JP3668624B2 - Inter-vehicle communication system and in-vehicle communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automobile communication system, and more particularly, to an inter-vehicle communication system for performing wireless communication between vehicles and an in-vehicle communication apparatus thereof.
[0002]
[Prior art]
Development of Intelligent Transport Systems (ITS), which integrates roads and vehicles, is being promoted in order to realize services aimed at improving safety, transport efficiency, and comfort. . In this system, these services are to be realized by road-to-vehicle communication performed between a base station installed on the road and a mobile station mounted on a vehicle, and vehicle-to-vehicle communication performed between mobile stations.
[0003]
As an example of a communication method in such an intelligent road traffic system, a standard “Toll Road Automatic Toll Collection System Standard ARIB STD-T55 Version 1.0” (November 1997) established by the Japan Radio Industry Association. 27th of March) is known.
[0004]
The above-mentioned standard defines a road-to-vehicle communication method by spot communication with a limited communication area, and uses different frequencies for downlink communication from the base station to the mobile station and uplink communication from the mobile station to the base station. It adopts full-duplex communication (roadside communication device) and adopts an adaptive slotted aloha system, which is a synchronous time-division communication system in which communication frames are time-divided into fixed-length sections called slots.
[0005]
Adaptive Slotted Aloha communication frames are broadly divided into communication slots and control slots, and message slots for exchanging data between road vehicles to enable communication with multiple mobile stations. A plurality of (MDS: Message Data Slot) are arranged, and this MDS includes communication data MDC. The control slot includes control information necessary for road-to-vehicle communication, and stores configuration information of a communication frame transmitted by the base station, a usage status of the communication slot, and the like (stores a frame control signal FCMC). It consists of a frame control message slot (FCMS) and an activation slot (ACTS: Activation Slot) for the mobile station to request the base station to allocate a communication slot (including the link request signal ACTC). .
[0006]
[Problems to be solved by the invention]
According to the above prior art, the communication area is spot communication that is fixed at the place where the base station is installed, and thus cannot be applied to communication between mobile stations. For this reason, a communication method for vehicle-to-vehicle communication is required, but considering the effective use of frequency resources and the cost of communication devices, the modulation method, frequency, etc. are set so that wireless circuits can be shared. It is desirable to be the same as the road-to-vehicle communication system. However, in this case, there is a problem that inter-vehicle communication becomes an obstacle to road-to-vehicle communication in a place where a communication area for road-to-vehicle communication is secured.
[0007]
An object of the present invention is to provide a vehicle-to-vehicle communication method capable of communication between vehicles without interfering with road-to-vehicle communication even in a communication area based on the road-to-vehicle communication method, and an in-vehicle communication device thereof. It is in.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the inter-vehicle communication system of the present invention transmits and receives data packets having a slot length less than the slot length determined by the road-to-vehicle communication system, using the frequency channel for uplink communication. In the road-to-vehicle communication area, the transmission of data packets is synchronized with the communication frame for road-to-vehicle communication, and data packets are transmitted and received during the frame control slot. Since the road-to-vehicle communication system does not use the frequency channel for uplink communication during the frame control slot period, vehicle-to-vehicle communication that does not interfere with road-to-vehicle communication within the road-to-vehicle communication area becomes possible.
[0009]
In order to achieve the above object, the vehicle-to-vehicle communication system in-vehicle communication device according to the present invention includes an uplink channel modulation means, an uplink channel demodulation means, and a vehicle-to-vehicle communication control means, which is less than the slot length determined by the road-to-vehicle communication system. The data packet is transmitted / received using the frequency channel for uplink communication. In the road-to-vehicle communication area, the road-to-vehicle communication control means detects a communication frame for road-to-vehicle communication and generates frame detection information. The inter-vehicle communication control means transmits the data packet in the frame control slot period in synchronization with the communication frame from the frame detection information. Since the road-to-vehicle communication system does not use an uplink communication frequency channel during the frame control slot period, an in-vehicle communication device capable of inter-vehicle communication without interfering with road-to-vehicle communication within the road-to-vehicle communication area is provided. It becomes possible to do.
[0010]
Furthermore, in addition to the vehicle-to-vehicle communication of the present invention, the road-to-vehicle communication control means has a function capable of road-to-vehicle communication by the above-described road-to-vehicle communication method in addition to the vehicle-to-vehicle communication of the present invention. An in-vehicle communication device capable of road-to-vehicle communication by a communication method can be provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the inter-vehicle communication system of the present invention will be described with reference to FIG.
In the embodiment of FIG. 1, a case where a communication frame for road-to-vehicle communication is configured with three slots is shown. In this configuration, according to the road-to-vehicle communication system, the downlink channel of slot 1 is used as a frame control slot, the uplink channel of slot 3 is used as a link request slot, and the downlink channels and slots of slot 2, slot 3 are used. The two uplink channels are used as communication slots for data exchange, and the uplink channel frequency of slot 1 in which the frame control slot is arranged is an unused slot that is not used in road-to-vehicle communication.
[0012]
In addition, a mobile station that performs road-to-vehicle communication using the above communication frame needs to synchronize with the communication frame transmitted by the base station in order to determine the position of the communication slot assigned to the mobile station. For this reason, in the road-to-vehicle communication system, the frame control signal FCMC of the frame control slot includes a signal MDC (communication data), an ACKC (delivery confirmation signal), and an ACTC (link request signal) arranged in other slots. Multiplexes different synchronization signal patterns so that the position of the frame control slot can be identified as the time reference of the communication frame. Since the frame control signal FCMC is multiplexed with frame configuration information such as the frame period and the slot position assigned to the own station, the mobile station can reproduce the communication frame.
[0013]
In the vehicle-to-vehicle communication system of the present invention, at least an uplink channel frequency used in road-to-vehicle communication by the road-to-vehicle communication system is a communication frequency, and a data packet having a packet length less than the slot length determined by the road-to-vehicle communication system is used. Exchange data between mobile stations.
[0014]
In addition, the frame control signal FCMC in the frame control slot of the communication frame transmitted from the base station is monitored to detect the road-to-vehicle communication area. When the road-to-vehicle communication area is detected, the communication frame is reproduced from the acquired frame control signal FCMC, the position of the unused slot in the communication frame is obtained, and the data packet for vehicle-to-vehicle communication is received at the time when this unused slot arrives. Send with. In addition, if the data packet is being transmitted at the time when the frame control signal FCMC is detected and the transmission of the remaining data cannot be completed within the period of the frame control slot, the transmission operation is stopped and unused after the communication frame is reproduced. Retransmission is performed during the slot period, and interference with the communication slot for road-to-vehicle communication is suppressed.
[0015]
From the above, according to the present embodiment, data packets exchanged by inter-vehicle communication can be exchanged in unused slots that are not used in road-to-vehicle communication within the road-to-vehicle communication area. And a vehicle-to-vehicle communication system that can communicate with each other without interference.
[0016]
Further, according to the road-to-vehicle communication system, for example, intermittent transmission of a communication frame such as one frame being paused after one frame transmission is permitted, and this transmission mode is also notified to the mobile station by a frame control signal FCMC. It is like that. In the communication area of the base station that performs this intermittent transmission, there is a period during which no communication frame is transmitted, and a mobile station that performs vehicle-to-vehicle communication can also communicate using this communication frame missing period. . This is because the transmission mode is detected from the frame control signal FCMC acquired in the communication frame reproduction process to know the frame missing period, or the frame control signal FCMC is calculated in the period of the frame control slot predicted in the reproduced communication frame. This can be dealt with by knowing that it cannot be detected.
[0017]
Furthermore, since the base station can also demodulate the uplink channel frequency used for inter-vehicle communication, the base station can communicate with the unused slot positions by executing the reception control procedure defined by inter-vehicle communication. It is also possible to intercept.
[0018]
Next, an embodiment of an in-vehicle communication device used in the inter-vehicle communication system of the present invention will be described with reference to FIG.
2, 301 and 302 are antennas, 303 is a downlink channel demodulation unit, 304 is an uplink channel modulation unit, 305 is an uplink channel demodulation unit, 306 is a road-to-vehicle communication control unit, 307 is a vehicle-to-vehicle communication control unit, and 308 is data. It is a processing unit.
[0019]
The data processing unit 308 realizes an application that uses vehicle-to-vehicle communication. In order to process data exchanged through vehicle-to-vehicle communication, the data processing unit 308 transmits data to the vehicle-to-vehicle communication control unit 307, and performs vehicle-to-vehicle communication control unit 307. Communication with the application at the other station is executed by receiving data from the other station.
[0020]
The vehicle-to-vehicle communication control unit 307 performs communication control for medium access, for example, by adding communication procedure control information or a synchronization signal to the application data passed from the data processing unit 308, and A data packet for communication is created, and this is transmitted to the partner station using the uplink channel modulation unit 304 and the antenna 302. Then, the uplink channel demodulation unit 305 waits for reception of a delivery confirmation data packet from the partner station. When the delivery confirmation is received, the retransmission process is determined, and the retransmission process is performed as necessary.
[0021]
The data packet transmitted from the partner station is transferred to the uplink channel demodulation unit 305 through the antenna 302, converted into a baseband signal, and then input to the inter-vehicle communication control unit 307. The inter-vehicle communication control unit 307 that has received the data packet from the other station inspects the data from, for example, control information of the communication procedure, creates a delivery confirmation data packet, and uses the uplink channel modulation unit 304 and the antenna 302 And reply to the other station. If reception of the data packet is successful, the multiplexed application data is extracted and passed to the data processing unit 308.
[0022]
In the inter-vehicle communication system of the present invention, since the data packet packet length is set to be less than the slot length determined by the road-to-vehicle communication system, the data length of the application data passed from the data processing unit 308 is the data packet length. It may be exceeded. However, in this case, application data having a long data length can be transmitted and received by dividing the application data into data packet lengths on the transmission side of the vehicle-to-vehicle communication control unit 307 and transmitting the divided data packets. .
[0023]
The road-to-vehicle communication control unit 306 receives as input the baseband signal obtained by demodulating the signal input from the antenna 301 by the downlink channel demodulation unit 303, and at least detects that the mobile station has entered the road-to-vehicle communication area. The frame control signal FCMC transmitted from the station in the frame control slot is detected. When the road-vehicle communication control unit 306 detects the frame control signal FCMC, the timing signal indicating the time reference of the communication frame passed to the vehicle-to-vehicle communication control unit 307 and the control information of the acquired frame control signal FCMC are valid. Notification is made within the period of the frame control slot in which the detected frame control signal FCMC is arranged. In addition, it is determined that the mobile station is located outside the road-to-vehicle communication area under the condition that the frame control signal FCMC cannot be detected for a certain period of time. It is notified that the control information of the signal FCMC is invalid.
[0024]
Correspondingly, when the vehicle-to-vehicle communication control unit 307 detects that the timing signal or control information from the road-to-vehicle communication control unit 306 is valid, the communication frame for road-to-vehicle communication is not reproduced from these information. The position of the used slot is obtained, and the transmission timing is adjusted so that the data packet is transmitted in the unused slot period. When the data packet is being transmitted at the time when the notification is received from the road-vehicle communication control unit 306, the vehicle-to-vehicle communication control 307 is required for the transmission obtained from the remaining time of the frame control slot and the remaining data amount. Comparing the time, if the remaining time of the frame control slot is short, the transmission operation is stopped, and after the communication frame is replayed, it is retransmitted in the unused slot period, thereby obstructing the communication slot of road-to-vehicle communication. Deter.
[0025]
From the above, according to the present embodiment, the road-to-vehicle communication control unit 306 and the vehicle-to-vehicle communication control unit 307 can synchronize with the communication frame transmitted by the base station in the road-to-vehicle communication area. Since the exchange of data packets in the inter-vehicle communication control unit 307 between stations can be performed in an unused slot that is not used in road-to-vehicle communication, inter-vehicle communication can be performed without interfering with each other in the road-to-vehicle communication area. An in-vehicle communication device capable of performing communication can be realized.
[0026]
In addition, according to the road-to-vehicle communication method, for example, intermittent transmission of a communication frame saying that one frame is paused after transmission of one frame is permitted, and this transmission mode is also notified to the mobile station by a frame control signal FCMC. It is like that. In the communication area of the base station that performs this intermittent transmission, there is a period during which no communication frame is transmitted, and a mobile station that performs vehicle-to-vehicle communication can also communicate using this communication frame missing period. . This is because the frame missing period is also reproduced by the communication frame reproduction processing performed by the inter-vehicle communication control unit 307, or the frame control slot period predicted by the communication frame reproduced by the inter-vehicle communication control unit 307. This can be dealt with by knowing the missing period of the communication frame by the method of determining the detection result of the frame control signal FCMC of the inter-vehicle communication control unit 306.
[0027]
Further, in the present embodiment, since the downlink channel demodulation unit 303 and the uplink channel modulation unit 304 are provided, a communication control means for road-to-vehicle communication is added to the road-to-vehicle communication control unit 306, and the connection indicated by the dotted line in FIG. By doing so, road-to-vehicle communication with the base station is also possible. At this time, processing necessary for detection of the frame control signal FCMC by the road-to-vehicle communication control unit 306 can also be used as part of the road-to-vehicle communication means.
[0028]
In the vehicle-to-vehicle communication system of the present invention, the frequency channel for uplink communication of the road-to-vehicle communication system is a communication frequency, the data packet length is set to be less than the slot length of the road-to-vehicle communication system, and a communication frame for road-to-vehicle communication The exchange procedure of data packets between vehicles shown in the inter-vehicle communication control unit 307 is limited to the method of the above-described embodiment. is not.
[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a vehicle-to-vehicle communication system that does not interfere with each other in the road-to-vehicle communication area.
[0030]
Further, according to the present invention, it is possible to realize an in-vehicle communication device capable of executing vehicle-to-vehicle communication without interfering with each other in the road-to-vehicle communication region. Further, by expanding the signal receiving means from the base station, it is possible to realize an in-vehicle communication device having a road-to-vehicle communication function.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a communication frame for explaining an embodiment of an inter-vehicle communication system of the present invention.
FIG. 2 is a block diagram showing a configuration of an embodiment of an in-vehicle communication device of an inter-vehicle communication system according to the present invention.
[Explanation of symbols]
301, 302 Antenna 303 Downlink demodulation unit 304 Uplink modulation unit 305 Uplink demodulation unit 306 Road-to-vehicle communication control unit 307 Vehicle-to-vehicle communication control unit 308 Data processing unit

Claims (2)

A frame control slot including control information necessary for road-to-vehicle communication is arranged, and a communication frame of a format in which at least a communication slot for data exchange is arranged subsequently is used, and transmission of control information in the frame control slot and Data transmission from the base station installed on the road in the communication slot to the mobile station mounted on the vehicle using the frequency allocated for downlink communication, data transmission from the mobile station to the base station in the communication slot, Vehicle-to-vehicle communication for performing communication between mobile stations using the same frequency as the road-to-vehicle communication method in an environment where communication based on the road-to-vehicle communication method performed using the frequency allocated for uplink communication is performed. in the method,
The frequency used for vehicle-to-vehicle communication is the frequency for uplink communication assigned in the road-to-vehicle communication method,
The data packet length used for inter-vehicle communication is less than the slot length determined by the road-to-vehicle communication method,
Even without least to detect the control information in the frame control slot play timing of said frame control slot, in the transmission period of the frame control slot of the road-to-vehicle communication, and performs transmission and reception of the data packet Inter-vehicle communication system. A frame control slot including control information necessary for road-to-vehicle communication is arranged, and a communication frame of a format in which at least a communication slot for data exchange is arranged subsequently is used, and transmission of control information in the frame control slot and Data transmission from the base station installed on the road in the communication slot to the mobile station mounted on the vehicle using the frequency allocated for downlink communication, data transmission from the mobile station to the base station in the communication slot, in environments where communication based on the road-to-vehicle communication method performed by using the frequencies allocated for uplink communication is performed, the row cormorants vehicle mounting a communication device communication between mobile stations using the road-to-vehicle communication method same frequency and In
A downlink channel demodulating means for demodulating the communication frame for road-to-vehicle communication transmitted at a frequency for downlink communication and outputting to the road-to-vehicle communication control means;
Road-to-vehicle communication control means for detecting at least the communication frame for road-to-vehicle communication and notifying the vehicle-to-vehicle communication control means of frame detection information;
Inter-vehicle transmission / reception control for data packets in which at least the packet length is less than the slot length determined in the road-to-vehicle communication method, and adjustment of data packet transmission timing by frame detection information output from the road-to-vehicle communication control means Communication control means;
An uplink channel modulation means for transmitting a data packet output from the vehicle-to-vehicle communication control means at a frequency for uplink communication assigned in the road-to-vehicle communication method;
An uplink channel demodulating means for demodulating a data packet from a signal of an uplink communication frequency assigned in the road-to-vehicle communication method and outputting the demodulated data packet to the vehicle-to-vehicle communication control means;
Comprising at least
In the period in which the road-to-vehicle communication control means detects the communication frame for the road-to-vehicle communication and validates the frame detection information, the vehicle-to-vehicle communication control means has at least a frame control slot period for road-to-vehicle communication. An in-vehicle communication device characterized by transmitting a data packet.

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