JP2012209610A - Ad-hoc network system, terminal device, control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit data to a desired terminal device configuring an ad-hoc network.SOLUTION: An ad-hoc network system comprises a plurality of terminal devices 1 configuring an ad-hoc network which have: a communication supervision part 11 for transmitting pseudo packets at predetermined time intervals to a terminal device to which the own device has transmitted data most frequently in the past; and a communication path selection part 10 for selecting an adjacent terminal device having the minimum coefficient Z, which is calculated by using a buffer number determined by transmission or transfer of pseudo packets by adjacent terminal devices adjacent to the own device, as a communication path to a desired terminal device in the case where a communication supervision part of each terminal device transmits the pseudo packets.

Description

  The present invention relates to an ad hoc network system, a terminal device, a control method, and a program. In particular, the present invention relates to an ad hoc network system for transmitting data to a desired terminal device constituting an ad hoc network, a terminal device constituting the ad hoc network, a control method for controlling the terminal device, and the terminal device Related to the program.

  Conventionally, in an ad hoc network, each terminal device has a relay function, and even a terminal device in a place where data cannot be directly received from the base station device can receive data via other terminal devices. It becomes. For example, an ad hoc network is useful when a large number of terminal devices transmit / receive data to / from each other in a limited space such as a concert hall, an event hall, or a company premises. In addition, the amount of data transmitted and received is increasing with the recent multifunctionalization of terminal devices, and it is considered that information transmission through a plurality of routes is more important than a single route in the future.

  However, when a large number of terminal devices transmit and receive data via an ad hoc network in a narrow space, each terminal device becomes a relay station of a plurality of routes, and thus congestion on the terminal device becomes a big problem. Such a problem is not limited to an ad hoc network, but may be a problem that may occur in common in a network in which a plurality of terminal devices operate as relay stations. There is an example in which an effect is improved by using a neural network, for example, as in the technique described in Non-Patent Document 1, for alleviating such congestion.

  However, the technique described in Non-Patent Document 1 has a problem that it is not practical because each terminal device serving as a relay station needs to acquire information about all relay stations on the network in advance. This is because in a network in which a terminal device serving as a relay station is configured as a mobile communication terminal device, such as an ad hoc network, the position of each relay station changes with time, and accurate information about all relay stations is stored in advance. This is because it is difficult to obtain.

  In view of the above circumstances, Patent Document 1 describes a communication path selection device and a communication path selection method for selecting a communication path on a network while avoiding congestion at a relay station.

JP 2011-055265 A

Physica A, vol. 1297, pp521-531 (2001)

  Even if a plurality of routes are selected, if the routes are close to each other, if a local terminal disappearance occurs in a certain region, all the plurality of routes may be disconnected. In the technique described in Patent Document 1, when the same problem occurs, all routes are not disconnected, but many routes may be disconnected, and sufficient measures are taken. It's hard to say.

  Furthermore, when congestion suddenly occurs at the end of an event at a concert venue or a greeting mail at a new year's meeting facility, it is desirable to select a plurality of routes corresponding to the congestion in advance.

  In order to solve the above problem, according to the first aspect of the present invention, there is provided an ad hoc network system for transmitting data to a desired terminal device constituting an ad hoc network, wherein a plurality of ad hoc networks are configured. Each terminal device is provided with a terminal device, and each terminal device communicates between each terminal device and a communication management unit that transmits pseudo packets to the terminal device with the largest number of data transmissions in the past. When the management unit transmits the pseudo packet, the adjacent terminal device having the smallest coefficient Z calculated using the number of buffers determined by the adjacent terminal device adjacent to the own device transmitting or transferring the pseudo packet is used. And a communication path selection unit that selects a communication path to a desired terminal device.

  According to the second aspect of the present invention, a pseudo packet is transmitted at predetermined time intervals to a terminal device that constitutes an ad hoc network and is addressed to the terminal device having the largest number of data transmissions in the past. Calculated by using the number of buffers determined by sending or transferring a pseudo packet by the neighboring terminal device adjacent to the own device when the communication management unit of each terminal device and the communication management unit of each terminal device send a pseudo packet. And a communication path selection unit that selects an adjacent terminal apparatus having the smallest coefficient Z as a communication path to a desired terminal apparatus.

  According to the third aspect of the present invention, there is provided a control method for controlling a terminal device that constitutes an ad hoc network, wherein a pseudo packet is addressed to a terminal device having the largest number of times the device itself has transmitted data in the past. Calculated using the number of buffers determined by transmitting or transferring a pseudo packet by a neighboring terminal device adjacent to the own device, as a result of transmitting a pseudo packet at each terminal device, and sending a pseudo packet at each terminal device. Selecting the adjacent terminal device having the smallest coefficient Z as a communication path to the desired terminal device.

  According to the fourth aspect of the present invention, there is provided a program for a terminal device constituting an ad hoc network, in which a pseudo packet is sent to a terminal device to which the terminal device has most frequently transmitted data in the past. Is determined by transmitting or transferring a pseudo packet by an adjacent terminal device adjacent to the own device. An adjacent terminal apparatus having the smallest coefficient Z calculated using the number of buffers is caused to function as a communication path selection unit that selects a communication path to a desired terminal apparatus.

  In addition, as described above, the summary of the invention does not enumerate all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  As is apparent from the above description, the present invention can effectively avoid local path loss. In addition, according to the present invention, a sub-optimal route can be quickly established even in a sudden congestion state.

It is a system configuration figure showing the system configuration of a communication system. 3 is a schematic block diagram illustrating a functional configuration of a terminal device 1. FIG. 5 is a flowchart showing an operation flow of a next terminal apparatus selection unit 108. It is a figure showing the result of simulation. It is a figure showing the result of simulation.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and are combinations of features described in the embodiments. Not all are essential to the solution of the invention.

  FIG. 1 is a system configuration diagram showing a system configuration of a communication system. The communication system includes a plurality of terminal devices 1 and a communication device 2 that can communicate with each other. When the terminal devices 1 can communicate with each other and cannot directly communicate from the data transmission source terminal device (transmission source terminal device 1S) to the data transmission destination terminal device (transmission destination terminal device 1E), The other terminal device 1 operates as a relay station to form a communication path from the transmission source terminal device 1S to the transmission destination terminal device 1E. As shown in FIG. 1, various communication paths are conceivable as a communication path from the transmission source terminal device 1S to the transmission destination terminal device 1E. One or more communication paths used for actual communication are selected by each terminal device 1. For example, each terminal device 1 communicates with other terminal devices 1 by operating in an ad hoc mode, which is one of the operation modes of an IEEE 802.11 wireless LAN (Local Area Network). Such a terminal device 1 is configured using, for example, a mobile phone or a mobile terminal (notebook personal computer, PDA (Personal Digital Assistants), smart phone, or the like).

  The communication device 2 is configured using a communication device such as a wireless communication base station (access point) such as a wireless LAN. The communication device 2 can communicate with at least the transmission source terminal device 1S and the transmission destination communication terminal device 1E, and notifies the transmission source terminal device 1S of the location information of the transmission destination terminal device 1E.

  FIG. 2 is a schematic block diagram illustrating a functional configuration of the terminal device 1. The terminal device 1 includes a CPU (Central Processing Unit) connected via a bus, a memory, an auxiliary storage device, and the like, and functions as a device including a communication path selection unit 10 and a communication management unit 11 by executing a communication program. . Note that all or a part of each function of the terminal device 1 may be realized by using hardware such as ASIC (Application Specific Integrated Circuit) or PLD (Programmable Logic Device).

  The communication path selection unit 10 includes an adjacent device information acquisition unit 101, an adjacent device information storage unit 102, an own device position information acquisition unit 103, an own device position information storage unit 104, a transmission destination position information acquisition unit 105, and a remaining buffer amount management unit. 106, a communicable distance storage unit 107, and a next terminal device selection unit 108. In response to a request from the communication management unit 11, the communication path selection unit 10 selects the next terminal device 1 (next terminal device) that becomes the communication path from the own device to the transmission destination terminal device 1E.

  The communication supervision unit 11 controls wireless communication between the own device and another terminal device 1. The communication manager 11 controls wireless communication with other terminal devices 1 by performing an operation in the ad hoc mode, for example. Upon receiving a communication route formation request from another terminal device 1, the communication management unit 11 sends a next terminal device selection request to the next terminal device selection unit 108 in order to form a communication route. In addition, the communication management unit 11 refers to the information stored in the communication history storage unit 12, and simulates at a predetermined time interval (cycle T) to the terminal device having the largest number of data transmissions in the past. Send the packet.

  The communication history storage unit 12 is configured by using a storage device such as a semiconductor storage device or a magnetic storage device, and stores history information of a destination terminal device of data transmitted from the own device.

  Next, each function part with which the communication path selection part 10 is provided is demonstrated. The adjacent device information acquisition unit 101 acquires adjacent device information. The adjacent device information includes the pseudo buffer amount of the adjacent device, the maximum buffer amount, the position information of the adjacent device, and the identification information of the adjacent device. The adjacent device is another terminal device 1 that can directly communicate with the own device, and is theoretically another terminal device 1 that is located within a communicable distance of the own device from the own device. For example, the neighboring device information acquisition unit 101 periodically communicates with neighboring neighboring devices using the wireless communication function of the terminal device 1 and receives neighboring device information from the neighboring devices. The neighboring device information acquisition unit 101 notifies the neighboring device of the pseudo buffer amount, the maximum buffer amount, the position information, and the identification information of the own device. Further, when the neighboring device information acquisition unit 101 receives a pseudo packet addressed to another terminal device from the neighboring device, the neighboring device information acquisition unit 101 transfers the pseudo packet so as to be sent to the destination terminal device.

  The adjacent device information storage unit 102 is configured using a storage device such as a semiconductor storage device or a magnetic storage device, and stores each adjacent device information acquired by the adjacent device information acquisition unit 101.

  The own device position information acquisition unit 103 acquires the position information of the own device. The own apparatus position information acquisition unit 103 acquires, as the own apparatus position information, the longitude and latitude at which the own apparatus is located by using, for example, GPS (Global Positioning System). The own device position information acquisition unit 103 notifies the communication device 2 of the own device position information.

  The own device position information storage unit 104 is configured using a storage device such as a semiconductor storage device or a magnetic storage device, and stores the own device position information acquired by the own device position information storage unit 103.

  The transmission destination position information acquisition unit 105 acquires the position information of the transmission destination terminal apparatus 1E that is the arrival destination of the data that the terminal apparatus 1 intends to transmit or transfer. The transmission destination position information acquisition unit 105 may acquire transmission destination position information from the communication device 2, for example. In this case, the communication device 2 is configured to be able to communicate with not only the transmission source terminal device 1S and the transmission destination terminal device 1E but also all the terminal devices 1 that can be relay stations. The communication device 2 acquires and stores the position information of each terminal device 1 by periodically communicating with each terminal device 1 capable of communication. The transmission destination location information acquisition unit 105 acquires location information (transmission destination location information) of the transmission destination terminal device 1E by communicating with the communication device 2 configured as described above.

  The remaining buffer amount management unit 106 manages the pseudo buffer amount and the remaining buffer amount of its own device. The remaining buffer amount is a value representing the remaining capacity of the buffer used when each terminal device 1 operates as a relay station, and represents the remaining number of communication paths that each terminal device 1 can accommodate as a relay station. The remaining buffer amount is a value obtained by subtracting the buffer amount (pseudo buffer amount: B) reserved for transmitting or transferring a pseudo packet from the maximum buffer capacity (MAXB) of the terminal device 1. . When the above buffer overflows, congestion occurs in the terminal device 1. The size of the maximum buffer capacity MAXB of each terminal device 1 may be common, or may be set to be different for each terminal device 1. The pseudo buffer amount B is reset every period T.

  The communicable distance storage unit 107 is configured by using a storage device such as a semiconductor storage device or a magnetic storage device, and stores a distance (communication distance R) in which the own device can directly communicate. The communicable distance of each terminal device 1 may be common or may be set to be different for each terminal device 1.

  The next terminal device selection unit 108 calculates the congestion coefficient C and the distance coefficient D, calculates the selection coefficient Z using the value obtained by multiplying the congestion coefficient C by a predetermined weighting coefficient α and the residence coefficient D, Based on the selection coefficient Z, the next terminal device is selected from among a plurality of adjacent devices. The distance coefficient D is a value related to the distance from each adjacent device to the transmission destination terminal device 1E, and is calculated based on Expression (1). The next terminal apparatus selection unit 108 calculates the distance coefficient D for each adjacent apparatus based on Expression (1).

  r_RE indicates the distance from each terminal device to the destination terminal device 1E. r_SE indicates a distance from the own apparatus to the transmission destination terminal apparatus 1E. R indicates the communicable distance of the own device.

  The congestion coefficient C is a value related to the number of communication paths in which each neighboring device can operate as a relay station without causing congestion, and is calculated based on Expression (2). The next terminal apparatus selection unit 108 calculates the congestion coefficient C for each adjacent apparatus based on Expression (2).

  AV is a value obtained by dividing the total value of the pseudo buffer amounts of all the adjacent devices by the number of adjacent devices, and indicates an average value of the pseudo buffer amounts of the adjacent devices. MAXB indicates the maximum buffer capacity of the adjacent device. B indicates the pseudo buffer amount of the adjacent device.

  The selection coefficient Z is calculated based on the formula (3). The next terminal apparatus selection unit 108 calculates the selection coefficient Z for each adjacent apparatus based on Expression (3).

  Next terminal apparatus selection section 108 selects an adjacent apparatus having the smallest selection coefficient Z among the adjacent apparatuses as the next terminal apparatus. That is, the next terminal apparatus selection unit 108 selects the next terminal apparatus based on the value obtained by multiplying the congestion coefficient by a predetermined weight coefficient α and the distance coefficient. The value of α may be a negative value or a positive value. Preferably, the value of α is a value between 0.3 and 2.0 and is a value other than 1. More preferably, the value of α is a value set as appropriate according to the situation of the communication system. For example, when the maximum buffer capacity of each terminal device 1 used in the communication system is relatively large with respect to the number of communication paths formed in the communication system, the value of α may be set to a smaller value. Good. If the maximum buffer capacity of each terminal device 1 used in the communication system is relatively small with respect to the number of communication paths formed in the communication system, the value of α may be set to a larger value. Good.

The next terminal device selection unit 108 excludes neighboring devices that meet any of the following conditions (exclusion conditions) from the selected devices, and selects the neighboring device having the smallest selection coefficient Z among the remaining neighboring devices as the next terminal device. May be.
Condition 1: Neighboring device with no remaining buffer capacity to secure a new communication route Condition 2: Neighboring device already selected as a communication route to be selected Condition 3: Already selected as another communication route Adjacent equipment

  FIG. 3 is a flowchart showing the flow of operation of the next terminal apparatus selection unit 108. Hereinafter, the operation flow of the next terminal apparatus selection unit 108 will be described with reference to FIG. First, the next terminal device selection unit 108 receives a next terminal device selection request from the communication management unit 11 (S101). The selection request for the next terminal device is a signal that is output to the communication route selection unit 10 when the communication management unit 11 receives a communication route formation request from another terminal device 1, and the next terminal device is used to form a communication route. Is a signal for requesting the communication path selection unit 10 to select. The next terminal device selection request includes the identification information of each terminal device 1 included in the communication path to be formed and the identification information of the transmission destination terminal device 1E. The communication path formation request is a signal that is transmitted to request the next terminal apparatus to form a communication path when the terminal apparatus 1 operates itself as the transmission source terminal apparatus 1S or a relay station. The communication path formation request includes identification information of the transmission destination terminal device 1E that is the destination of the communication path to be formed. The communication path formation request may be further configured to include location information of the transmission destination terminal device 1E.

  Next, the next terminal device selection unit 108 determines whether or not the own device is the transmission destination terminal device IE (S102). When the own device is the transmission destination terminal device 1E (S012: YES), the next terminal device selection unit 108 notifies the communication management unit 11 that the own device is the transmission destination terminal device 1E. In this case, the communication management unit 11 starts communication with the transmission source terminal device 1S using the communication path formed so far. Note that the determination process in step S102 may be performed by the communication management unit 11.

  When the own apparatus is not the transmission destination terminal 1E (S102: NO), the next terminal apparatus selection unit 108 refers to the adjacent apparatus information stored in the adjacent apparatus information storage unit 102, and includes the transmission destination terminal apparatus in the adjacent apparatus. It is determined whether 1E is included (S103). When the destination terminal device 1E is included in the adjacent devices (S103: YES), the next terminal device selection unit 108 selects the destination terminal device 1E as the next terminal device, and the selection result is shown in the communication management unit 11. Notify In this case, the communication management unit 11 transmits a communication path formation request to the selected next terminal device.

  On the other hand, when the transmission destination terminal device 1E is not included in the adjacent device (S103: NO), the next terminal device selection unit 108 refers to the adjacent device information stored in the adjacent device information storage unit 102 and excludes it. When there is no neighboring device that does not meet any of the conditions (S105: NO), the next terminal device selection unit 108, for the neighboring device (upstream side terminal) located on the upstream side via the communication management unit 11, A reselection request including identification information of the device itself is transmitted (S106). The next terminal device selection unit 108 of the terminal device 1 that has received the reselection request selects an adjacent device having the smallest selection coefficient Z from other adjacent devices excluding the adjacent device corresponding to the identification information included in the reselection request. select.

  When there is an adjacent device that does not meet the exclusion condition (S105: YES), the next terminal device selection unit 108 calculates a selection coefficient Z for each of the adjacent devices that do not meet the exclusion condition (S107). Then, the next terminal apparatus selection unit 108 selects an adjacent apparatus having the smallest selection coefficient Z as the next terminal apparatus (S108). In this case, the communication management unit 11 transmits a communication path formation request to the selected next terminal device.

  4 and 5 are diagrams showing the results of simulation. In the simulations shown in FIGS. 4 and 5, the value of the weighting coefficient α is set to 0.5. Hereinafter, the contents and results of the simulation will be described.

  The simulation space has an overall size of 1000 × 1000 squares and a radio wave arrival distance R of 200. The total number of terminals was 1000, and the breakdown was 1 target start point terminal, 1 target end point terminal, 89 pseudo start point terminals, 89 pseudo end point terminals, and 820 route terminals. In particular, in order to investigate the effect of forming a plurality of routes in a wider range, the target start point terminal and the pseudo start point terminal are arranged at equal intervals on a semicircle having a radius of 490, and the target end point terminal and the pseudo end point terminal are opposite to each other on the circle. It was arranged to become. The route terminals were randomly arranged. In addition, 20 multiple routes were searched from the target start point terminal.

  A description will be given of a conventional (Greedy) method of a plurality of paths (FIG. 4). The right end is the target start terminal, and the left end is the target end terminal. Although multiple routes have been created, since it is required to form the shortest distance, the multiple routes are closest to each other, and if a local terminal disappearance occurs, all the routes can be disconnected.

  On the other hand, in the plurality of routes of the proposed method (FIG. 5), a plurality of routes are created in a wide range, and even if a local terminal disappears, all the routes are not disconnected. In addition, it is considered that the function Z is more effective against congestion by the function Z that relatively avoids the route terminal having a large number of pseudo buffers. In addition, as seen in the lower left of FIG. 5, a route with an excessively large number of route terminals is also proposed. However, in the priority order of selection of a plurality of routes, a route with a smaller number of route terminals is given priority. It cannot be.

  As described above, the present invention has the following effects. The first effect is a system that effectively avoids the loss of a local route by constructing a plurality of routes in a wide area in an ad hoc network composed of a plurality of routes.

  Since the second effect is configured with a route that anticipates a congestion state in advance, it is expected that a semi-optimal route can be quickly constructed even in a sudden congestion state.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Terminal apparatus 2 Communication apparatus 10 Communication path selection part 11 Communication supervision part 12 Communication history storage part 101 Neighboring apparatus information acquisition part 102 Adjacent apparatus information storage part 103 Own apparatus position information acquisition part 104 Own apparatus position information storage part 105 Transmission destination position Information acquisition unit 106 Remaining buffer amount management unit 107 Communicable distance storage unit 108 Next terminal device selection unit

Claims (4)

An ad hoc network system for transmitting data to a desired terminal device constituting an ad hoc network,
A plurality of terminal devices constituting the ad hoc network;
Each terminal device is
A communication management unit that transmits a pseudo packet every predetermined time to a terminal device having the largest number of times the device has transmitted data in the past;
The coefficient Z calculated by using the number of buffers determined by transmitting or transferring the pseudo packet by the adjacent terminal device adjacent to the own device, as the communication management unit of each terminal device transmits the pseudo packet, An ad hoc network system comprising: a communication path selection unit that selects a smallest adjacent terminal apparatus as a communication path to the desired terminal apparatus. A terminal device constituting an ad hoc network,
A communication management unit that transmits a pseudo packet every predetermined time to a terminal device having the largest number of times the device has transmitted data in the past;
The coefficient Z calculated by using the number of buffers determined by transmitting or transferring the pseudo packet by the adjacent terminal device adjacent to the own device, as the communication management unit of each terminal device transmits the pseudo packet, A terminal device comprising: a communication path selection unit that selects a smallest adjacent terminal device as a communication path to the desired terminal device. A control method for controlling terminal devices constituting an ad hoc network,
A step of transmitting a pseudo packet to a terminal device having the largest number of times the device itself has transmitted data in the past, every predetermined time;
An adjacent terminal having the smallest coefficient Z calculated by using the number of buffers determined by transmitting or transferring a pseudo packet by an adjacent terminal device adjacent to the own device due to a pseudo packet transmitted by each terminal device Selecting a terminal device as a communication path to the desired terminal device. A program for a terminal device constituting an ad hoc network, wherein the terminal device is
A communication management unit that transmits a pseudo packet to a terminal device with the largest number of times the device itself has transmitted data in the past, every predetermined time,
The coefficient Z calculated by using the number of buffers determined by transmitting or transferring the pseudo packet by the adjacent terminal device adjacent to the own device, as the communication management unit of each terminal device transmits the pseudo packet, A program that causes a smallest adjacent terminal device to function as a communication route selection unit that selects a communication route to the desired terminal device.