JP2005295310A - Radio communication method, radio communication system, radio terminal, program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable stable multi-hop radio communication by preventing unbalanced battery consumption in each radio terminal on each communication path throughout an overall multi-hop radio communication system. <P>SOLUTION: A multi-hop radio communication network includes terminals M1-M4 in which each terminal exchanges path information through broadcast transmission, determines the reliability value of a transmission source using a frequency of receiving the path information, and selects a path so as to include a terminal having a higher reliability value, and thereby packets are relayed through communication paths passing through arbitrary terminals in an arbitrary order. In the above network, by changing transmission intervals of the path information according to the residual battery amount in the self-terminal, each of terminals M1-M4 changes the own reliability value viewed from other terminals, so as to control to reduce a probability that a path passing through a terminal having a small residual battery amount is selected. Thus, the residual battery amount in each terminal is equalized throughout the multi-hop communication network, and stable relay operation is continued. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radio communication technique, and more particularly, to a technique effective when applied to a multi-hop radio communication system and radio terminals constituting the multi-hop radio communication system.

  For example, in a mobile communication system such as a mobile phone, it is basic that a wireless terminal communicates with the nearest base station on a one-to-one basis, but geographically, such as an underpass or a valley of a building, is within the jurisdiction range of the base station Nevertheless, there is a problem that a region where communication is difficult locally, that is, a dead spot exists.

  For this reason, a multi-hop wireless communication network in which a wireless terminal forms a network while communicating directly with each other as well as with a base station is considered. By using this multi-hop wireless communication network, communication is possible even when the wireless terminal is in a dead spot, and there is a possibility that the network can be configured with only the wireless terminal without using a wired network or a fixed base station. Yes, it has been actively researched.

In a conventional multi-hop wireless communication system, an optimum transfer route of a packet to be transmitted is determined based on route information and reliability information held by a wireless terminal, and relay transfer is performed.
At this time, the reliability value of the communication path is determined according to the incoming rate of the path information of each terminal communicating between wireless terminals. For example, there is a method as described in Patent Document 1.

When the multi-hop wireless communication system as described above is battery-powered, the consumption amount of the battery of the wireless terminal is different for each route. Therefore, it is necessary to distribute the consumption amount evenly.
That is, in the conventional system, a relay destination wireless terminal that relays and transmits a packet is selected and relayed based on route information managed by the wireless terminal. At this time, an optimum route is selected based on the number of relay stages up to the final target terminal and the reliability value of communication between relay destination terminals. For this reason, unless there is a change in the communication path due to a communication error, etc., some communication paths with the minimum number of relay stages and the maximum reliability value are normally used, while other paths in the entire wireless system are used. In comparison with the above, the battery consumption of each relay terminal on this route becomes large. In particular, relay terminals used as a plurality of communication paths have a particularly large amount of battery consumption, and some of the relay terminals may become inoperable due to the remaining battery power remaining, and the relay paths themselves may not be usable.

  As a conventional route selection method for distributing the battery consumption to solve this, as shown in Patent Document 2, information on the battery consumption of each wireless terminal is exchanged between the wireless terminals. There is a method of selecting a route based on information.

However, in the method of Patent Document 2, it is necessary to exchange information between the wireless terminals by adding information indicating the remaining amount of the battery and information such as power amount for transmitting station for each route in addition to the normal route information. For this reason, the communication amount of the whole network increases, and the management of the remaining battery level becomes complicated. In particular, this problem becomes more prominent as the number of wireless terminals on the network increases.
JP 2000-13376 A JP-A-9-149079

  An object of the present invention is to prevent a bias in the consumption amount of the finite energy source of each wireless terminal for each communication path in the entire multihop wireless communication system without increasing the amount of communication data between wireless terminals, and to stabilize It is to realize multi-hop wireless communication.

  Another object of the present invention is to consume the finite energy source of each wireless terminal for each communication path in the entire multi-hop wireless communication system without requiring complicated remaining amount management of the finite energy source in each wireless terminal. The object is to realize a stable multi-hop wireless communication by preventing a bias in amount.

  A first aspect of the present invention is a multi-hop wireless communication method in which a plurality of wireless terminals operating with a finite energy source relay and transmit a transmission packet based on path information transmitted and received between each other, Each of the wireless terminals changes the transmission interval of the route information according to the remaining amount of the finite energy source, thereby allowing other wireless terminals to recognize the remaining amount of the finite energy source of the own wireless terminal. A communication method is provided.

  According to a second aspect of the present invention, a plurality of wireless terminals operating with a finite energy source mutually transmit / receive path information defining a communication path passing through the wireless terminal, and the path information and the reliability of the communication path A multi-hop wireless communication method for relaying transmission packets to each other based on a value, wherein each wireless terminal changes a transmission interval of the route information according to the remaining amount of the finite energy source A communication method is provided.

  According to a third aspect of the present invention, a plurality of wireless terminals operating with a finite energy source mutually transmit / receive path information defining a communication path passing through the wireless terminal, and the path information and the reliability value of the communication path A multi-hop wireless communication system that relays transmission packets based on each other, wherein each of the wireless terminals has a first function for detecting a remaining amount of the finite energy source, and the route according to the remaining amount. Provided is a radio communication system having a second function for changing an information transmission interval.

  According to a fourth aspect of the present invention, there is provided a wireless terminal that constitutes a multi-hop wireless communication system and operates with a finite energy source, wherein a first function for detecting a remaining amount of the finite energy source and the remaining amount A wireless terminal having a second function for changing the transmission interval of the route information is provided.

  According to a fifth aspect of the present invention, there is provided a program for controlling a wireless terminal comprising a computer that constitutes a multi-hop wireless communication system and operates with a finite energy source, and detects the remaining amount of the finite energy source in the computer. And a second function for changing a transmission interval of route information in accordance with the remaining amount.

  A sixth aspect of the present invention is a program for controlling a computer included in a wireless terminal that constitutes a multi-hop wireless communication system and operates with a finite energy source, the remaining amount of the finite energy source being stored in the computer. Provided is a computer-readable recording medium storing a program for realizing a first function to be detected and a second function for changing a transmission interval of route information according to the remaining amount.

  According to the present invention described above, each wireless terminal measures the remaining amount of a finite energy source such as a battery as a driving power source, determines a decrease in the remaining battery level held in the wireless terminal by a threshold or the like, By increasing the transmission interval of the route information held by the own terminal for selecting the communication route, the information on the remaining battery level of the own wireless terminal can be transmitted to other wireless terminals. Alternatively, the remaining battery information may be transmitted by intermittently operating the route information transmission process. In this case, the amount of communication information between wireless terminals does not increase at all, only by changing the transmission interval of route information.

  Then, in the wireless terminal that receives the surrounding route information, the incoming rate (the number of receptions per unit time) of the route information that passes through the wireless terminal whose battery level has changed as a relay terminal is low. When the size of the incoming call rate is used as a measure of the reliability value of the wireless terminal that is the source of the route information, the reliability of the route using the wireless terminal whose battery remaining amount is reduced as a repeater on the route information table When the value changes and the reliability value becomes lower than that of the other route having the same number of relay stages with respect to the target station, the use priority of the communication route including the wireless terminal is lowered. As a result, when packets are transmitted, the frequency of use of a route through which a wireless terminal having a low remaining battery capacity is routed as a relay terminal is relatively reduced, and the battery consumption of the relay terminal on this route is reduced. Can do.

As a result, it is possible to avoid a situation in which relay paths are continuously concentrated on a specific wireless terminal and the consumption of the battery is greatly biased to become inoperable, and stable multi-hop wireless communication can be realized.
In addition, by changing the transmission interval of the route information according to the remaining battery level, the other party can recognize the reliability of the own wireless terminal, so that the amount of battery consumption in each of the other wireless terminals at each wireless terminal No complicated processing such as managing data as data is required, and each wireless terminal for each communication path in the entire multi-hop wireless communication system does not require complicated battery remaining amount management in each wireless terminal. Thus, it is possible to realize a stable multi-hop wireless communication by preventing an uneven battery consumption amount.

  According to the present invention, without increasing the amount of communication data between wireless terminals, it is possible to prevent a bias in the consumption amount of the finite energy source of each wireless terminal for each communication path in the entire multihop wireless communication system and Multihop wireless communication can be realized.

  Further, it is possible to prevent uneven consumption of the finite energy source of each wireless terminal for each communication path in the entire multi-hop wireless communication system without requiring complicated remaining amount management of the finite energy source in each wireless terminal. Thus, stable multi-hop wireless communication can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram illustrating an example of a configuration of a wireless network using a multi-hop wireless communication system according to an embodiment of the present invention, and FIG. 2 is a wireless configuration of the multi-hop wireless communication system according to the present embodiment. FIG. 3 is a conceptual diagram illustrating an example of a configuration of a route information table included in the wireless terminal according to the present embodiment. FIG. 4 is a transmission interval included in the wireless terminal according to the present embodiment. It is a conceptual diagram which shows an example of a structure of a control table.

  In the multi-hop wireless communication system of the present embodiment illustrated in FIG. 1, a wireless communication network is configured by terminals M <b> 1 to M <b> 4 each including a wireless terminal 10. In FIG. 1, a dotted line indicates a communication path established as a communication path in a wireless section, and a numerical value on the path indicates a reliability value of the communication path. In this example, communication from the terminal M1 to the terminal M4 can be considered as a communication path via the terminal M3 and a communication path via the terminal M2.

  As illustrated in FIG. 2, the wireless terminal 10 constituting each of the terminals M1 to M4 stores a microprocessor 11 and a control program 12a that controls the microprocessor 11 to perform a control operation described later. A ROM (Read Only Memory) 12 (recording medium), a RAM (Random Access Memory) 13 in which information such as a path information table 20 and a transmission interval control table 30 described later accessed by the microprocessor 11 are stored, and an antenna 19 The computer includes a wireless transmission / reception unit 14 that exchanges data with the outside through wireless communication, a battery remaining amount detection unit 15, and a bus 16 serving as an information transmission path that connects these components to each other.

  The wireless terminal 10 is provided with a battery 17 that supplies operating power to the above-described units via the feeder line 18. The battery remaining amount detection unit 15 detects the remaining amount of the battery 17 and A function of notifying the processor 11 is provided.

  The battery 17 as a finite energy source includes, for example, a primary battery, a secondary battery, a fuel cell, and any other battery type power source. In the case of a primary battery or a secondary battery, the remaining amount of the battery is measured by a change in output voltage, output current or the like, and in the case of a fuel cell, it can be measured as the remaining amount of fuel.

  The control program 12a has a function of controlling information communication with another wireless terminal 10 via the wireless transmission / reception unit 14 based on route information and reliability values in the route information table 20 described later, and a unit of route information. A function (third function) for determining the reliability value of the wireless terminal 10 that is the transmission source of the route information based on the reception frequency (incoming rate) per time (determining that the higher the incoming rate, the higher the reliability); A function (first function) for detecting the remaining amount of the battery 17 in the own wireless terminal 10 via the remaining battery amount detection unit 15, the remaining amount of the battery 17 in the own wireless terminal 10, and setting of a transmission interval control table 30 described later Based on the contents, the microprocessor 11 is configured to execute a function (second function) for controlling the transmission interval of the broadcast transmission of the route information.

  FIG. 3 shows a configuration example of the route information table 20 managed by the wireless terminal 10 (this FIG. 3 is an example of the terminal M1) in the present embodiment. The route information table 20 stores a relay destination terminal number 21, a relay stage number 22, and a reliability value 23 in association with each destination final destination terminal.

  Each wireless terminal 10 includes a transmission interval control table 30 illustrated in FIG. This transmission interval control table 30 is for controlling the interval at which the route information is transmitted to other wireless terminals 10 according to the remaining amount of the battery 17, and is, for example, a plurality of stages of remaining battery amounts expressed as a percentage. 31 and the corresponding route information transmission interval 32 are set in association with each other.

  That is, in the setting example of FIG. 4, when the remaining battery level is 100%, the route information is transmitted 10 times per unit time T (transmission interval = T / 10), and the remaining battery level is 10%. Is set so as to transmit the path information once per unit time T (transmission interval = T), and the microprocessor 11 transmits the path information stored in the path information table 20. In addition, the transmission interval is determined based on the remaining battery level obtained from the remaining battery level detection unit 15 and the setting state of the transmission interval control table 30.

  In this embodiment, 10 / T is set to a standard frequency recommended in a multi-hop wireless communication protocol or the like, so that the frequency decreases as the remaining battery level decreases, thereby reducing the path. The amount of data does not increase due to an increase in the transmission frequency of the information itself.

  Hereinafter, the operation of the present embodiment will be described. In the present embodiment, as shown in FIG. 5, the control program 12a of the wireless terminal 10 broadcasts the route information of its own terminal at a fixed interval (broadcast transmission), and the surrounding terminals have the unit time route information. The reliability value of the route is determined based on the incoming rate. A terminal that transmits a packet selects a route to be used for communication based on the relay stage number 22 and the reliability value 23 of each route on the route information table 20.

  In the case of FIG. 1, the communication path from the terminal M1 to the terminal M4 is a path with a small number of relay stages 22 among relay terminals (relay destination terminal number 21) having the terminal M4 in the path information table 20 of FIG. Select first. At this time, when a plurality of routes exist with the same number of relay stages, a route having a high route reliability value 23 (in the example of FIGS. 1 and 3, a route to the terminal M3) is preferentially selected. The route in this case is terminal M1 → terminal M3 → terminal M4.

  At this time, the control program 12a of the microprocessor 11 of each terminal measures the remaining battery level of the own terminal, and when the remaining battery level of the own terminal decreases, the control program 12a holds it in the terminal in advance as shown in FIG. The transmission interval of the route information is controlled according to the setting information in the transmission interval control table 30 of the route information for the remaining battery level. For example, when the battery remaining of the terminal M3 is 80% or less, according to the information in the transmission interval control table 30, only eight times of the route information K1 to the route information K8 within the unit time T as illustrated in FIG. The route information is broadcast, and the transmission interval of route information to surrounding terminals is extended to T / 8.

  As a result, peripheral terminals (for example, the terminal M1 and the terminal M4) have a lower rate of incoming route information from the terminal M3 (number of times route information is received per unit time T). For this reason, when viewed from the terminal M1 and the terminal M4, since the reliability value information of the route using the terminal M3 is lowered, the priority order of the route having the terminal M3 as a relay terminal is the terminal M2 as the relay terminal. It becomes low with respect to a path | route, and the frequency of use of this path | route becomes low.

  FIG. 7 shows the updated route information table 20 in the terminal M1. Compared to the state of FIG. 3, for example, when the terminal terminal is the terminal M4, the relay destination terminal number 21 has the reliability value 23 of the terminal M3 decreased from 100% to 80%. % And the route via the terminal M3 is not selected. As a result, the priority of each route on the route table to the target terminal M4 varies in the terminal M1, and as a result, the microprocessor 11 changes the terminal M2 as a relay destination and transfers it. That is, the transfer path from the terminal M1 to the terminal M4 corresponding to the path information table 20 in FIG. 7 changes from the terminal M1 to the terminal M2 to the terminal M4 as illustrated in FIG.

  Further, as shown in FIG. 9, terminal M5 and terminal M6 are added to the configuration of FIG. 1, and communication from the terminal M5 to the terminal M6 (transfer route: terminal M5 → terminal M2 → terminal M6) is performed simultaneously. In this case, the remaining battery level of the terminal M2 further decreases, and accordingly, the transmission interval of the route information is widened based on the information of the transmission interval control table 30. Accordingly, the terminal M2 managed by the terminal M1 is used as a relay terminal. The reliability value of the route is low. At this time, when the route on the route information table to the target terminal M4 becomes lower than the reliability value of the route having the terminal M3 as a relay destination, the priority is changed as in the route information table 20 of FIG. Again, the transfer path from the terminal M1 to the terminal M4 is terminal M1 → terminal M3 → terminal M4. At this time, since there is only one path from the terminal M5 to the terminal M6, as shown in FIG. 11, the terminal M5 → Continue to use terminal M2 → terminal M6. As a result, the load concentrated on the terminal M2 as shown in FIG. 9 is reduced by being distributed to the terminal M3 as shown in FIG. 11, so that the battery 17 of the terminal M2 is consumed in a short time and relaying becomes impossible. A failure is surely prevented, and multihop wireless communication can be continued stably.

  In the above example, the case where the transmission interval of the route information is made variable according to the remaining amount of the battery 17 is illustrated. However, as shown in FIG. A method of transmitting intermittently so that the period is sandwiched may be used.

  As described above, according to the embodiment of the present invention, each wireless terminal 10 varies the transmission interval of the broadcast transmission of the route information according to the remaining amount of the battery 17, and the route information of each terminal. The multi-hop wireless communication system is configured by controlling the upper reliability value and, for example, controlling the route priority so that the frequency of selecting a communication route through a terminal with a small remaining battery 17 is low. The relay route can be selected so that the consumption amount of the battery 17 is equalized without unevenness among the plurality of terminals M1 to M6.

As a result, a communication failure such that the relay routes are concentrated on a specific terminal, the battery 17 is consumed, and the relay becomes impossible is avoided, so that stable multi-hop wireless communication is possible.
Further, since the priority of the route is controlled by changing the transmission interval of the route information according to the degree of consumption of the battery 17, for example, when the data on the amount of consumption of the battery 17 of all terminals are exchanged with each other. The amount of data does not increase and the communication load in the multi-hop wireless communication network does not increase. Furthermore, complicated processing such as managing the remaining amount of the battery 17 of all other wireless terminals at each wireless terminal is unnecessary.

  In the above description, the case where a battery is used as a finite energy source has been described as an example. However, the present invention can also be applied to a case where a general finite energy source whose remaining energy decreases with use is used.

It is a conceptual diagram which shows an example of a structure of the radio network by the multihop radio | wireless communications system which is one embodiment of this invention. It is a conceptual diagram which shows an example of a structure of the radio | wireless terminal which comprises the multihop radio | wireless communications system which is one embodiment of this invention. It is a conceptual diagram which shows an example of a structure of the path | route information table which the wireless terminal which is one embodiment of this invention has. It is a conceptual diagram which shows an example of a structure of the transmission interval control table which the radio | wireless terminal which is one embodiment of this invention has. It is a conceptual diagram which shows an example of the determination method of the reliability value based on the incoming rate of the routing information in the radio | wireless terminal which is one embodiment of this invention. It is a conceptual diagram which shows the example of a change of the reliability value based on the incoming rate of the routing information in the radio | wireless terminal which is one embodiment of this invention. It is a conceptual diagram which shows an example of the change of the route information table accompanying the change of the reliability value in the radio | wireless terminal which is one embodiment of this invention. It is a conceptual diagram which shows the example of a change of the communication path accompanying the change of the reliability value in the multihop radio | wireless communications system which is one embodiment of this invention. It is a conceptual diagram which shows the example of a change of the communication path accompanying the change of the reliability value in the multihop radio | wireless communications system which is one embodiment of this invention. It is a conceptual diagram which shows an example of the change of the route information table accompanying the change of the reliability value in the radio | wireless terminal which is one embodiment of this invention. It is a conceptual diagram which shows the example of a change of the communication path accompanying the change of the reliability value in the multihop radio | wireless communications system which is one embodiment of this invention. It is a conceptual diagram which shows the modification of the change method of the reliability value based on the incoming rate of the routing information in the radio | wireless terminal which is one embodiment of this invention.

Explanation of symbols

10 Wireless terminal 11 Microprocessor 12 ROM
12a Control program 13 RAM
14 Wireless transmission / reception unit 15 Battery remaining amount detection unit 16 Bus 17 Battery 18 Feed line 19 Antenna 20 Path information table 21 Relay destination terminal number 22 Relay stage number 23 Reliability value 30 Transmission interval control table 31 Battery remaining amount 32 Path information transmission interval K1 ~ K10 Route information M1 ~ M6 Terminal T Unit time

Claims (10)

A multi-hop wireless communication method in which a plurality of wireless terminals operating with a finite energy source relay transmission packets to each other based on path information transmitted and received between each other,
Each of the wireless terminals causes other wireless terminals to recognize the remaining amount of the finite energy source of the own wireless terminal by changing the transmission interval of the route information according to the remaining amount of the finite energy source. A wireless communication method characterized by the above. A plurality of wireless terminals operating with a finite energy source mutually transmit / receive path information defining a communication path passing through the wireless terminal, and transmit packets to each other based on the path information and the reliability value of the communication path A multi-hop wireless communication method for relay transmission,
A wireless communication method, wherein each of the wireless terminals changes a transmission interval of the route information according to a remaining amount of the finite energy source.   In each of the wireless terminals, the reliability value of the communication path passing through the wireless terminal that is the transmission source of the route information is determined based on the reception frequency of the route information within a unit time, and the finite energy source By increasing the transmission interval of the route information according to the decrease in the remaining amount of the mobile phone, the frequency of using the communication path including the wireless terminal with the low remaining amount of the finite energy source is relatively low The wireless communication method according to claim 2, wherein control is performed. A plurality of wireless terminals operating with a finite energy source mutually transmit / receive path information defining a communication path passing through the wireless terminal, and transmit packets to each other based on the path information and the reliability value of the communication path A multi-hop wireless communication system for relay transmission,
Each of the wireless terminals has a first function of detecting the remaining amount of the finite energy source and a second function of changing a transmission interval of the route information according to the remaining amount. Wireless communication system. Each of the wireless terminals further includes a third function of determining the reliability value of the communication path that passes through the wireless terminal that is the transmission source of the route information based on the reception frequency of the route information within a unit time. ,
The second function increases a transmission interval of the route information in proportion to a decrease in the remaining amount of the finite energy source, and lowers the reliability value of the own wireless terminal recognized by the other wireless terminals. The wireless communication system according to claim 4, wherein the use frequency of the communication path via the wireless terminal with a small remaining amount of the finite energy source is relatively reduced.   5. The wireless communication system according to claim 4, wherein the second function intermittently transmits the path information when a remaining amount of the finite energy source becomes a threshold value or less.   A wireless terminal constituting a multi-hop wireless communication system and operating with a finite energy source, wherein a first function for detecting a remaining amount of the finite energy source and a transmission interval of route information are changed according to the remaining amount A wireless terminal comprising a second function. A third function of determining a reliability value of a communication path that passes through the wireless terminal that is the transmission source of the route information based on a reception frequency of the route information within a unit time;
The second function increases a transmission interval of the route information in proportion to a decrease in the remaining amount of the finite energy source, and lowers the reliability value of the own wireless terminal recognized by the other wireless terminals. The wireless terminal according to claim 7, wherein control is performed so that the frequency of use of the communication path via the own wireless terminal with a small remaining amount of the finite energy source is relatively low.   A program for configuring a multi-hop wireless communication system to control a wireless terminal including a computer operating with a finite energy source, the computer having a first function for detecting a remaining amount of the finite energy source, and the remaining amount A program that realizes a second function that changes the transmission interval of route information in accordance with.   A program for controlling a computer included in a wireless terminal that constitutes a multi-hop wireless communication system and operates with a finite energy source, the computer having a first function for detecting a remaining amount of the finite energy source; A computer-readable recording medium storing a program for realizing a second function of changing a transmission interval of route information according to the amount.

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