JP2008311733A - Communication controller and method and program thereof, and inter-vehicle communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication controller which can efficiently reduce collisions and delays in transmission information by distributing the transmission timing among one or a plurality of other communication apparatuses existing at the periphery, and to provide control method and a program, and an inter-vehicle communication apparatus. <P>SOLUTION: The communication controller for controlling predetermined transmission information to be transmitted with a transmission timing which averts collisions among one or a plurality of movable communication apparatus, existing on the periphery comprises a means for determining a moment in time selected at random within a range of predetermined period centered on a moment in time after one predetermined period from an immediately preceding transmission timing as a next time transmission timing; and a means for transmitting transmission information at the next time transmission timing determined by the transmission timing determination means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication control device, a method and a program, and an inter-vehicle communication device, and in particular, by efficiently distributing the transmission time of each vehicle in order to eliminate communication failure of the vehicle due to simultaneous transmission of a plurality of vehicles. The present invention relates to a system for improving communication quality.

  Conventionally, an inter-vehicle communication device uses a wireless communication technology using autonomous distributed control, so that vehicles communicate directly with each other without using an infrastructure such as a roadside device. The purpose is to provide information.

  To achieve autonomous distributed control, CSMA (Carrier Sense Multiple Access) is adopted as an access method, so that carrier sense is performed when transmission traffic occurs, and a randomly determined time is set while waiting for transmission of other vehicles. A method for avoiding communication failure due to collision between packets transmitted by each vehicle by starting transmission after the lapse is generally known (see Non-Patent Document 1).

Hideaki Matsue and Masahiro Morikura, “IDG Information Communication Series 802.11 High-Speed Wireless LAN Textbook”, IDG Japan, Inc., March 29, 2003, p.66-p.84

  However, when the inter-vehicle communication apparatus adopting the CSMA method, which is the conventional method, is applied, when a plurality of vehicles try to transmit almost at the same time, the vehicles other than the vehicle that has started the transmission first wait until the next transmission starts. Therefore, the increase in delay cannot be solved.

  In addition, when applying an inter-vehicle communication device that adopts the CSMA method, carrier sense is performed and transmission processing is started after confirming that no other vehicle is transmitting, but until this transmission processing is started. The delay may not be negligible.

  That is, if another vehicle starts transmission before the transmission process starts, a communication failure occurs due to a collision with the transmission packet of the other vehicle. There was a problem that the probability of failure was high.

  In addition, when all vehicles transmit information at a predetermined cycle, once simultaneous transmission by a plurality of vehicles occurs, the transmission cycle of the plurality of vehicles is the same. Repeatedly occurred, and communication quality did not improve.

  Therefore, a communication control device, method, and program capable of reducing collision and delay of transmission information by efficiently distributing transmission timing with one or more other communication devices existing in the vicinity, and There is a need for an inter-vehicle communication device.

  In order to solve this problem, the communication control device according to the first aspect of the present invention provides predetermined transmission information at a transmission timing for avoiding a collision with one or a plurality of other movable communication devices existing in the vicinity. In the communication control device to be transmitted, (1) a time point selected at random within a predetermined period before and after a predetermined transmission period from the immediately preceding transmission timing is determined as the next transmission timing. A transmission timing determining unit; and (2) a transmission unit that transmits transmission information at the next transmission timing determined by the transmission timing determining unit.

  A communication control method according to a second aspect of the present invention is a communication control method for transmitting predetermined transmission information at a transmission timing that avoids a collision with one or a plurality of other movable communication devices existing in the vicinity. 1) A transmission timing in which the transmission timing determination means determines a time point selected at random within a predetermined period before and after a predetermined transmission period from the immediately preceding transmission timing as the next transmission timing. A determining step; and (2) a transmitting unit that transmits transmission information at a next transmission timing determined by the transmission timing determining unit.

  A communication control program according to a third aspect of the present invention is a communication control program for transmitting predetermined transmission information at a transmission timing for avoiding a collision with one or a plurality of other movable communication devices existing in the vicinity. (1) A transmission timing determining means for determining a time point selected at random within a predetermined period before and after a predetermined transmission period from the immediately preceding transmission timing as a next transmission timing, (2) It functions as a transmission means for transmitting transmission information at the next transmission timing determined by the transmission timing determination means.

  A vehicle-to-vehicle communication device according to a fourth aspect of the present invention is a vehicle-to-vehicle communication device that transmits and receives vehicle information of its own vehicle with a communication device mounted on one or more other vehicles present in the vicinity. The communication control means for intermittent transmission corresponds to the communication control device of the first aspect of the present invention.

  According to the communication control device, the method and the program, and the inter-vehicle communication device of the present invention, it is possible to reduce the collision and delay of transmission information by distributing the transmission timing among other communication devices existing in the vicinity. be able to.

(A) First Embodiment Next, a communication control device, method and program, and a vehicle-to-vehicle communication device according to a first embodiment of the present invention will be described in detail with reference to the drawings.

  In the inter-vehicle communication device of the first embodiment, the vehicles exchange vehicle information such as position information and speed information of the own vehicle with each other at a predetermined cycle, and based on the vehicle information of each vehicle (own vehicle, other vehicle), It is assumed that each vehicle is used in a system that supports safe driving by avoiding collisions with other vehicles.

(A-1) Configuration of the First Embodiment FIG. 1 is a functional block diagram showing a functional configuration of the inter-vehicle communication device 1 of the first embodiment.

  In FIG. 1, the inter-vehicle communication device 1 includes a transmission time notification unit 111, a vehicle state detection unit 112, a transmission time determination unit 113, an inter-vehicle communication transmission unit 114, a communication traffic amount detection unit 115, an inter-vehicle communication reception unit 121, and a notification determination unit. 122 and information output means 123 at least. The inter-vehicle communication device 1 is mounted in a vehicle.

  The transmission time notification unit 111 gives the next transmission time information acquired from the transmission time determination unit 113 to the vehicle state detection unit 112. In this way, by feeding back the next transmission time information to the vehicle state detection means 112, even if the next transmission time is changed to a time different from one cycle later, the detection time of the vehicle information is changed to the next time. By changing to the latest time that can be reflected in the transmission, it is possible to minimize the time from the detection of the vehicle information to the start of transmission. That is, it is possible to always keep the information to be transmitted the latest vehicle information.

  The vehicle state detection means 112 detects vehicle information such as position information and speed information of the own vehicle, and gives the detected vehicle information to the inter-vehicle communication transmission means 114 and the notification determination means 122. Here, the vehicle state detection unit 112 detects vehicle information such as position information and speed information of the own vehicle until the next transmission time information given from the transmission time notification unit 111, and detects the detected vehicle information. The vehicle information is given to the inter-vehicle communication transmission means 114.

  The transmission time determination unit 113 receives the communication traffic amount at the past transmission time from the communication traffic amount detection unit 115, determines the next transmission time based on the communication traffic amount at the past transmission time, and determines the next transmission time information. Is given to the transmission time notification means 111 and the inter-vehicle communication transmission means 114.

  Here, the transmission time determination unit 113 refers to the last (latest) communication traffic amount acquired from the communication traffic amount detection unit 115 when determining the next transmission time based on the communication traffic amount at the past transmission time. Or a method of referring to the past traffic traffic volume of several times, a method of referring to statistical data of the past traffic traffic volume of several times, or the like can be applied.

  As an example of a method for determining the next transmission time from the past communication traffic volume, the following method may be mentioned.

  The case where the amount of communication traffic at the past transmission time is large corresponds to the case where there are many other vehicles that transmit almost simultaneously with the transmission start time of the own vehicle. At this time, since each vehicle transmits transmission information at a predetermined cycle, the amount of communication traffic increases even at the next transmission time, and the probability that the delay from the transmission traffic generation of the own vehicle to the completion of transmission increases, or the own vehicle There is a high probability that transmission will fail due to a collision with a transmission packet of another vehicle.

  In this case, the transmission time determination unit 113 of the first embodiment does not use the value (time) after one cycle as the next transmission time information, but a random value ( The value (time) around one cycle obtained by adding or subtracting (time) is used as the next transmission time information, and the transmission time between the own vehicle and the other vehicle is shifted to avoid duplication of the transmission time. Avoid transmission failures due to increased transmission delays and collisions.

  As a method of obtaining the next transmission time information using a random value, a method of using a value (time) range corresponding to 0.5 cycles before and after the value (time) one cycle after the last transmission time is the center. Can be applied. As a result, transmission can be performed after a certain period on average, and the transmission interval can be prevented from becoming too large. Further, the probability distribution may be uniform, normal distribution, or the like.

  On the other hand, the case where the amount of communication traffic at the past transmission time is small corresponds to the case where there are few other vehicles transmitting almost at the same time as the transmission start time of the own vehicle. At this time, since each vehicle transmits transmission information in a predetermined cycle, the amount of communication traffic is small even at the next transmission time, and the probability that the delay from the transmission traffic generation of the own vehicle to the completion of transmission increases, or Is unlikely to fail due to a collision with a transmission packet of another vehicle, and it is considered unnecessary to shift the transmission time.

  In this case, the transmission time determination unit 113 uses the value (time) after one cycle as the next transmission time information.

  For example, when the vehicle transmits at a cycle of 100 milliseconds, and the amount of communication traffic at the last transmission time is large, the next transmission time is uniform between 50 and 150 milliseconds from the last transmission time. A value determined by a random number based on the probability density of the distribution is assumed to have elapsed, and when the amount of communication traffic is small, the next transmission time is assumed to be 100 milliseconds later.

  Here, the past communication traffic volume is represented as only two values, “large” and “small”, and the method of determining the next transmission time is classified into two ways, but the past transmission traffic volume is assumed to be a continuous value. It is also possible to use only one way of handling and determining the next transmission time. As an example, the next transmission time is a value (time) around one cycle obtained by adding or subtracting a random value (time) to a value (time) after one cycle, and the range of random values is a past communication traffic volume. There is a method of making the value proportional to. That is, when the past communication traffic volume is large, the range of random values becomes large, so it is possible to shift the transmission time, and when the past communication traffic volume is small, the random value range is small, It can be after a predetermined period.

  The vehicle-to-vehicle communication transmission unit 114 transmits the vehicle information acquired from the vehicle state detection unit 112 at the next transmission time acquired from the transmission time determination unit 113 and also transmits the vehicle-to-vehicle communication transmission unit 114 to the communication traffic amount detection unit 115. It provides information that serves as an index of the amount of communication traffic that can be detected by.

  Here, as an example of information serving as an index of the amount of communication traffic detectable by the vehicle-to-vehicle communication transmission unit 114, when the vehicle-to-vehicle communication transmission unit 114 adopts CSMA as an access method, transmission is completed from the generation of transmission traffic of the vehicle information. The time elapsed until is mentioned.

  If there is a large amount of communication traffic when transmission traffic occurs, that is, if there are many other vehicles transmitting at almost the same time as the transmission start time of the own vehicle, the transmission waiting time of the own vehicle due to the transmission of the other vehicle increases, The time elapsed from occurrence to completion of transmission increases.

  On the other hand, when the amount of communication traffic at the time of transmission traffic generation is small, that is, when there are few other vehicles transmitting almost at the same time as the transmission start time of the own vehicle, the opportunity of waiting for the transmission of the own vehicle by the transmission of the other vehicle is Therefore, the time elapsed from the generation of transmission traffic to the completion of transmission is reduced. As a result, the time elapsed from the generation of transmission traffic of the vehicle information to the completion of transmission can be used as an index of the amount of communication traffic.

  Note that the access method adopted by the inter-vehicle communication transmission unit 114 is not limited to CSMA, and other methods are possible, and an index of the amount of communication traffic that can be detected by the inter-vehicle communication transmission unit 114 according to the adopted method. It is also possible to change the content of the information.

  The vehicle-to-vehicle communication receiving unit 121 gives the information acquired from the vehicle-to-vehicle communication transmitting unit of the other vehicle to the notification determining unit 122, and also uses the communication traffic amount detecting unit as information indicating the amount of communication traffic that can be detected by the vehicle-to-vehicle communication receiving unit 121. 115.

  Here, as an example of information serving as an index of the amount of communication traffic that can be detected by the inter-vehicle communication receiving unit 121, when the inter-vehicle communication receiving unit 121 adopts CSMA as an access method, within a certain time centered on the transmission traffic generation time. The number of received packets from other cars in

  However, when the information used as an index of the amount of communication traffic that can be detected by the inter-vehicle communication transmission unit 114 is the time elapsed from the generation of the transmission traffic of the own vehicle information to the completion of the transmission, this information indicates the transmission status of other vehicles, That is, since the reception status of other vehicles is reflected, it is possible to realize an inexpensive device by eliminating the need for information serving as an index of the amount of communication traffic detectable by the inter-vehicle communication receiving unit 121.

  Note that the access method adopted by the inter-vehicle communication receiving means 121 is not limited to CSMA, and other methods are possible, and an indication of the amount of communication traffic that can be detected by the inter-vehicle communication receiving means 121 according to the adopted method. It is also possible to change the content of the information.

  The communication traffic amount detecting means 115 is detected by the inter-vehicle communication receiving means 121 received from the inter-vehicle communication receiving means 121 and the information used as an indicator of the communication traffic amount that can be detected by the inter-vehicle communication transmitting means 114 received from the inter-vehicle communication transmitting means 114. Based on information serving as an index of a possible communication traffic volume, a communication traffic volume at a past transmission time is detected. Further, the communication traffic amount detection unit 115 gives the detected communication traffic amount at the past transmission time to the transmission time determination unit 113.

  As described above, since the amount of communication traffic at the past transmission time is fed back to the transmission time determination means 113, the next transmission time of vehicles that transmit almost simultaneously can be changed to different times. However, it is possible to avoid repetition of simultaneous transmission that may occur when performing transmission in the same cycle.

  Even when the next transmission time is changed, the transmission is actually started after the vehicle state is acquired by changing the vehicle state detection time to the latest time that can be reflected in the next transmission information. It is possible to reduce the time until the time as much as possible. That is, it is possible to always keep the information to be transmitted the latest vehicle information.

  Here, as an example of a possible value of the communication traffic amount provided to the transmission time determination unit 113 by the communication traffic amount detection unit 115, there is a method of expressing only as a binary value of “large” or “small”.

  For example, when CSMA is adopted as an access method and only information that is an index of the amount of communication traffic detectable by the inter-vehicle communication transmission unit 114 received from the inter-vehicle communication transmission unit 114 is used, the transmission traffic is generated from the generation of the transmission traffic to the transmission completion. If the elapsed time is greater than the sum of the maximum back-off time and the transmission time due to the transmission packet length, there is always a transmission waiting time in slot time units due to carrier sensing of the transmission packets of other vehicles, The communication traffic volume is detected as “large”. In other cases, there is almost no waiting time due to the transmission packet of the other vehicle, and there is a high possibility that the transmission has been completed, so the communication traffic volume is detected as “small”.

  That is, even when two vehicles start transmission at almost the same time, the vehicle that has started transmission earlier than the other vehicles detects the next transmission by determining that the transmission traffic amount is “small”, and the transmission time determination unit 113 determines next transmission. The time is one cycle later, and the vehicle that started transmission later than the other vehicle detects that the amount of transmission traffic is “large” and changes the next transmission time. As a result, only the transmission time of one vehicle can be changed, and the transmission time of each vehicle can be efficiently distributed to different times.

  The notification determination unit 122 is based on vehicle information such as position information and speed information of the own vehicle detected by the vehicle state detection unit 112 and vehicle information such as position information and speed information of other vehicles acquired from the inter-vehicle communication reception unit 121. Thus, the presence / absence of the surrounding vehicle is determined, the necessity of notification to the driver is subsequently determined, and information on the surrounding vehicle is given to the information output means 123.

  The information output unit 123 notifies the driver of the presence of the surrounding vehicle based on the information on the surrounding vehicle acquired from the notification determining unit 122.

(A-2) Operation of First Embodiment Next, an operation of processing of the inter-vehicle communication device of the first embodiment will be described with reference to the drawings. FIG. 2 is an operation flowchart illustrating processing of the vehicle-to-vehicle communication device according to the first embodiment.

  Here, the vehicle-to-vehicle communication device 1 mounted on the vehicle exchanges vehicle information such as position information and speed information of the own vehicle with the vehicle-to-vehicle communication device of another vehicle at a predetermined cycle.

  First, in the inter-vehicle communication device 1, when the service of the first embodiment is started (step S101), the process proceeds to step S111 for determining whether or not to detect the vehicle information of the own vehicle, and at the same time, the vehicle information of the own vehicle is changed. The process proceeds to step S121 for determining whether or not to transmit, and step S131 for acquiring vehicle information of another vehicle by the inter-vehicle communication receiving unit 121.

  If it is determined in step S111 that the vehicle information of the own vehicle is not detected based on the next transmission time acquired from the transmission time notification unit 111, the process proceeds to step S102 for determining whether or not the service is ended. On the other hand, when it is determined that the vehicle information of the own vehicle is detected, the vehicle state detection unit 112 detects the vehicle information of the own vehicle (step S112), and the process proceeds to step S102 for determining whether the service is finished. .

  If it is determined in step S121 that the vehicle information of the host vehicle is not transmitted based on the next transmission time acquired from the transmission time determination unit 113, the process proceeds to step S102 for determining whether or not the service is ended. On the other hand, when it is determined that the vehicle information of the own vehicle is to be transmitted, the vehicle information of the own vehicle is subsequently notified to the other vehicle by the inter-vehicle communication transmission unit 114 (step S122), and the communication traffic amount detection unit 115 detects the communication traffic amount. (Step S123), the process proceeds to Step S102 for determining whether or not the service is completed.

  Next, in step S131, the vehicle state detection means 112 detects the vehicle information of the host vehicle (step S132), and the process proceeds to step S133 for determining whether there is a surrounding vehicle.

  If it is determined that there is no surrounding vehicle, the process proceeds to step S102 where it is determined whether or not the service has ended. On the other hand, if it is determined that there is a surrounding vehicle, the process proceeds to step S134 where it is determined whether or not notification to the driver is necessary. If it is determined that notification to the driver is unnecessary, the process proceeds to step S102 for determining whether or not the service is completed. If it is determined that notification to the driver is necessary, the information output means 123 notifies the driver of the presence of the surrounding vehicle (step S135), and the process proceeds to step S102 for determining whether or not the service has ended.

  If it is determined that the service will not be terminated, the process proceeds to step S111 for determining whether or not to detect the vehicle information of the own vehicle, and at the same time, step S121 for determining whether or not to transmit the vehicle information of the own vehicle, and inter-vehicle communication. The process proceeds to step S131 where vehicle information of another vehicle is acquired by the receiving means 121, and the above steps are repeated. If it is determined that the service has ended, the process proceeds to step S103, and the service is ended.

  9 to 17 are diagrams illustrating simulation results for confirming the effects of the first embodiment. 9 to 17, it is assumed that the safety support application is assumed, the packet length is 166 bytes, and this data is transmitted by the inter-vehicle device of each vehicle at a cycle of 100 milliseconds.

  9 to 15 are diagrams showing average packet error rate, packet error rate variance, maximum packet error rate, average delay, delay variance, average reception interval, and reception interval variance with respect to the number of transmission vehicles, respectively.

  Each simulation shown in FIGS. 9 to 15 shows results when the number of transmission packets per simulation is 1000 (that is, approximately 100 seconds) and the number of repetitions is 1000. 9 to 15, white circles are plots showing the simulation results of the first embodiment, and black circles (large) are plots showing the simulation results of the prior art.

  From the simulation results of FIGS. 9 to 15, the result of the first embodiment shows that the average reception interval is maintained at the same level as the conventional one as shown in FIG. Although the improvement effect is small, the average packet error rate (FIG. 9), packet error rate variance (FIG. 10), maximum packet error rate (FIG. 11), average delay (FIG. 12), delay variance (FIG. 13), reception interval It can be seen that the dispersion (FIG. 15) is improved.

  16 to 17 show the relationship between the sequence number of the transmission packet and the packet error rate. FIG. 16 shows the results when the number of vehicles is 10 and a transmission packet having a packet length of 166 bytes is transmitted in a cycle of 100 milliseconds. FIG. 17 shows the number of vehicles of 2, 5, 10, 20 This is the result when the number of units is increased to 50 units and 100 units.

  16 to 17 show results when the number of transmission packets per simulation is 100 (that is, approximately 10 seconds) and the number of repetitions is 100,000.

  Since the sequence number starts from “1” and increases by “1” every time transmission is performed, the results of sequence numbers “1” to “100” are obtained each time.

  From the simulation results of FIG. 16 to FIG. 17, the result of the first embodiment is that the packet error rate is improved and the value is constant by repeating transmission as shown in FIG. It can be seen that it has converged. Further, as shown in FIG. 17, it can be seen that although the improvement effect decreases as the number of transmission vehicles increases, the time for the packet error rate value to converge decreases.

(A-3) Effects of First Embodiment As described above, according to the first embodiment, in addition to the state of the host vehicle, information on other vehicles can be acquired by communication means, and safe traveling is possible. Therefore, it is possible to notify the driver of the danger that the driver cannot recognize and to support safe driving operation.

  In addition, according to the first embodiment, it is possible to avoid repetition of simultaneous transmission by a plurality of vehicles by feeding back the communication traffic amount at the time of past transmission to the transmission time determination means. By setting the time to a random value within a certain period, the transmission time of each car can be efficiently distributed to different times without the transmission interval becoming too large. By this, by reducing the probability that the transmission completion time of each car is delayed or the transmission of the own vehicle fails due to a collision, it is possible to achieve an improvement in communication quality such as a reduction in delay and a reduction in packet error rate, The improvement of system reliability can be expected.

  Furthermore, in the first embodiment, since the next transmission time is fed back to the vehicle state detection means, it becomes possible to always keep the information to be transmitted in the latest vehicle state. Improvement can be expected.

(B) Second Embodiment Next, a communication control device, method and program, and a vehicle-to-vehicle communication device according to a second embodiment of the present invention will be described with reference to the drawings.

(B-1) Configuration and Operation of Second Embodiment FIG. 3 is a functional block diagram showing a functional configuration of the vehicle-to-vehicle communication device of the second embodiment. In FIG. 3, the inter-vehicle communication apparatus 2 of the second embodiment includes a vehicle state detecting unit 112, a transmission time determining unit 113, an inter-vehicle communication transmitting unit 114, a communication traffic amount detecting unit 115, an inter-vehicle communication receiving unit 121, and a notification determining unit. 122 and information output means 123 at least.

  The inter-vehicle communication device 2 according to the second embodiment is different from the inter-vehicle communication device 1 according to the first embodiment in that the inter-vehicle communication device 2 according to the second embodiment does not include the transmission time notification unit 111. .

  Thereby, the functions of the vehicle state detection unit 112 and the transmission time determination unit 113 are different from those of the first embodiment. Since the other functions correspond to the functions described in the first embodiment, detailed description thereof is omitted.

  The transmission time determination unit 113 determines the next transmission time in the same manner as in the first embodiment, and gives the next transmission time only to the inter-vehicle communication transmission unit 114.

  The vehicle state detection means 112 detects vehicle information such as position information and speed information of the host vehicle at a predetermined cycle regardless of the next transmission time. That is, the point that the feedback of the next transmission time is not received from the transmission time notification unit 111 is different from the first embodiment.

  As described above, in the second embodiment, the next transmission time is not fed back to the vehicle state detection unit 112.

  In this case, the latest vehicle information may not always be acquired in accordance with the next transmission time. That is, when the transmission time determination unit 113 determines the next transmission time within a range corresponding to 0.5 cycles before and after the value after one cycle, the vehicle information acquisition time and the transmission traffic generation time The maximum difference is 1.5 cycles.

  However, depending on the inter-vehicle communication device 2 installed in the vehicle, real-time vehicle information may not be required. Therefore, in the second embodiment, in such a case, the vehicle information of the host vehicle can be acquired at a predetermined cycle without performing feedback of the next transmission time.

  FIG. 4 is an operation flowchart illustrating processing of the inter-vehicle communication system according to the second embodiment.

  In FIG. 4, when the service of the second embodiment is started in the inter-vehicle communication device 2 (step S101), unlike the first embodiment, step S111 does not exist. The vehicle information of the own vehicle is detected (step S112).

  At the same time as the process proceeds to step S112, the process proceeds to step S121 for determining whether or not to transmit the vehicle information of the own vehicle, and to step S131 for acquiring the vehicle information of the other vehicle by the inter-vehicle communication receiving means 121. This point is the same as in the first embodiment.

  Since the processing of steps S121 to S123 and the processing of steps S131 to S135 have been described in the first embodiment, detailed description thereof will be omitted.

(B-2) Effects of the Second Embodiment As described above, according to the second embodiment, since the next transmission time is not fed back to the vehicle state detection means, the vehicle state acquisition time, the transmission traffic generation time, For example, in a system in which this time difference is not a problem, an effect substantially equivalent to that of the first embodiment can be expected. As a result, it can be expected to realize a device that is less expensive than the device described in the first embodiment.

(C) Third Embodiment Next, a communication control device, method and program, and a vehicle-to-vehicle communication device according to a third embodiment of the present invention will be described with reference to the drawings.

(C-1) Configuration and Operation of Third Embodiment FIG. 5 is a functional block diagram showing a functional configuration of the inter-vehicle communication device of the third embodiment. In FIG. 5, the inter-vehicle communication device 3 according to the third embodiment includes a transmission time notifying unit 111, a vehicle state detecting unit 112, a transmission time determining unit 113, an inter-vehicle communication transmitting unit 114, an inter-vehicle communication receiving unit 121, and a notification determining unit 122. , And at least information output means 123.

  The inter-vehicle communication device 3 of the third embodiment is different from the inter-vehicle communication device 1 of the first embodiment in that the communication traffic amount detection means 115 is not provided.

  Thereby, the functions of the transmission time determination unit 113, the inter-vehicle communication transmission unit 114, and the inter-vehicle communication reception unit 121 are different from those of the first embodiment.

  The transmission time determination means 113 always determines the next transmission time autonomously as a random value, and gives the next transmission time to the transmission time notification means 111 and the inter-vehicle communication transmission means 114. The difference from the first embodiment is that the next transmission time is not determined according to the communication traffic volume at the past transmission time.

  That is, for example, the transmission time determination unit 113 generates a random value determined by generating a random number within the range corresponding to 0.5 cycles before and after the value one cycle after the last transmission time. The transmission time of

  In the first embodiment, when the amount of communication traffic is small, one cycle after the last transmission time is set as the next transmission time. However, in the third embodiment, all the communication traffic amounts are used regardless of the amount of communication traffic. Determine at random.

  Similar to the first embodiment, the vehicle-to-vehicle communication transmission unit 114 transmits the vehicle information received from the vehicle state detection unit 112 at the next transmission time acquired from the transmission time determination unit 113. The vehicle information is different from that of the first embodiment in that information indicating the amount of communication traffic that can be detected by the vehicle-to-vehicle communication transmission unit 114 of vehicle information is not given to the communication traffic amount detection unit 115 when the vehicle information is transmitted.

  Similar to the first embodiment, the inter-vehicle communication receiving unit 121 gives information acquired from other vehicles to the notification determining unit 122. The difference from the first embodiment is that information serving as an index of the amount of communication traffic detectable by the inter-vehicle communication receiving unit 121 is not given to the communication traffic amount detecting unit 115.

  FIG. 6 is an operation flowchart illustrating processing of the inter-vehicle communication system according to the third embodiment.

  In FIG. 6, when the service of the third embodiment is started in the inter-vehicle communication device 3 (step S101), the process proceeds to step S111 for determining whether or not the vehicle information of the own vehicle is detected, and at the same time, the vehicle of the own vehicle. The process proceeds to step S121 for determining whether or not to transmit information, and step S131 for acquiring vehicle information of another vehicle by the inter-vehicle communication receiving means 121.

  Since the processing in steps 111 and S112 has been described in the first embodiment, a detailed description thereof will be omitted.

  In step S121, as in the first embodiment, if it is determined not to transmit the vehicle information of the own vehicle based on the next transmission time acquired from the transmission time determination unit 113, whether or not the service is terminated is determined. The process proceeds to determination step S102. On the other hand, when it is determined that the vehicle information of the own vehicle is transmitted, the vehicle information of the own vehicle is subsequently notified by the inter-vehicle communication transmission unit 114 (step S122).

  The amount of communication traffic at the time of notification of the vehicle information of the host vehicle is not detected, and the next transmission time according to the amount of communication traffic is not determined.

  In addition, since the processing of steps S131 to S135 has been described in the first embodiment, detailed description thereof will be omitted.

  9 to 15 are diagrams illustrating simulation results for confirming the effects of the third embodiment. Specifically, FIGS. 9 to 15 are diagrams showing the average packet error rate, packet error rate variance, maximum packet error rate, average delay, delay variance, average reception interval, and reception interval variance for the number of transmission vehicles, respectively. is there.

  9 to 15, assuming a safety support application, the packet length is 166 bytes, and the inter-vehicle device of each vehicle transmits this data at a cycle of 100 milliseconds.

  9 to 15, black circles (small) are plots showing the simulation results of the third embodiment, and black circles (large) are plots showing the simulation results of the prior art.

  From the simulation results of FIG. 9 to FIG. 15, the results of the third embodiment show that the reception interval variance is larger as shown in FIG. 15 than the conventional technique, but the average packet error rate (FIG. 9) and average While maintaining the delay (FIG. 12), delay dispersion (FIG. 13), and average reception interval (FIG. 14), the improvement effect decreases as the number of transmission vehicles increases, but the packet error rate dispersion (FIG. 10), maximum packet error It can be seen that the rate (FIG. 11) has improved.

  FIG. 16 shows the relationship between the sequence number of the transmission packet and the packet error rate. When the number of vehicles is 10 and a transmission packet with a packet length of 166 bytes is transmitted in a cycle of 100 milliseconds. It is a result.

  From the simulation results shown in FIG. 16, it can be seen that the result according to the third embodiment has no change in the relationship between the sequence number, that is, the repetition of the number of transmissions and the packet error rate, as in the prior art.

(C-2) Effects of the Third Embodiment As described above, according to the third embodiment, since the communication traffic amount at the time of past transmission is not fed back to the transmission time determination means, it is related to the communication traffic amount. In addition, by determining the next transmission time to be a random value for all vehicles, the effect of efficiently distributing the transmission time of each vehicle to different times is smaller than in the first embodiment, but simultaneous transmission by a plurality of vehicles is not possible. Since it becomes possible to avoid repetition, reducing the repetition of the failure of the transmission of the vehicle due to a collision is less effective than the first embodiment, but the maximum packet error rate, packet error rate dispersion Communication quality improvement such as reduction can be achieved, and improvement in system reliability can be expected. As a result, according to the third embodiment, it can be expected to realize a device that is less expensive than the first embodiment.

(D) Fourth Embodiment Next, a communication control apparatus, method and program, and a vehicle-to-vehicle communication apparatus according to a fourth embodiment of the present invention will be described with reference to the drawings.

(D-1) Configuration and Operation of the Fourth Embodiment FIG. 7 is a functional block diagram showing a functional configuration of the inter-vehicle communication device 4 of the fourth embodiment. In FIG. 7, the inter-vehicle communication device 4 of the fourth embodiment includes a vehicle state detecting unit 112, a transmission time determining unit 113, an inter-vehicle communication transmitting unit 114, an inter-vehicle communication receiving unit 121, a notification determining unit 122, an information output unit 123, At least.

  The inter-vehicle communication device 4 of the fourth embodiment is different from the inter-vehicle communication device 1 of the first embodiment in that the transmission time notifying unit 111 and the communication traffic amount detecting unit 115 are not provided.

  Thereby, the functions of the vehicle state detection unit 112, the transmission time determination unit 113, the inter-vehicle communication transmission unit 114, and the inter-vehicle communication reception unit 121 are different from those of the first embodiment.

  The transmission time determination means 113 always determines the next transmission time autonomously as a random value, and gives the next transmission time to the transmission time notification means 111 and the inter-vehicle communication transmission means 114. The difference from the first embodiment is that the next transmission time is not determined according to the communication traffic volume at the past transmission time.

  The vehicle state detection means 112 detects vehicle information such as position information and speed information of the host vehicle at a predetermined cycle regardless of the next transmission time. That is, the point that the feedback of the next transmission time is not received from the transmission time notification unit 111 is different from the first embodiment.

  Similar to the first embodiment, the vehicle-to-vehicle communication transmission unit 114 transmits the vehicle information received from the vehicle state detection unit 112 at the next transmission time acquired from the transmission time determination unit 113. The vehicle information is different from that of the first embodiment in that information indicating the amount of communication traffic that can be detected by the vehicle-to-vehicle communication transmission unit 114 of vehicle information is not given to the communication traffic amount detection unit 115 when the vehicle information is transmitted.

  Similar to the first embodiment, the inter-vehicle communication receiving unit 121 gives information acquired from other vehicles to the notification determining unit 122. The difference from the first embodiment is that information serving as an index of the amount of communication traffic detectable by the inter-vehicle communication receiving unit 121 is not given to the communication traffic amount detecting unit 115.

  FIG. 8 is an operation flowchart illustrating processing of the inter-vehicle communication system according to the fourth embodiment.

  In FIG. 8, when the service of the fourth embodiment starts in the inter-vehicle communication device 4 (step S101), unlike the first embodiment, step S111 does not exist, so the vehicle state detection unit 112 has a predetermined cycle. The vehicle information of the own vehicle is detected (step S112).

  At the same time as the process proceeds to step S112, the process proceeds to step S121 for determining whether or not to transmit the vehicle information of the own vehicle, and to step S131 for acquiring the vehicle information of the other vehicle by the inter-vehicle communication receiving means 121.

  In step S121, as in the first embodiment, if it is determined not to transmit the vehicle information of the own vehicle based on the next transmission time acquired from the transmission time determination unit 113, whether or not the service is terminated is determined. The process proceeds to determination step S102. On the other hand, when it is determined that the vehicle information of the own vehicle is transmitted, the vehicle information of the own vehicle is subsequently notified by the inter-vehicle communication transmission unit 114 (step S122).

  The amount of communication traffic at the time of notification of the vehicle information of the host vehicle is not detected, and the next transmission time according to the amount of communication traffic is not determined.

  Moreover, since the process of step S131-S135 was demonstrated in 1st Embodiment, detailed description is abbreviate | omitted.

(D-2) Effects of the Fourth Embodiment As described above, according to the fourth embodiment, since the next transmission time is not fed back to the vehicle state detection means, the vehicle state acquisition time, the transmission traffic generation time, For example, in a system in which this time difference is not a problem, an effect substantially equivalent to that of the third embodiment can be expected. As a result, according to the fourth embodiment, it can be expected to realize a device that is less expensive than the third embodiment.

(E) Other Embodiments In the first to fourth embodiments, the hardware configuration of the inter-vehicle communication devices 1 to 4 is not shown, but includes, for example, a CPU, a ROM, a RAM, an EEPROM, and the like. For example, the CPU executes a predetermined processing program stored in a ROM or the like or a predetermined processing program installed through a predetermined interface, thereby realizing a function described later.

  In the first to fourth embodiments, the description has been made on the assumption that the inter-vehicle communication apparatus used in the inter-vehicle communication system is used, but the present invention can also be applied as a communication control apparatus that is not mounted on the vehicle. For example, a wireless communication control device in a wireless LAN system, for example, a wireless communication control device installed in a mobile phone, a PDA, etc., for example, wireless in a short-range wireless communication system represented by Bluetooth (registered trademark), Zigbee (registered trademark), etc. It can be widely applied to communication control devices and the like.

It is a functional block diagram which shows the internal structure of the vehicle-to-vehicle communication apparatus of 1st Embodiment. It is an operation | movement flowchart which shows the inter-vehicle communication process of 1st Embodiment. It is a functional block diagram which shows the internal structure of the vehicle-to-vehicle communication apparatus of 2nd Embodiment. It is an operation | movement flowchart which shows the vehicle-to-vehicle communication process of 2nd Embodiment. It is a functional block diagram which shows the internal structure of the vehicle-to-vehicle communication apparatus of 3rd Embodiment. It is an operation | movement flowchart which shows the inter-vehicle communication process of 3rd Embodiment. It is a functional block diagram which shows the internal structure of the vehicle-to-vehicle communication apparatus of 4th Embodiment. It is an operation | movement flowchart which shows the vehicle-to-vehicle communication process of 4th Embodiment. It is a figure which shows the simulation result which showed the effect of 1st Embodiment and 3rd Embodiment by the average packet error rate. It is a figure which shows the simulation result which showed the effect of 1st Embodiment and 3rd Embodiment by packet error rate dispersion | distribution. It is a figure which shows the simulation result which showed the effect of 1st Embodiment and 3rd Embodiment by the maximum packet error rate. It is a figure which shows the simulation result which showed the effect of 1st Embodiment and 3rd Embodiment by the average delay. It is a figure which shows the simulation result which showed the effect of 1st Embodiment and embodiment of the measure 3 by delay dispersion | distribution. It is a figure which shows the simulation result which showed the effect of 1st Embodiment and 3rd Embodiment by the average reception interval. It is a figure which shows the simulation result which showed the effect of 1st Embodiment and 3rd Embodiment by receiving interval dispersion | distribution. It is a figure which shows the simulation result which showed the effect of 1st Embodiment and 3rd Embodiment by the relationship between the sequence number of a transmission packet, and an average packet error rate. It is a figure which shows the simulation result which showed the effect of 1st Embodiment with the relationship between the sequence number of a transmission packet, and an average packet error rate according to the number of transmission vehicles.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1-4 ... Vehicle communication apparatus, 111 ... Transmission time notification means, 112 ... Vehicle state detection means, 113 ... Transmission time determination means, 114 ... Inter-vehicle communication transmission means, 115 ... Communication traffic amount detection means, 121 ... Inter-vehicle communication reception means 122 ... Notification determining means, 123 ... Information output means.

Claims (6)

In a communication control device that transmits predetermined transmission information at a transmission timing that avoids a collision with one or a plurality of other movable communication devices existing in the vicinity,
A transmission timing determining means for determining a time point selected at random within a range of a predetermined period around the time point after a predetermined one transmission period from the immediately preceding transmission timing as a next transmission timing;
A communication control apparatus comprising: a transmission unit configured to transmit the transmission information at a next transmission timing determined by the transmission timing determination unit. Transmission information acquisition means for acquiring the transmission information to be exchanged with each of the communication devices existing in the vicinity, and providing the acquired transmission information to the transmission means;
Transmission timing notifying means for feeding back the next transmission timing determined by the transmission timing determining means to the transmission information acquiring means, and
The transmission information acquisition means acquires the transmission information and provides the transmission means to the transmission means just before the next transmission timing in accordance with the next transmission timing received from the transmission timing notification means. The communication apparatus according to claim 1. Receiving means for receiving information transmitted from each of the other communication devices present in the vicinity, and acquiring reception status information within a predetermined period;
Communication traffic volume detection means for obtaining a communication traffic volume at a past transmission timing based on the reception status information from the reception means and the transmission status information related to transmission of the transmission information, and
The transmission timing determination means determines the next transmission timing by a method for determining the next transmission timing according to the communication traffic volume obtained by the communication traffic volume detection means. The communication control device described. In a communication control method for transmitting predetermined transmission information at a transmission timing for avoiding a collision with one or a plurality of other movable communication devices existing in the vicinity,
A transmission timing determining step in which the transmission timing determining means determines a time point selected at random within a predetermined period before and after a predetermined transmission period from the immediately preceding transmission timing as a next transmission timing. When,
And a transmission step of transmitting the transmission information at the next transmission timing determined by the transmission timing determination means. In a communication control program for transmitting predetermined transmission information at a transmission timing for avoiding a collision with one or a plurality of other movable communication devices existing in the vicinity,
On the computer,
A transmission timing determination means for determining a time point selected at random within a predetermined period before and after the time point after a predetermined one transmission cycle from the immediately preceding transmission timing as a next transmission timing;
A communication control program that functions as a transmission unit that transmits the transmission information at the next transmission timing determined by the transmission timing determination unit. In the inter-vehicle communication device that exchanges vehicle information of the vehicle with a communication device mounted on one or more other vehicles present in the vicinity,
The vehicle-to-vehicle communication device, wherein the communication control means for intermittently transmitting the vehicle information of the own vehicle corresponds to the communication control device according to any one of claims 1 to 3.

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