JP2006180177A - Execution method for communication route search, and radio communication terminal using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an execution method for a communication route search which can reduce power consumption in a communication route search on a wireless communication network and also has the instantaneousness of data transfer, and a radio communication terminal which uses the same. <P>SOLUTION: When a communication route search is executed on a radio communication network through which a plurality of radio communication terminals data-communicate between each other while moving, one radio communication terminal calculates its relative distance based upon its movement distance and position information from the other radio communication terminal. When the calculated movement distance or a relative distance exceeds a designated value, a communication route search process is executed. Prior to the generation of transmitted data, a communication route search is made and its result is stored, when the transmitted data are transmitted, data communication with the other radio communication terminal is started without a delay based upon the latest stored communication route to secure the instantaneousness of the data transfer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for executing a communication path search between wireless communication terminals in a wireless communication network in which a plurality of wireless communication terminals move and perform data communication with each other, and a wireless communication terminal using the method.

  In recent years, a wireless ad hoc network, which is a communication network temporarily constituted by a moving wireless 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 wireless communication terminals temporarily gathered within a distance range close to each other. And since it takes the form of multi-hop communication that can transfer data between wireless communication terminals without intervening base stations or access points, it is effective as a simple network construction means in places without network infrastructure. It is.

  In this type of network, there is no base station or the like, and each wireless communication terminal always moves, so the network topology is not fixed. For this reason, communication path information is not managed, and each wireless communication terminal in the network starts communication after specifying the communication path by itself when performing communication.

  Various methods for communication path search have been proposed, but roughly divided into two methods, namely, proactive type and reactive type. As the former method, there are, for example, TRPPF (Topology Dissociation Based on Reverse-Path Forwarding) by OLTF (International Engineering Task Force), OLSR (Optimized Link State Prototype), and the like. In these methods, as illustrated in FIG. 3, by regularly exchanging route information with neighboring nodes periodically even during non-communication, each node determines and updates its own communication route information. is doing.

  FIG. 3 is a flowchart for explaining the execution timing of the communication route search method according to these methods in the wireless communication terminal. That is, a communication path search execution cycle is set in advance, and when the execution time comes (Y in ST31), for example, a communication path search by the above method is executed (ST32). If there is transmission data (Y in ST33), data communication is performed (ST34). As described above, the wireless communication terminal always has the latest communication path information, and is transmitted immediately after the data transmission request is generated. However, the communication traffic in the network increases due to the exchange of communication path information that is periodically performed.

  On the other hand, as the latter method, there are also AODV (Ad Hoc On Demand Distance Vector Routing) by IETF and DSR (The Dynamic Source Routing Protocol Hoc Networks). In these methods, since searching for a communication path is started when a request for data communication is generated, it takes time until actual data communication is started.

  When performing a communication route search using these methods, the node that requested the route search first broadcasts the route request packet, and the node that received this broadcast further broadcasts, and these are repeated in a chain to repeat the entire network. Transmission is performed by a method called flooding that causes a route request packet to reach the destination. For this reason, communication traffic in the network increases during communication route search.

In such a communication path search in a network, an ad hoc network routing method for obtaining information on peripheral nodes with less communication traffic is disclosed (for example, see Patent Document 1). In the method disclosed in Patent Document 1, each node determines whether or not to transmit peripheral node information known to itself when searching for the peripheral node, and then, if necessary, the peripheral Node information is being sent.
JP 2004-32559 A (page 8, FIG. 1)

  The wireless communication network as described above is effective as a means for exchanging information such as data communication in various activities in regions where the communication network infrastructure cannot be used. When used as a means for exchanging information of this type, a wireless communication terminal is required to have particularly low power consumption, for example, considering portability suitable for mobile operation. In addition, immediacy of data communication between wireless communication terminals is indispensable, and when transmission data is generated, it is required to deliver data to a target wireless communication terminal with a delay as short as possible. For this purpose, for example, as in the proactive method described above, each wireless communication terminal performs route search processing at regular time intervals, obtains the latest network topology in advance, and constantly It is necessary to establish a communication path to the wireless communication terminal.

  However, for example, in the conventional communication route search method shown in FIG. 3, when the execution time interval of this route search is shortened, the transmission opportunity of the wireless communication terminal increases, and the power of the wireless communication terminal accompanying the radio wave emission increases. Consumption increases. In addition, the traffic in the network increases, the chances of collision between transmission data also increase, and the communication speed decreases. Furthermore, even when the amount of movement of the wireless communication terminal is small and the route search process is not necessary, the event has occurred by executing the route search process.

  On the other hand, if the execution time interval of the route search process is increased, it becomes impossible to follow the change in the network topology accompanying the movement of the wireless mobile terminals. For this reason, the communication path established in advance is no longer effective, and re-searching is required, resulting in an increase in delay time in data transfer.

  The present invention has been made in consideration of the above-described circumstances, and reduces the power consumption when searching for a communication path in a wireless communication network and uses a method for executing a communication path search having immediacy of data transfer. An object of the present invention is to provide a wireless communication terminal.

  In order to achieve the above object, a communication path search execution method according to the present invention provides a method for performing communication path search between wireless communication terminals in a wireless communication network in which a plurality of wireless communication terminals moving while acquiring self-location information perform mutual data communication Whether or not the wireless communication terminal has acquired self-location information continuously, calculated its own movement distance based on the acquired self-location information, and has moved beyond a predetermined value. If it has moved beyond the predetermined value, or if it has not moved beyond the predetermined value, the position information and the self-position information of other wireless communication terminals in the wireless communication network The communication path search is executed when the mutual relative distance calculated based on the above exceeds a predetermined range.

  The wireless communication terminal of the present invention is a wireless communication terminal used in a wireless communication network that performs communication path search while moving and performs mutual data communication, and is a self-location that continuously acquires self-location information. Based on the information acquisition means and the self-position information acquired by the self-position information acquisition means, the self-movement distance is calculated, and when the movement distance exceeding a predetermined value is detected, the acquired self-position information is A transmission distance determining means for transmitting to the other wireless communication terminals in the wireless communication network and outputting a request for executing a communication route search; and for the other wireless communication terminals transmitted from the other wireless communication terminals in the wireless communication network. Calculate the relative distance from the other wireless communication terminal based on the position information and the self-position information acquired by the self-position information acquisition means, the relative exceeding the predetermined range Relative distance determination means for outputting a communication path search execution request when a separation is detected, a communication path search execution request from the movement distance determination means, or a communication path search execution request from the relative distance determination means And a communication path search executing means for searching for a communication path with another wireless communication terminal in the wireless communication network.

  ADVANTAGE OF THE INVENTION According to this invention, while reducing the power consumption at the time of the communication path search in a radio | wireless communication network, the execution method of the communication path search which ensured the immediacy of data transfer, and a radio | wireless communication terminal using the same can be obtained.

  Hereinafter, a communication route search execution method according to the present invention and a best mode for carrying out a wireless communication terminal using the same will be described with reference to FIG. 1 and FIG.

  FIG. 1 is a block diagram showing an embodiment of a wireless communication terminal according to the present invention. As shown in FIG. 1, the wireless communication terminal 1 includes a self-location information acquisition unit 11, a movement distance determination unit 12, a relative distance determination unit 13, a communication route search execution unit 14, and a transmission / reception unit 15.

  The self-location information acquisition unit 11 autonomously and continuously acquires the position information of the wireless communication terminal 1 itself and sends it to the movement distance determination unit 12 and the relative distance determination unit 13. In this embodiment, the latitude and longitude acquired by the GPS as the self-location information are sequentially sent to the movement distance determination unit 12 and the relative distance determination unit 13.

  When the movement distance determination unit 12 receives the self-position information from the self-position information acquisition unit 11 and continuously calculates its own movement distance and detects a movement distance exceeding a predetermined value, the movement distance determination unit 12 The position information is sent to the transmission / reception unit 15 described later, and a communication route search execution request is sent to the communication route search execution unit 14. The relative distance determination unit 13 determines the relative position between the other wireless communication terminal and the own position based on the position information from the other wireless communication terminal received via the transmission / reception unit 15 and the own position information from the own position information acquisition unit 11. When the distance is calculated and a relative distance exceeding the predetermined range is detected, a communication path search execution request is sent to the communication path search execution unit 14.

  The communication route search execution unit 14 includes, for example, a communication route search process using a reactive method, and receives the communication route search execution request from the movement distance determination unit 12 and the relative distance determination unit 13 and executes the communication route search process. To do. The transmission / reception unit 15 transmits / receives radio waves to / from other wireless communication terminals in the wireless communication network, transmits the self-location information from the movement distance determination unit 12 to the other wireless communication terminals, and the other wireless communication terminals transmit. The position information is received and sent to the relative distance determination unit 13. At the same time, when the communication route search process is executed, data exchanged with the communication route search execution unit 14 in accordance with the execution of the process is transmitted / received to / from other wireless communication terminals.

  Here, the self-location information acquisition unit 11 corresponds to the self-location information acquisition unit. The movement distance determination unit 12 and the transmission / reception unit 15 correspond to the movement distance determination unit. The relative distance determination unit 13 and the transmission / reception unit 15 correspond to the relative distance determination unit. The communication path search execution unit corresponds to the communication path search execution unit 14 and the transmission / reception unit 15.

  Next, with reference to the flowcharts of FIG. 1 and FIG. 2 described above, the operation of the wireless communication terminal 1 according to the present invention configured as described above at the time of execution of the communication route search will be described.

  FIG. 2 is a flowchart for explaining the operation of the wireless communication terminal 1 when executing the communication route search. First, when the wireless communication terminal starts moving, the self-location information acquisition unit 11 continuously acquires the position information of the wireless communication terminal 1 itself by GPS. The acquired self-position information is sequentially sent to the movement distance determination unit 12 and the relative distance determination unit 13 (ST21).

  The movement distance determination unit 12 receives this self-position information, continuously calculates the movement distance from the self-position when the previous communication route search execution request was issued, and then the calculated movement distance exceeds a predetermined value. (ST22). As a result of the determination, when the vehicle moves beyond a predetermined value (Y in ST22), this self-location information is transmitted and received in order to notify the self-location information at this time to other radio communication terminals in the radio communication network. Sent to the unit 15. And it transmits to the other radio | wireless communication terminal from the transmission part 15 (ST23).

  At the same time, a communication path search execution request is sent to the communication path search execution unit 14. When receiving the communication path search execution request, the communication path search execution unit 14 starts executing the communication path search process provided in itself. Then, while exchanging data with the other wireless communication terminal via the transmission / reception unit 15, the communication path with the other wireless communication terminal is acquired / updated and stored (ST27).

  On the other hand, if the result of determination in step ST22 is that the vehicle has not moved beyond a predetermined value (N in ST22), it is checked whether new position information has been received from another wireless communication terminal. That is, the relative distance determination unit 13 determines whether new position information of another wireless communication terminal has been sent from the transmission / reception unit 15 (ST24). As a result, when it is sent, the relative distance determination unit 13 determines the position and self-position of the other wireless communication terminal from the position information and the latest self-position information from the self-position information acquisition unit 11. Is calculated (ST25).

  As a result, when the calculated relative distance exceeds the predetermined range, a communication route search execution request is sent from the relative distance determination unit 13 to the communication route search execution unit 14 (Y in ST26). Upon receiving this communication route search execution request, the communication route search execution unit 14 executes the communication route search process in the same manner as the above-described step ST27 and stores the result (ST27).

  After the communication route search is executed in this way, if there is data to be transmitted to another wireless communication terminal in this wireless communication terminal 1 (Y in ST28), the latest stored in the communication route search execution unit 14 Data communication is executed based on the communication route search result (ST29). Then, the operation according to each step described above is repeated until the operation end is instructed (ST210).

  As described above, in the present embodiment, when a search for a communication path is performed in a wireless communication network in which a plurality of wireless communication terminals move and perform data communication with each other, their own moving distance and other wireless communication terminals The relative distance is calculated based on the position information from. Then, when either the calculated movement distance or relative distance exceeds a predetermined value, the communication route search process is executed. Thereby, the frequency | count of transmission by emitting the electromagnetic wave performed for a communication path search can be reduced, and the power consumption of a radio | wireless communication terminal can be reduced. At the same time, communication traffic in the wireless communication network can be reduced.

  The communication path search is executed in advance prior to the generation of transmission data, and the result is stored. Thereby, when transmission data is generated, data communication with another wireless communication terminal can be started without delay based on the latest stored communication path, and immediacy of data transfer can be ensured.

The block diagram which shows one Example of the radio | wireless communication terminal which concerns on this invention. The flowchart for demonstrating the operation | movement at the time of execution of the communication route search of the radio | wireless communication terminal 1 of FIG. The flowchart for demonstrating the execution timing of the conventional communication path search in a radio | wireless communication terminal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication terminal 11 Self-position information acquisition part 12 Movement distance determination part 13 Relative distance determination part 14 Communication path search execution part 15 Transmission / reception part

Claims (5)

A method for performing a communication path search between the wireless communication terminals in a wireless communication network in which a plurality of wireless communication terminals moving while acquiring self-location information perform data communication with each other,
The wireless communication terminal continuously acquires self-location information,
Based on this acquired self-location information, calculate the movement distance of the self and determine whether it has moved beyond a predetermined value,
When moving beyond the predetermined value,
Or
If it has not moved beyond the predetermined value,
A communication route search, wherein a communication route search is executed when a mutual relative distance calculated based on position information of other wireless communication terminals in the wireless communication network and the self-location information exceeds a predetermined range. How to run   The communication path search according to claim 1, wherein when the wireless communication terminal moves beyond the predetermined amount, the acquired self-location information is transmitted to another wireless communication terminal in the wireless communication network. How to run   The communication path search according to claim 1 or 2, wherein the position information of other wireless communication terminals in the wireless communication network is obtained by receiving self-position information transmitted from these wireless communication terminals. How to run A wireless communication terminal used in a wireless communication network that performs a communication path search while moving to perform data communication with each other,
Self-location information acquisition means for continuously acquiring self-location information;
Based on the self-location information acquired by the self-location information acquisition means, the self-movement distance is calculated, and when the movement distance exceeding a predetermined value is detected, the acquired self-location information is stored in the wireless communication network. A travel distance determining means for transmitting to the other wireless communication terminal and outputting a request for executing a communication path search;
Based on the position information of the other wireless communication terminals transmitted from the other wireless communication terminals in the wireless communication network and the self-position information acquired by the self-position information acquisition means, the relative distance from the other wireless communication terminals is calculated, A relative distance determination means for outputting a request for executing a communication path search when the relative distance exceeding a predetermined range is detected;
In response to a communication route search execution request from the movement distance determination means or a communication route search execution request from the relative distance determination means, a search for a communication path with another wireless communication terminal in the wireless communication network is executed. A wireless communication terminal comprising communication path search execution means.   The wireless communication terminal according to claim 4, wherein the self-location information is acquired by GPS.

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