JP2005229173A - Communication method and communication system between mobile bodies - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication method and a communication system between mobile bodies having a wide communication range whereby a communication load due to traffic related to network control can be relieved and an information transmission probability between subscriber stations can be enhanced in a wireless communication network employing a comparatively low speed communication channel wherein the participation/retire of a mobile terminal station is less. <P>SOLUTION: Each subscriber station has a subscriber layout table for maintaining/controlling the network and broadcasts own positional information and station name identification information and the positional information of subscriber stations communicable with the own station which are edited/updated by each other, when the own station moves by a prescribed distance or longer. Further, the other subscriber station located between subscriber stations located at the outside of a radio wave arrival range relays communication between the subscriber stations, and selects a communication path employing few numbers of relaying paths also in this case. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication network in which subscriber stations move and perform data communication with each other by radio waves, and in particular, wireless communication with less joining / leaving to / from a terminal station network using a relatively low-speed communication line. The present invention relates to a communication method between mobile units in a network and a communication system between mobile units.

  In recent years, a wireless ad hoc network, which is a communication network that is temporarily configured by a mobile communication terminal incorporating a data relay function, has been proposed. This wireless ad hoc network provides a communication means for transmitting and receiving data between mobile terminals temporarily gathered within a distance range close to each other. And since it takes the form of multi-hop communication that allows connection between mobile terminals without using a base station or access point using a relatively high-speed communication line, it can be easily used in locations without network infrastructure. It is effective as a means to construct a secure network.

  However, in this network communication environment, it is difficult to manage the location information of each mobile terminal and the communication route information between mobile terminals, and since there is no fixed network topology, there is no link between terminals. It may not always be certain. For this reason, the traffic for maintaining and controlling the network naturally increases in addition to the communication for the original data transmission.

  An example that can be applied to such a traffic problem in a wireless ad hoc network is disclosed (for example, see Patent Document 1). In addition, a case regarding a communication path between mobile terminals is also disclosed (for example, see Patent Document 2).

  An example of a conventional wireless communication network is schematically shown in FIG. In FIG. 5, the total number of subscriber stations as mobile terminals of this wireless communication network is four stations: a subscriber station W, a subscriber station X, a subscriber station Y, and a subscriber station Z. Although they are located within the radio wave reach from the station W and can communicate directly with each other, the subscriber station Z is located outside the radio wave reach from the subscriber station W. Exemplifies a case where direct communication is difficult. In addition, a relatively low-speed communication line is used for communication between each subscriber station.

In such a situation, when data is transmitted from the subscriber station W to the subscriber station Z, the operator of the subscriber station X or the subscriber station Y located between these stations manually connects the data relay equipment. By making the own station function as a relay station by operation, a communication path from the subscribing station W to the subscribing station Z is set, enabling data exchange.
JP 2001-285345 A (page 11, FIG. 1) Japanese Patent Laying-Open No. 2001-244983 (page 7, FIG. 1)

  If a relay function is actively incorporated into each subscriber station of this conventional wireless communication network and the above-described wireless ad hoc network method is applied, communication between subscriber stations located outside the radio wave reachable range in FIG. Can be done.

  However, in this case, traffic due to control data necessary for each subscriber station to self-manage communication path information with other subscriber stations increases, and this is a heavy load especially for a network using a low-speed communication line. It was. Further, when there are a plurality of communication paths, a communication path capable of reliable information transmission is not necessarily selected, and the link may become unstable.

  The present invention has been made in consideration of the above-mentioned circumstances, and in particular, in a wireless communication network using a relatively low-speed communication line and with little mobile terminal station joining / leaving, communication by traffic related to network control. An object of the present invention is to provide a mobile communication method and a mobile communication system having a wide communication range in which a load is reduced and an information transmission probability between subscriber stations is improved.

  To achieve the above object, the inter-mobile communication method of the present invention is a subscriber station layout table having position information of all moving subscriber stations and communication path information including relay paths from the own station to other subscriber stations. A mobile communication method in which subscriber stations move and communicate with each other using radio waves, and each subscriber station obtains its own location information and identifies the location information of its own station. Information and the station name identification information of the subscriber station communicable with the own station and the position information thereof are broadcasted at a predetermined time interval, and the position information from other subscriber stations broadcasted and the subscriber stations communicable with the station are communicated. The station name identification information and its position information are received, and based on the received position information from other subscriber stations and the station name identification information of the communicable subscriber station and its position information. A subscriber station layout table is edited / updated, a communication path with the specific subscriber station is selected based on the edited / updated subscriber station layout table, and data communication is performed with the specific subscriber station. To do.

  Further, the inter-mobile communication system of the present invention uses a subscriber station layout table having location information of all moving subscriber stations and communication route information including a relay route from the own station to another subscriber station. In this communication system, mobile stations communicate with each other by radio waves while moving, and each subscriber station acquires position information acquisition means for acquiring its own position information and position information from this position information acquisition means. The station name identification information of the station, the station name identification information of the subscriber station that can communicate with the own station and the position information thereof, and broadcast means for transmitting at a predetermined time interval, and the position information from other subscriber stations broadcasted And receiving means for receiving the station name identification information of the communicable subscriber station and its position information, and the position information from other subscriber stations that could be received by this receiving means, and Table editing / updating means for editing / updating the subscriber station layout table based on the station name identification information of communication stations that can be communicated and its position information, and the subscriber station layout edited / updated by the table editing / updating means Communication path selection means for selecting a communication path with the specific subscriber station based on the table, and data communication means for performing data communication with the specific subscriber station through the communication path selected by the communication path selection means It is characterized by.

  According to the present invention, it is possible to obtain a communication method between mobile units and a communication system between mobile units with a wide communication range in which a communication load due to traffic related to network control is reduced and an information transmission probability between subscriber stations is improved. it can.

  The best mode for carrying out the inter-mobile communication method and the inter-mobile communication system according to the present invention will be described below with reference to FIGS.

  FIG. 1 is a diagram showing an embodiment of a wireless communication network to which a mobile communication method and a mobile communication system according to the present invention are applied. In the present embodiment, each terminal station (subscriber station) is not limited to a large number of unspecified stations that are intensively joining / leaving the network due to movement, but is limited to a certain extent within an area, for example, and is composed of four stations. Is taken up. Also, there is no special repeater in this network, and when relaying is required, it is relayed by another subscriber station located within the reach of its own radio wave. Furthermore, the communication line is also a relatively low speed line.

  In FIG. 1, a wireless communication network 1 is formed by a subscriber station A11, a subscriber station B12, a subscriber station C13, and a subscriber station D14. A representative state of the wireless communication network 1 at three different moments is modeled and shown. That is, in FIG. 1 (a), the three subscribing stations of the subscribing station A11, the subscribing station B12, and the subscribing station C13 are capable of direct one-to-one communication with each other, but the subscribing station D14 is connected to the other three stations. The state which is isolated from the radio wave reachable range from any of the subscriber stations is illustrated.

  In FIG. 1 (b), from the state of FIG. 1 (a), the subscriber station C13 and the subscriber station D14 are positioned within the radio wave reachable range so that they can communicate with each other in a one-to-one direct manner. This is an example of a possible state. FIG. 1C illustrates a state in which the subscriber station A11 and the subscriber station C13 are outside the radio wave reachable range from the state of FIG.

  FIG. 2 shows an example of a subscriber station layout table that each subscriber station edits / updates within its own station. This subscriber station layout table is composed of station name identification information, position information, and communication path information to other subscriber stations. The station name identification information is identification information unique to each subscriber station for identifying each subscriber station. The position information indicates the latest position information of each subscriber station. In this embodiment, this position information is the latitude / longitude acquired by each subscriber station using GPS. The communication route information to other subscriber stations indicates communication route information including a relay route that can reach a specific subscriber station.

  Next, the operation of the radio communication network to which the mobile communication method and the inter-mobile communication system according to the present invention is applied, the operation flow diagram of FIG. 3 and the subscriber station layout table of FIG. Will be described with reference to FIG. Hereinafter, the operation of the subscriber station A11 will be described.

  First, the operation of the subscriber station A11 in the state illustrated in FIG. When the own station starts up, the position information acquisition unit acquires the position information of the own station. In this embodiment, the position information of the own station is the latitude / longitude acquired by GPS. The acquired position information is written in the corresponding column of the subscriber station layout table (ST1).

  Next, the station name identification information of the own station, the position information, the station name identification information of the communicable subscriber station and the position information thereof are broadcasted. In this case, the station name identification information of the own station is A, the latitude / longitude acquired in ST1 as the position information, and there are no subscriber stations that can communicate immediately after the start-up, and these are broadcasted (ST2).

  In response to this broadcast transmission, the subscriber station B12 and the subscriber station C13 similarly transmit their own station name identification information and position information, as well as station name identification information and position information of communicable subscriber stations. However, the subscriber station D14 does not respond because it is outside the radio wave coverage of the subscriber station A11. The subscriber station A11 receives the responses from the subscriber stations B12 and B13 (ST3).

  Based on the received contents, the subscriber station A11 edits the subscriber station layout table in its own station. That is, the latitude / longitude is written in the position information column of the subscriber station of the corresponding station name identification information, and the relay route is written in the communication route information column together with the fact that direct communication is possible. An example of the subscriber station layout table edited at this time is shown in FIG. 4A (ST4). Similarly, in the subscriber station B12 and the subscriber station C13, the subscriber station layout table in each station is edited, and the state of FIG. 1A is established.

  If transmission data exists subsequently (YES in ST5), the subscriber station A11 selects a communication path based on the subscriber station layout table in its own station. In this embodiment, the communication path with the smallest number of relays is selected. For example, when data transmission to the subscriber station B12 is necessary, a route for directly communicating with the subscriber station B12 is selected instead of a route for relaying the subscriber station C13 (ST6). Then, the data is directly transmitted from the subscriber station A11 to the subscriber station B12 (ST7).

  Thereafter, the subscriber station A11 continuously obtains the location information of the moving own station, and updates the corresponding column in the subscriber station layout table (ST8). When a predetermined time elapses from the previous broadcast transmission and the latest information transmission time is reached (YES in ST9), it is determined whether or not it has moved a predetermined distance from the previous position (ST10). (YES in ST10) Broadcast transmission of the latest position information, station name identification information that can be communicated, and position information thereof. However, when the vehicle has not moved beyond a predetermined distance (NO in ST10), broadcast transmission is not performed and traffic in the network is reduced. Then, by terminating these operations, the subscriber station A11 leaves the wireless communication network (ST11).

  Next, the operation of the subscriber station A11 when the subscriber station D14 enters from the state of FIG. 1A and transitions to the state illustrated in FIG. 1B will be described.

  After the subscriber station C13 and the subscriber station D14 are located within the radio wave reachable range from the state of FIG. 1 (a), and the one-to-one direct communication with each other becomes possible, the subscriber station A11 receives the broadcast transmission from the subscriber station C13 in the operation step of ST3. Based on the received contents, the subscriber station layout table is updated in the operation step of ST4. An example of the updated subscriber station layout table is shown in FIG. That is, the latitude / longitude of the position information column of the newly added subscriber station D14 that has entered the wireless communication network is displayed in the position information column, and the communication path information column is relayed between the subscriber station C13 or the subscriber station B13 and the subscriber station C13. The fact that communication is possible is written.

  If transmission data addressed to the subscriber station D14 is generated at this time (YES in ST5), a communication path via the subscriber station C13 with a small number of relays is selected in the subsequent operation step of ST6, and in the operation step of ST7. The target data is transmitted.

  Further, the operation of the subscriber station A11 when the state shown in FIG. 1B is changed to the state illustrated in FIG. 1C will be described.

  In FIG. 1C, from the state of FIG. 1B, the subscriber station A11 and the subscriber station C13 are out of the radio wave reachable range and cannot communicate directly. In this case, the broadcast transmission from the subscriber station C13, which has been received as it moves, is not received in the operation step of ST4, and the location information of the subscriber station C13 included in the broadcast transmission from the subscriber station B12 that can be continuously received. In step ST4, the subscriber station layout table is updated. An example of the updated subscriber station layout table is shown in FIG. That is, the location information of the subscriber station C13 is relayed and updated by the subscriber station B12, and the communication path information is also updated to the contents of only the relay path because direct communication becomes impossible.

  At this time, for example, when transmission data addressed to the subscriber station C13 is generated (YES in ST5), a communication path via the subscriber station B12 is selected in the subsequent operation step of ST6, and the target in the operation step of ST7. Data is sent.

  As described above, in this embodiment, each subscriber station has a subscriber station layout table for maintaining and controlling this network in its own station, and its own location information and its own station for editing and updating each other. Station name identification information and location information of a subscriber station that can communicate with the mobile station when the own station has moved a predetermined distance or more. As a result, traffic related to network control can be reduced, and smooth data communication can be performed particularly in a network using a relatively low-speed communication line.

  Further, communication between subscriber stations located outside the radio wave reachable range can be relayed by other subscriber stations located between them. Furthermore, also in this case, a communication path with a small number of relays can be selected, and an alternative communication path can be secured. Thereby, the information transmission probability between the subscriber stations can be improved in a wide communication range.

The figure which shows one Example of the radio | wireless communication network to which the mobile communication method and mobile communication system which concern on this invention are applied. The figure which shows an example of a subscriber station layout table. The operation | movement flowchart for demonstrating operation | movement of the subscriber station in the radio | wireless communication network of FIG. FIG. 2 is a diagram showing an example of contents of a subscriber station layout table in a subscriber station A in each state of the wireless communication network of FIG. The figure which shows an example of the conventional radio | wireless communication network.

Explanation of symbols

1 Wireless communication network 11 Subscriber station A
12 Subscriber B
13 Subscriber station C
14 Subscriber D

Claims (8)

Using the subscriber station layout table having the location information of all the moving subscriber stations and the communication route information including the relay route from the own station to other subscriber stations, the subscriber stations perform data communication with each other by radio waves while moving between the subscriber stations. A communication method between mobiles,
Each subscriber station acquires its own location information,
This position information is broadcast at a predetermined time interval together with the station name identification information of the own station and the station name identification information of the subscriber station that can communicate with the own station and the position information,
Receiving the location information from other subscriber stations broadcasted and the station name identification information and location information of the communicable subscriber stations;
Edit and update the subscriber station layout table based on the location information from other subscriber stations that can be received, the station name identification information of the subscriber station that can communicate and the location information,
A communication method between mobile units, wherein a communication path to the specific subscriber station is selected based on the edited / updated subscriber station layout table, and data communication is performed with the specific subscriber station.   2. The inter-mobile communication method according to claim 1, wherein the position information of the local station is acquired by GPS.   3. The inter-mobile communication method according to claim 1 or 2, wherein the broadcast transmission is performed only when the local station has moved a predetermined distance or more from a position where the broadcast transmission was performed last time.   4. The inter-mobile communication method according to claim 1, wherein when selecting a communication path with the specific subscriber station, a communication path with the smallest number of relays is selected. 5. . Using the subscriber station layout table having the location information of all the moving subscriber stations and the communication route information including the relay route from the own station to other subscriber stations, the subscriber stations perform data communication with each other by radio waves while moving between the subscriber stations. A mobile communication system,
Each subscriber station has position information acquisition means for acquiring its own position information;
Transmitting means for broadcasting the position information from the position information acquiring means at predetermined time intervals together with the station name identification information of the own station and the station name identification information of the subscriber station that can communicate with the own station, and the position information;
Receiving means for receiving the position information from other subscriber stations broadcasted and the station name identification information of the communicable subscriber station and the position information;
Table editing / updating means for editing / updating the subscriber station layout table based on the position information from other subscriber stations received by the receiving means, station name identification information of the communicable subscriber station, and the position information; ,
A communication path selection means for selecting a communication path with the specific subscriber station based on the subscriber station layout table edited / updated by the table editing / update means;
A communication system between mobile units, comprising: data communication means for performing data communication with the specific subscriber station through a communication path selected by the communication path selection means.   6. The inter-mobile communication system according to claim 5, wherein the position information acquisition unit acquires the position of the own station by GPS.   The inter-mobile communication method according to claim 5 or 6, wherein the transmission means performs the broadcast transmission only when the local station has moved a predetermined distance or more from the position where the local station broadcasted the previous time.   The communication path selection unit selects a communication path with the smallest number of relays when selecting a communication path with the specific subscriber station. Mobile communication system.

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