JP4600064B2 - Wireless communication method or wireless communication terminal - Google Patents

Description

  The present invention relates to a wireless communication method including a mobile terminal such as inter-vehicle communication and road-to-vehicle communication, and a wireless communication terminal.

  There is known a wireless communication technique in which a network is dynamically configured to communicate between a plurality of terminals including mobile terminals such as mobile phones and inter-vehicle communication devices. There is an ad hoc network as such a dynamic network configuration method. In an ad hoc network, a part of communication terminals is set as a terminal having a router function, a table of other terminals capable of communication is constructed, and the constructed table information is exchanged between router terminals. Then, by communicating via the router terminal, P2P (Peer to Peer) communication is possible with a partner that cannot communicate directly. Among these, LAR (Location Aided Routing) is known as a technique for constructing an ad hoc network using location information. In this method, routing is performed according to position / velocity, physical distance, and the like.

In Patent Document 1, when data is transmitted from the own terminal to the destination terminal for each destination terminal, the relay terminal to be transmitted first and the number of hops necessary for the relay are stored as a terminal information table. Then, the terminal information table is updated at the time of data reception, and when communication between specific wireless terminals is interrupted, the unreachable information is inquired by communicating with a terminal that can directly communicate with the wireless terminal. This is intended to reduce the time required for route reconstruction.
JP 2001-127797 A

  However, when inter-vehicle communication is performed in a situation where a large number of vehicles move on a variety of road networks at a relatively high speed as in an urban area, the position / speed and physical distance of each mobile terminal change from moment to moment. Then, it becomes necessary to correct the table information frequently. As a result, the communication for creating the table information occupies most of the traffic, and the data transfer efficiency decreases. If the update frequency of the table information is lowered, the difference between the route information to the destination created from the table information and the actual state becomes large, and there is a possibility that the transmission data does not reach the destination. Moreover, useless data relays increase, leading to a decrease in communication traffic.

  Accordingly, the present invention provides a wireless communication method and a wireless communication terminal used therefor, which do not require frequent update of table information in a communication network including a mobile body, and enable reliable transfer of data and efficient use of traffic. The task is to do.

In order to solve the above problems, a wireless communication method according to the present invention constructs a wireless communication network by relaying between a plurality of terminals including at least one mobile terminal, and the source terminal designates the destination terminal by the destination address. In the wireless communication method that relays and transmits the data transmitted directly or by another terminal, (1) the terminal terminal sets the road section specifying information for specifying the road section where the terminal is located in the map data Adding the transmission data to the position / speed information of the terminal itself, and (2) performing data transmission by designating the destination address by the destination road section specifying information which is the terminal road section specifying information of the destination terminal, (3) The terminal that has received the data detects its own terminal position, and determines whether or not the road section indicated by the received destination road section identification information is the road section in which the terminal is located. Doing, the step of determining whether the address is the destination address specifies the own terminal to the destination terminal, and determining the presence and position of other terminals with (4) the same terminal road section identifying information (5) When it is determined that the terminal that received the data is not the data that designates the terminal as the destination terminal from the destination address, the road segment specifying information and the map data of each of the source terminal and the destination terminal Same as the case where the own terminal has the same terminal road section information as the source or relay source terminal after determining the necessity of relay after grasping the positional relationship between the source terminal, own terminal and destination terminal wherein the self-terminal in a terminal having a terminal road section information is provided with a step of relaying the received data except if not the closest terminal to the source or relay source terminal

A mobile communication terminal used for this wireless communication method includes (1) means for determining the position / speed information of the terminal itself, and (2) a map in which map data for specifying a road section is stored as road section specifying information. Data storage means; (3) reference means for mutually referring to the terminal position information and road section specifying information based on the map data storage means; and (4) the road on which the own terminal is set by the reference means. A data transmission means for transmitting the data by specifying the destination address by the destination road section specifying information which is the road section specifying information where the destination terminal is located and giving the terminal road section specifying information which is the section specifying information to the transmission data; (5) The reference section obtains the road section where the destination terminal is located from the destination road section identification information indicated by the destination address in the received data, and the road section where the terminal is located A determination unit own terminal by comparing the whether included in the destination terminal, means for determining the presence or absence and the position of the other terminals having the same terminal road section identifying information using the reference means (6) (7) The necessity of relaying is determined by determining the necessity of relaying from the position of the source terminal and destination terminal obtained from the terminal road section specifying information of the source terminal and destination terminal and the position of the terminal itself by referring means. Even if the terminal has the same terminal road section information as the source or relay source terminal, the terminal is not the closest to the source or relay source terminal among the terminals having the same terminal road section information And a means for instructing execution of relay except in some cases .

  According to the wireless communication method and the wireless communication terminal according to the present invention, each road section (which may be set as a road section between intersections) in the map data is given road section specifying information for specifying the road section. Yes. The road section where the terminal is located can be specified by a navigation system or the like. The destination terminal is designated using the road section as a destination address, and the receiving terminal selects information destined for the terminal by checking the road section where the terminal is located and the road section indicated by the destination address.

  The road section specifying information may be a unique index added to the road section or information indicating the position coordinates of the road section. As a unique index assigned to a road section, there may be a format in which a number is continuously assigned to a road section, a number is assigned to each intersection, and a branch number is assigned to a road section branched from the road section. As the position coordinates of the road section, any one of both ends of the corresponding road section, a waypoint, or a combination of a plurality of position coordinate information (for example, longitude and latitude) may be used. Here, it is preferable to give separate specific information on the upper and lower lines, and in the case of multiple lanes, the specific information may be given for each lane.

  When it is determined that the terminal that received the data is not the data that designates the terminal as the destination terminal from the destination address, the road terminal identification information and map data of each of the source terminal and the destination terminal, the source terminal from the own terminal position, The wireless communication method may further include a step of grasping a positional relationship between the own terminal and the destination terminal and selecting whether or not to perform relaying. The wireless communication further includes means for determining the necessity of relaying from the position of the source terminal, the destination terminal and the own terminal position obtained from the terminal road section specifying information of the source terminal and the destination terminal by the reference means It can be realized by a terminal.

  The position of the transmission source terminal and the position of the destination terminal are specified by referring to the road section in the map data from the road section specifying information given to the transmission data. By considering the relationship between these and the own terminal position, it is determined whether or not the own terminal position is on the communication path from the transmission source to the destination terminal.

  A road section does not correspond to each terminal on a one-to-one basis, and a plurality of vehicles can exist in the same road section. And if the road section is set appropriately, not only within the road section, but also directly with the terminal located in the road section adjacent to the road section where the terminal is located and the terminal located in the area beyond that Communication is possible. The presence / absence of other terminals in the same road section is determined, terminals that perform relaying with other road sections are limited, and data transmission / reception with the same content between adjacent road sections is limited.

  The process of identifying the road section area and the terminal arrangement within the area that can be directly communicated based on the directly received data, and when the relay is necessary, the destination terminal position, the road section area, and the terminal arrangement within the area are collated, A wireless communication method may further include a step of discarding relay data when there is no other terminal in the road section area where the destination terminal position can be directly communicated. This means that, based on the directly received data, means for specifying the road section area and the terminal arrangement in the area that can be directly communicated using the reference means, the destination terminal position determined by the reference means, the road section area, and the area Wireless communication, further comprising: means for collating the terminal arrangement with the terminal arrangement; and means for discarding relay data when there is no other terminal in the road section area where the destination terminal position is directly communicable Terminal.

  Knowing the presence / absence / location of terminals in an area where direct communication is possible, and receiving communication that should be relayed to a road section where it is known that the terminal does not exist, Discard.

  The source terminal selects the transmission route to the destination terminal based on the map data, and adds the required number of relays to the transmission data, and subtracts the required number of relays added to the relay data when the terminal that relays the data is relayed A wireless communication method further comprising: In the case of a transmission source terminal, the transmission route to the destination terminal is selected based on the map data, and the required number of relays is added to the transmission data. At the time of data relay, the required number of relays added to the relay data This is realized by a wireless communication terminal further comprising means for subtracting.

  Based on the map data, the transmission route (the road section where the relay is performed) is selected, and the necessary number of relays is set based on this. At this time, propagation loss due to diffraction or the like during communication to other road sections may be stored in advance, and the most efficient route may be set with reference to the propagation loss. The number of relays is preferably not the shortest number of relays determined from the route set at this time, but a margin number is given to this. Thus, the number of relays (hops) is set in consideration of the communication path.

  The source terminal is a mobile terminal mounted on the vehicle, and further includes a step of predicting the course of the host vehicle and a step of designating a destination address based on the host vehicle path predicted by the source terminal. A wireless communication method may be used. This is a wireless communication terminal mounted on a vehicle, further comprising means for predicting the course of the own vehicle, and the data transmission means is realized by a wireless communication terminal that designates a destination address based on the predicted course of the own vehicle Is done.

  In the case of a mobile terminal mounted on a vehicle, the course of the vehicle is predicted based on, for example, the current speed of the vehicle, the steering status, the setting of a direction indicator, and the course set by a navigation system or the like. Then, based on the predicted direction, necessary information is notified to the course direction and the rear, the opposite direction, and the crossing direction of the host vehicle.

  By specifying the destination address using the road section identification information, it is possible to communicate with a terminal located in a desired road section without knowing which terminal is specifically located in a road section Can do. For this reason, for example, prior notification can be performed without using table information for front vehicles, rear vehicles, and vehicles entering a front intersection in inter-vehicle communication. For this reason, it is basically unnecessary to update the table information, data can be transferred reliably, and traffic can be used efficiently.

  When the road section specifying information is set as a unique index or position coordinate information, it becomes easy to search for the corresponding road section from the road section specifying information. In addition, when the position coordinate information is used, it is possible to cope with the case where the corresponding road section is not set in the map data (new road or construction road).

  By determining the necessity of relaying in consideration of the positional relationship between the source terminal, destination terminal and the terminal itself, it is possible to avoid unnecessary repetition of relaying by terminals located in a road section off the relay route. it can. For this reason, an increase in communication traffic due to unnecessary relaying can be prevented.

  Each terminal knows the status of other terminals in the road section, and only one of them is used for relay, so that terminals in the same road section can relay the same data redundantly. Can be suppressed. As a result, unnecessary relays are suppressed and an increase in communication traffic is suppressed.

  By grasping the status of terminals in the area, each terminal can play a part of the role of the router. For this reason, when there is no destination terminal due to movement of the terminal or the like, data can be discarded at an early stage without continuing relay / transmission of data without a destination, and an increase in communication traffic can be suppressed.

  By setting the transmission route based on the map data and setting the required number of relays and hops, it is possible to cancel the relay in the direction deviating from the transmission route at an early stage and discard the data. Can be suppressed. At this time, by setting a relay path in consideration of propagation loss and the like, it is possible to achieve both compatibility with reliable data relay.

  When the mobile terminal is a terminal installed in a vehicle, it predicts the course of the vehicle and designates the destination address accordingly, so that information on the driving status and traffic status of the vehicle can be directed in an appropriate direction. This makes it possible to communicate and improve usability of inter-vehicle communication.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

  FIG. 1 is a block configuration diagram showing an embodiment of a wireless communication terminal according to the present invention, and FIG. 2 is a wireless communication network including the wireless communication terminal (for realizing the wireless communication method according to the present invention). )).

  The wireless communication terminal 100 according to the present embodiment is a vehicle-mounted type and is used in vehicle-to-vehicle communication and road-to-vehicle communication. The wireless communication means 5 is, for example, a wireless communication device capable of bidirectional communication using a gigahertz band, and is connected to a communication antenna 6. The transmission / reception data processing means 1 for processing transmission / reception data includes a reception data processing unit 10 for processing reception data, a relay processing unit 11 for processing relay data in the reception data, and a transmission data processing unit 12 for processing transmission data. Yes.

  On the other hand, the navigation means 2 is connected to an antenna 7 that receives a signal from a GPS (Global Positioning System) satellite, receives a GPS receiver 21 that receives the signal, a gyro device 22 used for inertial navigation, and these data. Based on the position determination means 23 for determining the current position of the vehicle based on the storage device 25 storing map information / road information, etc., the stored information in the storage device 25 and the determination result of the position determination means 23 are collated. And reference means 24.

  The transmission / reception data processing means 1 and the navigation means 2 are controlled by inputting / outputting data to / from the arithmetic control means 3. The calculation control means 3 is connected to the in-vehicle LAN 4, and various operation means 80, a vehicle speed sensor 81, an actuator 82, a departure determination device 83, and the like are connected to the in-vehicle LAN 4.

  As shown in FIG. 2, in the wireless communication network, not only between the wireless communication terminals 100 mounted on each vehicle 200 but also a fixed communication terminal 110 for relaying or road-to-vehicle communication arranged on the roadside, A two-way or one-way communication is performed by configuring a network with a mobile terminal 120 such as a telephone by wireless and wired (optical communication or electrical communication).

  In the wireless communication network using the wireless communication terminal 100 according to the present invention, as a destination address designation method for the wireless communication terminal 100 and the mobile terminal 120, in addition to a method of statically or dynamically assigning a unique address to the machine The destination can be specified based on the terminal position.

  This terminal position is specified by using the road position as an index. FIG. 3 is a diagram for explaining the index concept. Consider a road structure as shown in FIG. Here, each intersection (not limited to crossroads, including T-shaped roads, five-way intersections, etc.) and branch portions are used as nodes, and roads between the nodes are used as links (see FIG. 3B). Here, the roads between the nodes may be handled as separate links in the vehicle flow direction (see FIG. 3C). Furthermore, in the case of a one-side multi-lane, it is preferable to divide the link for each lane.

  In addition to the method of assigning a unique number and symbol to each node / link independently, the index can be specified in addition to a unique number / symbol assigned to each node. A unique branch number and branch symbol are assigned to each node. Similarly, a unique number and symbol are assigned to each node, and a link is defined by the upstream node and the downstream node. A method of identifying by branch symbols, a format of indexing using node / link position coordinates (corresponding to position coordinates of road passing points), and the like are conceivable.

  FIG. 4 shows a data format of data transmitted and received in this wireless communication network. The transmission / reception data includes a management information part in which a destination and a transmission destination are described, and a real information part in which data to be actually transmitted is described. The actual information section includes vehicle position, vehicle speed, various signal states of the vehicle, and other transmission data set by the driver. The management information includes a transmission source address, a transmission destination address, the number of hops that is the number of relays, a routing request, and the like. The actual transmission / reception data may be obtained by adding predetermined header information and footer information before and after the management information part and the real information part. In addition, unique header information and footer information may be given to each of the management information part and the real information part. As the source address and destination address, in addition to IDs unique to the terminal (including cases where each terminal is fixed and dynamically changed), the road position is indexed. ID information (hereinafter, the case where an intersection / road is represented as a node / link is taken as an example, and this ID information is referred to as link information) is included. These two types of ID information may be used in combination with both of them as needed.

  Next, a vehicle-to-vehicle communication method using the wireless communication terminal 100 will be described with a specific example. FIG. 5 is a flowchart showing one form of transmission processing in the wireless communication terminal 100. Here, in the transmission data processing unit 12, it is assumed that the actual information part itself of the transmission data has been created, and the vehicle is approaching the vehicle that is about to enter the intersection ahead of the vehicle. An example of this will be described. This transmission process is repeatedly executed following the creation of the actual information part of the transmission data at a predetermined timing.

  First, the nearest node ahead is searched from the road information stored in the storage device 25 by the reference means 24 (step S1). This forward nearest node means an intersection closest to the traveling direction. Next, it is determined whether or not this forward nearest node is within a certain range (step S2). This is because when the distance is more than a certain range, it is less necessary to notify the approach to the intersection.

  If the forward nearest node is far from a certain range, the process is terminated without performing any processing. On the other hand, when the nearest node in front is within a certain range, the inflow link to this node (connected to this node, corresponding to the lane in which the vehicle is traveling toward this node, Lane = link) is retrieved from the road information in the storage device 25 by the reference means 24 and stored (step S3).

  When the inflow link is searched, the process proceeds to step S4, where the transmission data processing unit 12 sets the link information (link number) in the transmission destination address to create a management information unit, and the wireless communication means 5 transmits the data. Perform (step S5). Here, if a plurality of link information can be set at the same time for the transmission destination address, transmission data in which all destination links are set may be created and transmitted. If only one piece of link information can be specified for the destination address or less than the number of destination links, create multiple types of transmission data that specify the destination link within the specifiable number of ranges, and send the created data These operations may be repeated sequentially.

  By specifying the destination using the position information in this way, the vehicle running on the road flowing into the intersection without knowing the presence or absence of the vehicle approaching the intersection and the unique ID of the in-vehicle terminal is known. On the other hand, the approach of the own vehicle can be notified. For this reason, it is not necessary to exchange table information in advance for routing, and communication traffic can be limited to a minimum. Thereby, the arrival probability of information is improved, and information can be transmitted early. For example, even when the time for passing between intersections is short and the amount of traffic is large, each vehicle can appropriately transmit the approach information of the own vehicle.

  FIG. 6 is a flowchart showing a link information setting method when a unique index is not assigned to a link. This is performed by reading the road information stored in the storage device 25 by the reference means 24. First, a node at the other end of the link is searched (step S11). Then, the coordinate values of the link ends and, if necessary, the passing point are obtained (step S12). Then, the coordinate information (start point and end point) at both ends of the link and, if necessary, the coordinate information of the passing point are given to link information (step S13). By setting the coordinate values in the order of the start point and end point, the flow direction of the vehicle on the link can be specified. The passing point information is used to distinguish another road whose both ends coincide. In addition, you may specify by the coordinate position of a passage point instead of a start point or an end point. When there are a plurality of lanes, branch numbers and branch symbols indicating lanes may be given. In this case, since it is not necessary to set the index information in the road information in advance, the storage capacity of the storage device 25 can be reduced. It can also be used when transmitting information to communication terminals with different indexing formats.

  Next, the reception process of the data sent in this way will be described. FIG. 7 is a flowchart of received data processing. First, the reception data processing unit 10 reads reception data received by the wireless communication means 5 using the antenna 6 (step S21). Next, the destination address = link information described in the management information in the received data is extracted (step S22). And it is determined by this reference means 24 whether this link information points out the road where the own vehicle is located (step S23). If link information indicating the road where the host vehicle is located is not included, the data is discarded and the process is terminated (step S24). Here, information relay is not considered. On the other hand, if link information indicating the road where the vehicle is located is included, the received data processing unit 10 performs necessary data processing (step S25), notifies the driver, etc. and ends the processing. To do.

  By performing determination using the position information also in the reception process, it is possible to receive appropriate information without transmitting information from the host vehicle for routing in advance. And there also exists an advantage which can suppress the increase in communication traffic. Furthermore, when the destination address of a vehicle is directly specified, a vehicle deviating from the target road position may be specified as a destination due to a time delay between routing and actual communication, or conversely, the vehicle exists at the target road position. Information may not be reliably transmitted to the vehicle existing at the target road position due to the fact that the destination vehicle cannot be specified as the destination. On the other hand, appropriate information can be conveyed.

  Next, an example of relaying will be described. FIG. 8 is a flowchart of data transmission processing when relaying is required. First, transmission data is generated (step S31). Next, the routing request in the management information is turned on (step S32). Then, the number of hops is calculated based on the destination road position and the road position of the host vehicle and set in the management information (step S33). For example, when the host vehicle is present on link a shown in FIG. 3B and the destination is link i, it is necessary to relay twice over nodes A to C and three nodes. What is necessary is just to set 2 which is the required number of relays as the number of hops. Note that the number of hops may be further increased (for example, 3 obtained by adding 1) in anticipation of safety. Then, the set data is transmitted by the wireless communication means 5 (step S34), and the process is terminated.

  FIG. 9 is a flowchart of data reception processing considering relay. First, the reception data processing unit 10 reads reception data received by the wireless communication unit 5 using the antenna 6 (step S41). Next, the routing request described in the management information in the received data is checked (step S42). If the routing request is off, the subsequent processing is skipped and the process ends. In this case, the received data shown in FIG. 7 may be processed.

  If the routing request is on, the number of hops is checked (step S43). If the number of hops is 0, data may be transmitted to another link beyond the necessary number of relays, so the data is discarded and the process is terminated (step S44). If the number of hops is 1 or more, the relationship between the destination address and the road position of the transmission address and the current vehicle position is checked (step S45). If the current vehicle position does not exist between the road position specified by the destination address and the road position specified by the transmission address, that is, if it is determined that the current vehicle position is deviated from the direction to be relayed, the relay is not performed. The process ends. On the other hand, if it is determined that the current vehicle position exists between the road position specified by the destination address and the road position specified by the transmission address, and the host vehicle is positioned in the direction to be relayed, step S46 is performed. Migrate to This determination may be made based on the link information of the destination address, the link information of the transmission address, and the link information of the road where the vehicle is located.

  In step S46, it is determined whether the number of hops is sufficient for relaying to the destination. If it is determined that the number of hops is not sufficient for relaying, it is considered that the data is relayed by deviating from the direction to be relayed, and thus the process is terminated without relaying. When a sufficient number of hops remain in the relay, the relay processing unit 11 performs the relay by subtracting 1 from the number of hops (step S47) and then transmits data by the wireless communication unit 5 (step S48). .

  Here, when there are a plurality of vehicles on the same link (road between intersections), if each vehicle relays, the same relay content is congested, which may increase communication traffic. Therefore, a method for suppressing unnecessary increase in communication traffic by specifying a vehicle to be relayed and not relaying other vehicles will be described with reference to the flowcharts of FIGS. Here, consider a case where vehicles 200a to 200c exist in a link a sandwiched between the same nodes A and B as shown in FIG.

  FIG. 10 is a flowchart of processing for acquiring router information in a link. First, the reception data processing unit 10 reads the reception data received by the wireless communication means 5 using the antenna 6 (step S51). Each vehicle 200a to 200c (including vehicles existing on other links) repeatedly transmits the position and speed information of the vehicle toward the other vehicle at a predetermined timing, and is set using the transmission information at this time. I do. Next, a source address (link information) is taken out (step S52). Then, by referring to the road information stored in the storage device 25 by the reference unit 24, the link information and the link where the vehicle is located are collated (step S53). If it is a link where the host vehicle is located, the position / speed information of the other vehicle is acquired (step S54), and the positional relationship of the vehicle on the link is stored (step S55). After step S55 is completed, or when the link information received in step S53 does not match the link where the host vehicle is located, the process proceeds to step S56 where the received data is discarded and the process is terminated.

  By this process, the vehicle arrangement within the link to which the host vehicle belongs can be acquired. This information is hereinafter referred to as a vehicle arrangement table. In the relay process using the vehicle arrangement table, step S49 shown in FIG. 11 is added between step S46 and step S47 shown in FIG. Here, by referring to the vehicle arrangement table, it is determined whether or not the own vehicle corresponds to the last vehicle in the communication transmission direction from the transmission source to the transmission destination (in FIG. 12, communication is transmitted from node B to node A). In this case, the vehicle 200c corresponds to this last vehicle). In the case of the last vehicle, this vehicle is used as a relay vehicle (router), and the relay processing after step S47 is performed. On the other hand, if it is not the last vehicle, for example, in the case of the vehicles 200a and 200b in the above-described case, the processing is ended as it is.

  In this way, by using the vehicle located at the end of the communication direction in the link for relaying, communication congestion is suppressed and increase in communication traffic is suppressed. Thereby, the data communication efficiency is improved.

  In addition, when the road between nodes is a multilane, it is preferable to store all the vehicle arrangement | positioning of the parallel lane in a vehicle arrangement | positioning table, and use one of them as a router. In this case, a priority order as a router among a plurality of lanes may be set, for example, by giving priority to the left lane. Here, the last vehicle is a router, but of course, the first vehicle may be set or a vehicle near the center of the link may be set as a router. When the last vehicle is used as a router in either the communication direction or the vehicle flow direction, the link relationship of the relay vehicle can be the same even if the delay of the communication processing is taken into account. If it is, the vehicle close to the immediately preceding relay transmission vehicle) can be used as the relay vehicle, and the relay can be performed reliably.

  Further, when the update interval of the vehicle arrangement table based on the received data is relatively long, the vehicle arrangement table may be updated during the update interval based on the position / speed information. In this case, a vehicle arrangement table may be created including inflow information from the end node.

  Next, a method for creating a communication route using the road structure (referred to as routing) will be described. A radio wave in the gigahertz band as used in the wireless communication terminal of the present embodiment has high straightness and is not easily diffracted, and the reach distance varies depending on the traveling direction of the radio wave depending on the landform or a building on the roadside. Therefore, the route with the highest arrival probability is not necessarily the route connecting the transmission destination to the destination with the shortest distance, and it is necessary to select the route with the low propagation loss.

  Therefore, the propagation loss is stored in advance in the storage device 25 for each link and each node, and the propagation loss until reaching the destination is obtained for each communication path using this, and the path that minimizes the propagation loss is selected. By doing so, do proper routing. For example, in a road structure as shown in FIG. 13, link tables and node tables as shown in Tables 1 and 2 are created in advance and stored in the storage device 25. The propagation loss used for these link table and node table may be a value obtained by simulation based on the topography or the state of the building, or a value set empirically, in addition to the actually measured value.

In this case, the propagation loss from the node a to the node c is x + β + z obtained by adding the propagation loss β from the link 1 to the link 3 read from the node table to the propagation loss x and z in the link 1 and link 3 read from the link table. It becomes.

  Next, unnecessary packet processing in this embodiment will be described. In packet communication, the number of hops indicating the number of possible relays is set, and the number of hops is subtracted for each relay, and data with zero hops is not relayed and discarded packets are suppressed, thereby suppressing unnecessary relays. Thus, a technique for improving the efficiency of communication traffic is known. In this embodiment as well, unnecessary packets are discarded based on the same number of hops as described in the processing flow shown in FIG. 9. Here, a technique for discarding unnecessary packets based on the vehicle arrangement will be described.

  FIG. 14 is a flowchart showing a vehicle placement table creation process for discarding unnecessary packets. Here, it is assumed that each vehicle repeatedly transmits its own vehicle position and speed information to other vehicles at a predetermined timing.

  First, the reception data processing unit 10 reads the reception data received by the wireless communication means 5 using the antenna 6 (step S61). Next, a source address (link information) is taken out (step S62). And the vehicle presence flag (set for every link) which shows that the vehicle exists in the link is set to ON (step S63). Next, position / speed information is read (step S64). Then, it is determined whether or not it is the furthest link in the direction from the own vehicle link (step S65). If received data already exists from a position farther in the link direction, the subsequent processing is skipped and the processing is terminated. On the other hand, when it is determined that the link is the farthest link in the link direction, the link number is stored as a boundary link number, and the process is terminated.

  By repeating this, in the vehicle arrangement table, the vehicle presence flag is turned on for the link where the vehicle exists in the area where direct communication is possible, and the link number of the end where the vehicle exists in the area where direct communication is possible Is stored as the boundary link number.

  Next, unnecessary packet discard processing using this data will be described. FIG. 15 is a flowchart of this process.

  First, the reception data processing unit 10 reads the reception data received by the wireless communication unit 5 using the antenna 6 (step S71). Next, a destination address (link information) is taken out (step S72). Then, it is determined whether or not the link (destination link) indicated by the destination address is located in the area where direct communication is possible defined by the boundary link number (step S73). If the destination link exists within the area, it is further determined whether or not a vehicle exists by verifying the vehicle presence flag of the destination link (step S74). If there is no vehicle on the destination link, the process proceeds to step S75 where the packet is discarded and the process is terminated. On the other hand, if it is determined in step S74 that a vehicle is present at the destination link, and if it is determined in step S73 that the destination link is beyond the boundary link number and is outside the range where direct communication is possible, the process proceeds to step S76. And transfer data. For the transfer process itself, for example, the process shown in the flowchart of FIG. 9 may be performed.

  Here, the destination link may be designated manually by the driver, but it is appropriate according to the type of information to be transmitted based on the operating states of various operation means 80 and actuator 82 and the determination result of the deviation determination device 83. It is preferable to select an appropriate destination link because communication traffic can be effectively used.

  FIG. 16 is a flowchart of the destination link designation process. First, it is determined whether an application (for example, a collision avoidance program or a driving support program) that can automatically specify a destination is in operation (step S81). If it is in operation, the process proceeds to step S82 to determine whether or not the target link number can be specified by the application. When an information transmission command is issued from an application to a predetermined link, this specified state and other states can be identified by turning on a predetermined flag.

  If it is determined that the state can be specified, the process further proceeds to step S83, the destination link is specified, and data is transmitted from the antenna 6 by the wireless communication means 5 based on the specified address (step S84). finish. Here, Table 3 shows an example of setting the transmission link direction by the application.

  If it is determined in step S81 that the application that can specify the destination is not operating, or if it is determined in step S82 that the target link number cannot be specified from the application, the process proceeds to step S85 to specify the link number by the user. The process is performed, and the process proceeds to step S84 to transmit data and end the process.

  Thus, by specifying the destination link by the application of the in-vehicle system, information can be transmitted only to an appropriate destination, the information arrival probability can be improved, and generation of useless communication traffic can be suppressed. Furthermore, when constructing an application that uses inter-vehicle communication, by configuring the transmission link destination in the same manner, there is an advantage that the designation of the communication direction can be made common, and the construction and implementation of the application become easy.

  In the present embodiment, the destination link and the transmission source link are designated based on the road information stored in the storage device 25. By the way, the road information and map information stored in the storage device 25 may not match the current state due to road construction or the like. Even if the update frequency of road information and map information is increased, it is difficult to make them completely coincide. The present embodiment further has a function of automatically updating the map information in such a case.

Here, consider a case where a road is set between existing links x and y shown in FIG. 17 and nodes a to c and links A and B are added (existing links x and y are x ₁ and x, respectively). ₂ and y ₁ , y ₂ ). FIG. 18 is a flowchart showing processing when link setting is performed by receiving data transmitted from another vehicle passing through the additional link, and FIG. 19 is a link when the own vehicle passes through the additional link. It is a flowchart which shows the process in the case of setting.

  First, the processing shown in FIG. 18 will be described. First, the reception data processing unit 10 reads the reception data received by the wireless communication means 5 using the antenna 6 (step S91). Next, a source address (link information) is extracted (step S92). And it is searched by the reference means 24 whether the taken out link information is stored in the road information in the memory | storage device 25 (step S93). When the transmission source link exists in the road information in the storage device 25, the processing is terminated as it is, and normal data reception processing and relay processing are performed. If the transmission source link does not exist in the road information in the storage device 25, the link addition processing after step S94 is performed.

  First, the vehicle position of the transmission source vehicle is acquired from the received data (step S94). This is stored as a link shape point (step S95). Thereby, with the movement of the transmission destination vehicle, it is possible to acquire link information of the road that has traveled from the vehicle trajectory. In this case, there is an advantage that link information can be acquired even on a road on which the host vehicle is not passing. In this case, when the transmission source vehicle itself does not store road information on which the vehicle is traveling, coordinate information is sent as link information.

  Next, the process shown in FIG. 19 will be described. This process is performed while traveling and is performed independently of the operation of the wireless communication means 5. First, based on the position information of the host vehicle, the reference unit 24 determines whether or not the position of the vehicle has branched from an existing link in which information is stored in the storage device 25 (step S101). If the vehicle is not branched, that is, if the vehicle is traveling on a road for which road information is stored in the storage device 25, the processing is terminated as it is.

  On the other hand, if it is determined that the link has branched from the existing link, the process proceeds to step S102, where the branched coordinate position is set as a new node position. When there are a plurality of branch positions, the closest position is set as a node. Then, link information is set based on the traveling vehicle track (step S103). Thereafter, it is determined whether or not the vehicle has joined the existing link by comparing the position information of the host vehicle with the link information in the storage device 25 (step S104). If it is determined that they have not joined, the process returns to step S103, and the link information setting process is continued. When it determines with having joined, it transfers to step S105, sets a joining position to a new node position, and complete | finishes a process.

  By updating the link information based on the traveling state of the host vehicle, the road information can be adjusted to the current state. In the case of the process shown in FIG. 18 in which the link information is updated based on the communication information from other vehicles, if the data transmission time interval is long, each position interval is opened, and the position accuracy of the road shape is affected. However, when the position information of the host vehicle is used as the basis, it is possible to update the data regardless of the transmission interval, so that the position accuracy can be improved. Therefore, even when the host vehicle travels on a road having the link information acquired in the process of FIG. 18, it is preferable to improve the accuracy of the position information by performing the process of FIG.

  In the above description, inter-vehicle communication has been described as an example. However, the present invention is applicable to a wireless communication network including a fixed terminal as long as it is a wireless communication network including a wireless communication terminal capable of acquiring its own terminal position such as an in-vehicle communication terminal. Is suitably applicable. That is, it is not limited to inter-vehicle communication, but may include road-to-vehicle communication, or may be connected to a wired communication network.

It is a block block diagram which shows one Embodiment of the radio | wireless communication terminal which concerns on this invention. It is the schematic of the radio | wireless communication network which implement | achieves the radio | wireless communication method based on this invention including the radio | wireless communication terminal of FIG. It is a figure explaining the index concept of the road position in this invention. 3 shows a data format of data transmitted and received in the wireless communication network of FIG. It is a flowchart which shows one form of a transmission process. It is a flowchart which shows the setting method of link information when the intrinsic | native index is not provided to the link. It is a flowchart of a reception data process. It is a flowchart of the data transmission process when a relay is required. It is a flowchart of the data reception process which considered the relay. It is a flowchart of the process which acquires the router information in a link. FIG. 10 is a flowchart of an added portion when a relay process using a vehicle arrangement table is added to the process flow of FIG. 9. It is a figure explaining the router position in a link. It is a figure which shows the road structure in description of routing. It is a flowchart which shows the preparation process of the vehicle arrangement | positioning table for unnecessary packet discard. It is a flowchart of a discard process of unnecessary packets. It is a flowchart of a destination link designation | designated process. It is a figure which shows the case where a road is set between the existing links and a node and a link are added. It is a flowchart which shows the process in the case of performing link setting by receiving the data transmitted from the other vehicle which passes the additional link of FIG. It is a flowchart which shows the process in the case of performing link setting when the own vehicle passes the additional link of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Transmission / reception data processing means, 2 ... Navigation means, 3 ... Operation control means, 4 ... In-vehicle LAN, 5 ... Wireless communication means, 6, 7 ... Antenna, 10 ... Reception data processing part, 11 ... Relay processing part, 12 ... Transmission data processing unit, 21 ... GPS receiver, 22 ... gyro device, 23 ... position determination means, 24 ... reference means, 25 ... storage device, 80 ... operation means, 81 ... vehicle speed sensor, 82 ... actuator, 83 ... deviation determination Device: 100: Wireless communication terminal, 110: Fixed communication terminal, 120: Mobile terminal, 200: Each vehicle.

Claims (12)

A wireless communication network is constructed by relaying between a plurality of terminals including at least one mobile terminal, and data transmitted by a source terminal with a destination terminal specified by a destination address is relayed directly or transmitted by another terminal In the wireless communication method,
A step in which the source terminal sets terminal road section specifying information for specifying the road section where the terminal is located in the map data and adds the position / speed information of the terminal to the transmission data;
A step of performing data transmission by designating a destination address by destination road section specifying information which is terminal road section specifying information of the destination terminal;
The terminal that has received the data detects its own terminal position, and determines whether or not the road section indicated by the received destination road section specifying information is the road section in which the terminal is located. Determining whether the terminal is an address that designates a destination terminal;
Determining the presence and location of other terminals having the same terminal road section identification information;
When it is determined that the terminal that received the data is not the data that designates the terminal as the destination terminal from the destination address, the road terminal identification information and map data of each of the source terminal and the destination terminal, the source terminal from the own terminal position, After determining the necessity of relay by grasping the positional relationship between the own terminal and the destination terminal, when the own terminal has the same terminal road section information as the source or relay source terminal, the same terminal road section A step of relaying received data except when the terminal is not the closest to the source or relay source terminal among the terminals having information; and
A wireless communication method comprising:   The wireless communication method according to claim 1, wherein the road section specifying information is a unique index added to the road section.   The wireless communication method according to claim 1, wherein the road section specifying information is information representing position coordinates of a road section. Identifying a road section area that can be directly communicated based on directly received data and a terminal arrangement in the area;
When relaying is required, the destination terminal position is compared with the road section area and the terminal arrangement within the area, and if the destination terminal position is within the road section area and no other terminal exists at the position, the relay data is discarded. Process,
The wireless communication method according to any one of claims 1 to 3, characterized in that it further comprises a. A process in which the source terminal selects a transmission route to the destination terminal based on the map data, and adds the necessary number of relays to the transmission data;
A step of subtracting the necessary number of relays added to the relay data at the time of relay by the terminal that relays the data;
The wireless communication method according to any one of claims 1 to 4, characterized in that it further comprises a. The source terminal is a mobile terminal mounted on the vehicle, and the process of predicting the course of the own vehicle;
A step of designating a destination address based on the own vehicle course predicted by the source terminal;
The wireless communication method according to any one of claims 1 to 5, characterized in that it further comprises a. A wireless communication network is constructed by relaying between a plurality of terminals including at least one mobile terminal, and data transmitted by a source terminal with a destination terminal specified by a destination address is relayed directly or transmitted by another terminal A wireless communication terminal used in a wireless communication system,
Means for determining the position / speed information of the terminal itself;
Map data storage means for accumulating map data for identifying road sections as road section specifying information;
Based on the map data storage means, reference means for mutually referring to the terminal location information and road section identification information;
The terminal road section specifying information, which is the road section specifying information where the terminal is located, set by the reference means is added to the transmission data, and the destination address is determined by the destination road section specifying information which is the road section specifying information where the destination terminal is located. A data transmission means for transmitting data by designating;
The reference means obtains the road section where the destination terminal is located from the destination road section identification information indicated by the destination address in the received data, and compares this with the road section where the terminal is located, so that the own terminal Determining means for determining whether or not included in,
Means for determining the presence and position of another terminal having the same terminal road section specifying information using the reference means;
The reference means determines the necessity of relaying from the location of the source terminal and destination terminal obtained from the terminal road section identification information of the source terminal and destination terminal and the location of the terminal itself. Except when the terminal has the same terminal road section information as the source or relay source terminal and when the terminal is not the closest to the source or relay source terminal among the terminals having the same terminal road section information Means for instructing the relay implementation,
A wireless communication terminal comprising: 8. The wireless communication terminal according to claim 7, wherein the road section specifying information is a unique index added to the road section. 8. The wireless communication terminal according to claim 7, wherein the road section specifying information is information representing position coordinates of the road section. Based on the directly received data, means for specifying the road section area and the terminal arrangement in the area that can be directly communicated using the reference means;
Means for collating the destination terminal position determined by the reference means with the road section area, terminal arrangement in the area;
Means for discarding relay data when the destination terminal position is within the road section area and there is no other terminal at the position;
The wireless communication terminal according to claim 7 , further comprising: In the case of a source terminal, means for selecting a transmission route to a destination terminal based on map data, adding the necessary number of relays to the transmission data, and subtracting the necessary number of relays added to the relay data at the time of data relay The wireless communication terminal according to claim 7 , further comprising: The wireless communication terminal is a terminal mounted on a vehicle, and further includes means for predicting a course of the host vehicle, and the data transmission unit specifies a destination address based on the predicted host vehicle path. The wireless communication terminal according to any one of claims 7 to 11 .

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