JP7568485B2 - Radio and wireless communication systems - Google Patents

Description

The present invention relates to a radio and a wireless communication system.

A wireless communication system is known that performs wireless communication using communication waves in the same frequency band as the radar waves used to detect objects (see, for example, Patent Document 1).

In the wireless communication system disclosed in Patent Document 1, when radar waves are detected, wireless communication is stopped to suppress interference with the radar waves, and when radar waves are no longer detected, wireless communication is resumed.

A radar detection circuit is used to detect radar waves. The radar detection circuit detects radar waves based on the reception level or type of received radio waves. When the radar detection circuit detects radar waves, packet transmission is stopped.

JP 2001-237846 A

However, in the above-mentioned wireless communication system, if a packet is being transmitted when radar waves are detected, the communication waves used to transmit the packet may cause mutual interference with the radar waves.

In this case, the receiving radio in the wireless communication system will be unable to receive packets correctly and will need to request the transmitting radio to resend the packets. This can cause communication delays within the wireless communication system.

The present invention has been made in consideration of the problems inherent in such conventional technology. The object of the present invention is to provide a radio and a radio communication system that can avoid communication delays while suppressing mutual interference between communication waves used for wireless communication and radar waves used to detect objects when the communication waves and radar waves use the same frequency band.

A wireless device according to an embodiment of the present invention includes a setting unit that alternately sets a detection period in which an object is detected using radar waves and a communication period in which wireless communication is performed using communication waves in the same frequency band as the radar waves, and notifies other wireless devices of the setting information for the communication period, a transmission unit that transmits the radar waves used to detect the object and the communication waves used for wireless communication, a detection unit that transmits the radar waves via the transmission unit during the detection period to detect the object, a generation unit that generates position information of the object, and a communication processing unit that transmits the communication waves via the transmission unit during the communication period to perform wireless communication with other wireless devices, and the communication processing unit notifies the other wireless devices of the position information of the object at the start of wireless communication during the communication period.

The present invention provides a radio and a radio communication system that can avoid communication delays while suppressing mutual interference between communication waves used for wireless communication and radar waves used for detecting targets when the communication waves and radar waves use the same frequency band.

FIG. 1 is a diagram showing an overall schematic configuration of a wireless communication system according to this embodiment. FIG. 2 is a functional block diagram of the first wireless device according to the present embodiment. FIG. 3 is a functional block diagram of the detection unit according to the present embodiment. FIG. 4 is a functional block diagram of the communication processing unit according to the present embodiment. FIG. 5 is a diagram showing an example of setting a communication period and a detection period according to the present embodiment. FIG. 6 is a diagram showing an example of a detection period according to the present embodiment. FIG. 7 is a functional block diagram of a second wireless device according to the present embodiment. FIG. 8 is a diagram showing an example of ride information according to the present embodiment. FIG. 9 is a diagram showing an example of a communication determination table according to the present embodiment. FIG. 10 is a diagram showing a flowchart of a process of switching between a detection period and a communication period by the first wireless device according to the present embodiment. FIG. 11 is a diagram showing a flowchart of a communication period optimization process performed by a first wireless device according to a modified example of this embodiment. FIG. 12 is a diagram illustrating an example of a hardware configuration of the first wireless device of the present embodiment.

The first radio device and wireless communication system according to this embodiment will be described in detail below with reference to the drawings. Note that identical or similar reference symbols are used for identical functions and configurations, and descriptions thereof will be omitted as appropriate.

[Overall Schematic Configuration of In-Vehicle System]
1 is a schematic diagram of an entire wireless communication system 10. In this embodiment, the wireless communication system 10 is mounted on a vehicle 1 and controls a wireless communication network formed within the vehicle 1. The wireless communication method used in the wireless communication network is a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) method. Note that the wireless communication method is not limited to the CSMA/CA method.

As shown in FIG. 1, the vehicle 1 includes a driver's seat 3, a passenger seat 5, and a rear seat 7. The rear seat 7 includes a rear seat right side 7a, a rear seat center portion 7b, and a rear seat left side 7c. In FIG. 1, an occupant P1 is sitting in the driver's seat 3.

For ease of explanation, the width direction of the vehicle 1 is defined as the vehicle width direction, and the longitudinal direction of the vehicle 1 is defined as the vehicle length direction. In the vehicle length direction, the side where the driver's seat 3 and passenger seat 5 are installed is defined as the front side, and the side where the rear seat 7 is installed is defined as the rear side. In the vehicle width direction, the side where the driver's seat 3 is installed is defined as the right side, and the side where the passenger seat 5 is installed is defined as the left side.

The wireless communication system 10 includes a first wireless device 20 and second wireless devices 30a to 30h. The first wireless device 20 and the second wireless devices 30a to 30h are set to be able to communicate with each other, forming a wireless communication network. The first wireless device 20 is also referred to as the "wireless device." The second wireless devices 30a to 30h are also referred to as the "other wireless devices."

The first radio 20 is installed in the upper center of the vehicle 1. Note that the installation location of the first radio 20 is not limited to the upper center of the vehicle 1, and may be any location that allows wireless communication with the second radios 30a to 30h and allows identification of the riding status inside the vehicle 1.

The first radio device 20 performs wireless communication with the second radio devices 30a to 30h using radio waves (millimeter waves) with a frequency of 30 GHz to 300 GHz. The first radio device 20 uses license-free radio waves in the 60 GHz band, for example, as specified by the wireless communication standard IEEE802.11ad. Radio waves used for wireless communication are called "communication waves."

The first radio device 20 detects objects using radio waves (millimeter waves) with a frequency of 30 GHz to 300 GHz, in addition to wireless communication using communication waves. For example, when using radio waves in the 60 GHz band, the first radio device 20 can use an ultra-wideband of 7 GHz bandwidth, allowing it to detect objects with a more accurate distance resolution. The radio waves used to detect objects are called "radar waves." In this way, the radar waves used to detect objects use the same frequency band as the communication waves used for wireless communication.

In this embodiment, the first radio 20 uses radar waves to detect occupants present at each of the riding positions A to E in the vehicle 1 in order to identify the riding status inside the vehicle 1. Riding position A corresponds to the location where the driver's seat 3 is installed. Riding position B corresponds to the location where the passenger seat 5 is installed. Riding position C corresponds to the right side 7a of the rear seat. Riding position D corresponds to the center 7b of the rear seat. Riding position E corresponds to the left side 7c of the rear seat.

The first wireless device 20 generates position information of the detected object. Specifically, the first wireless device 20 generates the riding position where the detected occupant is present, among riding positions A to E, as riding information. The riding information is also referred to as "occupant position information."

The first wireless device 20 alternates between a communication period during which wireless communication is performed with the second wireless devices 30a to 30h using communication waves, and a detection period during which target objects are detected using radar waves. Specifically, the first wireless device 20 alternates between a communication period during which wireless communication is performed with the second wireless devices 30a to 30h using communication waves, and a detection period during which occupants in the vehicle 1 are detected using radar waves.

The first wireless device 20 notifies the second wireless devices 30a to 30h in advance of the setting information for the communication period. Note that the first wireless device 20 may also notify the second wireless devices 30a to 30h in advance of the setting information for the detection period in addition to the setting information for the communication period.

The first wireless device 20 notifies the second wireless devices 30a to 30h of synchronization information and object position information at the start of wireless communication during the communication period. Specifically, the first wireless device 20 notifies the second wireless devices 30a to 30h of synchronization information and boarding information at the start of wireless communication during the communication period.

Each of the second radio devices 30a to 30h, like the first radio device 20, uses radio waves (communication waves) with a frequency of 30 GHz to 300 GHz to wirelessly communicate with the first radio device 20 or other second radio devices. Each of the second radio devices 30a to 30h uses, for example, license-free radio waves in the 60 GHz band defined by wireless communication standards such as IEEE802.11ad.

Each of the second radio devices 30a to 30h uses the synchronization information to adjust the transmission timing for the communication waves. Each of the second radio devices 30a to 30h uses the position information of the target object to determine which of the first radio device 20 and the other second radio devices is capable of communication.

Specifically, each of the second wireless devices 30a to 30h uses the boarding information to determine which of the first wireless device 20 and the other second wireless devices it is capable of communicating with. When each of the second wireless devices 30a to 30h determines which wireless device it is capable of communicating with, it performs wireless communication with the wireless device it is capable of communicating with during the communication period set by the first wireless device 20. The wireless device it is capable of communicating with is also referred to as the "destination wireless device."

In this embodiment, the second radio 30a is installed in front of the driver's seat 3 in the vehicle length direction and on the right side in the vehicle width direction. The second radio 30c is installed in front of the passenger seat 5 in the vehicle length direction and on the left side in the vehicle width direction. The second radio 30b is installed in the center between the second radios 30a and 30c in the vehicle width direction.

The second radio 30d is installed behind the driver's seat 3 in the vehicle length direction and on the right side in the vehicle width direction. The second radio 30e is located behind the passenger seat 5 in the vehicle length direction and on the left side in the vehicle width direction. The second radio 30f is installed in front of the rear seat 7 in the vehicle length direction and on the right side in the vehicle width direction. The second radio 30g is installed in front of the rear seat 7 in the vehicle length direction and on the left side in the vehicle width direction. The second radio 30h is installed behind the rear seat 7 in the vehicle length direction and in the center in the vehicle width direction.

In addition, since the first radio 20 is installed in a position where it can perform wireless communication with the second radios 30a to 30h, each of the second radios 30a to 30h may perform wireless communication with other second radios via the first radio 20. In this case, the first radio 20 relays communication between the second radios.

[Function block configuration of in-vehicle system]
Next, the functional block configuration of the wireless communication system 10 will be described. Specifically, the functional block configuration of the first wireless device 20 and the second wireless devices 30a to 30h will be described. Only the parts related to the features of this embodiment will be described below. Therefore, the first wireless device 20 and the second wireless devices 30a to 30h naturally include other functional blocks that are not directly related to the features of this embodiment.

First, the functional block configuration of the first radio device 20 will be described. FIG. 2 is a functional block configuration diagram of the first radio device 20. The first radio device 20 includes a transmitting unit 41, a receiving unit 43, a control unit 45, a memory unit 47, an input/output unit 49, a detecting unit 51, a generating unit 53, a communication processing unit 55, and a setting unit 57.

The transmitter 41 transmits, via the antenna, radar waves used to detect objects during the detection period. The transmitter 41 transmits, via the antenna, communication waves used for wireless communication during the communication period. The transmitter 41 notifies synchronization information and boarding information during the communication period. The transmitter 41 transmits signals for data communication during the communication period.

The receiving unit 43 receives reflected waves of radar waves via the antenna during the detection period. The receiving unit 43 receives communication waves used for wireless communication via the antenna during the communication period. The receiving unit 43 receives signals for data communication during the communication period.

Note that in FIG. 2, the number of antennas is one, but this is not limited to this. The number of antennas may be multiple.

The control unit 45 controls the overall processing in the first radio device 20. Specifically, the control unit 45 controls the operation of each of the detection unit 51, the generation unit 53, the communication processing unit 55, and the setting unit 57.

The memory unit 47 stores time information, communication period setting information, detection period setting information, synchronization information, and boarding information. The time information includes the time of an internal timer that is kept in real time.

The setting information for the communication period includes, for example, the start timing and end timing of the communication period, and the transmission timing for the communication waves used to transmit the communication waves. The setting information for the detection period includes, for example, the start timing and end timing of the detection period, and the transmission timing for the radar waves used to transmit the radar waves.

The synchronization information is used to synchronize the transmission timing of communication waves between the first radio 20 and the second radios 30a to 30h. The boarding information includes the boarding position where the occupant is present, detected by the detection unit 51, among the boarding positions A to E shown in FIG. 1.

The input/output unit 49 transmits and receives information to and from external devices. Examples of external devices include on-board sensors, on-board cameras, and electronic control units (ECUs).

During the detection period, the detection unit 51 generates radar waves and transmits the generated radar waves via the transmission unit 41. The detection unit 51 receives reflected waves of the transmitted radar waves via the reception unit 43, and detects an object using the received reflected waves.

The detection unit 51 detects passengers in the vehicle 1 using a pulse radar method. FIG. 3 is a functional block diagram of the detection unit 51. As shown in FIG. 3, the detection unit 51 includes a radar wave generating circuit 51a, a signal processing circuit 51b, and an analysis circuit 51c. The radar wave generating circuit 51a generates a pulse wave as a radar wave, and radiates the generated pulse wave via the transmission unit 41 in the direction of one of the boarding positions A to E in the vehicle 1 at the transmission timing for the radar wave set by the setting unit 57.

The signal processing circuit 51b receives the reflected wave of the emitted pulse wave via the receiving unit 43 and obtains the time difference between the pulse wave and the reflected wave. The analysis circuit 51c determines whether the obtained time difference is valid. If the time difference is valid, the analysis circuit 51c transmits a valid signal to the generating unit 53.

In addition to the pulse radar method, the detection unit 51 may detect occupants in the vehicle 1 using a frequency modulation (FM)-continuous wave (CW) method or the like. When the FM-CW method is used, the radar wave generation circuit 51a generates a continuous wave as a radar wave and frequency-modulates the generated continuous wave. The radar wave generation circuit 51a radiates a frequency-modulated continuous wave via the transmission unit 41 in the direction of one of the boarding positions A to E in the vehicle 1 at the transmission timing for the radar wave set by the setting unit 57.

The signal processing circuit 51b receives the reflected wave of the emitted continuous wave via the receiving unit 43, and obtains the frequency difference (beat frequency) between the continuous wave and the reflected wave. The analysis circuit 51c determines whether the obtained frequency difference is valid. If the frequency difference is valid, the analysis circuit 51c transmits a valid signal to the generating unit 53.

When the detection unit 51 has one antenna, it rotates the antenna during the detection period to radiate radar waves in the direction of each of the riding positions A to E in the vehicle 1. In this case, when the analysis circuit 51c transmits a valid signal, it includes in the valid signal identification information of the direction from which the radar waves are radiated. When the detection unit 51 has multiple antennas, it uses the multiple antennas to radiate radar waves during the detection period to each of the riding positions A to E in the vehicle 1. In this case, when the analysis circuit 51c transmits a valid signal, it includes in the valid signal identification information of the antenna that radiated the radar waves.

When the generation unit 53 receives a valid signal from the detection unit 51, it uses the identification information included in the valid signal to identify the riding position where the occupant is present. When there is one antenna, the generation unit 53 identifies the riding position where the occupant is present, for example, by referring to a pre-stored link between the direction in which the radar wave is emitted and the riding position. When there are multiple antennas, the generation unit 53 identifies the riding position where the occupant is present, for example, by referring to a pre-stored link between the antenna and the riding position.

The generation unit 53 generates boarding information including the identified boarding location. The generation unit 53 stores the generated boarding information in the storage unit 47.

During the communication period, the communication processing unit 55 generates a communication wave and transmits the generated communication wave via the transmission unit 41 to perform wireless communication with the second wireless devices 30a to 30h. During the communication period, the communication processing unit 55 notifies the synchronization information and boarding information stored in the memory unit 47 via the transmission unit 41. During the communication period, the communication processing unit 55 transmits information received by the input/output unit 49 using a data communication signal via the transmission unit 41. During the communication period, the communication processing unit 55 receives a data communication signal via the reception unit 43. The communication processing unit 55 transmits information acquired from the data communication signal to an external device via the input/output unit 49.

Figure 4 is a functional block diagram of the communication processing unit 55. As shown in Figure 4, the communication processing unit 55 includes a signal generation circuit 55a, a baseband (BB) circuit 55b, and a radio frequency (RF) circuit 55c. The signal generation circuit 55a generates a data signal based on the synchronization information and boarding information stored in the storage unit 47. The BB circuit 55b modulates the data signal using a predetermined modulation method to generate a BB signal. The RF circuit 55c converts the BB signal into an RF signal in the high frequency range (millimeter wave range) to generate a notification signal. The RF circuit 55c notifies the synchronization information and boarding information using the notification signal via the transmission unit 41 at the transmission timing for the communication wave set by the setting unit 57. Note that the communication processing unit 55 may separately notify the synchronization information and boarding information using different notification signals.

Similarly, the signal generation circuit 55a generates a data signal based on information acquired from an external device via the input/output unit 49. The BB circuit 55b modulates the data signal using a predetermined modulation method to generate a BB signal. The RF circuit 55c converts the BB signal into an RF signal in the high frequency range (millimeter wave range) to generate a signal for data communication. The RF circuit 55c transmits the information received by the input/output unit 49 using the signal for data communication via the transmission unit 41 at the transmission timing for communication waves set by the setting unit 57.

When the RF circuit 55c receives a data communication signal as an RF signal via the receiver 43, it converts the received RF signal into a BB signal. The BB circuit 55b demodulates the BB signal using a predetermined modulation method to generate a data signal. The signal generation circuit 55a transmits information obtained from the data signal to an external device via the input/output unit 49.

The setting unit 57 alternately sets a detection period in which an object is detected using radar waves and a communication period in which wireless communication is performed using communication waves. That is, the setting unit 57 sets the detection period and the communication period so that the time when the detection unit 51 transmits radar waves and the time when the communication processing unit 55 transmits communication waves do not overlap. The setting unit 57 basically sets the detection period based on the operation of the detection unit 51, and then sets the communication period to the interval between the detection periods.

Specifically, the setting unit 57 sets the transmission timing for the radar waves and the transmission timing for the communication waves on the time axis so that the time for transmitting the communication waves and the time for transmitting the radar waves do not overlap. Here, the detection period corresponds to the period on the time axis during which the transmission timing for the radar waves is set continuously. The communication period corresponds to the period on the time axis during which the transmission timing for the communication waves is set continuously.

The setting unit 57 generates setting information for the communication period including the start timing and end timing of the communication period and the transmission timing for the communication waves, and stores the generated setting information for the communication period in the storage unit 47. The setting unit 57 generates setting information for the detection period including the start timing and end timing of the detection period and the transmission timing for the radar waves, and stores the generated setting information for the detection period in the storage unit 47. The setting unit 57 notifies the second radio devices 30a to 30h of the setting information for the communication period in advance.

Figure 5 is a diagram showing an example of setting the communication period and the detection period. As shown in Figure 5, the communication period is a period during which the first radio device 20 and the second radio devices 30a-30 transmit communication waves and perform wireless communication with each other. The communication period includes a notification period and a data communication period. In this case, the setting unit 57 generates setting information for the communication period including the start and end timings of the notification period, the start and end timings of the data communication period, and the transmission timing for the communication waves.

The notification period is the time required for the first radio 20 to notify the synchronization information and boarding information at the start of wireless communication. The data communication period is the time required for the first radio 20 and one of the second radios 30a-30 to transmit one or more communication frames, which are the transmission units of signals for data communication, after the first radio 20 has notified the synchronization information and boarding information. Thus, the communication period includes, at a minimum, the time required to notify the synchronization information and boarding information and the time required to transmit one communication frame.

The detection period is the period during which the first radio device 20 transmits radar waves to detect an object. FIG. 6 is a diagram showing an example of a detection period. As shown in FIG. 6, the detection period includes at least the time from the transmission start timing t1, at which the first radio device 20 transmits radar waves, to the reception completion timing t2, at which the first radio device 20 is estimated to receive the reflected wave of the radar wave.

When there is one antenna, the antenna is rotated to irradiate radar waves in the direction of each of the riding positions A to E in the vehicle 1 to detect objects. For this reason, the setting unit 57 sets the detection period to, for example, the time from the transmission start timing when the first radio 20 transmits the first radar wave to the reception completion timing when the reflected wave of the fifth radar wave is estimated to be received.

When there are multiple antennas, the multiple antennas are used to radiate radar waves in the direction of each of the riding positions A to E in the vehicle 1 to detect objects. For this reason, the setting unit 57 sets the detection period to, for example, the time from the transmission start timing when the first radio 20 transmits radar waves from the first antenna to the reception completion timing when it is estimated that the reflected wave of the radar wave transmitted from the fifth antenna is received.

The setting unit 57 sets a first switching period or a second switching period between the communication period and the detection period. The first switching period is the time required to transition from the communication period to the detection period. Specifically, the control unit 45 refers to the time information and the communication period setting information stored in the memory unit 47, and when it determines that the time on the internal timer has reached the end timing of the communication period, it transitions the communication processing unit 55 to a stopped state and transitions the detection unit 51 to an active state during the first switching period. The detection unit 51 refers to the time information and the detection period setting information stored in the memory unit 47, and when it determines that the time on the internal timer has reached the start timing of the detection period, it detects an object. Note that the control unit 45 may transition the communication processing unit 55 to a standby state during the first switching period without transitioning the communication processing unit 55 to a stopped state.

The second switching period is the time required to transition from the detection period to the communication period. Specifically, the control unit 45 refers to the time information and the detection period setting information stored in the memory unit 47, and when it determines that the time on the internal timer has reached the end timing of the detection period, it transitions the detection unit 51 to a stopped state and transitions the communication processing unit 55 to an active state during the second switching period. When the communication processing unit 55 refers to the time information and the communication period setting information stored in the memory unit 47, and when it determines that the time on the internal timer has reached the start timing of the communication period, it performs wireless communication. Note that the control unit 45 may transition the detection unit 51 to a standby state during the second switching period without transitioning the detection unit 51 to a stopped state.

The active state is a state in which the detection unit 51 or the communication processing unit 55 executes processing. The stopped state is a state in which the detection unit 51 or the communication processing unit 55 stops processing. The standby state is a state in which the detection unit 51 or the communication processing unit 55 waits for processing. When the control unit 45 transitions the communication processing unit 55 to the stopped state or the standby state, the communication processing unit 55 temporarily stores untransmitted communication frames in the memory unit 47. When the communication processing unit 55 enters the active state, it resumes transmission of communication frames temporarily stored in the memory unit 47.

Next, the functional block configuration of the second radio devices 30a to 30h will be described. FIG. 7 is a functional block configuration diagram of the second radio devices 30a to 30h. Note that since the second radio devices 30a to 30h have the same configuration, the description of the second radio devices 30b to 30h will be omitted. As shown in FIG. 7, the second radio device 30a includes a transmitting unit 61, a receiving unit 63, a control unit 65, a memory unit 67, an input/output unit 69, a communication processing unit 71, and a determining unit 73.

The transmitter 61 transmits, via the antenna, a communication wave used for wireless communication during a communication period set by the first radio device 20. The transmitter 41 transmits a signal for data communication during the communication period.

The receiving unit 63 receives, via the antenna, communication waves used for wireless communication during a communication period set by the first radio 20. The receiving unit 63 receives synchronization information and boarding information during the communication period. The receiving unit 63 receives a signal for data communication during the communication period.

Note that in FIG. 7, the number of antennas is one, but this is not limited to this. The number of antennas may be multiple.

The control unit 65 controls the overall processing in the second radio 30a. Specifically, the control unit 65 controls the operation of each of the communication processing unit 71 and the determination unit 73. The control unit 65 adjusts the transmission timing for the communication wave included in the setting information of the communication period notified in advance, using the synchronization information received by the receiving unit 63. The control unit 65 stores the boarding information received by the receiving unit 63 in the storage unit 67. When the receiving unit 63 receives the synchronization information and the boarding information using a notification signal, the control unit 65 acquires the synchronization information and the boarding information from the received notification signal.

The memory unit 67 stores time information, boarding information, and communication period setting information. The time information includes the time of an internal timer that is kept in real time. The boarding information includes the boarding position, among boarding positions A to E, at which the occupant detected by the first wireless device 20 is present. The communication period setting information includes the start and end timings of the communication period and the transmission timing for the communication waves, and is notified in advance by the first wireless device 20. The memory unit 67 also stores in advance a communication determination table, which will be described later (see FIG. 9).

The input/output unit 69 transmits and receives information to and from external devices. Examples of external devices include on-board sensors, on-board cameras, and electronic control units (ECUs).

The communication processing unit 71 generates a communication wave during a communication period set by the first radio 20, and transmits the generated communication wave via the transmitting unit 41 to perform wireless communication with the first radio 20 and the second radios 30b to 30h. During the communication period, the communication processing unit 71 transmits information received by the input/output unit 49 using a data communication signal via the transmitting unit 61. During the communication period, the communication processing unit 71 receives the data communication signal via the receiving unit 43. The communication processing unit 55 transmits information obtained from the data communication signal to an external device via the input/output unit 49.

The communication processing unit 71 includes a signal generation circuit, a BB circuit, and an RF circuit, similar to the communication processing unit 55 of the first radio 20.

When the control unit 65 determines, with reference to the time information and communication period setting information stored in the memory unit 47, that the time on the internal timer has reached the start timing of the notification period within the communication period, it transitions the communication processing unit 71 to an active state. During the notification period within the communication period, the control unit 65 adjusts the transmission timing for the communication waves using the synchronization information received by the receiving unit 63. When the communication processing unit 71 determines, with reference to the time information and communication period setting information stored in the memory unit 47, that the time on the internal timer has reached the start timing of the data communication period within the communication period, it performs wireless communication.

The control unit 65 refers to the time information and communication period setting information stored in the memory unit 67, and when it determines that the time on the internal timer has reached the end timing of the data communication period within the communication period, it transitions the communication processing unit 71 to a stopped state. Note that the control unit 65 may transition the communication processing unit 71 to a standby state without transitioning the communication processing unit 71 to a stopped state.

The determination unit 73 refers to the boarding information stored in the memory unit 67 and recognizes the boarding position where the occupant is present among boarding positions A to E. The determination unit 73 refers to the communication determination table stored in the memory unit 67 and determines the destination radio with which communication is possible among the first radio 20 and the second radios 30b to 30h based on the identified boarding position.

The determination unit 73 stores the determined destination radio in the memory unit 67. The communication processing unit 71 identifies the destination radio stored in the memory unit 67 during the communication period and performs wireless communication with the destination radio. Note that, if the other second radio to which the data communication signal is to be transmitted is not compatible with the destination radio, the communication processing unit 71 may transmit the data communication signal to the other second radio via the first radio 20.

Figure 8 is a diagram showing an example of passenger information. In the example shown in Figure 8, occupants P1 to P3 are present in the vehicle 1. Occupant P1 is sitting in the driver's seat 3. Occupant P2 is sitting in the rear seat right side 7a. Occupant P3 is sitting in the rear seat left side 7c.

During the detection period, the detection unit 51 of the first wireless device 20 uses radar waves to detect the presence of an occupant at each of the boarding positions A, C, and E. When the generation unit 53 of the first wireless device 20 identifies the boarding positions A, C, and E where an occupant is present, it generates boarding information including the identified boarding positions A, C, and E, and stores the generated boarding information in the memory unit 47.

During the communication period, the communication processing unit 55 of the first radio 20 uses a notification signal to notify the boarding information stored in the memory unit 47. The control unit 65 of each of the second radios 30a to 30h stores the boarding information received by the receiving unit 63 in the memory unit 67. The determination unit 73 of each of the second radios 30a to 30h references the boarding information stored in the memory unit 67 and the communication determination table to determine the destination radio with which communication is possible.

Figure 9 is a diagram showing an example of a communication determination table. Specifically, Figure 9 shows a communication determination table that is held in advance by the second radio 30f. As shown in Figure 9, when an occupant is present at riding position A, the second radio 30f can communicate with the first radio 20 and the second radios 30d, 30g, and 30h. When an occupant is present at riding position B, the second radio 30f can communicate with the first radio 20 and the second radios 30a, 30d, 30g, and 30h.

When an occupant is present at riding position C, the second radio 30f can communicate with the first radio 20 and the second radios 30a and 30d. When an occupant is present at riding position D, the second radio 30f can communicate with the first radio 20 and the second radios 30a and 30d. When an occupant is present at riding position E, the second radio 30f can communicate with the first radio 20 and the second radios 30a, 30d, and 30h.

Therefore, when the first wireless device 20 reports boarding information including boarding positions A, C, and E during the reporting period within the communication period, the determination unit 73 of the second wireless device 30f determines the first wireless device 20 and the second wireless device 30d as the destination wireless devices. The communication processing unit 71 of the second wireless device 30f performs wireless communication with the first wireless device 20 and the second wireless device 30d during the data communication period within the communication period.

[Operation of wireless communication system]
Next, a description will be given of the operation of the wireless communication system 10. Specifically, a switching process between a detection period and a communication period will be described.

[Detection Period/Communication Period Switching Process]
Fig. 10 is a diagram showing a flowchart of a switching process between a detection period and a communication period by the first wireless device 20. In Fig. 10, the control unit 45 of the first wireless device 20 first shifts the communication processing unit 55 to a stopped state and shifts the detection unit 51 to an active state, causing the detection unit 51 to detect an object during the detection period. Note that the control unit 45 may first shift the detection unit 51 to a stopped state and shift the communication processing unit 55 to an active state, causing the communication processing unit 55 to perform wireless communication during the communication period.

Before performing the switching process shown in FIG. 10, the control unit 45 causes the setting unit 57 to set the detection period, the first switching period, the communication period, and the second switching period. Here, as described above, the detection period corresponds to the period on the time axis during which the transmission timing for the radar wave is set continuously. The communication period corresponds to the period on the time axis during which the transmission timing for the communication wave is set continuously. The setting unit 57 generates setting information for the communication period and setting information for the detection period, and stores the generated setting information for the communication period and setting information for the detection period in the storage unit 47.

As shown in FIG. 10, when the detection unit 51 determines that the time on the internal timer has reached the start timing of the detection period by referring to the time information and detection period setting information stored in the memory unit 47, it uses radar waves to detect an object (S11).

During the detection period, when the detection unit 51 detects an object, the generation unit 53 generates position information of the object. Specifically, when the detection unit 51 detects an occupant in the vehicle 1, the generation unit 53 generates position information of the occupant as riding information.

The control unit 45 refers to the time information and the detection period setting information stored in the memory unit 47 and determines whether the time of the internal timer has reached the end timing of the detection period (S13). If the control unit 45 determines that the time of the internal timer has not reached the end timing of the detection period, it causes the detection unit 51 to continue the process of S11.

When the control unit 45 determines that the time on the internal timer has reached the end of the detection period, it transitions the detection unit 51 to a stop state and transitions the communication processing unit 55 to an active state (S15). When the communication processing unit 55 determines, by referring to the time information and communication period setting information stored in the memory unit 47, that the time on the internal timer has reached the start of the notification period within the communication period, it performs wireless communication using communication waves (S17).

During the notification period within the communication period, the communication processing unit 55 of the first wireless device 20 refers to the time information and communication period setting information stored in the memory unit 47, and notifies the synchronization information and the target object's position information via the transmission unit 41. Specifically, the communication processing unit 55 of the first wireless device 20 notifies the synchronization information and the boarding information via the transmission unit 41.

The control unit 65 of each of the second radio devices 30a to 30h transitions the communication processing unit 71 to an active state when it determines that the time on the internal timer has reached the start timing of the notification period within the communication period, by referring to the time information and communication period setting information stored in the memory unit 67. During the notification period within the communication period, the control unit 65 of each of the second radio devices 30a to 30h adjusts the transmission timing for the communication wave included in the communication period setting information, using the synchronization information received by the receiving unit 63.

During the notification period within the communication period, the determination unit 73 of each of the second radios 30a to 30h refers to the object's position information received by the receiving unit 63 to recognize the object's location and determine the destination radio with which communication is possible. Specifically, the determination unit 73 of each of the second radios 30a to 30h refers to the boarding information received by the receiving unit 63 to recognize the boarding location where the occupant is present and determine the destination radio with which communication is possible.

The communication processing unit 55 of the first radio device 20 refers to the time information and communication period setting information stored in the memory unit 47 to determine whether the time on the internal timer has reached the start timing of the data communication period within the communication period. When the communication processing unit 55 of the first radio device 20 determines that the time on the internal timer has reached the start timing of the data communication period within the communication period, it transmits a signal for data communication to each of the second radio devices 30a to 30h via the transmission unit 41.

The communication processing unit 71 of each of the second radio devices 30a to 30h refers to the time information and communication period setting information stored in the memory unit 67 to determine whether the time on the internal timer has reached the start timing of the data communication period within the communication period. When the communication processing unit 71 of each of the second radio devices 30a to 30h determines that the time on the internal timer has reached the start timing of the data communication period within the communication period, it transmits a signal for data communication to the destination radio device via the transmission unit 61.

During the data communication period within the communication period, the first radio device 20 and the second radio devices 30a to 30 perform wireless communication using the CSMA/CA method.

The control unit 45 of the first radio device 20 refers to the time information and communication period setting information stored in the storage unit 47 and determines whether the time on the internal timer has reached the end timing of the data communication period within the communication period (S19). If the control unit 45 determines that the time on the internal timer has not reached the end timing of the data communication period within the communication period, it causes the communication processing unit 55 to continue the process of S17.

When the control unit 45 determines that the time on the internal timer has reached the end timing of the data communication period within the communication period, it determines whether or not to end the switching process (S21). When the control unit 45 determines that the switching process is to be ended, the series of processes ends. When the control unit 45 determines that the switching process is not to be ended, it transitions the communication processing unit 55 to stop information, transitions the detection unit 51 to an active state, and returns to the process of S11 (S23).

When the control unit 65 of each of the second radios 30a to 30h determines that the time on the internal timer has reached the end of the data communication period within the communication period, it transitions the communication processing unit 55 to stop information.

[Action and Effects]
According to this embodiment, the first wireless device 20 alternately sets a detection period in which the first wireless device 20 detects an object using radar waves and a communication period in which the first wireless device 20 performs wireless communication using communication waves in the same frequency band as the radar waves, and notifies the second wireless devices 30a to 30h of the setting information of the communication periods. This makes it possible to reliably prevent the communication waves used for wireless communication from being transmitted while the radar waves used for object detection are being transmitted.

According to this embodiment, the first radio 20 generates position information of the target object and notifies the second radios 30a to 30h of the target object position information at the start of wireless communication during the communication period. Therefore, each of the second radios 30a to 30h can identify the position of the target object that is an obstacle to wireless communication and select the optimal communication path.

Therefore, according to this embodiment, it is possible to provide a first radio 20 and a wireless communication system 10 that can avoid communication delays while suppressing mutual interference between the communication waves used for wireless communication and the radar waves used for detecting objects.

According to this embodiment, the first radio device 20 notifies the second radio devices 30a to 30h of synchronization information at the start of wireless communication during a communication period. Therefore, even if a time difference occurs between the internal timer of the first radio device 20 and the internal timer of the second radio devices 30a to 30h, the first radio device 20 and the second radio devices 30a to 30h can use the synchronization information to align the transmission timing for the communication waves.

According to this embodiment, the first wireless device 20 detects occupants in the vehicle 1 using radar waves, generates position information of the detected occupants, and notifies the second wireless devices 30a to 30h of the occupant's position information at the start of wireless communication during the communication period. Therefore, the second wireless devices 30a to 30h can identify the positions of occupants who are obstacles to wireless communication in the vehicle 1 and select the optimal communication path.

[Modification]
In the above embodiment, the communication period set by the first wireless device 20 is fixed, but is not limited to this. If the position of the object does not change for a long time, the detection unit 51 does not need to detect the object at short intervals. For this reason, in this modification, the first wireless device 20 performs optimization processing of the communication period based on whether or not there is a change in the position information of the object. Specifically, if the position information of the object generated for each detection period does not change for a predetermined period, the first wireless device 20 sets the communication period to be long. This extends the interval between detection periods.

In particular, when the riding conditions inside the vehicle 1 do not change for a long period of time, the detection unit 51 does not need to detect occupants inside the vehicle 1 at short intervals. For example, when an occupant is present only in the driver's seat 3, the detection unit 51 does not need to detect occupants inside the vehicle 1 at short intervals. For this reason, in this modified example, the first wireless device 20 performs optimization processing of the communication period based on whether or not there is a change in the riding information. Specifically, when the riding information generated every detection period does not change for a predetermined period of time, the first wireless device 20 sets the communication period to be long. This extends the interval between detection periods.

Figure 11 is a diagram showing a flowchart of the optimization process of the communication period by the first wireless device 20. In the optimization process of the communication period, if the boarding information generated for each detection period is not changed N or more consecutive times, the setting unit 57 of the first wireless device 20 lengthens the data communication period within the communication period by X times.

The values of N and X can be set arbitrarily and are stored in advance in the storage unit 47. For example, when N=10 and X=2, if the boarding information generated for each detection period is not changed 10 or more consecutive times, the setting unit 57 doubles the data communication period. Before performing the optimization process for the communication period, the value of the extension parameter T is initially set to 1, and the value of the number parameter n is initially set to 0.

The setting unit 57 receives the boarding information generated for each detection period from the generation unit 53, and determines whether there is a change in the boarding information (S31). If the setting unit 57 determines in S31 that there is a change in the boarding information, it determines whether the value of the extension parameter T is X (S33).

When the setting unit 57 determines in S33 that the value of the extension parameter T is X, it changes the value of the extension parameter T to 1 (S35). As a result, if there is a change in the boarding information, the setting unit 57 returns the data communication period to the normal length and changes the setting information of the communication period. The communication processing unit 55 notifies the changed setting information of the communication period at an appropriate timing.

When the setting unit 57 changes the value of the extension parameter T to 1, it resets the value of the number of times parameter n to 0 (S37). When the setting unit 57 determines in S33 that the value of the extension parameter T is not X, it resets the value of the number of times parameter n to 0 (S37).

When the setting unit 57 resets the value of the number parameter n to 0, it determines whether or not to end the optimization process (S39). If the setting unit 57 determines in S39 that the optimization process is to be ended, the series of processes ends. If the setting unit 57 determines in S39 that the optimization process is not to be ended, it returns to the process of S31 and determines whether or not there is a change in the ride information generated in the subsequent detection period.

When the setting unit 57 determines in S31 that there is no change in the boarding information, it adds 1 to the value of the number of times parameter n and counts up the value of the number of times parameter n (S41). After counting up the value of the number of times parameter n, the setting unit 57 determines whether the value of the number of times parameter n is N or greater (S43). When the setting unit 57 determines in S43 that the value of the number of times parameter n is N or greater, it determines whether the value of the extension parameter T is 1 (S45).

When the setting unit 57 determines in S45 that the value of the extension parameter T is 1, it changes the value of the extension parameter T to X (S47). As a result, if the boarding information generated for each detection period is not changed N consecutive times, the setting unit 57 lengthens the data communication period by X times and changes the setting information of the communication period. The communication processing unit 55 notifies the changed setting information of the communication period at an appropriate timing.

When the setting unit 57 changes the value of the extension parameter T to X, it resets the value of the number parameter n to 0 (S37) and determines whether to end the optimization process (S39).

If the setting unit 57 determines in S43 that the value of the number parameter n is less than N, or if the setting unit 57 determines in S45 that the value of the extension parameter T is not 1, it determines whether to end the optimization process (S39).

In this modified example, the first radio 20 extends the communication period if the object's position information or boarding information does not change for a specified period of time. Therefore, if the object's position does not change for a long period of time, or if the occupant in the vehicle 1 does not move for a long period of time, the period for wireless communication can be set to be long, further avoiding communication delays.

[Other embodiments]
In the above-described embodiment, the wireless communication and the detection of the target are performed using millimeter waves with a frequency of 30 GHz to 300 GHz, but this is not limited thereto. As long as the wireless communication and the detection of the target can be performed using radio waves in the same frequency band, microwaves with a frequency of 3 GHz to 30 GHz may be used instead of millimeter waves.

In the above-described embodiment, the wireless communication system 10 is used in the vehicle 1, but is not limited thereto. As long as wireless communication and object detection can be performed using radio waves in the same frequency band in the same space, the wireless communication system 10 may be used in situations other than the vehicle 1.

In the above-described embodiment, the first wireless device 20 notifies the synchronization information and the boarding information using millimeter waves, but this is not limited to this. The first wireless device 20 may also notify the synchronization information and the boarding information using a beacon or radio waves in a frequency band other than millimeter waves, such as microwaves.

In the above-described embodiment, in the first radio 20, the radar wave generating circuit 51a of the detection unit 51 generates radar waves during the detection period, and the RF circuit 55c of the communication processing unit 55 generates communication waves during the communication period, but this is not limited to this. In the first radio 20, a shared transmission/reception circuit may be used instead of the radar wave generating circuit 51a and the RF circuit 55c. In this case, the shared transmission/reception circuit generates radar waves during the detection period, and the shared transmission/reception circuit generates communication waves during the communication period.

In the above-described embodiment, if the first radio device 20 and the second radio devices 30a to 30h cannot directly communicate with each other wirelessly due to the presence of an obstruction, a long communication distance, or other reasons, they may use general relay transmission to communicate wirelessly.

The block diagrams (Figures 2 to 4 and 7) used to explain the above-mentioned embodiments show functional blocks. These functional blocks are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. For example, each functional block may be realized using one device or circuit that is physically or logically coupled, or may be realized using two or more devices or circuits that are physically or logically separated and directly or indirectly connected to each other, and using these multiple devices or circuits. A functional block may be realized by combining one device or multiple devices with software.

FIG. 12 is a diagram showing an example of the hardware configuration of the first radio device 20. As shown in FIG. 12, the first radio device 20 includes a processor 1001, a memory 1003, a storage 1005, a communication interface 1007, a sensor 1009, and a communication device 1011.

In the first radio 20, the functions of the transmitter 41, receiver 43, and detector 51 in detecting an object are realized by a sensor 1009 that emits radar waves. In the first radio 20, the functions of the transmitter 41, receiver 43, and communication processor 55 in wireless communication are realized by a communication device 1011 that emits communication waves. The function of the input/output unit 49 is realized by a communication interface 1007.

The functions of the control unit 45 are realized by the processor 1001. The functions of the memory unit 47 are realized by the storage 1005. The functions of the generation unit 53 and the setting unit 57 are realized by the processor 1001 performing calculations according to predetermined software (programs) and controlling the reading and writing of data in the memory 1003 and the storage 1005.

The processor 1001 performs calculations according to a specific software (program) and controls the operation of the sensor 1009 and the reading and writing of data in the memory 1003 and storage 1005, thereby detecting the object.

The processor 1001 performs calculations according to a specific software (program) and controls the operation of the communication device 1011 and the reading and writing of data in the memory 1003 and storage 1005, thereby realizing wireless communication.

The functions of the control unit 45, the storage unit 47, the detection unit 51, the generation unit 53, the communication processing unit 55, and the setting unit 57 may be realized by dedicated circuits. In addition, in FIG. 12, the sensor 1009 and the communication device 1011 are integrated within the first wireless device 20, but the sensor 1009 may be installed at a location away from the first wireless device 20 and connected wirelessly or by wire.

The hardware configuration of the second radio devices 30a to 30 is the same as the hardware configuration of the first radio device 20, except for the sensor 1009.

Although the present embodiment has been described above, the present embodiment is not limited to these, and various modifications are possible within the scope of the gist of the present embodiment.

10 Wireless communication system 20 First wireless device 30a to 30h Second wireless device 41 Transmitter 45 Controller 47 Memory 51 Detector 53 Generator 55 Communication processor 57 Setting unit 73 Determinator

Claims (9)

A radio device,
a setting unit that alternately sets a detection period in which a target object is detected using a radar wave and a communication period in which wireless communication is performed using a communication wave in the same frequency band as the radar wave, and notifies other wireless devices of setting information of the communication periods;
a transmitter that transmits a radar wave used for detecting the object and a communication wave used for the wireless communication;
a detection unit that detects the object by transmitting the radar wave via the transmission unit during the detection period;
A generating unit that generates position information of the object;
a communication processing unit that transmits the communication wave via the transmission unit during the communication period to perform the wireless communication with the other wireless device;
Equipped with
the communication processing unit notifies the other wireless devices of position information of the object at the start of the wireless communication during the communication period ;
The wireless device and the other wireless device are mounted in a vehicle,
The detection unit detects an occupant in the vehicle by using the radar wave,
The generation unit generates position information of the occupant,
The communication processing unit is a wireless device that notifies the other wireless devices of position information of the occupant at the start of the wireless communication during the communication period . The radio device according to claim 1, wherein the communication processing unit notifies the other radio devices of synchronization information at the start of the wireless communication during the communication period. The wireless device according to claim 1 or 2, wherein the setting unit extends the communication period if the position information of the object generated for each detection period is not changed for a predetermined period. The wireless device according to claim 1 , wherein the setting unit extends the communication period when the position information of the occupant generated for each detection period is not changed for a predetermined period. A first radio;
a second radio device forming a wireless communication network with the first radio device;
Equipped with
The first radio device includes:
a detection period in which a target object is detected using a radar wave and a communication period in which wireless communication is performed using a communication wave in the same frequency band as the radar wave are alternately set;
notifying the second wireless device of setting information of the communication period;
During the detection period, the radar wave is transmitted to detect the object;
During the communication period, the communication wave is transmitted to perform the wireless communication with the second wireless device;
The first radio device includes:
generating position information of the object;
during the communication period, at the start of the wireless communication, position information of the object is notified to the second wireless device;
A wireless communication system in which the second wireless device determines a wireless device with which communication is possible using position information of the object. The wireless communication system according to claim 5 , wherein the first wireless device notifies the second wireless device of synchronization information at the start of the wireless communication during the communication period. The wireless communication system according to claim 5 , wherein the first wireless device extends the communication period when the position information of the object generated for each detection period does not change for a predetermined period. The first radio device and the second radio device are mounted on a vehicle,
The first wireless device detects an occupant in the vehicle by using the radar wave,
The first radio generates position information of the occupant;
the first wireless device notifies the second wireless device of position information of the occupant at the start of the wireless communication during the communication period;
The wireless communication system according to claim 5 or 6 , wherein the second wireless device determines a wireless device with which communication is possible by using position information of the passenger. The wireless communication system according to claim 8 , wherein the first wireless device extends the communication period when the position information of the occupant generated for each detection period does not change for a predetermined period.

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