JP2006295325A - Communication method and wireless terminal - Google Patents

Abstract

Means for performing efficient and effective communication in an ad hoc wireless network is provided.
A communication method in an ad hoc wireless communication network, wherein a plurality of markers with different marker IDs are installed on a road, and a relay terminal acquires a marker ID from the nearest marker and transmits a packet. When received, the marker ID stored in the packet is compared with the marker ID obtained from the nearest marker to determine whether or not to relay the packet. The marker installation interval is preferably adjusted according to the radio wave arrival distance at the location.
[Selection] Figure 2

Description

  The present invention relates to a technique for performing wireless communication between wireless terminals via one or a plurality of relay terminals.

  In a so-called ad hoc wireless network in which a wireless terminal communicates with another wireless terminal via one or a plurality of relay terminals, how to relay a packet is important in order to deliver the packet to the target wireless terminal.

  As the simplest method, there is a method in which all wireless terminals that have received a packet relay the packet to adjacent wireless terminals. By repeating relay transmission to adjacent wireless terminals in this way, information can be distributed to all the wireless terminals in the network. This method is called a flooding method. In this method, since all wireless terminals that have received a packet perform relay transmission, the wireless band is consumed due to excessive relaying. Also, radio wave collisions easily occur between adjacent wireless terminals.

  As a relay terminal determination method for reducing the number of relays, techniques described in Patent Documents 1 and 2 are known. That is, this is a method in which each wireless terminal holds route control information (routing table) and determines a wireless terminal to relay based on this route control information.

As a method for determining a relay terminal without using route control information, a method using GPS (Global Positioning System) is known. In this method, the relay terminal grasps the relative position (distance) between the terminal itself and the transmission terminal by GPS, and determines whether or not to relay the packet based on the relative position.
JP 2003-8591 A JP 2001-358541 A

  However, the following problems have arisen in the conventional techniques as described above.

  In the method using the routing control information, extra traffic for generating routing control information is generated before starting communication of data packets. In particular, when the network topology changes frequently as in a network between mobile terminals (for example, in-vehicle terminals), it is inefficient because the route control information must be updated each time.

  In the method using GPS, route control information is not necessary. However, this method is based on the assumption that the reach of radio waves is constant regardless of location, so in areas where the reach of radio waves is short such as curved roads with poor visibility and urban areas with many shields. It is not valid.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an efficient and effective communication method in an ad hoc wireless network.

In order to achieve the above object, the present invention uses a marker installed on a road. The marker has a unique ID (marker ID), and has means for notifying this marker ID to the terminal. This means may be an active method in which radio waves, light, sound waves, etc. are emitted from the marker and notified, and a passive method, in which radio waves, light, sound waves, etc. radiated from the terminal are reflected. A passive method may be used.

  Placing such a marker on the road is equivalent to dividing the road and attaching an ID to each section. That is, the marker ID is not only an identifier for the marker but also an identifier for a road section. By setting the marker in this way, the terminal can recognize the section where the terminal is located only by acquiring the marker ID from the nearest marker.

  Specific examples of marker configurations include RF-ID (Radio Frequency Identification) and magnets embedded in roads and roadsides, and roadside machines that emit radio waves, light, and sound waves, as examples of using an active method. In addition, as a marker configuration using a passive method, for example, there is a millimeter wave reflector embedded in a road or a roadside.

  A first aspect of the present invention is a communication method in which a relay terminal relays a packet when a transmitting terminal and another wireless terminal perform wireless packet communication. Here, the relay terminal obtains the marker ID from the nearest marker, and when receiving the packet, compares the marker ID stored in the packet with the marker ID obtained from the nearest marker, Decide whether to relay.

  Since the determination is performed based on the marker ID, route control information is not necessary. Therefore, it is not necessary to perform communication for creating routing control information, and efficient communication is possible.

  Further, as described above, since the marker ID specifies a road section, it is possible to relay according to the section distance on the road by comparing the marker ID. This is effective in situations where the reach of radio waves cannot be determined by the straight line distance between two points.

  Here, the marker installation interval is preferably adjusted according to the radio wave arrival distance at the installation location. For example, each marker is installed such that the installation interval between adjacent markers or the installation interval between markers that are a certain number apart is equal to the radio wave arrival distance at the installation location. Specifically, it is conceivable to set the marker installation interval on a curved road shorter than the marker installation interval on a straight road. This is because the radio wave reach is generally shorter on a curved road than on a straight road. As a result, the relay terminal can make a relay determination based on the actual radio wave arrival distance.

  The most efficient relay method is that relay terminals near the end of the radio wave reach range perform relay transmission. If the marker installation interval is adjusted as described above, it is possible to easily determine whether the relay terminal is located at the end of the radio wave reachable range, so that efficient relay determination can be performed.

  The relay terminal determination method according to the first aspect of the present invention may be performed by the following processing. That is, the transmission terminal acquires the marker ID from the nearest marker, calculates the marker ID of the relay position from the marker ID, stores the calculated marker ID of the relay position in a packet, and transmits the packet. Then, the relay terminal that has received this packet relays the packet when the marker ID acquired from the nearest marker by the terminal matches the marker ID of the relay position stored in the packet.

Moreover, the relay terminal determination method in the 1st aspect of this invention may be performed by the following processes. That is, the transmitting terminal acquires a marker ID from the nearest marker, stores this marker ID in a packet, and transmits it. The relay terminal that has received this packet calculates the relay position from the marker ID stored in the packet, and the marker ID of the calculated relay position matches the marker ID acquired from the nearest marker by the terminal itself And relay the packet.

  In these relay terminal determination methods, the process of determining the marker ID of the relay position from the marker ID of the transmitting terminal is performed by the following method, for example. The relay position is preferably calculated as the marker ID of the marker within the radio wave reachable range and the farthest from the transmitting terminal. Further, for example, a table in which a transmission source marker ID and a relay position marker ID are associated with each other is held in advance, and the table may be determined using this table. Note that the calculated relay position marker ID does not have to be one, and may be plural. In this case, the marker ID acquired from the nearest marker matches the marker ID at the relay position means that the marker ID acquired from the nearest marker matches at least one of the marker IDs at a plurality of relay positions.

  A second aspect of the present invention is a wireless terminal used for relaying a packet when a transmitting terminal communicates with another wireless terminal, and includes a marker ID acquisition unit and a wireless communication unit.

  The marker ID acquisition means acquires the marker ID attached to the marker from the marker installed on the road. The wireless communication means compares the marker ID stored in the received packet with the marker ID of the nearest marker acquired by the marker ID acquisition means, and determines whether to relay the packet.

  Thus, since the determination based on the marker ID is performed, route control information becomes unnecessary. Therefore, it is not necessary to perform communication for creating routing control information, and efficient communication is possible.

  Further, by comparing the marker IDs, relaying according to the section distance on the road becomes possible. This is effective in situations where the reach of radio waves cannot be determined by the straight line distance between two points.

  The wireless communication means in the second aspect of the present invention may be configured as follows. That is, the wireless communication unit relays the packet when the marker ID stored in the packet as the relay position by the transmission terminal matches the marker ID acquired by the marker ID acquisition unit.

  The wireless communication means in the second aspect of the present invention may be configured as follows. That is, the wireless communication means acquires the marker ID acquired by the transmitting terminal from the nearest marker and stored in the packet. Then, the wireless communication unit calculates the marker ID of the relay position from this marker ID. The wireless communication unit relays the packet when the calculated marker ID of the relay position matches the marker ID of the nearest marker acquired by the marker ID acquisition unit.

  In addition, the present invention may be configured as a vehicle including the wireless terminal according to the second aspect.

  According to the present invention, efficient and effective communication can be performed in an ad hoc wireless network.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First embodiment)
<System configuration>
[Wireless terminal]
In the ad hoc wireless network according to the present embodiment, the wireless terminal configuring the network is a mobile terminal. As a specific example, an in-vehicle terminal (mobile terminal) provided in a vehicle performs an inter-vehicle ad hoc wireless communication. In this inter-vehicle ad hoc wireless network, traffic congestion information and accident information are distributed, and warning information is distributed in accordance with the activation of the airbag and sudden braking, thereby supporting smooth traffic.

  FIG. 1 is a diagram illustrating a configuration of a vehicle equipped with a wireless terminal according to the present embodiment. The vehicle 1 includes a marker ID acquisition unit 2, a marker ID storage unit 3, an antenna 4, and a communication processing unit 5.

  The marker ID acquisition unit 2 acquires a marker ID from the marker 6 embedded on the road or road side or installed on the road side, and stores it in the marker ID storage unit 3. The marker ID storage unit 3 is configured as a memory. The configuration of the marker ID acquisition unit 2 will be described together with the description of the configuration of the marker 6.

  The antenna 4 has directivity in the front and the rear. This is because the vehicles are usually arranged in a straight line on the road, and it is not necessary to radiate radio waves to the left and right. In addition, there are many obstacles such as walls and buildings on the left and right sides of the vehicle, and this is also to prevent interference of radio waves due to reflected waves. In this embodiment, a wireless LAN (Local Area Network) such as IEEE802.11x, IEEE802.16, IEEE802.20, or the like is assumed as a wireless communication method. However, other methods may be adopted.

  The communication processing unit 5 uses the marker ID stored in the marker ID storage unit 3 to determine whether or not to relay a packet received by the antenna 4. In the present embodiment, the antenna 4 and the communication processing unit 5 constitute a wireless communication unit. The communication processing unit 5 includes a CPU (Central Processing Unit) that executes a program stored in a memory or the like.

[Marker]
The marker 6 is configured as an RF-ID or a millimeter wave reflecting plate embedded in a road or roadside, or as a roadside machine that emits radio waves, light, sound waves, or the like.

  When the marker 6 is an RF-ID embedded in a road or road, the marker ID acquisition unit 2 is configured as an RF-ID reader. In this case, the vehicle 1 moves while radiating RF energy from the RF-ID reader. When the RF-ID is supplied with power by RF energy, the marker ID is transmitted on a carrier wave. The RF-ID reader receives this and acquires the marker ID.

  When the marker 6 is a millimeter wave reflector embedded on the road or road side, the marker ID acquisition unit 2 is configured as a millimeter wave radar. In this case, the vehicle 1 moves while radiating millimeter waves from the millimeter wave radar. The millimeter wave radar receives the reflected wave reflected by the millimeter wave reflector and acquires the marker ID from the reflected wave.

  When the marker 6 is a roadside device that radiates radio waves installed on the roadside, the marker ID acquisition unit 2 is configured as a wireless receiver. The marker 6 may be configured as a roadside device that emits light or sound waves instead of radio waves. In this case, the marker ID acquisition unit 2 is configured as a light or sound wave receiver. The marker 6 continues to radiate by placing the marker ID on a radio wave or the like, and a vehicle passing through the communication range receives the radio wave or the like by the marker ID acquisition unit 2 and acquires the marker ID.

[Marker installation interval]
FIG. 2 shows the markers 10 to 16 installed on the road side. The installation interval of each marker is adjusted according to the reach of radio waves at that position. That is, the installation interval between adjacent markers is determined as the distance that the radio wave of a predetermined reference output reaches. Here, the distance that the radio wave reaches (radio wave arrival distance) is the maximum distance at which stable communication can be performed using the radio wave.

  In this embodiment, an antenna having strong directivity in the front-rear direction is used, so that the front and rear vehicles are angularly separated from the boresight (main beam direction) on a curved road. For this reason, compared with a straight road, the inter-vehicle distance that radio waves reach becomes shorter. On curved roads, there are many cases in which a vehicle is shielded by a structure along the road, which also causes a reduction in the distance between vehicles where radio waves reach compared to a straight road. Therefore, the installation interval of the markers 10 to 14 on the curved road is shorter than the installation interval of the markers 14 to 16 on the straight road.

  It is preferable that the vehicle can acquire the marker ID at any location on the road. However, when the marker installation interval is longer than the marker communication distance, there is a location where the marker ID cannot be acquired. In this case, in order to be able to communicate with the marker at any location on the road, it is conceivable to install an auxiliary marker and attach the same marker ID to the adjacent marker to the marker. Further, there is a method in which the auxiliary marker is not used and the vehicle acquires a marker ID when passing through the marker, stores it in the marker ID storage unit 3, and uses the marker ID until the next marker ID is acquired. By doing in this way, each vehicle can always grasp | ascertain the position of the own vehicle by marker ID.

  The marker installation interval is standardized by the radio wave arrival distance of the reference output radio wave, so that each vehicle has a range of stable radio wave arrivals up to the number of markers ahead of its own radio wave output. Is known in advance. Hereinafter, the number of markers is referred to as transmission capability.

  It is preferable that marker ID is attached | subjected to the marker using the predetermined rule. Specifically, it is preferable that the arrival position of the radio wave transmitted from the wireless terminal from the position of a certain marker is obtained from the marker ID of the transmission source position and the transmission capability of the wireless terminal. In FIG. 2, sequential marker IDs are attached to markers arranged on the road, and marker IDs 10 to 16 are assigned 1000 to 1006 as marker IDs. In this way, by adding the serial number marker ID to the marker, the arrival position of the radio wave is obtained by adding or subtracting the transmission capability of the wireless terminal from the marker ID of the transmission position. For example, assume that the transmission capability of the vehicle 22 in FIG. Then, it can be seen that the radio wave transmitted by the vehicle 22 reaches the marker IDs “1006” and “1002” obtained by adding and subtracting the transmission capability 2 from the marker ID “1004” of the nearest marker.

  In this way, by attaching a marker ID to a marker using a predetermined rule, it is possible to always obtain the radio wave arrival position using the same calculation formula regardless of the location of the vehicle.

  FIG. 2 shows vehicles 20 to 24. In the following description, it is assumed that the transmission capability of each vehicle is all 2.

<Packet structure>
The structure of a packet used in this embodiment will be described with reference to FIG. The packet includes a packet identification number 31, a destination 32, a relay position marker ID 33, and a data part 34. The packet identification number 31 stores a number for identifying a packet. The destination 32 stores a value for specifying a destination terminal, a value indicating a broadcast packet destined for all terminals, and the like. The relay position marker ID 33 stores a marker ID specified as a relay position. A plurality of marker IDs may be stored in the relay position marker ID 33. The data part 34 stores information data to be transmitted.

<Communication method>
Processing when the vehicle 22 in FIG. 2 performs broadcast communication to all communicable vehicles will be described.

  First, processing of the vehicle 22 that is a transmission terminal will be described based on the flowchart of FIG.

  The marker ID storage unit 3 of the vehicle 22 stores the marker ID “1004” of the nearest marker 14.

  In step S <b> 41, the communication processing unit 5 calculates the marker ID of the relay position using the marker ID “1004” stored in the marker ID storage unit 3. Since the transmission capability of the vehicle 22 is 2, the radio wave transmitted by the vehicle 22 reaches the range of the marker IDs “1002” to “1006”. The communication processing unit 5 calculates the marker ID “1002” and the marker ID “1006” as the relay position in order to set the end of the radio wave reachable range as the relay position.

  In step S42, the communication processing unit 5 stores the packet identification number 31 in the packet identification number 31 of the packet to be transmitted, stores a value indicating broadcast in the destination 32, and calculates the relay position marker ID33. The position marker ID “1002” and the marker ID “1006” are stored, and information data to be transmitted to the data unit 34 is stored.

  In step S43, the communication processing unit 5 transmits this packet from the antenna 4.

  This packet is received by the vehicles 21, 23, 24 within the radio wave reachable range. The processing of the terminal that has received the broadcast packet will be described with reference to the flowchart of FIG.

  The vehicle that has received the broadcast packet acquires the packet identification number 31 in step S51, and determines whether or not the packet has already been received in step S52. If this packet has already been received, the process proceeds to step S56, and the communication processing unit 5 discards this packet. If this packet has not yet been received, this packet is processed.

  The vehicle 23 that has received the packet has not received this packet yet and performs processing. Since this packet is a broadcast packet and the vehicle 23 is also included in the destination, the communication processing unit 5 acquires and processes information data stored in the data unit 34. Then, it is determined whether or not to relay.

  Similarly, for the vehicles 21 and 24, since this packet has not yet been received, the communication processing unit 5 processes this packet.

  In step S53, the relay position marker ID 33 stored in the packet is acquired. In step S54, the relay position marker ID 33 is compared with the nearest marker ID stored in the marker ID storage unit 3. If they match, the packet is relayed and transmitted in step S55. If they do not match, the process ends.

In the case of the vehicle 23, the marker ID “1002” and the marker ID “1006” are stored in the relay position marker ID 33 of the received packet. On the other hand, the marker ID storage unit 3 has
The marker ID “1004” of the nearest marker 14 is stored. Since the marker ID “1004” is not included in the relay position marker ID 33, the relay transmission is not performed and the process is terminated.

  In the case of the vehicle 24, the marker ID “1006” of the nearest marker 16 is stored in the marker ID storage unit 3. Since the marker ID “1006” is stored in the relay position marker ID 33 of the received packet, the vehicle 24 relays the packet. When performing relay transmission, the communication processing unit 5 of the vehicle 24 calculates the next relay position marker ID “1008” and the marker ID “1004” based on the marker ID “1006” of the own vehicle, and stores them in the packet. Then, relay transmission is performed by the antenna 4.

  Also in the case of the vehicle 21, the marker ID “1002” of the nearest marker 12 is stored in the marker ID storage unit 3. Since the marker ID “1002” is stored in the relay position marker ID 33 of the received packet, the vehicle 21 relays the packet. When relay transmission is performed, the communication processing unit 5 of the vehicle 21 calculates the next relay position marker ID “1000” and the marker ID “1004” based on the marker ID “1002” of the own vehicle, and stores them in the packet. Then, relay transmission is performed by the antenna 4.

  The packet relayed by the vehicle 21 is received by the vehicle 20 and the vehicle 22 that are within the radio wave reachable range. Hereinafter, processing performed by the vehicle 20 and the vehicle 22 will be described.

  The vehicle 22 acquires the packet identification number 31 of the received packet (step S51), and determines whether the packet has already been processed (step S52). Since this packet is transmitted by the vehicle 22, the communication processing unit 5 discards this packet (step S56) and ends the process.

  Similarly, the vehicle 20 acquires the packet identification number 31 of the received packet (step S51), and determines whether the packet has already been processed (step S52). Since the vehicle 20 has not yet processed this packet, the communication processing unit 5 processes this packet. The communication processing unit 5 knows that the packet is a broadcast packet from the packet destination 32 and processes the information data stored in the data unit 34. The communication processing unit 5 compares the marker ID “1000” and the marker ID “1004” stored in the relay position marker ID 33 with the marker ID stored in the marker ID storage unit 3 (step S54). Since the marker ID “1000” of the nearest marker 10 is stored in the marker ID storage unit 3, the communication processing unit 5 performs relay transmission of this packet (step S55).

  In this way, by repeating relay transmission, broadcast packets are distributed to all vehicles in the ad hoc wireless network. At this time, since relay determination is performed without using route control information, unnecessary communication does not occur and efficient communication is possible. Also, since the position that is within the radio wave reach using the marker and is the farthest from the transmitting terminal is designated as the relay position, the relay does not break by designating the position where the radio wave does not reach as the relay position. . For example, when the relay terminal is determined based on the relative position (distance) between the terminals using GPS, the relay terminals of the packet transmitted by the vehicle 22 are designated as the vehicle 20 and the vehicle 24. Packets reach the vehicle 24, but radio waves are difficult to reach the vehicle 20 due to the shielding effect of the structure and the influence off the main beam, and good communication cannot be obtained and relaying is interrupted. In this embodiment, such a problem is avoided and a packet is delivered to all the vehicles in the network.

Moreover, in the above description, although the broadcast which distributes information with respect to all the vehicles in a network was demonstrated, it can utilize also when distributing information only to the vehicle ahead or back from the own vehicle. In this case, the vehicle that transmits the packet stores a value indicating that the communication is for the vehicle ahead or behind in the destination 32, and the marker ID obtained by subtracting the transmission capability from the marker ID of the nearest marker in the relay position marker ID33. Can be stored and transmitted. It can also be used when distributing information with a specific vehicle as a destination.

(Second Embodiment)
Since the second embodiment of the present invention is basically the same as the first embodiment, only different parts will be described.

  A packet structure used in the present embodiment will be described with reference to FIG. The packet identification number 31, the destination 32, and the data part 34 are the same as in the first embodiment. The transmission source marker ID 35 stores the marker ID of the marker nearest to the vehicle that transmits or relays the packet. The transmission capability 36 stores the transmission capability of the vehicle that performs transmission or relay transmission. As described above, the transmission capability is a value indicating how many markers the radio wave transmitted by the vehicle reaches.

  Processing when the vehicle 22 in FIG. 2 performs broadcast communication to all communicable vehicles will be described.

  First, processing of the vehicle 22 that is a transmission terminal will be described based on the flowchart of FIG. In step S61, the communication processing unit 5 of the vehicle 22 stores a packet identification number in the packet identification number 31 of the packet to be transmitted, stores a value indicating broadcast in the destination 32, and stores it in the transmission source marker ID 35. The marker ID “1004” of the nearest marker stored in the marker ID storage unit 3 is stored, “2” which is the transmission capability of the vehicle is stored in the transmission capability 36, and information data to be transmitted to the data unit 34 is stored. Store. In step S 62, the communication processing unit 5 transmits this packet from the antenna 4.

  This packet is received by the vehicles 21, 23, 24 within the radio wave reachable range. The processing of the terminal that receives the broadcast packet will be described with reference to the flowchart of FIG.

  Steps S71, S72, and S76 are the same as steps S51, S52, and S56 in the flowchart of FIG. 5 in the first embodiment, and thus the description thereof is omitted. Hereinafter, only processing for determining whether or not to relay a received packet will be described.

  In step S73, the vehicle that has received the broadcast packet calculates the relay position as the marker ID from the transmission source marker ID 35 and the transmission capability 36 stored in the received packet. In this embodiment, the marker ID of the relay position can be calculated by adding or subtracting the transmission capability 36 from the transmission source marker ID 35. In step S74, it is determined whether the calculated marker ID of the relay position matches the marker ID of the nearest marker stored in the marker ID storage unit 3. If they match, the packet is relayed and transmitted in step S75. If they do not match, the process ends.

  In the broadcast packet transmitted by the vehicle 22, the marker ID “1004” is stored in the transmission source marker ID 35, and “2” is stored in the transmission capability 36. Therefore, the marker ID of the relay position calculated in step S73 is the marker ID “1006” and the marker ID “1002” at all receiving terminals.

  Since the marker ID “1005” of the nearest marker 15 is stored in the marker ID storage unit 3 of the vehicle 23 and does not match the calculated marker ID of the relay position, relay transmission is not performed.

  The marker ID storage unit 3 of the vehicle 21 stores the marker ID “1002” of the nearest marker 12 and matches the calculated marker ID of the relay position, so relay transmission is performed. When relay transmission is performed, the communication processing unit 5 of the vehicle 21 stores the marker ID “1002” of the own vehicle in the transmission source marker ID 35 and the transmission capability value “2” of the own vehicle in the transmission capability 36, and then the antenna. 4 for relay transmission.

  The marker ID storage unit 3 of the vehicle 24 stores the marker ID “1006” of the nearest marker 16 and matches the calculated marker ID of the relay position, so relay transmission is performed. When performing relay transmission, the communication processing unit 5 of the vehicle 24 stores the own vehicle marker ID “1006” in the transmission source marker ID 35 and the own vehicle transmission capability value “2” in the transmission capability 36, and then transmits the antenna. 4 for relay transmission.

  The packet relayed by the vehicle 21 is received by the vehicle 20 and the vehicle 22 that are within the radio wave reachable range. Hereinafter, processing performed by the vehicle 20 and the vehicle 22 will be described.

  Since the vehicle 22 is transmitting this packet, it discards it (steps S72 and S76).

  Since the vehicle 20 has not yet processed this packet, the communication processing unit 5 processes this packet. The marker ID of the relay position is calculated from the transmission source marker ID 35 and transmission capability 36 stored in the packet (step S73). In this case, the marker ID of the relay position is calculated as “1004” and “1000” from the marker ID “1002” and the transmission capability value “2”. The marker ID storage unit 3 stores the marker ID “1000” of the nearest marker 10 and matches the marker ID of the calculated relay position (step S74). Therefore, the communication processing unit 5 performs relay transmission of this packet (step S75).

  In this way, by repeating relay transmission, broadcast packets are distributed to all vehicles in the ad hoc wireless network. Further, as in the first embodiment, since the relay terminal is determined based on the marker ID of the marker, efficient and effective broadcast communication can be performed.

  When all vehicles use the same output radio wave, broadcast communication may be performed without storing the transmission capability in the packet.

  In each of the above embodiments, a highly directional antenna is used forward and backward, but the present invention is effective regardless of the antenna directivity, and an omnidirectional antenna may be used. .

It is a figure which shows the vehicle carrying a radio | wireless terminal. It is a figure which shows the structural example of a marker and a vehicle. It is a figure which shows the structure of the packet used in 1st Embodiment. It is a flowchart which shows the process of the transmission terminal in 1st Embodiment. It is a flowchart which shows the process of the receiving terminal in 1st Embodiment. It is a figure which shows the structure of the packet used in 2nd Embodiment. It is a flowchart which shows the process of the transmission terminal in 2nd Embodiment. It is a flowchart which shows the process of the receiving terminal in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Marker ID acquisition part 3 Marker ID memory | storage part 4 Antenna 5 Communication processing part 6, 10, 11, 12, 13, 14, 15, 16 Marker 20, 21, 22, 23, 24 Vehicle 31 Packet identification number 32 Destination 33 Relay position marker ID
34 Data part 35 Source marker ID
36 Transmission capability

Claims (9)

A communication method in which a relay terminal relays a packet when a transmitting terminal and another wireless terminal perform wireless packet communication,
A plurality of markers with different marker IDs are installed on the road,
When the relay terminal acquires the marker ID from the nearest marker and receives the packet, the relay terminal compares the marker ID stored in the packet with the marker ID obtained from the nearest marker, and determines the packet. Decide whether to relay,
A communication method characterized by the above. The marker installation interval is adjusted according to the radio wave arrival distance at the installation location.
The communication method according to claim 1. Marker installation interval on curved road is shorter than marker installation interval on straight road,
The communication method according to claim 1 or 2. The transmitting terminal acquires the marker ID from the nearest marker, calculates the marker ID of the relay position from the marker ID, stores the calculated marker ID of the relay position in a packet, and transmits the packet.
The relay terminal relays the packet when the marker ID acquired from the nearest marker matches the marker ID of the relay position stored in the packet.
The communication method according to any one of claims 1 to 3. The transmitting terminal obtains the marker ID from the nearest marker, stores this marker ID in a packet, transmits it,
The relay terminal calculates a relay position from the marker ID stored in the packet, and relays the packet when the calculated marker ID of the relay position matches the marker ID acquired from the nearest marker. ,
The communication method according to any one of claims 1 to 3. A wireless terminal used to relay a packet when a transmitting terminal communicates with another wireless terminal;
Marker ID acquisition means for acquiring a marker ID attached to the marker from markers installed on the road;
A wireless communication unit that compares the marker ID stored in the received packet with the marker ID acquired by the marker ID acquisition unit and determines whether to relay the packet;
A wireless terminal characterized by comprising: The wireless communication means relays the packet when the marker ID stored in the packet as the relay position by the transmitting terminal matches the marker ID of the nearest marker acquired by the marker ID acquisition means.
The wireless terminal according to claim 6. The wireless communication means acquires the marker ID acquired by the transmitting terminal from the nearest marker and stored in the packet, calculates the marker ID of the relay position from the marker ID stored in the packet, and determines the marker ID of the relay position and When the marker ID of the nearest marker acquired by the marker ID acquisition unit matches, the packet is relayed.
The wireless terminal according to claim 6.   A vehicle comprising the wireless terminal according to claim 6.

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