WO2024204760A1 - Radio wave transceiver, radio wave transmission/reception method, and radio wave transmission/reception program - Google Patents

Abstract

This radio wave transceiver comprises: a transmission/reception unit that alternately performs a communication operation for communicating by radio waves and a radar operation for acquiring radar data by radio waves; and a control unit that controls the transmission/reception unit. The control unit adjusts a first period from the final time of radar data acquisition in a radar operation prior to the start of a communication operation until the start time of radar data acquisition in the next radar operation after the communication operation is terminated so that said first period becomes a natural number multiple of a second period which is the interval of radar data acquisition in the radar operation.

Description

Radio wave transmitting/receiving device, radio wave transmitting/receiving method, and radio wave transmitting/receiving program

The present invention relates to a radio wave transmitting/receiving device, a radio wave transmitting/receiving method, and a radio wave transmitting/receiving program.

UWB (Ultra-Wide Band) communication transmits and receives pulse signals with a short pulse width (wide frequency bandwidth and high distance resolution) between two communication devices, and can estimate the distance between the communication devices from the time it takes for the pulse signal to travel back and forth between the communication devices. Due to this property, UWB communication can detect and manage whether a key terminal held by a user is within a specific distance range from the vehicle, and in recent years has begun to be used for vehicle smart keys as a countermeasure against relay attacks. Smart keys, also known as smart entry systems, can lock and unlock vehicle doors and start and stop the engine without using a mechanical key.

Distance measurement using UWB communication is similar to radar in that it converts the round-trip time of a pulse signal into distance. A communication device capable of UWB communication can be relatively easily turned into a radar without hardware modifications by receiving part of the pulse signal it transmits (the reflected signal reflected by a surrounding detection target) by itself, in other words, by performing UWB communication with itself.

For example, Patent Document 1 discloses a wireless device that realizes multiple functions, such as a smart entry function (communication function) and a radar function, based on information obtained by transmitting and receiving UWB signals. In the wireless device disclosed in Patent Document 1, the transmission and reception of UWB signals is time-division in order to realize the various functions.

Patent No. 7008868

In the wireless device disclosed in Patent Document 1, for example, time division is performed for the transmission and reception of radio waves to realize communication and radar functions. Here, the communication period of communication such as UWB communication is determined by the communication protocol. Furthermore, since radar repeats the transmission and reception of radio waves at a fixed cycle, the radar period is determined by the number of repetitions. In this way, the communication protocol that determines the communication period and the cycle and number of repetitions that determine the radar period are independent parameters, so in reality the communication period and the radar period will never be the same.

As described above, radar repeatedly transmits and receives radio waves at regular intervals, and detects the presence and distance of an object by periodically processing the radar signal (radar data) received from the reflected radio waves. In a wireless device that performs signal processing of radar signals at regular intervals, if radio waves are transmitted and received in a time-division manner as described above, the timing of the radar's transmission and reception of radio waves and the timing of the radar signal processing will differ depending on the communication period. This timing difference means that signal processing of the radar signal, such as Fourier transform processing, cannot be performed correctly, and there is a risk that the presence and distance of an object cannot be detected correctly.

The object of the present invention is to provide a radio wave transmitting/receiving device, a radio wave transmitting/receiving method, and a radio wave transmitting/receiving program that can correctly process radar signals even when communication operations and radar operations are performed alternately.

The radio wave transmitting/receiving device according to the present invention comprises:
a transmitting/receiving unit that alternately performs a communication operation for performing communication by radio waves and a radar operation for acquiring radar data by the radio waves;
A control unit that controls the transmission/reception unit;
Equipped with
The control unit adjusts the first period from the final time of radar data acquisition in the radar operation before the start of the communication operation to the start time of radar data acquisition in the next radar operation after the end of the communication operation so that the first period is a natural number multiple of a second period, which is the interval between radar data acquisition in the radar operation.

The radio wave transmitting and receiving method according to the present invention comprises:
The transmitting and receiving unit performs a communication operation to communicate by radio waves,
performing a radar operation for acquiring radar data by the radio waves in the transmitting/receiving unit;
When the communication operation and the radar operation are performed alternately, a first period from the final time of radar data acquisition in the radar operation before the start of the communication operation to the start time of radar data acquisition in the next radar operation after the end of the communication operation is adjusted so that the first period is a natural number multiple of a second period, which is the interval between radar data acquisition in the radar operation.

The radio wave transmitting/receiving program according to the present invention comprises:
On the computer,
A process of performing a communication operation for performing communication by radio waves in a transmitting/receiving unit;
A process of performing a radar operation to acquire radar data by the radio waves in the transmitting/receiving unit;
a process of adjusting a first period from a final time of radar data acquisition in the radar operation before the start of the communication operation to a start time of radar data acquisition in the next radar operation after the end of the communication operation, when the communication operation and the radar operation are alternately performed, so that the first period is a natural number multiple of a second period that is an interval between radar data acquisition in the radar operation;
Execute the command.

According to the present invention, radar signals can be processed correctly even when communication operations and radar operations are performed alternately.

1 is a schematic diagram showing a vehicle equipped with a radio wave transmitting and receiving device according to an embodiment of the present invention. 2 is a block diagram showing an example of the radio wave transmitting/receiving device shown in FIG. 1 . 2 is a flowchart illustrating an example of a radio wave transmitting and receiving method according to an embodiment of the present invention. 4 is a flowchart for determining a radar start time in the radio wave transmitting and receiving method shown in FIG. 3 . 5 is a time chart illustrating an example of an alternating operation of a radar operation and a communication operation by the radio wave transmitting and receiving method according to the embodiment of the present invention. 11 is a graph showing I data and Q data of radar data in the case of radar operation alone. 13 is a graph showing I data and Q data of radar data when communication operation and radar operation are performed alternately, the graph showing the case where a radio wave transmission and reception method according to an embodiment of the present invention is applied and the case where the method is not applied. 8 is a graph showing the calculation results obtained by processing the radar data shown in FIG. 6 and FIG. 7 by fast Fourier transform.

The following describes in detail an embodiment of the present invention with reference to the drawings.

[Radio wave transmitting/receiving device]
Fig. 1 is a schematic diagram showing a vehicle 100 equipped with a UWB communication device 10, which is an example of a radio wave transmitting and receiving device according to the present embodiment. Fig. 2 is a block diagram showing an example of the UWB communication device 10.

The UWB communication device 10 is placed in the center of the interior of the vehicle 100, for example, on the ceiling. The UWB communication device 10 is basically used to operate the smart key of the vehicle 100, and by performing UWB communication with the key terminal 20 carried by the user, it is possible to perform operations such as locking and unlocking the doors of the vehicle 100 and starting and stopping the engine without using a mechanical key.

In FIG. 1, an example is shown in which one UWB communication device 10 is installed in the center of the vehicle (on the ceiling) so that UWB communication can be properly performed throughout the vehicle and with the key terminal outside the vehicle, but the number and locations of the UWB communication devices 10 are not limited to the example shown in FIG. 1 and can be changed as appropriate.

After the vehicle 100 stops, the UWB communication device 10 starts UWB communication with the key terminal 20 carried by the user, and continuously measures the distance to the key terminal 20 based on the response time between the UWB communication device 10 and the key terminal 20. The UWB communication device 10 then detects that the key terminal 20 has moved a predetermined distance or more away from the vehicle 100 based on the results of the distance measurement with the key terminal 20 via UWB communication, and locks the doors of the vehicle 100 in response to this detection.

Note that here, the key terminal 20 is used as an example of a mobile terminal that communicates with the UWB communication device 10, but instead of the key terminal 20, a terminal such as a smartphone that has UWB communication capabilities may also be used.

In this embodiment, the above-mentioned UWB communication device 10 is used as a radar for detecting a detection target T, such as a living body inside a vehicle, for example, a child (infant) or a pet.

Specifically, after the doors of the vehicle 100 are locked, the UWB communication device 10 alternates between UWB communication with the key terminal 20 and radar operation in a time-division manner, and during radar operation, detects whether a child, pet, etc. has been left behind inside the vehicle. Note that the start operation for alternating between communication operation and radar operation is merely an example, and may be started based on a locking operation by other means (manual locking, remote locking), etc.

In this way, the UWB communication device 10 that can be used as a radar has the configuration shown in Figure 2. Specifically, the UWB communication device 10 has at least a control unit 11, a transmission unit 12, a reception unit 13, a signal processing unit 14, and an alarm output unit 15.

The control unit 11, not shown in the figure, has a CPU (Central Processing Unit) as an arithmetic/control device, a ROM (Read Only Memory) and a RAM (Random Access Memory) as main storage devices, and functions as a so-called computer. The transmission unit 12, reception unit 13, signal processing unit 14, and alarm output unit 15 are all controlled by the CPU.

The control unit 11 basically controls the transmission unit 12 and reception unit 13 to perform UWB communication with the key terminal 20 and operate the smart key. Then, in response to the start operation described above, the control unit 11 controls the transmission unit 12 and reception unit 13 to alternate between communication operation and radar operation, and to perform living body detection during radar operation.

The transmitter 12 has a transmission antenna 12a. The transmitter 12 radiates, for example, a UWB pulse signal with a short pulse width using microwaves or the like, throughout the interior of the vehicle and outside the vehicle via the transmission antenna 12a. During radar operation, the transmitter 12 periodically radiates a UWB pulse signal throughout the interior of the vehicle and outside the vehicle via the transmission antenna 12a.

The receiving unit 13 has a receiving antenna 13a. The receiving unit 13 receives a pulse signal from the key terminal 20 via the receiving antenna 13a. In this embodiment, during radar operation, the receiving unit 13 periodically receives a reflected signal, which is a UWB pulse signal radiated from the transmitting unit 12 and reflected by the detection target, via the receiving antenna 13a. When a living body is present inside the vehicle, the receiving unit 13 receives a reflected signal from the living body (detection target) present around the UWB communication device 10, i.e., inside the vehicle.

The above-mentioned transmitting unit 12 and receiving unit 13 correspond to the transmitting/receiving unit in the present invention.

When the radar is operating, the signal processing unit 14 performs signal processing on the reflected signal received by the receiving unit 13 to detect a living body (detection target) present inside the vehicle. The signal processing unit 14 converts the reflected signal received by the receiving unit 13 into, for example, CIR (Channel Impulse Response) I, Q (In-Phase/Quadrature-Phase) data (radar data) in which distance and the strength of the reflected signal are paired. When a detection target is detected, the CIR I, Q data contains data that includes the distance to the detection target and the strength of the reflected signal from the detection target.

The signal processing unit 14 performs signal processing (frequency analysis) on the above-mentioned I and Q data, for example, using FFT (Fast Fourier Transform) which performs discrete Fourier transform processing, to determine whether or not there is data in a frequency band that indicates the fluctuating movement of a living body. If the fluctuating movement of a living body is, for example, breathing, a frequency band of 0.16 Hz to 1.0 Hz is used. This allows the signal processing unit 14 to determine the presence or absence of a living body, and to detect the distance to the living body using the CIR number which corresponds to the distance to the living body.

In this embodiment, after the doors of the vehicle 100 are locked, the UWB communication device 10 alternates between communication and radar operations. Therefore, for example, when a user carrying the key terminal 20 approaches the vehicle 100, the door is unlocked, the alternating operation between communication and radar operations is stopped, and only communication operations are performed.

In this way, the UWB communication device 10 alternates between communication and radar operations, so when a user carrying the key terminal 20 approaches the vehicle 100, the doors can be unlocked instantly, allowing biometric detection to be performed without impairing the user's experience.

If the alarm output unit 15 determines that a living organism is present inside the vehicle, it outputs an alarm to notify people around the vehicle 100 that a living organism is present inside the vehicle. For example, if it determines that a child, pet, etc. has been left behind inside the vehicle, the alarm output unit 15 uses the lights of the vehicle 100 (e.g., headlights, etc.) to output an alarm by flashing the lights, etc. to notify people around the vehicle 100 that the animal has been left behind. The alarm output unit 15 may also use an audio output device (e.g., a horn, speaker, etc.) to output an alarm by sound or voice from the audio output device to notify people around the vehicle 100 that the animal has been left behind.

[Radio wave transmission method]
The radio wave transmission and reception method in the UWB communication device 10 described above will be described with reference to Fig. 3 to Fig. 5. Fig. 3 is a flow chart for explaining an example of the radio wave transmission and reception method according to the present embodiment. Fig. 4 is a flow chart for determining the radar start time in the radio wave transmission and reception method shown in Fig. 3. Fig. 5 is a time chart for explaining an example of the alternating operation of radar operation and communication operation in the radio wave transmission and reception method according to the present embodiment.

The alternating operation of radar operation and communication operation is initiated, for example, after the doors of the vehicle 100 are locked, as described above.

(Step S11)
The control unit 11 calculates the communication start time _ts of the communication operation in accordance with the communication protocol of the communication operation. In this embodiment, the communication start time _ts is calculated in accordance with the communication protocol of UWB communication.

(Step S12)
The control unit 11 starts radar operation using the transmitting unit 12, the receiving unit 13, etc., and acquires radar data at an acquisition interval t _i1 (a second period in the present invention) of the radar operation. For example, as shown in Fig. 5, radar data is acquired m times (m is a natural number) at an acquisition period t _i1 . In this case, the radar operation period t _r of the radar operation is t _r = m × t _i1 .

(Step S13)
The control unit 11 checks whether it is the communication start time _ts of the communication operation using its own clock function, and if it is the communication start time _ts (YES), proceeds to step S14, and if it is not the communication start time _ts (NO), repeats step S13. That is, the control unit 11 repeats step S13 until it reaches the communication start time _ts .

(Step S14)
The control unit 11 stops the radar operation, and stores the final time t _p , which is the time when the radar data was last acquired during the radar operation before the start of the communication operation.

(Step S15)
The control unit 11 starts a communication operation using the transmission unit 12, the reception unit 13, etc. Note that, although the communication start time _ts and the final time _tp are set to be the same timing here, the communication start time _ts may be after the final time _tp . As long as the communication operation can be started and ended during a period t _i2 (a first period in the present invention) described later, the communication start time _ts and the final time _tp do not have to be the same timing.

When a communication operation is started, the control unit 11 first puts the receiving unit 13 into a receiving state and waits for a transmission signal from the key terminal 20. When a transmission signal is received, a specified communication protocol is implemented.

(Step S16)
The control unit 11 stops the communication operation and calculates the communication start time t _s of the next communication operation in accordance with the communication protocol of the communication operation.

(Step S17)
The control unit 11 adjusts the period t _i2 from the final time t _p to the radar start time t _n of radar data acquisition in the next radar operation so that it becomes n (n is a natural number) times the acquisition interval t _i1 . That is, as shown in Fig. 5, the period t _i2 is adjusted so that t _i2 = n x t _i1 . The period t _i2 and the natural number n will be described later with reference to Fig. 4.

(Step S18)
The control unit 11 uses its own clock function to check whether it is the radar start time _tn of the radar operation, and if it is the radar start time _tn (YES), proceeds to step S19, and if it is not the radar start time _tn (NO), repeats step S18. In other words, the control unit 11 repeats step S18 until it reaches the radar start time _tn .

(Step S19)
The control unit 11 checks whether or not an end operation has been performed, and if an end operation has been performed (YES), ends the series of procedures, and if an end operation has not been performed (NO), returns to step S12. After the vehicle 100 is locked, the control unit 11 basically repeats the above-mentioned steps S11 to S19, but if an end operation such as a stop switch of the UWB communication device 10 has been performed, the control unit 11 ends the processing of the above-mentioned steps S11 to S19.

Here, the period t _i2 and the natural number n will be described with reference to Fig. 4. The flowchart shown in Fig. 4 is executed as a subroutine of step S17, for example. In addition, here, the communication start time t _s and the end time t _p are assumed to be the same timing.

(Step S21)
The control unit 11 obtains the end time t _c when the communication operation is stopped.

(Step S22)
The control unit 11 obtains a natural number n that satisfies the following formula (1). When minimizing a delay time _td, which will be described later, the smallest n is obtained from among the natural numbers n that satisfy the following formula (1). By using the smallest n, it is possible to reduce the delay time _td , which will be described later, and it is possible to efficiently switch between communication operation and radar operation.

n>(t _c -t _p )/t _i1 ... (1)

(Step S23)
The control unit 11 obtains the radar start time _tn from the following formula (2): The radar start time _tn is a time after the end time _tc .

t _n =t _p +n×t _i1 ... (2)

(Step S24)
The control unit 11 calculates the delay time t _d from the following equation (3).

t _d = t _n -t _c ... (3)

In this way, the delay time _td is calculated, and when the delay time _td has elapsed from the end time _tc , the radar operation is started (resumed). The delay time _td from the end time _tc can be used to adjust the period _ti2 to be n times the acquisition interval _til . Even if the timing of the communication start time _ts and the final time _tp are not the same, and the communication start time _ts is after the final time _tp , the delay time _td from the end time _tc can be used to adjust the period _ti2 to be n times the acquisition interval _til .

In this way, the communication operation period t _i2 is adjusted to be n times the acquisition interval t _i1 including the delay time t _d . Therefore, when acquiring radar data in the next radar operation, there is no mismatch between the timing of radar data acquisition and the timing of radar data signal processing. As a result, the radar data signal processing, for example, Fourier transform processing, can be performed correctly, and the presence and distance of an object can be correctly detected.

Here, FIG. 6 is a graph showing the I data and Q data of radar data when radar operation is performed alone. Also, FIG. 7 is a graph showing the I data and Q data of radar data when communication operation and radar operation are performed alternately, when the radio wave transmission and reception method according to this embodiment is applied and when this method is not applied.

In FIG. 7, the solid line (aligned data) represents the case where the radio wave transmission and reception method according to this embodiment is applied, and the dashed line (not-aligned data) represents the case where the radio wave transmission and reception method according to this embodiment is not applied. Note that in FIG. 7, the signal amplitudes of I and Q data during communication operation are set to 0.

As shown in FIG. 7, when comparing the case where the radio wave transmission and reception method according to this embodiment is applied (see solid line) with the case where this radio wave transmission and reception method is not applied (see dashed line), the measurement period of the radar data (signal amplitude) shifts over time in the latter case.

Figure 8 is a graph showing the calculation results of processing the radar data shown in Figures 6 and 7 using fast Fourier transform.

In Figure 8, the solid line (ideal) is the calculation result of radar data when radar is operating alone. The long dashed line (aligned sample) is the calculation result of radar data when the radio wave transmission and reception method of this embodiment is applied. The short dashed line (not-aligned sample) is the calculation result of radar data when the radio wave transmission and reception method of this embodiment is not applied.

As can be seen from FIG. 8, the peak frequencies of the radar data calculation results when the radar is operating alone (solid line) and the radar data calculation results when the radio wave transmission and reception method according to this embodiment is applied (long dashed line) are the same or nearly the same. This is because when the radio wave transmission and reception method according to this embodiment is applied, the radar data can be acquired at the same timing as the signal processing timing of the radar data when the radar is operating alone.

On the other hand, there is a difference in peak frequency between the radar data calculation results when radar is operating alone (solid line) and the radar data calculation results when the radio wave transmission and reception method of this embodiment is not applied (short dashed line). This is because when the radio wave transmission and reception method of this embodiment is not applied, the radar data is acquired at a timing that differs from the timing of the radar data signal processing when radar is operating alone.

In this way, by applying the radio wave transmission and reception method according to this embodiment to acquire radar data, the radar signal can be processed correctly even when communication operations and radar operations are performed alternately. This makes it possible to correctly detect detection objects, such as infants left behind in the vehicle. Also, when detecting gestures of vehicle occupants as detection objects, the gestures can be correctly detected.

The above describes an embodiment of the present invention. Note that the above description is an example of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this. In other words, the description of the configuration of the device and the shape of each part is one example, and it is clear that various modifications and additions to these examples are possible within the scope of the present invention.

The entire disclosures of the specification, drawings and abstract contained in the Japanese application No. 2023-059238, filed on March 31, 2023, are incorporated herein by reference.

The present invention is useful for detecting living bodies using vehicle communication devices.

REFERENCE SIGNS LIST 10 UWB communication device 11 Control unit 12 Transmitter 13 Receiver 14 Signal processor 15 Alarm output unit 20 Key terminal 100 Vehicle

Claims (5)

1. a transmitting/receiving unit that alternately performs a communication operation for performing communication by radio waves and a radar operation for acquiring radar data by the radio waves;
   A control unit that controls the transmission/reception unit;
   Equipped with
   the control unit adjusts a first period from a final time of radar data acquisition in the radar operation before the start of the communication operation to a start time of radar data acquisition in the next radar operation after the end of the communication operation so that the first period is a natural number multiple of a second period that is an interval between radar data acquisition in the radar operation.
   Radio wave transmitting and receiving device.
2. the control unit selects, as the natural number, a natural number that is greater than a value obtained by dividing a difference between the end time and the final time of the communication operation by the second period and that is a minimum natural number.
   2. The radio wave transmitting/receiving device according to claim 1.
3. The control unit adjusts the first period by delaying the start time after the communication operation is completed.
   2. The radio wave transmitting/receiving device according to claim 1.
4. The transmitting and receiving unit performs a communication operation to communicate by radio waves,
   performing a radar operation for acquiring radar data by the radio waves in the transmitting/receiving unit;
   adjusting a first period from a final time of radar data acquisition in the radar operation before the start of the communication operation to a start time of radar data acquisition in the next radar operation after the end of the communication operation to be a natural number multiple of a second period which is an interval between radar data acquisition in the radar operation, when the communication operation and the radar operation are alternately performed;
   Radio wave transmission and reception method.
5. On the computer,
   A process of performing a communication operation for performing communication by radio waves in a transmitting/receiving unit;
   A process of performing a radar operation to acquire radar data by the radio waves in the transmitting/receiving unit;
   a process of adjusting a first period from a final time of radar data acquisition in the radar operation before the start of the communication operation to a start time of radar data acquisition in the next radar operation after the end of the communication operation, when the communication operation and the radar operation are alternately performed, so that the first period is a natural number multiple of a second period that is an interval between radar data acquisition in the radar operation;
   A radio wave transmission and reception program that executes the above.

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