JP2006229492A - System and terminal for radio communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the presence of an abnormal radio communication terminal when any radio communication terminal is abnormal in a radio communication system for performing radio communication among a plurality of radio communication terminals. <P>SOLUTION: A communication processor 16 in the radio communication terminal 1 stops radio communication for the same period tuned to other radio communication terminals. The communication processor 16 determines that the radio communication terminal is abnormal which performs the radio communication for the communication stop period, thus allowing the radio communication terminal 1 to detect the presence of the abnormal radio communication terminal. A normal radio communication terminal 1 copes with the abnormal radio communication terminal, by transmitting and receiving data to and from other radio communication terminals in a period when the abnormal radio communication terminal stops radio communication, and by using a communication channel that the abnormal radio communication terminal does not use for transmitting and receiving the data to and from other radio communication terminals. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication system that performs wireless communication between a plurality of wireless communication terminals.

  For the purpose of improving vehicle safety and driving support, wireless communication between a plurality of vehicles traveling on a road has been studied. In such inter-vehicle communication, it has also been proposed to install a monitoring base station on the roadside and support inter-vehicle communication by the monitoring base station. However, in this case, each vehicle traveling on the road can receive support for inter-vehicle communication only within the communication area of the monitoring base station. Therefore, it is preferable that the plurality of vehicles perform wireless communication directly without going through the monitoring base station. A technique related to inter-vehicle communication in which wireless communication is performed directly between a plurality of vehicles is described in, for example, Japanese Patent Application Laid-Open No. 2002-290310.

  In inter-vehicle communication in which wireless communication is performed directly between a plurality of vehicles, it is preferable to adopt a broadcast method using a CSMA / CD (Carrier Sense Multiple Access with Collision Detection) method as a communication protocol. In the broadcast method, information transmission by a vehicle is not performed by designating a specific vehicle as a transmission destination, but is performed for all vehicles in the communicable area without designating the transmission destination. Such a communication method that does not designate a transmission destination is suitable for transmitting information to an unspecified number of vehicles in the communicable area in a situation where vehicles in the communicable area change every moment. However, in this communication method, even when the transmitted information is not properly received by the surrounding vehicles, the information is not retransmitted or corrected. This is because, in an environment where communication objects move at high speed and unexpected communication interruption may occur, there is a low possibility that the retransmitted information is properly received even if data retransmission is requested. In vehicle control for the purpose of improving safety, there is a possibility of delaying control if information is retransmitted / corrected, so it is better to wait for the next information transmission than to retransmit / correct information. There are also circumstances that are appropriate.

In the broadcast method, as described above, information is unilaterally transmitted to all vehicles in the communicable area, so the CSMA / CD method that does not require adjustment of information transmission timing between vehicles is used. It is preferable. In the CSMA / CD method, each vehicle sets a transmission timing after a random standby time and tries to transmit information at the transmission timing in order to avoid collision of transmission signals. Each vehicle confirms the presence or absence of information transmission by other vehicles at the set transmission timing, and performs information transmission by itself when there is no information transmission by other vehicles. On the other hand, when there is information transmission by another vehicle, each vehicle sets transmission timing after a random standby time again and tries information transmission at the transmission timing. In the CSMA / CD system, the transmission timing is determined without exchanging information with other vehicles in advance, so a broadcast system in which information is unilaterally transmitted to other vehicles is suitable.
JP 2002-290310 A

  However, when the broadcast method using the CSMA / CD method is adopted as a communication protocol, if an abnormality occurs in the wireless communication terminal of any vehicle in the communicable area, the communication between the vehicles in the communicable area. A situation occurs in which wireless communication cannot be performed. For example, (1) when an abnormality occurs in the reception system of the wireless communication terminal of any vehicle, information transmission by another vehicle cannot be recognized. Even if the transmission timing should be set, information transmission is performed. (2) In addition, when an abnormality occurs in the transmission system of the wireless communication terminal of any vehicle, information transmission by another vehicle can be recognized, but the vehicle transmits information without stopping information transmission. will have to go. As a result, each normal vehicle in the vicinity of the abnormal vehicle continues to transmit information by the abnormal vehicle. Therefore, the information cannot be transmitted even at the transmission timing at which the information should be transmitted. Interfering with wireless communication.

  Note that the above-described problem may occur not only for vehicles traveling on roads but also for other mobile radio communication systems. For example, the above-described problem also occurs when a wireless communication terminal is mounted on a mobile object such as an aircraft or a ship. Further, the above-described problem occurs even in wireless communication between a plurality of wireless communication terminals fixedly installed.

  In view of the above, an object of the present invention is to detect the presence of an abnormal wireless communication terminal when there is an abnormality in any of the wireless communication terminals in a wireless communication system that performs wireless communication between a plurality of wireless communication terminals. To do. It is another object of the present invention to deal with an abnormal wireless communication terminal when the presence of the abnormal wireless communication terminal is detected.

  The invention according to claim 1 is a wireless communication system in which wireless communication is performed between a plurality of wireless communication terminals, and each wireless communication terminal stops wireless communication in the same period in synchronization with the other wireless communication terminals. And a communication prohibiting unit, and an abnormality determining unit that determines other wireless communication terminals that perform wireless communication during the communication suspension period as abnormal. According to this configuration, each wireless communication terminal stops wireless communication in synchronism with other wireless communication terminals, so that a communication stop period in which wireless communication is not performed between the wireless communication terminals occurs. Therefore, each wireless communication terminal can determine that the wireless communication terminal that performs wireless communication during the period in which communication should not be performed originally is abnormal. Thereby, the process which copes with the radio | wireless communication terminal by which abnormality determination was carried out can be performed.

  According to a second aspect of the present invention, in the wireless communication system according to the first aspect, each of the wireless communication terminals analyzes a period during which the wireless communication terminal determined to be abnormal by the abnormality determination unit stops wireless communication. It further comprises analysis means and communication means for performing wireless communication with the other wireless communication terminal during the period analyzed by the analysis means. According to this configuration, the period during which the wireless communication terminal determined to be abnormal stops wireless communication is analyzed by the analyzing means of the wireless communication terminal. During the period, since the wireless communication terminal determined to be abnormal stops wireless communication, normal wireless communication between other wireless communication terminals is not disturbed. Therefore, a normal wireless communication terminal can perform wireless communication during the period.

  According to a third aspect of the present invention, in the wireless communication system according to the first aspect, each of the wireless communication terminals determines a communication channel that is not used by the wireless communication terminal that has been determined to be abnormal by the abnormality determination unit. It further comprises communication channel determination means and communication means for performing wireless communication with the other wireless communication terminal using the communication channel determined to be unused by the communication channel determination means. According to this configuration, each normal wireless communication terminal determines a communication channel that is not used by the wireless communication terminal that has been determined to be abnormal, and performs wireless communication using the communication channel. Thus, each normal wireless communication terminal can perform wireless communication with other normal wireless communication terminals without being disturbed by the abnormal wireless communication terminal.

  According to a fourth aspect of the present invention, in the wireless communication system according to any one of the first to third aspects, the wireless communication terminals perform broadcast-type transmission to the other wireless communication terminals. And In broadcast-type transmission, each wireless communication terminal only transmits unilaterally, and therefore processing for notifying abnormality from a normal wireless communication terminal to an abnormal wireless communication terminal cannot be performed. Therefore, the wireless communication system having the configuration according to claims 1 to 3 has a great effect of dealing with the wireless communication terminal determined to be abnormal.

  According to a fifth aspect of the present invention, there is provided a wireless communication terminal constituting a wireless communication system, a communication prohibiting means for stopping wireless communication in the same period at the same time as another wireless communication terminal, and wireless communication during the communication stop period. And an abnormality determining unit that determines that the other wireless communication terminal that performs communication is abnormal. According to this configuration, each wireless communication terminal stops wireless communication in synchronism with other wireless communication terminals, so that a communication stop period in which wireless communication is not performed between the wireless communication terminals occurs. Therefore, each wireless communication terminal can determine that the wireless communication terminal that performs wireless communication during the period in which communication should not be performed originally is abnormal. Thereby, it is possible to cope with the wireless communication terminal determined to be abnormal.

  The present invention can detect the presence of an abnormal wireless communication terminal when there is an abnormality in any of the wireless communication terminals in a wireless communication system that performs wireless communication between a plurality of wireless communication terminals.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to a wireless communication system of the invention will be described with reference to the drawings. The wireless communication system of the present embodiment is constructed by a plurality of vehicles in a communicable area on a road on which a large number of vehicles travel. Since each vehicle travels and moves, the plurality of vehicles in the communicable area change with time. That is, the wireless communication system is a system that performs wireless communication with a communication target that changes over time within a communicable area centered on the vehicle.

  Each vehicle that constructs a wireless communication system is equipped with a wireless communication terminal. FIG. 1 shows a schematic configuration of a wireless communication terminal 1 mounted on each vehicle. The wireless communication terminal 1 is roughly divided into a communication device 10 disposed at a vehicle position where radio waves from other vehicles are easily received, and a control device 20 disposed in the vehicle apart from the communication device 10. It is configured. The communication device 10 and the control device 20 are connected by a signal line 18 and can transmit and receive data to and from each other. The configurations of the communication device 10 and the control device 20 will be described in more detail.

  The communication device 10 includes an antenna 12 for transmitting and receiving radio waves, a transmission / reception circuit 14 connected to the antenna 12, and a communication processing unit 16 for performing various processes related to communication. When the transmission / reception circuit 14 takes in transmission data to be transmitted to another vehicle from the communication processing unit 16, the transmission / reception circuit 14 transmits a radio wave including the transmission data via the antenna 12 at a communication timing set by the CSMA / CD method. In addition, when the transmission / reception circuit 14 receives a radio wave from another vehicle via the antenna 12, the transmission / reception circuit 14 outputs reception data included in the radio wave to the communication processing unit 16.

  The communication processing unit 16 includes a CPU, a memory, and the like, and performs communication with other vehicles according to a predetermined communication protocol. Here, the adopted communication protocol is a broadcast method using the CSMA / CD method. The CSMA / CD method is a method for transmitting information after the communication device 10 confirms that information has not been transmitted between vehicles for a predetermined time or more. The broadcast method is a method in which information is unilaterally transmitted to all vehicles in the vicinity without specifying a vehicle that should receive transmission data. The communication processing unit 16 captures time information output from a GPS (Global Positioning System) device. The time information output from the GPS device is extremely accurate.

  The control device 20 includes a signal processing unit 24 that exchanges data with the communication device 10, a transmission data generation unit 22 that generates own vehicle data to be transmitted to other vehicles, and received data from other vehicles. And a driving support control unit 26 that supports driving by the driver. When the signal processing unit 24 captures the transmission data from the transmission data generation unit 22, the signal processing unit 24 outputs the transmission data to the communication processing unit 16 via the signal line 18. Thereafter, the transmission data is transmitted as a radio wave from the antenna 12. On the other hand, when the signal processing unit 24 takes in the reception data from the surrounding vehicle from the communication processing unit 16, the signal processing unit 24 extracts necessary information from the reception data and outputs it to the driving support control unit 26.

  The transmission data generated by the transmission data generation unit 22 includes various information related to the own vehicle. The information included in the transmission data includes, for example, an identification ID set for each vehicle, vehicle position information detected by a GPS device, vehicle speed information detected by a vehicle speed sensor, and a vehicle detected by a steering angle sensor. Direction information, turn signal switch ON / OFF information, and the like. The transmission data is repeatedly generated by the transmission data generation unit 22 at regular time intervals and output to the signal processing unit 24.

  The driving support control unit 26 takes in received data of another vehicle from the signal processing unit 24 and performs control for supporting driving of the vehicle by the driver in accordance with the traveling state of other vehicles in the vicinity. For example, when it is determined that another vehicle is approaching the host vehicle, a warning is given to the driver using a display or a speaker, a brake intervention control that applies a strong brake, or steering of the vehicle Steering intervention control is performed.

  The above-described wireless communication terminal 1 performs processing for dealing with an abnormal vehicle when there is an abnormal vehicle related to communication around the vehicle. Specifically, an abnormality handling processing program is incorporated in the communication protocol executed by the communication processing unit 16, and the communication processing unit 16 performs communication processing with other vehicles according to the abnormality handling processing program. Is addressed. Hereinafter, the abnormality handling process of the communication processing unit 16 will be described with reference to the flowchart of the abnormality handling process shown in FIG.

  The communication processing unit 16 first performs processing for transmitting the transmission data fetched from the signal processing unit 24 (S201). At this time, the transmission data has a specific data format according to the standard of inter-vehicle communication. Next, the communication processing unit 16 determines whether or not a communication stop period (for example, several milliseconds to several tens of milliseconds every 10 seconds) is determined (S202). If the communication stop period has already been determined, it is determined whether the current time is the start timing of the communication stop period (S205). If the current time is not the start timing of the communication stop period, the process of transmitting transmission data is repeated while avoiding a collision with information transmission of other vehicles until the start timing is reached (S201, S205). ).

  On the other hand, if it is determined in step 202 that the communication stop period has not yet been determined, the highly accurate time information output by the GPS device is captured (S203), and the communication is stopped using the time information. Processing for determining a period is performed (S204). Here, the reference information for determining the communication stop period is stored in the memory of the communication processing unit 16 of each vehicle, and the communication processing unit 16 of each vehicle determines the communication stop period based on the reference information. decide. Since the reference information stored in all the vehicles is common, the communication processing unit 16 of all the vehicles determines the same period as the communication stop period. In addition, the communication stop period determined by all the vehicles is made into the exact same period by determining a communication stop period using the highly accurate time information which a GPS apparatus outputs. It is preferable to accurately set the same communication stop period in a plurality of vehicles in order to reliably perform the abnormality handling process.

  Thereafter, the communication processing unit 16 determines whether or not the current time is the start timing of the communication stop period (S205). If the current time is not the start timing of the communication stop period, the process of transmitting transmission data is repeated while avoiding a collision with information transmission of other vehicles until the start timing is reached (S201, S205). ). On the other hand, when the current time is the start timing of the communication stop period, the communication processing unit 16 performs a process of stopping transmission of transmission data (S206). That is, the communication processing unit 16 serves as a communication prohibition unit that stops wireless communication in the same period in time with other vehicles.

  Next, the communication processing unit 16 determines whether or not there is another vehicle performing wireless communication during the communication stop period in which transmission of transmission data is stopped (S207). Specifically, this determination is performed by determining whether there is data received from another vehicle. Here, when there is another vehicle that performs wireless communication, it is determined that there is an abnormality in the vehicle. That is, the communication processing unit 16 serves as an abnormality determination unit that determines other vehicles that perform wireless communication during the communication stop period as abnormal. Then, the identification ID of the vehicle is extracted from the received data from the abnormal vehicle and stored in the memory. Thereby, the history of the identification ID of the abnormal vehicle is created (S208). In addition, the communication processing unit 16 performs processing for determining handling of an abnormal vehicle (S209). For example, the received data from the abnormal vehicle is ignored and discarded without being used, or only the presence of the abnormal vehicle is recognized and used for the control process of the driving support control unit 26.

  In the present embodiment, as described above, since the wireless communication terminal 1 of each vehicle stops wireless communication in the same period in time with the wireless communication terminals of other vehicles, a period in which wireless communication is not performed between the vehicles. Is born. Thus, if there is a vehicle that performs wireless communication during a communication stop period during which wireless communication is not supposed to be performed, there is a high possibility that the wireless communication terminal mounted on the vehicle has an abnormality. Therefore, the wireless communication terminal 1 of each vehicle can detect an abnormal vehicle by detecting a vehicle that is performing wireless communication during the communication stop period, and further performs processing for dealing with the abnormal vehicle. be able to.

  When it is determined in step 207 that there is no other vehicle that performs wireless communication, or after the processing in step 209 is completed, the communication processing unit 16 determines that the current time is the end timing of the communication suspension period. It is determined whether or not (S210). Here, when the current time is not the end timing of the communication stop period, the communication processing unit 16 repeats the determination of an abnormal vehicle until the communication stop period ends (S206 to S210). On the other hand, when the current time is the end timing of the communication stop period, the communication processing unit 16 performs a transmission restart process so as to restart the wireless communication (S211). Thereby, the wireless communication by the wireless communication terminal 1 is resumed.

  Next, the communication processing unit 16 determines whether or not an abnormal vehicle history has been created in step 208 (S212), and if there is abnormal vehicle history information, all of the registered history information is registered. Data notifying the abnormality is transmitted to the abnormal vehicle, and the wireless communication terminal is notified that there is an abnormality (S213). For example, an abnormal vehicle may repeat transmission of transmission data every certain time (for example, 0.5 msec). In such a case, since the abnormal vehicle does not perform the next transmission process until a certain time has elapsed after the abnormal vehicle performs the transmission process, the period during which the abnormal vehicle stops transmitting the transmission data. Will occur. During this period, since the wireless communication terminal of the abnormal vehicle can receive data, the abnormal vehicle receives data notifying the abnormality and recognizes that the wireless communication terminal is abnormal from the received data. Then, the abnormal vehicle performs processing such as forcibly terminating information transmission. The communication processing unit 16 transmits data notifying the abnormality to the monitoring base station installed on the road side in addition to contacting the abnormal vehicle, and notifies the monitoring base station of the presence of the abnormal vehicle. Good.

  Next, the communication processing unit 16 determines whether or not the inter-vehicle communication should be terminated (S214). If there is no determination to end the inter-vehicle communication by the vehicle, the communication processing unit 16 returns to Step 201 and repeats the processing of Step 201 to Step 214. On the other hand, if it is determined by the vehicle to end the inter-vehicle communication, the communication processing unit 16 ends the communication process and the abnormality handling process. The process described above is an abnormality handling process executed by the communication processing unit 16.

  The communication processing unit 16 analyzes a transmission pattern of the abnormal vehicle when the presence of the abnormal vehicle is determined in the process of step 207 of the flowchart described above, and the period during which the abnormal vehicle stops wireless communication. May be analyzed. As described above, when an abnormal vehicle repeats transmission of transmission data at regular intervals, the abnormal vehicle does not perform the next transmission process until a certain time has elapsed after performing the transmission process. There is a period in which an abnormal vehicle stops transmitting transmission data. A normal vehicle predicts a period during which an abnormal vehicle stops transmission by analyzing the transmission pattern of the abnormal vehicle, and sets the transmission timing of transmission data so that transmission processing of transmission data is performed during that period. That's fine. Thus, normal vehicles can transmit and receive data to and from each other using a period in which wireless communication is not disturbed by an abnormal vehicle. Further, a normal vehicle may notify the abnormal vehicle of the abnormality or notify the monitoring base station of the presence of the abnormal vehicle by transmitting transmission data during a period in which the abnormal vehicle stops transmitting. In the above processing, the communication processing unit 16 serves as an analysis unit that analyzes a period during which an abnormal vehicle stops wireless communication, and further serves as a communication unit that performs wireless communication with another vehicle during the period. ing.

  Further, the communication processing unit 16 may determine the presence or absence of a communication channel that is not used by an abnormal vehicle when it is determined in step 207 in the flowchart described above that an abnormal vehicle exists. When there is a communication channel that is not used by an abnormal vehicle, normal vehicles can send and receive data to and from each other using an unused communication channel. As a result, a normal vehicle can reliably transmit and receive data even in a situation where communication is blocked by an abnormal vehicle. In addition, a normal vehicle may notify an abnormal vehicle of an abnormality by transmitting transmission data using an unused communication channel, or may notify a monitoring base station of the presence of an abnormal vehicle. In the above processing, the communication processing unit 16 is a determination unit that determines a communication channel that is not used by an abnormal vehicle, and further performs wireless communication with another vehicle using an unused communication channel. It is a communication means to do.

  In addition, although embodiment mentioned above demonstrated the case where a radio | wireless communications system was constructed | assembled by the radio | wireless communication terminal 1 mounted in each of a some vehicle, this invention is not limited to this. For example, a wireless communication system may be constructed by a wireless communication terminal mounted on a mobile body such as an aircraft or a ship. Further, a wireless communication system may be constructed by a plurality of wireless communication terminals fixedly installed.

It is the schematic which shows the structure of the radio | wireless communication terminal mounted in the vehicle. It is a flowchart which shows the abnormality coping process of a radio | wireless communication terminal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wireless communication terminal, 10 ... Communication apparatus, 12 ... Antenna, 14 ... Transmission / reception circuit, 16 ... Communication processing part, 18 ... Signal line, 20 ... Control apparatus, 22 ... Transmission data generation part, 24 ... Signal processing part, 26 ... Drive support control unit.

Claims (5)

In a wireless communication system that performs wireless communication between a plurality of wireless communication terminals,
Each wireless communication terminal is
Communication prohibiting means for stopping wireless communication in the same period in time with other wireless communication terminals;
An abnormality determining means for determining other wireless communication terminals that perform wireless communication during the communication suspension period as abnormal,
A wireless communication system comprising: Each wireless communication terminal is
Analysis means for analyzing a period during which the wireless communication terminal determined to be abnormal by the abnormality determination means stops wireless communication;
Communication means for performing wireless communication with the other wireless communication terminal during the period analyzed by the analysis means;
The wireless communication system according to claim 1, further comprising: Each wireless communication terminal is
A communication channel determination unit that determines a communication channel that is not used by the wireless communication terminal that has been determined to be abnormal by the abnormality determination unit;
Communication means for performing wireless communication with the other wireless communication terminal using the communication channel determined to be unused by the communication channel determining means;
The wireless communication system according to claim 1, further comprising:   The wireless communication system according to claim 1, wherein each of the wireless communication terminals performs broadcast transmission to the other wireless communication terminal. A wireless communication terminal constituting a wireless communication system,
Communication prohibition means for stopping wireless communication in the same period in time with other wireless communication terminals;
An abnormality determining means for determining other wireless communication terminals that perform wireless communication during the communication suspension period as abnormal,
A wireless communication terminal comprising:

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