JP2007088689A - Inter-vehicle wireless communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inter-vehicle wireless communication apparatus capable of attaining communication between vehicles even when the distance between the vehicles making communication with each other is longer. <P>SOLUTION: Antennas 3F, 3R have strong directivity in front and rear directions of a vehicle. Transmission sections 23, 25 and reception sections 24, 26 carry out packet transmission reception with other communication nodes before and behind the vehicle via the antenna 3F or 3R. A control section 20 is a means for acting the inter-vehicle wireless communication apparatus 2 like a communication node of an adhoc wireless network as its control and controls packet transmission processing, packet reception processing, and relay processing of packets addressed to the other communication node received via the reception sections. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inter-vehicle wireless communication apparatus that is mounted on a vehicle such as a motorcycle and performs wireless communication with other vehicles.

There is an inter-vehicle communication system in which a wireless communication device is mounted on a plurality of vehicles traveling in a row so that wireless communication can be performed between the wireless communication devices. Patent Document 1 determines the initiative of generation of a synchronization signal indicating the communication timing of the wireless communication device of each vehicle according to the positional relationship of the vehicles constituting the platoon as this type of inter-vehicle wireless communication system. Is disclosed. This inter-vehicle wireless communication system has an advantage that it can flexibly cope with a change in the arrangement order of vehicles in the platoon, separation / concentration of vehicles, and the like.
JP-A-8-163018

  By the way, the conventional inter-vehicle communication system described above may not be able to wirelessly communicate between a vehicle near the head of the platoon and a vehicle near the tail when the platoon consisting of a plurality of vehicles becomes long. There was a problem. In addition, there is a change in the order of the vehicles within the formation, and as a result, the distance between the two vehicles performing wireless communication becomes long, and wireless communication between the vehicles may become impossible. In order to eliminate such inconvenience, it is necessary to increase the transmission power of the wireless communication device of each vehicle and extend the communicable distance. However, when the transmission power of the wireless communication device is increased, there is a problem that the battery of each vehicle is consumed and its life is shortened.

  The present invention has been made in view of the circumstances described above, and an object thereof is to provide an inter-vehicle wireless communication device that enables communication between vehicles even when the distance between vehicles that perform communication becomes long. Yes.

The present invention provides an inter-vehicle wireless communication apparatus that is provided in each of a plurality of traveling vehicles and serves as a communication node to perform wireless communication with a communication node of another vehicle, and has strong directivity in the forward direction and the backward direction of the vehicle. A transmission / reception unit that transmits / receives a packet to / from another communication node via the antenna, and a unit that performs control for causing the inter-vehicle wireless communication device to function as a communication node of an ad hoc wireless network. A reception process for receiving a packet destined for the wireless communication device via the transmission / reception means, a transmission process for transmitting a packet addressed to another communication node via the transmission / reception means, and a reception process received via the transmission / reception means. Control means for controlling relay processing for transmitting packets addressed to other communication nodes by the transmission / reception means. Providing both between the radio communication devices.
According to such an inter-vehicle wireless communication device, the inter-vehicle wireless communication device of each vehicle traveling in a row functions as a communication node of an ad hoc wireless network. Accordingly, each inter-vehicle wireless communication device can transmit a packet to another communication node located at a distance from one or more communication nodes as relay nodes. In addition, since the antenna of each inter-vehicle wireless communication device has a strong directivity in the front-rear direction of the vehicle, even if the transmission power is low, a communication node with a relatively long distance in the front-rear direction of the vehicle Wireless communication is possible.

Embodiments of the present invention will be described below with reference to the drawings.
An inter-vehicle communication system according to an embodiment of the present invention includes a wireless communication device provided in a plurality of motorcycles (hereinafter simply referred to as “vehicles”) that travel in a row, each of which is a communication node of an ad hoc wireless network. Thus, wireless packet communication is performed with other communication nodes in the network. FIG. 1 shows a vehicle 5 equipped with a device serving as a communication node in the present embodiment and a helmet 4 worn by a driver of the vehicle 5. In FIG. 1, a short-range wireless communication device 1 is provided in a helmet 4, and an inter-vehicle wireless communication device 2 is provided in a vehicle 5. Here, the short-range wireless communication device 1 has a function of exchanging voice with a driver wearing the helmet 4. Further, the short-range wireless communication device 1 has a function of performing bidirectional short-range wireless communication with the inter-vehicle wireless communication device 2. A front antenna 3F having strong directivity in the front direction of the vehicle 5 is provided at the front of the vehicle 5, and a rear antenna 3R having strong directivity in the rear direction of the vehicle 5 is provided at the rear of the vehicle 5. ing. The vehicle-to-vehicle wireless communication device 2 has a function of performing wireless communication with the vehicle-to-vehicle wireless communication device 2 of another vehicle in the forward direction and the backward direction of the vehicle 5 using these antennas 3F and 3R. However, although the front antenna 3F and the rear antenna 3R are weak, they also have transmission capability and reception capability in the left-right direction of the vehicle 5. Therefore, the inter-vehicle wireless communication device 2 can also perform wireless communication with the inter-vehicle wireless communication device 2 of the side vehicle if the distance is short.

  FIG. 2 is a block diagram showing an electrical configuration of the short-range wireless communication device 1 and the inter-vehicle wireless communication device 2. The short-range wireless communication device 1 includes a transmission unit 11, a reception unit 12, a microphone 13, left and right speakers 14 </ b> L and 14 </ b> R, and an antenna 15. Here, the microphone 13 is fixed at a position below the front surface of the helmet 4 (see FIG. 1), picks up a voice emitted by the driver, and outputs a voice signal. The transmission unit 11 places this audio signal on a carrier and transmits it from the antenna 15. Speakers 14 </ b> L and 14 </ b> R are fixed at positions facing the driver's left and right ears in helmet 4. The receiving unit 12 demodulates the audio signal from the signal received by the antenna 15 and supplies it to the speakers 14L and 14R.

  Next, the inter-vehicle wireless communication device 2 will be described. The transmission unit 21 and the reception unit 22 are devices that exchange signals with the short-range wireless communication device 1 via the antenna 29. The transmission unit 23 and the reception unit 24 are devices that perform wireless packet communication with the inter-vehicle wireless communication device 2 of another vehicle via the front antenna 3F. The transmitter 25 and the receiver 26 are devices that perform wireless packet communication with the inter-vehicle wireless communication device 2 of another vehicle via the rear antenna 3R. The control unit 20 is a device that controls each unit of the inter-vehicle wireless communication device 2, and includes a CPU, a ROM that stores a program executed by the CPU, a RAM that is used as a work area by the CPU, and the like. Yes. The main ones of the controls performed by the control unit 20 are as follows.

a. Control for controlling the inter-vehicle wireless communication device 2 as a transmission node (control of transmission processing)
When the driver of the vehicle 5 makes a call with another driver, the control unit 20 uses the voice information received from the short-range wireless communication device 1 by the receiving unit 22 as a payload portion, and on the other hand, inter-vehicle wireless communication A packet is formed by adding a header including the ID given to the device 2 as the caller ID and the ID of the inter-vehicle wireless communication device 2 that is the destination as the destination ID. Is transmitted to the front and rear of the vehicle 5.

b. Control for controlling the inter-vehicle wireless communication device 2 as a reception node (control of reception processing)
When the packet is received by the receiving unit 24 or 26 and the destination ID in the header of the packet is the ID of the inter-vehicle wireless communication device 2, the control unit 20 extracts the voice information from the payload portion of the packet, and this voice Information is transmitted to the short-range wireless communication device 1 by the transmission unit 21.

c. Control for controlling the inter-vehicle wireless communication device 2 as a relay node (control of relay processing)
The control unit 20 stores a route table in the RAM. This routing table is a table stored in each communication node so that a packet sent from an arbitrary sending node to the ad hoc wireless network is appropriately relayed to the receiving node specified by the destination ID. For each destination ID, when a packet having the destination ID is received, an ID (hereinafter referred to as a transfer destination ID) of another communication node (inter-vehicle wireless communication device 2) to which the packet is to be transferred is defined. . The control unit 20 receives the packet by the reception unit 24 or 26, determines whether or not the transfer destination ID associated with the destination ID in the header of the packet is defined in the route table, and the corresponding transfer destination When the ID is stored, the transmission unit 23 and 25 transfers the received packet to the transfer destination ID.

Each communication node can acquire a route table used for such control by a known protocol proposed for an ad hoc wireless network. As this kind of protocol, there are a so-called always-on method or a proactive method and a so-called on-demand method or a reactive method. In the former protocol, regardless of the presence or absence of communication, each communication node periodically exchanges information for route control, and updates the route table to the one corresponding to the network configuration. In the latter protocol, when communication is performed, a route table is set in a related communication node prior to the communication. As a representative protocol of the latter, INET (Internet Engineering Task Force) MANET WG (Mobile
AODV (Ad hoc) proposed by Ad hoc NETwork Working Group
On-demand Distance Vector) protocol. In this AODV protocol, a route request message is transmitted from a transmission node to a reception node, and a route reply message is transmitted from the reception node to the transmission node, thereby setting a route table in each related communication node.

d. Control for switching the packet transmission form in the system in response to a decrease in communication quality When the distance between the vehicle 5 and the first other vehicle in the forward direction becomes longer, it becomes difficult to transmit or relay the packet in the forward direction. Become. The same applies when the distance between the vehicle 5 and the first other vehicle in the rearward direction becomes longer. Further, since the front antenna 3F has a strong directivity in the forward direction and the rear antenna 3R has a strong directivity in the rear direction, the vehicle enters a curve, the position of the front vehicle is shifted obliquely forward, Even when the position of the vehicle is shifted obliquely backward, it is difficult to transmit or relay packets forward or backward. In these cases, the control unit 20 performs control for causing each communication node involved to perform broadcast transmission of a packet. That is, downstream of the inter-vehicle radio communication device with respect to one or a plurality of communication nodes on the upstream side of the inter-vehicle radio communication device 2 on the route of the packet flowing via the inter-vehicle radio communication device 2 The broadcast request processing is performed in which the transmission unit 23 or 25 transmits a broadcast request accompanied with the designation of the nearest communication node (the destination of the packet for which transmission or relay becomes difficult).

  There are two possible modes for sending the broadcast request. In the first aspect, the control unit 20 transmits a broadcast request when a predetermined button provided on the vehicle 5 is pressed. In the second mode, the control unit 20 monitors whether or not the reception response Ack is received from the transmission destination for the transmitted packet. When the reception response Ack is not received continuously for the predetermined number of packets, the control unit 20 Send an information request. After transmission of the broadcast request according to the first or second mode, when the communication state with the vehicle ahead or behind returns to a good state, it is no longer necessary to perform the broadcast transmission. In this case, the control unit 20 transmits a packet carrying a broadcast release request instructing to restore the packet transmission form to the related neighboring communication nodes by the transmission units 23 and 25.

  The control unit 20 may receive the broadcast request described above from another communication node. In that case, the control unit 20 subsequently multicasts the received packet to both the transfer destination communication node determined by the route table and the communication node specified by the broadcast request by the transmission unit 23 or 25. . When a broadcast release request is received, the packet transmission form is returned to the original unicast thereafter.

  Next, a characteristic operation example of the present embodiment will be described. 3 and 4, 5-A, 5-B, 5-C, and 5-D are vehicles, and the vehicle-to-vehicle wireless communication device 2 has IDs A, B, C, and D, respectively. Are provided.

  In the example shown in FIG. 3, a communication node (not shown) located behind the vehicle 5-A sends a packet to a communication node (not shown) located ahead of the vehicle 5-D. The inter-vehicle wireless communication devices 2 of 5-A, 5-B, 5-C, and 5-D relay packets in the same direction as the traveling direction of the vehicle. Here, the front antenna 3 </ b> F and the rear antenna 3 </ b> R of each inter-vehicle wireless communication device 2 have strong directivity in the forward direction and backward direction of the vehicle. For this reason, even if the distance between vehicles becomes a little long, as shown in the figure, each vehicle falls within the communicable area 41 of the inter-vehicle wireless communication device 2 of the following vehicle, and the inter-vehicle wireless communication device of each vehicle 2 can receive a packet from the inter-vehicle wireless communication device 2 of the following vehicle.

  In the example shown in FIG. 4, the inter-vehicle wireless communication device 2 mounted on a vehicle (not shown) located in front of the vehicle 5-D is addressed to a vehicle (not shown) located behind the vehicle 5-A. The inter-vehicle wireless communication devices 2 of the vehicles 5-D, 5-C, 5-B, and 5-A relay the packets in the direction opposite to the traveling direction of the vehicle. Also in this case, the vehicle is similar to the example shown in FIG. 4, and each vehicle is within the communicable area 42 of the inter-vehicle wireless communication device 2 of the preceding vehicle, and the inter-vehicle wireless communication device 2 of each vehicle is the preceding vehicle. Packets can be received from the inter-vehicle wireless communication device 2.

  5 and 6 show an operation example in which broadcast transmission of a packet is performed according to deterioration of communication quality. Similar to the example shown in FIG. 3, in the example shown in FIG. 5, the communication node located behind the vehicle 5-A is located ahead of the vehicle 5-D and the communication node whose ID is Y is used. A packet is sent to the destination. Here, in the route table of the inter-vehicle wireless communication device 2 of the vehicle 5-A, the transfer destination ID = B is defined in association with the destination ID = Y, and the route of the inter-vehicle wireless communication device 2 of the vehicle 5-B is defined. In the table, transfer destination ID = C is defined in association with destination ID = Y. The same applies hereinafter, and in the route table of the inter-vehicle radio communication device 2 of each vehicle up to the receiving node, the ID of the inter-vehicle radio communication device 2 of the nearest vehicle ahead in the traveling direction of the vehicle is the destination ID = Y. Is defined as a transfer destination ID corresponding to. For this reason, the packet whose destination ID is Y is relayed in the same direction as the traveling direction of the vehicle by the inter-vehicle wireless communication devices 2 of the vehicles 5-A, 5-B, 5-C, and 5-D.

  However, in the example shown in FIG. 5, the reception response Ack is not returned from the vehicle 5-D to the vehicle 5-C although the packet is sent from the vehicle 5-C. For this reason, the control unit 20 of the inter-vehicle wireless communication device 2 of the vehicle 5-C has a predetermined number of communication nodes closest to the upstream side of the packet flow, that is, the vehicles 5-B and 5-A in this example. For each inter-vehicle radio communication device 2, a transmitter 23 sends a broadcast request packet with the designation of the ID (= D) of the inter-vehicle radio communication device 2 of the vehicle 5-D which is the nearest downstream communication node. And 25 for multicasting. The transmission request is transmitted by both of the transmission units 23 and 25 because the packet reaches the inter-vehicle wireless communication devices 2 of the vehicles 5-B and 5-A even when the order of the formation is changed. It is for doing so.

  FIG. 6 shows a packet transmission state between the communication nodes after transmission of the broadcast request. First, when the inter-vehicle wireless communication device 2 of the vehicle 5-A that has received the broadcast request receives a packet whose transfer destination ID is B (for example, a packet whose destination ID is Y) according to the route table, The packets are multicast by the transmission units 23 and 25 to the inter-vehicle radio communication device 2 of the vehicle 5-D designated by the broadcast request and the inter-vehicle radio communication device 2 of the vehicle 5-B that is the transfer destination. Similarly, the inter-vehicle wireless communication device 2 of the vehicle 5-B that has received the broadcast request receives a packet whose transfer destination ID is C (for example, a packet whose destination ID is Y) according to the route table. The transmission units 23 and 25 multicast the packet to the inter-vehicle radio communication device 2 of the vehicle 5-D designated by the broadcast request and the inter-vehicle radio communication device 2 of the vehicle 5-C that is the transfer destination. Then, the inter-vehicle wireless communication device 2 of the vehicle 5-C transmits the packet having the destination ID Y received from the inter-vehicle wireless communication device 2 of the vehicle 5-B to the inter-vehicle wireless communication device 2 of the vehicle 5-D. To do.

  As described above, after transmission of the broadcast request, a packet whose destination ID is Y is transmitted from the inter-vehicle wireless communication device 2 of the vehicle 5-A, 5-B, 5-C to the vehicle 5-D. It is transmitted to the wireless communication device 2. The inter-vehicle wireless communication device 2 of the vehicle 5-D has a good communication state with the inter-vehicle wireless communication device 2 of any one of the vehicles 5-A, 5-B, and 5-C. A packet with destination ID = Y can be received from the wireless communication apparatus 2 and transmitted toward the downstream communication node. If the communication state between the nodes up to the destination node is good, the packet transmitted by the inter-vehicle wireless communication device 2 of the vehicle 5-D reaches the destination node.

  Thereafter, when the communication state between the vehicle 5-C and the vehicle 5-D returns to a good state, the control unit 20 of the inter-vehicle wireless communication device 2 of the vehicle 5-C is based on the packet transmission form. A packet carrying a broadcast release request instructing to return is multicast to the inter-vehicle wireless communication devices 2 of the vehicles 5-A and 5-B by the transmission units 23 and 25. As a result, the inter-vehicle wireless communication device 2 of the vehicles 5-A and 5-B returns the packet transmission form to the original unicast.

  The case where the packet flow direction is the same as the vehicle traveling direction has been described above as an example, but the same control is performed when the packet flow direction is opposite to the vehicle traveling direction. That is, when the packet flow is in the direction opposite to the vehicle traveling direction, the inter-vehicle wireless communication device 2 determines that the neighboring vehicle in front of the vehicle when the reception response Ack is not returned from the vehicle behind the packet sent to the vehicle behind. On the other hand, the broadcast request is multicast and the packet is transmitted.

  As described above, according to the present embodiment, the inter-vehicle wireless communication device 2 of each vehicle that travels in a row functions as a communication node of an ad hoc wireless network. Therefore, each inter-vehicle wireless communication device 2 can transmit a packet to a destination communication node located remotely by using one or more other inter-vehicle wireless communication devices 2 as a relay node. In addition, since the antennas 3F and 3R of each inter-vehicle wireless communication device 2 have strong directivity in the front-rear direction of the vehicle, even when the transmission power is low, the antennas 3F and 3R are relatively far in the front-rear direction of the vehicle. Wireless communication with other communication nodes is possible. Further, according to the present embodiment, when a certain inter-vehicle wireless communication device 2 detects that a packet does not reach a downstream communication node, a broadcast request is sent to a nearby inter-vehicle wireless communication device 2, Thus, the plurality of inter-vehicle wireless communication devices 2 transmit the same packet to the downstream communication node. For this reason, the possibility that the packet reaches the downstream communication node is increased, and resistance to a packet reception error can be increased.

  In the above embodiment, when the inter-vehicle wireless communication device 2 detects the deterioration of the communication state with the downstream communication node in the packet flow, the broadcast request is sent to a predetermined number of upstream communication nodes. However, the broadcast request may be sent to a communication node in the communication area without specifying the destination and using both the antennas 3F and 3R.

Next, another embodiment of the present invention will be described with reference to FIG. In the above embodiment, an antenna having a strong directivity in the forward direction is used as the front antenna 3F, and an antenna having a strong directivity in the backward direction is used as the rear antenna 3R. For this reason, when each vehicle travels in a straight line, it is possible to improve the reachability of packets. However, when the vehicle enters a curve, the position of the vehicle ahead is shifted diagonally forward and out of the communicable area, or the position of the vehicle behind is shifted diagonally backward and out of the communicable area, which causes packet communication to fail. It may happen that it ends. In order to cope with such a situation, in this embodiment, as the front antenna 3F and the rear antenna 3R, an antenna capable of selecting the directivity pattern shown in FIG. 7A or the directivity pattern shown in FIG. 7B. Is used. And the control part 20 of the radio | wireless communication apparatus 2 between vehicles monitors the output signal of the yaw rate sensor which detects the speed (yaw rate) in which the vehicle 5 rotates rightward or leftward toward the advancing direction. When it is determined that the vehicle 5 is not rotating and the vehicle 5 is traveling straight from the output signal of the yaw rate sensor, the control unit 20 displays the directivity patterns of the front antenna 3F and the rear antenna 3R as shown in FIG. As shown in FIG. 3, the vehicle 5 has a strong pattern in the front-rear direction. When it is determined that the vehicle is rotating and the vehicle 5 is traveling in a curve from the output signal of the yaw rate sensor, the control unit 20 displays the directivity patterns of the front antenna 3F and the rear antenna 3R. As shown in FIG. 7B, a directivity pattern having an appropriate transmission capability and reception sensitivity is obtained over a wide azimuth angle range. When it is determined from the output signal of the yaw rate sensor that the vehicle 5 has returned to the straight traveling state, the control unit 20 changes the directivity patterns of the front antenna 3F and the rear antenna 3R to the directivity patterns shown in FIG. return.
According to the present embodiment, as described above, the directivity of the antenna is switched depending on whether the vehicle travels in a straight line or in a curve, so that it is possible to improve the reachability of the packet during the straight line travel and the packet communication during the curve travel with a small control burden. Error reduction can be realized.

It is a figure which shows the apparatus mounted in the vehicle and the helmet for the inter-vehicle radio | wireless communication in the inter-vehicle communication system which is one Embodiment of this invention. It is a block diagram which shows the structure of the short-range radio | wireless communication apparatus and inter-vehicle radio | wireless communication apparatus in the system. It is a figure which shows the example of the packet transfer performed between each communication node in the same system. It is a figure which shows the other example of the packet transfer performed between each communication node in the same system. It is a figure which shows the example of the condition where the broadcast transmission of a packet is performed in the same system. It is a figure which shows the example of the broadcast transmission of the packet performed in the same system. It is a figure which illustrates the directivity pattern of the antenna used in other embodiment of this invention.

Explanation of symbols

5 ... Vehicle, 2 ... Inter-vehicle wireless communication device, 3F ... Front antenna, 3R ... Rear antenna, 20 ... Control unit, 23, 25 ... Transmission unit, 24, 26 ... Reception unit.

Claims (3)

In the inter-vehicle wireless communication device that is provided in each of a plurality of traveling vehicles and performs wireless communication with a communication node of another vehicle as a communication node,
An antenna having strong directivity in the forward direction and the backward direction of the vehicle;
Transmission / reception means for transmitting / receiving packets to / from other communication nodes via the antenna;
Receiving processing for controlling the inter-vehicle wireless communication device to function as a communication node of an ad hoc wireless network, receiving a packet destined for the wireless communication device via the transmitting / receiving unit, another communication node Control means for controlling transmission processing for transmitting a packet addressed to the communication node via the transmission / reception means and relay processing for transmitting a packet addressed to another communication node received via the transmission / reception means by the transmission / reception means. A vehicle-to-vehicle wireless communication device. The control means includes
For the communication node in the vicinity of the inter-vehicle wireless communication device, a broadcast request accompanied with the designation of the nearest communication node on the downstream side on the route of the packet flowing via the inter-vehicle wireless communication device is sent by the transmitting / receiving means. A broadcast request means to send;
When a broadcast request with designation of a communication node is received via the transmission / reception means, the packet received via the transmission / reception means is designated by the broadcast request with the original communication node of the transmission destination The inter-vehicle wireless communication apparatus according to claim 1, further comprising: a broadcast unit that transmits to both communication nodes by the transmission / reception unit. The antenna is an antenna capable of controlling directivity,
The inter-vehicle wireless communication apparatus according to claim 1 or 2, wherein the control means includes directivity control means for controlling the directivity of the antenna according to the rotation of the vehicle.

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