JP4655005B2 - Communication device - Google Patents

Description

  The present invention relates to a communication device.

  In the past, systems that provide various types of information to vehicles traveling on the road such as ITS (Intelligent Transport Systems) and VICS (Vehicle Information and Communication Systems) have been introduced. . In addition, it is possible to grasp information on the course of the own vehicle by communicating information such as traffic information possessed by other vehicles and each vehicle's own driving conditions, surrounding conditions detected by the own vehicle, etc. Inter-vehicle and inter-road communication systems are known.

  The radio wave used in such a communication system has a high frequency in the gigahertz band, and has a straight line and high diffraction loss. Therefore, the range in which direct communication can be performed is limited. Therefore, as a technique for expanding the communication range, a technique for relaying information by relaying another vehicle or a communication device on the road surface is effective.

As a technology for such relay communication, in order to prevent communication traffic from increasing due to repeated useless relays, a communication device that relays data determines the priority and appropriateness of information and deletes unnecessary data. A technique has been proposed in which the occupation time of information to be relayed is reduced as the number of transfers increases (for example, Patent Document 1). As a result, communication traffic can be appropriately maintained, and communication with a small delay according to priority can be performed.
JP-A-2005-191691

  However, in the prior art, since communication devices that relay transfer data need to perform unnecessary data deletion processing with low priority, there is a risk that relay communication will be delayed. For example, when a large number of vehicles (communication devices) concentrate on one communication device and transfer data, compared to the case where only data sent from one vehicle is transferred, unnecessary data is deleted and transferred for relaying. The load increases. For this reason, relay communication may be delayed depending on the processing capability and transfer rate.

  Therefore, the present invention has been made to solve such a technical problem, and when relay communication is performed in inter-vehicle and inter-road communication, an increase in traffic of the relay communication is avoided, and the load required for the relay processing An object of the present invention is to provide a communication device that reduces the above-mentioned problem.

That is, the communication apparatus according to the present invention includes a communication environment information unit that acquires peripheral communication environment information, a relay information setting unit that sets relay information including at least the number of times of relaying based on the communication environment information, comprising a transmission information generating means for generating transmission information based on the priority of the data length and transmission data item based on the number of relays, and a transmitting means for transmitting the transmission information to the other communication apparatus, the transmission information generation When the number of relays is large by setting the data length when the number of relays is N to 1 / (N + 1) with respect to the entire transmission data length when the number of relays is 0 As described above, the data length of the transmission information is shortened.

  According to the present invention, it is necessary to perform unnecessary data deletion processing in a communication device that relays information by setting the number of relays on the transmission side, generating information of a data length corresponding to the number of relays in advance, and performing relay communication. Therefore, the load required for relay processing can be reduced.

  According to the present invention, as the number of relays increases, the length of transmission data is made shorter than the conventionally transmitted information (basic configuration of communication data), whereby the traffic occupation time of transmission data related to relay communication is reduced. It is shortened, and even if relay communication is interposed, it becomes possible not to press the communicable time zone of another vehicle.

  The communication device according to the present invention is characterized in that the communication device is mounted on a mobile body.

  According to the present invention, since the communication device is mounted on the vehicle, a base station for managing and monitoring communication traffic becomes unnecessary.

  According to the present invention, when relay communication is performed in inter-vehicle and inter-road communication, a load required for relay processing can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  A communication device according to an embodiment of the present invention is mounted on a vehicle, for example, and is used for inter-vehicle communication or inter-road communication. As a communication method of this communication device, for example, a CSMA (Carrier Sense Multiple Access) method is used. In the CSMA system, a communication apparatus transmits a signal after confirming a free state (idle state) of a communication path.

  FIG. 1 is a schematic hardware configuration diagram of a communication apparatus according to an embodiment of the present invention. The communication apparatus according to this embodiment includes an antenna 1, a receiving unit 2, an ECU 3, an output unit 4, and a transmitting unit 5. Here, an ECU (Electronic Control Unit) is a computer of an automobile device that is electronically controlled, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, and the like. Configured.

  The antenna 1 is preferably used for both transmission and reception. Since communication between vehicles and between roadways is performed using, for example, a frequency in a high frequency band, the antenna 1 is suitable for signal transmission / reception in a high frequency band.

  The receiving unit 2 is connected to the antenna 1 and, for example, a high frequency amplifier circuit that amplifies a high frequency signal received by the antenna 1, a frequency conversion circuit that converts an output signal of the high frequency amplifier circuit into an intermediate frequency signal, and a gain of the intermediate frequency signal A gain control circuit for controlling a frequency, a frequency conversion circuit for converting a gain-controlled intermediate frequency signal into a baseband signal, an analog / digital conversion circuit for converting a baseband analog signal into a digital signal, and the like. The signal received at 1 is converted and output to the ECU 3.

  The ECU 3 includes a reception processing unit 31, a signal processing unit 32, and a transmission processing unit 33. The reception processing unit 31 has a function of reconstructing a packet based on data obtained from the reception unit and storing the packet in a memory.

  The signal processing unit 32 refers to the information stored in the memory by the reception processing unit 31, performs vehicle status determination, risk determination, support means selection, output timing calculation, and the like, and outputs the calculation result to the output unit 4 and the transmission processing unit 33. The function to output to.

  The transmission processing unit 33 has a function of determining the number of relays and creating transmission data with reference to a data format obtained from the number of relays.

  The functions realized in the ECU 3 do not necessarily have to be realized by hardware, and can also be realized by software.

  The output unit 4 has a function of appealing to the driver's vision and hearing, and transmitting a driving situation and a vehicle situation, and includes, for example, a display, an indicator, a buzzer, a speaker, and the like.

  The transmission unit 5 performs an operation reverse to that of the reception unit 2, and a digital / analog conversion circuit that converts the baseband signal from the signal processing unit 32 into an analog signal, and the analog-converted baseband signal as an intermediate frequency A frequency conversion circuit that converts the signal into a signal, a gain control circuit that controls the gain of the intermediate frequency signal, and a frequency conversion circuit that converts the gain-controlled intermediate frequency signal into a high-frequency signal are configured. The transmission unit 5 outputs a high frequency signal to the antenna 1.

  Next, the operation of the communication apparatus according to this embodiment will be described.

  FIG. 2 is a flowchart showing the transmission operation of the communication apparatus according to this embodiment. The start timing of the transmission control process in FIG. 2 is separately determined by a system timer or the like. For example, when there is data that needs to be transmitted, transmission processing is started each time, and when there is vehicle information that needs to be transmitted at regular intervals, it is repeatedly executed at a predetermined timing.

  When the control process of FIG. 2 is started, as shown in S10 of FIG. 2, a process of grasping the communication environment is performed. For example, information on the surrounding radio wave environment, information on whether or not a communication device installed on a vehicle or road surface exists, and information on the number and distance of surrounding communication devices. For example, regarding the information on the radio wave environment, it is only necessary to determine what the radio wave condition is based on whether or not the information can be transmitted and received. The presence confirmation of other communication devices may be determined, for example, by transmitting data for existence confirmation to an unspecified number of people and returning a signal to the communication device. The same applies to the distance, and it may be determined from the intensity of the response signal to the transmission, the diffraction time, and the destination transmission time.

  When S10 ends, the process proceeds to a process for determining whether the relay communication is available (S12). S12 is a process for making a determination based on information on the surrounding communication environment. For example, if it is determined that there is no communication device on the vehicle or road surface, it is determined that relay communication is not possible, and the process proceeds to no relay (S18). In S18, for example, the number of relays is determined as 0. On the other hand, for example, when the presence of the communication device can be confirmed in other surrounding vehicles, it is determined that relay communication is possible, and the process proceeds to processing for determining whether relay communication is necessary (S14).

  S14 is a process in which the host vehicle determines whether to perform relay communication. For example, when communicating with a specific partner, if the distance to the specific partner is extremely close, or if there is no object that blocks communication radio waves between the specific partner and the vehicle, there is no need for relay communication. Transition (S18). S18 is determined, for example, as the number of relay times 0. On the other hand, when communicating with a specific partner and radio waves do not reach the specific partner directly or when it is necessary to sequentially transmit information to a large number of unspecified partners, the process proceeds to processing for determining the number of relays (S16). ).

  S16 is a process for determining how far the information is transmitted with reference to the own vehicle. For example, when information is transmitted to an unspecified number of people, the number of relays may be set to 1 or 2 if the information only needs to be known only by vehicles around the host vehicle. In the case of transmission to a specific partner, it is only necessary to determine and determine how many times the own vehicle should relay using information obtained from grasping the communication environment.

  When S16 ends, the process proceeds to a process for determining the transmission data length (S20). S20 is a process of determining the transmission data length from the number of relays, and details will be described later.

  When S20 ends, the process proceeds to a process of referring to the data format table (S22). S22 is a process of preparing a data format corresponding to the data length to be transmitted, and data with low priority is excluded from transmission targets. The data format when the data length is set short will be described later using an embodiment. Further, it is possible to determine in advance data to be excluded from transmission according to the number of relays and the target system, and prepare a data format in advance. For example, when the data length is close to the length A, the data format “a” is selected, and when the data length is close to the length B, the data format “b” is selected.

  When S22 ends, the process proceeds to a process of determining whether or not data necessary for the operating system is insufficient (S24). S24 is processing for checking whether data used in the communication system, preferential data, or the like is missing in the data format determined in S22. For example, if the transmission data length calculated in S20 is shorter than the length of the data item with high priority, the data is insufficient. Further, even when the data format determined in advance by the transmission data length determined from the number of relays is replaced, a case where the essential data item is not in the data format is assumed. In these cases, it is considered that there is no relay, and the process proceeds to S18.

  If it is determined in S24 that there is no data shortage, the transmission target data is collected (S26). S26 is a process of collecting data according to the determined data format item.

  When S26 ends, the process proceeds to the process of substituting the number of relays (S28). S28 is a process of inputting the number of relays determined in S16 into the transmission data.

  When S28 ends, the process proceeds to a transmission packet construction process (S30). S30 is processing for dividing the transmission data and adding header information.

  When S30 ends, the process proceeds to transmission processing (S32). S32 is processing for converting the data packetized in S30 into a signal and transmitting the signal. When S32 ends, the communication process ends.

  As described above, it is necessary to perform unnecessary data deletion processing in a communication device that relays information by setting the number of relays on the transmission side, generating information of a data length corresponding to the number of relays in advance, and performing relay communication. Therefore, the load required for the relay process can be reduced.

  FIG. 3 is a flowchart showing reception and relay operations of the communication apparatus according to the present embodiment. The reception control process in FIG. 3 is started at a timing when the antenna 1 receives a reception signal.

  First, reception processing is performed (S40). S40 is a process for converting the transmitted signal into data.

  When S40 ends, the process proceeds to a received packet analysis process (S42). S42 is a process for making it possible to read what information has been sent by combining the received packets based on the packet header information.

  When S42 ends, the process proceeds to processing for reading destination information and the number of relays (S44).

  When S44 ends, the process proceeds to a process of determining whether or not relay communication is necessary (S46). S46 is a process for determining whether the received data should be relayed from the destination and the number of relays. For example, it is confirmed whether the read destination information is the host vehicle. Also, it is confirmed whether the number of relays is zero. If the destination is the subject vehicle or the number of relays is 0, the data part reading process or packet discarding is performed and the process ends (S48).

  If relay processing is required, the process proceeds to processing for grasping the communication environment (S50). S50 is, for example, information on the surrounding radio wave environment, information on whether or not there is a communication device installed on a vehicle or road surface, and information on the number and distance of surrounding communication devices. For example, regarding the information on the radio wave environment, it is only necessary to determine what the radio wave condition is based on whether or not the information can be transmitted and received. The presence confirmation of other communication devices may be determined, for example, by transmitting data for existence confirmation to an unspecified number and determining that a communication device that has returned a signal exists. The same applies to the distance, and it may be determined from the intensity of the response signal to the transmission, the diffraction time, and the destination transmission time.

  When S50 ends, the process proceeds to a process of determining whether or not relay communication is available (S52). S52 is a process for making a determination based on information on the surrounding communication environment. For example, if it is determined that there is no communication device on the vehicle or road surface, it is determined that relay communication is not possible, and the process proceeds to packet discard (S48). For example, when the presence of the communication device can be confirmed in other surrounding vehicles, it is determined that relay communication is possible, and the process proceeds to a process of reducing the number of relays by 1 (S54).

  When S54 ends, the process proceeds to a process of substituting the number of relays (S56). S56 is a process of inputting the number of relays calculated in S54 into the transmission data.

  When S56 ends, the process proceeds to a transmission packet construction process (S58). S58 is processing for dividing the transmission data and adding header information.

  When S58 ends, the process proceeds to transmission processing (S60). S60 is a process of converting the data packetized in S58 into a signal and transmitting it. When S60 ends, the relay process ends.

  Since the transmission operation, the reception operation, and the relay operation of the communication device according to the above-described embodiment are all performed based on information obtained by inter-vehicle or inter-road communication, the communication device of the present invention is mounted on the vehicle. This eliminates the need for a base station for managing and monitoring communication traffic.

  Next, an example of determining the transmission data length from the number of relays will be described as an example according to the present embodiment.

4 and 5 are specific examples showing changes in the data length according to the number of relays according to the present embodiment. The data transmitted from the host vehicle is Original, and the data relayed for the Nth time is Pass (N) (N is an integer). When the number of relays is 0, the time for occupying the communication to transmit data of length L is T seconds. Here, when relaying N times, the time T _N seconds required for data transmission is expressed by the following equation.

T _N = T · (N + 1)
From the above, _TN increases in proportion to the number of relays. Here, in order to reduce the time occupied by relay communication, the time that can be occupied during data transmission of relay communication is set to T seconds regardless of the number of relays. At this time, if the rate of reduction of the transmission occupancy time of Original data when relayed N times is α, the time _TN seconds required for data transmission is expressed by the following equation.

T _N = α · T · (N + 1) = T
From the above, the original data transmission occupation time reduction rate α is expressed by the following equation.

α = 1 / (N + 1)
From this, when the number of relays is 0, there is no reduction in the transmission time of Original data, but when the number of relays is 1, 1/2, when the number of relays is 2, 1/3, the number of relays is By reducing the transmission occupation time of Original data to 1 / (N + 1) at N times, the transmission occupation time required for the entire data transmission can be always constant. Thereby, even if relay communication is interposed, it becomes possible not to press the communicable time zone of the other vehicle.

  The above calculation does not necessarily require a constant traffic occupation time regardless of the number of relays, and the effect of reducing communication traffic can be obtained by shortening the data length as the number of relays increases.

  Further, the above calculation yields the same result even when the occupation time is calculated as the data length. For example, the communication data length of the Original data may be shortened, and calculation may be performed assuming that the entire data length is L regardless of the number of relays.

  Next, a configuration example of the data format of transmission data will be described as an example according to the present embodiment.

  FIG. 5 is a configuration example of a data format according to the number of relays according to the present embodiment. The transmission data includes, for example, a communication basic data part, a vehicle situation data part, and a message data part.

  The communication basic data part includes information indispensable for carrying out inter-vehicle and inter-road communication. For example, header and preamble 0, ID information 1, data format version 2, destination 4 and number of relays 5 and other communication control information such as vehicle type 3, owned system 6, and active system 7 are included.

  The vehicle status data section includes information related to the traveling status of the host vehicle. For example, the header information 8, the vehicle speed 9, the current position 10, the traveling direction 11, the brake state 12, the blinker state 13, various SW signals 14, Various sensor signals 15 and vehicle control signals 16 are included.

  The message data part includes external information and error control information related to the host vehicle. For example, header information 17, emergency vehicle information 18, message part 19, message part 20, transfer data 21, commercial service data 22 , Specified group exclusive data 23, quality control data 24, diagnosis data 25, footer and CRC, checksum 26, and the like are included.

  Here, the contents of the vehicle status data part and the message data part can be prioritized. For example, for a car that is traveling directly next to the host vehicle, information indicating the turn signal status of the host vehicle is also important, but for a vehicle far from the host vehicle, the turn signal information of the host vehicle is the position of the host vehicle. It is not important information compared to information. From this, it is possible to give priority to the items of transmission information relatively.

  Based on the above priority order, the configuration that depends on the specified number of times allows the length of the transmission data to be shorter than the conventionally transmitted information (basic configuration of communication data) as the number of relays increases. It becomes.

  As described above, according to the communication apparatus according to the present embodiment, the relay number is set on the transmission side, and the data length information corresponding to the relay number is generated in advance and relay communication is performed, thereby relaying the information. Since it is not necessary to delete unnecessary data in the apparatus, the load required for relay processing can be reduced.

  In addition, according to the communication apparatus according to the present embodiment, the larger the number of relays, the shorter the transmission data length than the conventionally transmitted information (basic configuration of communication data), which occurs in the entire relay. The traffic occupation time and the traffic occupation time for one normal transmission can be made constant. Thereby, the traffic occupation time of the transmission data concerning relay communication is shortened, and even if relay communication is interposed, it becomes possible not to compress the communicable time zone of other vehicles.

  Furthermore, according to the communication apparatus according to the present embodiment, since the communication apparatus is mounted on the vehicle, a base station for managing and monitoring communication traffic becomes unnecessary.

  The embodiment described above shows an example of a communication apparatus according to the present invention. The communication device according to the present invention is not limited to the communication device according to these embodiments, and the communication device according to the embodiment may be modified or otherwise changed without changing the gist described in each claim. It may be applied to.

It is a block diagram which shows the structure outline | summary of the communication apparatus which concerns on embodiment of this invention. It is a flowchart which shows the transmission operation | movement of the communication apparatus of FIG. 3 is a flowchart showing reception and relay operations of the communication apparatus of FIG. 1. It is explanatory drawing of the relay of transmission data according to the frequency | count of relay permission, and occupation time. It is explanatory drawing of transmission according to the frequency | count of relay permission. It is a data structural example of transmission data.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Reception part, 3 ... ECU, 31 ... Reception processing part, 32 ... Signal processing part, 33 ... Transmission processing part, 4 ... Output part, 5 ... Transmission part.

Claims (2)

Communication environment information means for acquiring surrounding communication environment information;
Relay information setting means for setting relay information including at least the number of relays at the time of transmission based on the communication environment information;
Transmission information generating means for generating transmission information based on the data length based on the number of times of relaying and the priority of transmission data items;
Transmitting means for transmitting the transmission information to another communication device;
Equipped with a,
The transmission information generating means sets the data length when the number of relays is N to 1 / (N + 1) with respect to the entire transmission data length when the number of relays is 0, so that the relay The shorter the number of times, the shorter the data length of the transmission information;
A communication device characterized by the above. The communication device according to claim 1, wherein the communication device is mounted on a mobile body.

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