3B. In the second radar transceiver slot TR2, three second radar frames F2A, F2B, and F2C are sequentially transmitted (repeating steps S236, S238, S240, and S244). In step S240, it is determined that the second radar frame F2A is interfered with, so step S242 is executed accordingly, and the retry count CRETRY is incremented from 1 to 2. The other two second radar frames F2B and F2C are not interfered with.

[0063] Next, proceed to step S246, where it is determined that the retry count CRETRY has not yet reached zero. Therefore, step S250 is executed to determine whether the second remaining time of the second radar transceiver slot TR2 is sufficient. At this time, the second remaining time of the second radar transceiver slot TR2 is still sufficient to accommodate one radar frame. Therefore, proceed to step S252, where the second retry radar frame F2D is transmitted in the second radar transceiver slot TR2, and the second retry reflected echo corresponding to the second retry radar frame F2D is received. Next, in step S254, it is determined whether the second retry radar frame F2D is interfered with based on the waveform of the second reflected echo. At this time, since it is determined that the second retry radar frame F2D is not interfered with, step S256 is executed to decrease the retry count CRETRY from 2 to 1.

[0064] Returning to step S246, it is determined that the retry count CRETRY has not yet been returned to zero. Step S250 is then entered again, where it is determined that the remaining time of the second radar transceiver slot TR2 is insufficient to accommodate another radar frame. Step S258 is then entered to determine if the working cycle TPD has expired. This is the last radar transceiver slot in the working cycle TPD (i.e., the second radar transceiver slot TR2), therefore it can be determined that the working cycle TPD has expired and there is no longer a next radar transceiver slot. This indicates that the surrounding interference is quite severe, and even using another working cycle TPD to send as many retry radar frames as possible cannot meet the current target frame count (6 frames) for each working cycle TPD. The control unit 180 of the WiFi radar communication circuit 100 executes step S260, appropriately adjusting the settings of the WiFi radar communication circuit 100 and resetting the retry count CRETRY to zero.

[0065] For example, the above-mentioned appropriate adjustments may include increasing the signal gain of the power amplifier 124 to the transmitted signal, adjusting the sensitivity of the low noise amplifier 126, adjusting the setting of the filter 129, or reducing the number of target frames, etc.

[0066] By periodically resetting the retry count CRETRY to zero in step S260, the retry count CRETRY can be prevented from accumulating continuously, which would cause this mechanism to fail (for example, if a large number of retry count CRETRY are accumulated by TPD in the same working cycle due to noise, TPD in other working cycles without noise will need to send retry radar frames).

[0067] In the second embodiment of Figure 3C above, the first radar transceiver time slot TR1 and the second radar transceiver time slot TR2 jointly refer to the retry count CRETRY to control whether to send at least one retry radar frame (e.g., the first retry radar frame F1D and the second retry radar frame F2D). In addition, if the target frame quantity cannot be met when the duty cycle TPD expires, appropriate adjustments can be made in step S260 and the retry count CRETRY can be reset to zero.

[0068] In the above embodiments, the WiFi radar control method 200 provides a mechanism in which multiple radar transceiver time slots share the remaining time with each other to send retry radar frames, so that each working cycle TPD can reach the target number of frames as much as possible, which can improve the stability and accuracy of radar detection in each working cycle TPD.

[0069] This disclosure is not limited to the WiFi radar control method 200 shown in Figures 2A and 2B. Please refer to Figures 4 and 5A. Figure 4 illustrates a flowchart of a WiFi radar control method 300 according to some embodiments of this disclosure. Figure 5A illustrates a schematic diagram of the fourth embodiment when the radar frame of the radar transceiver slot TR does not encounter interference.

[0070] As shown in Figures 1, 4, and 5A, the WiFi radar communication circuit 100 first executes step S302, transmitting and receiving WiFi communication packets PW1 on the WiFi communication frequency band BWF in the first WiFi communication time slot TW1. Then, when the first WiFi communication time slot TW1 ends (i.e., the radar transceiver time slot TR begins), step S304 is executed, switching the operation of the WiFi radar communication circuit 100 from the WiFi communication frequency band BWF to the radar transceiver frequency band BRAD.

[0071] Next, in the radar transceiver slot TR, the control unit 180 of the WiFi radar communication circuit 100 executes step S306, sends the radar frame FA, and receives the reflected echo corresponding to the radar frame FA.

[0072] Next, step S308 is executed, and the control unit 180 of the WiFi radar communication circuit 100 determines whether the radar frame FA is interfered with based on the waveform of the reflected echo of the radar frame FA.

[0073] At this time, step S308 determines that the radar frame FA is not interfered with, so it proceeds to step S310 and decreases the target frame count CTARGET from the predicted value of 3 to 2, which means that a valid radar frame FA has been sent.

[0074] Next, the control unit 180 executes step S312 to determine whether the target frame count CTARGET has been returned to zero. At this time, it is determined that the target frame count CTARGET has not yet been returned to zero, so the process proceeds to step S314 to determine whether the remaining time of the radar transceiver slot TR is sufficient. At this time, it is determined that the remaining time of the radar transceiver slot TR is still sufficient, so the process proceeds to step S306 to continue transmitting another radar frame FB in the radar transceiver slot TR.

[0075] Similarly, when the radar frame FB and radar frame FC are sent, the target frame count CTARGET is sequentially decreased to 1 and then to 0. At this time, step S312 determines that the target frame count CTARGET has returned to zero, so it proceeds to step S316, and at least some of the circuit elements in the WiFi radar communication circuit 100 are turned off in advance, until the relevant circuit elements are woken up again when the second WiFi communication slot TW2 is entered.

[0076] Step S316 can turn off one or more circuit elements in the analog front-end circuit 120, digital-to-analog converter 140, analog-to-digital converter 150 and digital signal processor 160 in the WiFi radar communication circuit 100 shown in Figure 1, thereby saving the power consumption caused by these circuit elements.

[0077] Next, step S320 is executed to switch the operation of the WiFi radar communication circuit 100 from the radar transceiver band BRAD to the WiFi communication band BWF. In the second WiFi communication time slot TW2, step S322 is executed to send and receive WiFi communication packets PW2.

[0078] Please refer to Figure 5B, which is a schematic diagram of the fifth embodiment when a portion of the radar frame in the radar transceiver slot TR encounters interference.

[0079] As shown in Figures 1, 4 and 5B, the WiFi radar communication circuit 100 first sends a radar frame FA without interference, so it proceeds to step S310, where the target frame count CTARGET is reduced from the predicted value of 3 to 2, which means that a valid radar frame FA has been sent.

[0080] Next, the WiFi radar communication circuit 100 sends the radar frame FB, and step S308 determines that the radar frame FB is interfered with, so the target frame count CTARGET does not decrease and remains at 2.

[0081] Whether the radar frame FB is interfered with can be determined based on the difference between the waveform of the reflected echo of the radar frame FB and the linear sweep signal contained in the radar frame FB, but this disclosure is not limited to this. In other embodiments, the control unit 180 of the WiFi radar communication circuit 100 can also determine whether the radar frame is interfered with based on spectrum analysis, beat frequency analysis, channel status information detection, or autocorrelation function detection.

[0082] Next, the WiFi radar communication circuit 100 sends radar frame FC, and step S308 determines that the radar frame FB is not interfered with, and executes step S310 to decrease the target frame count CTARGET from 2 to 1.

[0083] Next, proceed to step S314 to determine if the remaining time of the radar transceiver time slot TR is sufficient. If it is determined that the remaining time of the radar transceiver time slot TR is still sufficient (as shown in Figure 5B, the radar transceiver time slot TR includes the retransmission time TRL to accommodate additional radar frames), proceed to step S306 to continue transmitting another radar frame FD in the radar transceiver time slot TR. When step S308 determines that the radar frame FD is not interfered with, execute step S310 to decrement the target frame count CTARGET from 1 to 0.

[0084] After determining in step S312 that the target frame count CTARGET has returned to zero, step S316 is executed to shut down at least some of the circuit elements in the WiFi radar communication circuit 100 in advance, until the relevant circuit elements are woken up again when entering the second WiFi communication slot TW2.

[0085] Next, step S320 is executed, switching the operation of the WiFi radar communication circuit 100 from the radar transceiver band BRAD to the WiFi communication band BWF. In the second WiFi communication time slot TW2, step S322 is executed to send and receive WiFi communication packets PW2.

[0086] Please refer to Figure 5C, which is a schematic diagram of the sixth embodiment when a portion of the radar frame in the radar transceiver slot TR encounters interference.

[0087] As shown in Figures 1, 4 and 5C, the WiFi radar communication circuit 100 first sends a radar frame FA without interference, so it proceeds to step S310, where the target frame count CTARGET is reduced from the predicted value of 3 to 2, which means that a valid radar frame FA has been sent.

[0088] Next, the WiFi radar communication circuit 100 sequentially sends radar frame FB and radar frame FC, and in both steps S308 it is determined that radar frame FB and radar frame FC are interfered with, so the target frame count CTARGET does not decrease and remains at 2.

[0089] Next, in step S312, it is determined that the target frame count CTARGET has not yet reached zero, and the process proceeds to step S314 to determine whether the remaining time of the radar transceiver time slot TR is sufficient. At this point, it is determined that the remaining time of the radar transceiver time slot TR is still sufficient, so the process proceeds to step S306, where another radar frame FD is transmitted in the radar transceiver time slot TR. When step S308 determines that the radar frame FD is not interfered with, step S310 is executed, and the target frame count CTARGET is decremented from 2 to 1.

[0090] After step S312, it is determined that the target frame count CTARGET has not yet returned to zero. The WiFi radar communication circuit 100 sends radar frames FE and FF in sequence. In both steps S308, it is determined that radar frames FE and FF are interfered with. Therefore, the target frame count CTARGET does not decrease and remains at 1.

[0091] In step S312, it is determined that the target frame count CTARGET has not yet reached zero, and the process proceeds to step S314 to determine whether the remaining time of the radar transceiver slot TR is sufficient. At this time, step S314 determines that the remaining time of the radar transceiver slot TR is insufficient to accommodate more radar frames. The control unit 180 executes step S318 to appropriately adjust the settings of the WiFi radar communication circuit 100. For example, the appropriate adjustments may include increasing the signal gain of the power amplifier 124 for the transmitted signal, adjusting the sensitivity of the low noise amplifier 126, adjusting the settings of the filter 129, or reducing the number of target frames, etc.

[0092] Next, step S320 is executed to switch the operation of the WiFi radar communication circuit 100 from the radar transceiver band BRAD to the WiFi communication band BWF. In the second WiFi communication time slot TW2, step S322 is executed to send and receive WiFi communication packets PW2.

[0093] In the embodiment shown in Figure 4, radar frames are retransmitted individually on a per-radar transceiver time slot (TR) basis to maximize the number of valid radar frames. When the predetermined number of valid radar frames is achieved, at least some circuit elements in the WiFi radar communication circuit 100 (e.g., Figures 5A and 5B) can be shut down earlier to save energy and ensure the stability and accuracy of radar detection. If the predetermined number of valid radar frames cannot be achieved, the WiFi radar communication circuit 100 can be appropriately adjusted (e.g., Figure 5C). [Simplified Explanation of the Diagram]

[0006] To make the above and other objects, features and embodiments of this disclosure more apparent and understandable, the accompanying drawings are described as follows: Figure 1 illustrates a schematic diagram of a WiFi radar communication circuit according to some embodiments of this disclosure; Figures 2A and 2B illustrate flowcharts of a WiFi radar control method according to some embodiments of this disclosure; Figure 3A illustrates a schematic diagram in a first embodiment when the radar frames of the first and second radar transceiver slots do not encounter interference; Figure 3B illustrates a schematic diagram in a second embodiment when some radar frames in the first radar transceiver slot encounter interference while the radar frames of the second radar transceiver slot do not encounter interference; Figure 3C illustrates a schematic diagram in a third embodiment when some radar frames in the first and second radar transceiver slots encounter interference; Figure 4 illustrates a flowchart of a WiFi radar control method according to some embodiments of this disclosure; Figure 5A illustrates a schematic diagram in a fourth embodiment when the radar frames of the radar transceiver slots do not encounter interference. Figure 5B illustrates a schematic diagram of the fifth embodiment when a portion of the radar frame in the radar transceiver slot encounters interference; and Figure 5C illustrates a schematic diagram of the sixth embodiment when a portion of the radar frame in the radar transceiver slot encounters interference. [Biomaterial Storage]

[0095] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A WiFi radar control method, comprising: sequentially transmitting a plurality of first radar frames by a WiFi radar communication circuit in a first radar transceiver time slot, and receiving a plurality of first reflected echoes corresponding to the plurality of first radar frames; determining whether the plurality of first radar frames are interfered with based on a waveform of the plurality of first reflected echoes; incrementing a retry count when it is determined that the plurality of first radar frames are interfered with; and transmitting at least one retry radar frame in the first radar transceiver time slot or a second radar transceiver time slot following the first radar transceiver time slot when the retry count is not zero.

2. The WiFi radar control method as described in claim 1 further includes: in the first radar transceiver time slot, when the retry count is not zero, determining whether a first remaining time in the first radar transceiver time slot is sufficient; when the first remaining time is sufficient, transmitting a first retry radar frame in the first radar transceiver time slot and receiving a first retry reflected echo corresponding to the first retry radar frame; determining whether the first retry radar frame is interfered with based on the waveform of the first retry reflected echo; and when it is determined that the first retry radar frame is not interfered with, decrementing the retry count.

3. The WiFi radar control method as described in claim 2 further includes: determining whether a working cycle has expired, wherein a length of the working cycle is greater than a length of the first radar transceiver slot and greater than a length of the second radar transceiver slot; and if the working cycle has expired, resetting the retry count to zero.

4. The WiFi radar control method as described in claim 1 further includes: switching the WiFi radar communication circuit from a WiFi communication frequency band to a radar transceiver frequency band at the beginning of the first radar transceiver time slot; switching the WiFi radar communication circuit from the radar transceiver frequency band to the WiFi communication frequency band at the end of the first radar transceiver time slot; and transmitting and receiving a WiFi communication packet.

5. The WiFi radar control method as described in claim 1 further includes: sequentially transmitting a plurality of second radar frames in the second radar transceiver time slot, and receiving a plurality of second reflected echoes corresponding to the plurality of second radar frames; determining whether the plurality of second radar frames are interfered with based on a waveform of the plurality of second reflected echoes; and incrementing the retry count when it is determined that the plurality of second radar frames are interfered with.

6. The WiFi radar control method as described in claim 1 further includes: in the second radar transceiver time slot, when the retry count is not zero, determining whether a second remaining time of the second radar transceiver time slot is sufficient; when the second remaining time is sufficient, transmitting a second retry radar frame in the second radar transceiver time slot and receiving a second retry reflected echo corresponding to the second retry radar frame; determining whether the second retry radar frame is interfered with based on a waveform of the second retry reflected echo; and when it is determined that the second retry radar frame is not interfered with, decrementing the retry count.

7. The WiFi radar control method as described in claim 1, wherein: When the retry count has reached zero, at least a portion of the circuit elements in the WiFi radar communication circuit are turned off in advance in the first radar transceiver slot or the second radar transceiver slot.

8. The WiFi radar control method as described in claim 1, wherein the first radar transceiver slot and the second radar transceiver slot jointly refer to the retry count to control whether to send the at least one retry radar frame.

9. A WiFi radar control method, comprising: transmitting a radar frame by a WiFi radar communication circuit in a radar transceiver time slot, and receiving a reflected echo corresponding to the radar frame; determining whether the radar frame is interfered with based on a waveform of the reflected echo; decrementing a target frame count when it is determined that the radar frame is not interfered with; and continuing to transmit another radar frame in the radar transceiver time slot when the target frame count is not zero.

10. A WiFi radar communication circuit, comprising: an analog front-end circuit coupled to a transmitting antenna and a receiving antenna, for controlling the transmitting antenna and the receiving antenna to operate in a WiFi communication frequency band or a radar transceiver frequency band; and a control unit coupled to the analog front-end circuit, the control unit being configured to: sequentially transmit a plurality of first radar frames to the transmitting antenna via the analog front-end circuit in a first radar transceiver time slot, and receive a plurality of first reflected echoes corresponding to the plurality of first radar frames from the receiving antenna; determine whether the plurality of first radar frames are interfered with based on the waveforms of the plurality of first reflected echoes; increment a retry count when it is determined that the plurality of first radar frames are interfered with; and when the retry count is not zero, transmit at least one retry radar frame in the first radar transceiver time slot or a second radar transceiver time slot following the first radar transceiver time slot.

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