JP2005079827A - Method for selecting gateway for public network access in ad hoc network, terminal, and gateway - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a terminal belonging to an ad hoc network to select an optimal gateway from among a plurality of gateways having a function of accessing a public network. <P>SOLUTION: When the terminal A prepares a gateway request message and transmits it by broadcast in order to try access a terminal N belonging to the public network, the gateway request message is received by the gateways X, Y and Z via terminals B and C, terminals D and E and terminals F and G. The gateways X, Y and Z prepare band information notification messages which describe information about bands monitored by the gateways X, Y and Z, and transmit them to the terminal A. Information about peripheral radio bands monitored by the terminals B to F themselves is added and repeated to the band information notification messages and repeated. The terminal selects the optimal gateway based on the band information notification messages. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention has a function of communicating with one or more terminals having a wireless transceiver having a function of relaying a radio signal packet transmitted from another terminal, and a function of connecting to a public network. The present invention relates to a method for selecting an optimal gateway from a plurality of gateways having a function of connecting to a public network when a terminal belonging to an ad hoc network composed of two or more gateways connects to and communicates with a terminal belonging to the public network. .

  An ad hoc network is a network composed of mobile terminals having wireless communication functions. A function that relays mobile terminals between mobile terminals that do not receive radio waves and cannot exchange information directly, that is, a multi-hop function. Therefore, it is possible to exchange information with each other (Non-Patent Document 1). In general, in order for a mobile terminal belonging to an ad hoc network to connect to and communicate with a terminal belonging to a public network, a gateway having a function of connecting to the public network is installed in the ad hoc network. Here, the public network generally refers to the Internet fixed network.

  The ad hoc network will be described with reference to the drawings. FIG. 7 illustrates a state in which two terminals belonging to an ad hoc network are adjacent to each other, 11 and 12 are adjacent terminals, and 13 and 14 are wireless radio wave ranges transmitted by the terminals 11 and 12, respectively. Represents. When the terminal 11 is in the circle of 13 and the terminal 12 is in the circle of 14, the terminal 11 and the terminal 12 are in a state where they can transmit and receive communication data or packets by radio waves, and in this ad hoc network Adjacent. This state is indicated by connection 15.

  An ad hoc network is formed by a collection of terminal groups that are adjacent to each other. FIG. 8 illustrates the case where there is only one gateway in the ad hoc network. A to G and X are terminals belonging to the ad hoc network 110, and only X has a function of connecting to the public network 111. It is. N is a terminal belonging to the public network 111, and X can connect to the terminal N using the route 17 in the public network to perform communication. The connection group 16 in the ad hoc network 110 in FIG. 8 is a set of the connections 15 in FIG. 7, thereby forming the ad hoc network 110. Terminals that are not connected 16 to each other are not adjacent to each other and cannot directly communicate with each other by transmitting radio waves, but have other terminals relay transmission packets, that is, for an ad hoc network having a multi-hop relay function By using the routing protocol, it is possible to communicate even between terminals that are not within the direct wireless reach. That is, in FIG. 8, all the terminals A to G and X belonging to the ad hoc network 110 can communicate with each other using the multi-hop relay function. For example, in the ad hoc network 110 of FIG. 8, terminal D is adjacent to terminals E and A, and terminal D can directly transmit and receive data or packets to and from terminals E and A using radio waves. Although terminal D is not adjacent to terminal B and cannot directly transmit and receive radio waves, terminal D and terminal B can communicate with each other by relaying data or packets transmitted by terminal D or terminal B. Communication is possible.

  Furthermore, in order for terminal A to connect to and communicate with terminal N belonging to public network 111, terminal A uses X, which is a gateway having a connection function with public network 111 and belonging to ad hoc network 110. There must be. A technique for establishing a route required when the terminal A communicates with the terminal N belonging to the public network using the gateway is described in Patent Document 1, but the terminal A tries to communicate with the terminal N. First, it should be noted that it is necessary to know the presence of X, which is a gateway that has a function of connecting to the public network 111 and belongs to the ad hoc network 110, and the route from the terminal A to the X.

  A method for a terminal belonging to an ad hoc network to find one gateway existing in the ad hoc network is described in Non-Patent Document 2, and there are two methods.

  The first is a protocol in which a gateway periodically broadcasts an advertisement message to all terminals in an ad hoc network for the purpose of notifying the existence of the gateway. Second, when the terminal 1 in the ad hoc network needs to connect to the public network, the terminal 1 multicasts a request message addressed to all gateways existing in the ad hoc network for the purpose of discovering the gateway. In this protocol, the gateway that has received the request message transmits an advertisement message for notifying the existence of the gateway itself to the terminal 1. By using either of these two gateway discovery protocols, a terminal in the ad hoc network can discover a gateway having a public network connection function. Since these gateway discovery protocols operate on an ad hoc network routing protocol having a multi-hop relay function, when the terminal 1 discovers a gateway, the terminal 1 wirelessly transmits a route to the gateway or a packet to the gateway. One of the adjacent relay terminals (next hop terminals) to which the radio wave should be transmitted is known, and this is described in the route table (routing table) of the terminal 1. Whether the content that the terminal 1 can know is information about the entire route to the gateway, or whether it is an adjacent next hop relay terminal that should transmit a radio wave when transmitting a packet to the gateway. Since it depends on the type of routing protocol operating in the network and the specifications of the terminal 1 and is irrelevant to the object of the present invention and the effects of the present invention, 1 assumes that the entire route to the gateway is known and can be described in the route table of the terminal 1.

  For example, in FIG. 8, the terminal A in the ad hoc network 110 discovers the gateway X based on one of the above two gateway discovery protocols, and the route leading to X, that is, the route reaching X via the terminals B and C is the terminal A. In the routing table. When terminal A transmits a packet destined for the address of terminal N, terminal A transmits this packet to gateway X based on the routing table. This packet is relayed by the terminals B and C in the ad hoc network 110 and reaches the gateway X, and reaches the terminal N via the gateway X and the route 17.

  As described above, by using the prior art, a terminal in an ad hoc network can find one gateway existing in the ad hoc network and connect to the public network using the gateway. However, the above-described two methods related to gateway discovery are specified in the above document only when there is only one gateway in the ad hoc network.

In addition, since the ad hoc network that is the subject of the present invention is a network composed of a plurality of terminals that share one radio channel, if there are other terminal groups within the radio wave reach of the terminals, The bandwidth that the terminal can use for wireless communication is much narrower than the bandwidth that the original wireless channel itself has. This fact indicates that the bandwidth of the multi-hop route in the ad hoc network through which the packet passes is originally due to the characteristic that the multi-hop operation in which the packet transmitted in the ad hoc network is relayed by a terminal on the way is repeated and transmitted to the destination. This means that it is narrower than the bandwidth of the wireless channel itself. In addition, since the terminals in the ad hoc network can move, the radio band around the terminals in the ad hoc network and the band of the multi-hop path change dynamically every moment. In order to calculate the effective bandwidth of a multi-hop route in an ad hoc network, each terminal needs to monitor the usage status of the surrounding wireless channels and calculate the bandwidth of the multi-hop route based on it. Become. Note that a technique in which each terminal monitors the usage status of the surrounding wireless channels is introduced as “Definition of busy ratio” in Non-Patent Document 3. The method of calculating the bandwidth of the multi-hop route is not necessarily one, and for example, the following method can be considered. For example, in FIG. 8, the neighboring wireless band effective value monitored by terminal A is 4 Mbps, the neighboring wireless band effective value monitored by terminal B is 5 Mbps, the neighboring wireless band effective value monitored by terminal C is 2 Mbps, and the vicinity monitored by gateway X Assuming that the effective value of the wireless band is 3 Mbps and the bandwidth of the wired route for connection to the public network monitored by the gateway X is 100 Mbps, the terminal A is connected to the public via the route 51 to the terminal B, the terminal C, and the gateway X. When connecting to the terminal N belonging to the network 111, the minimum value of the wireless bandwidth value monitored by each terminal A, B, C, X on this route 51, that is, the bandwidth value of this route 51 is 2 Mbps monitored by the terminal C. Can be defined as
JP 2002-354016 A Charles Perkins "Ad Hoc Networking" Addison-Wesley Pub Co Publishing December 2000 "Global connectivity for IPv6 Mobile Ad Hoc Networks." By R. Wakikawa, JT Malinen, CE Perkins, A. Nilsson, AJ Tuominen (2002, IETF (Internet Engineering Task Force) Internet-Draft, draft-wakikawa-manet-globalv6 -02.txt) Junichi Hakoda, Hideyuki Uehara, Mitsuo Yokoyama, "Evaluation of Ad Hoc Routing Protocol Considering Link Lifetime and Node Load" (Journal of the Institute of Electronics, Information and Communication Engineers B, vol. J85-B. No. 12, pp. 2108-2118 , December 2002), p. 2110, section 3

  The conventional gateway discovery protocol described above is a method that assumes a case where there is only one gateway in the ad hoc network, and does not assume that there are a plurality of gateways in the ad hoc network. When there are a plurality of gateways, each gateway is connected to the public network with each communication quality, and the quality is not necessarily equal in all gateways. In addition, as described in [Background Art], the quality of each route in the ad hoc network leading to each gateway is greatly different for each route and dynamically changes. Therefore, even if a terminal in an ad hoc network can discover a plurality of gateways based on the conventional protocol described above, it is determined which of the plurality of discovered gateways is optimal. There is no clear standard.

  Accordingly, a first object of the present invention is to solve this problem and provide a method for a terminal connected to a public network to select an optimal gateway from a plurality of gateways.

  As described above, the biggest problem in communication quality in an ad hoc network is the narrowness of the bandwidth of a multi-hop route in an ad hoc network and its dynamic change.

  Accordingly, a second object of the present invention is to provide a method that allows a terminal connected to a public network to consider a bandwidth condition of a route in an ad hoc network as described above when selecting a gateway. is there.

  In addition, when a terminal in an ad hoc network discovers a gateway, it may know that there are multiple routes to the same gateway. In such a case, which route should be selected? In general, the number of hops has been used as a standard. However, as described in the [Background Art] section, in ad hoc networks, the narrowness of the multi-hop route and its dynamic change are major obstacles to communication quality. It is a third object of the present invention to provide a mechanism for appropriately selecting a route from a terminal to a gateway using information on a multi-hop route band.

  Furthermore, a fourth object of the present invention is to provide a terminal and a gateway for carrying out the above method.

In order to achieve the above object, according to the gateway selection method of the present invention, a communication function between one or more terminals having a wireless transceiver having a function of relaying a wireless signal packet transmitted from another terminal and the terminal is provided. In an ad hoc network composed of two or more gateways having a connection function with a public network
When there is a terminal trying to connect to the public network,
Each gateway creates a bandwidth information notification message describing information about the bandwidth monitored by the gateway itself, and the gateway sends a bandwidth information notification message to the terminal;
Adding other information about the wireless band around the other terminal, which is monitored by the other terminal on the route from the gateway to the terminal, and relaying the information to the band information notification message; and
The terminal that has received the bandwidth information notification message has a step of selecting an optimum gateway based on the bandwidth information notification message.

  Since the bandwidth information notification message is additionally written by the relay terminal with the bandwidth information, the bandwidth information notification message contains information about the bandwidth for the route through which the bandwidth information notification message has passed. Therefore, the terminal that has received the bandwidth information notification message can not only know the existence of the gateway, but can also acquire information regarding the bandwidth of the route to the gateway.

  In an embodiment of the present invention, the terminal includes a step of broadcasting a gateway request message in the ad hoc network for the purpose of discovering a gateway, wherein each gateway creates and transmits the bandwidth information notification message. When the gateway request message is received from the terminal, the bandwidth information notification message is transmitted to the terminal. When the terminal needs to connect to the public network, Select the gateway using the bandwidth information of the route.

  In another embodiment of the present invention, the step of the gateway creating and transmitting the bandwidth information notification message includes periodically creating the bandwidth information notification message and periodically transmitting the bandwidth information notification message. The gateway is selected using the bandwidth information of the route to the gateway without requiring an operation of newly discovering the gateway when a terminal in the ad hoc network connects to the public network.

  In another embodiment of the present invention, the gateway creates and transmits a bandwidth information notification message, and the gateway detects that the bandwidth monitored by the gateway itself has changed, and this change is triggered by the change. It includes sending a bandwidth information notification message, and immediately notifies the terminal of information related to the bandwidth monitored by the gateway, thereby providing the terminal with the latest bandwidth information of the route to the gateway.

  In another embodiment of the present invention, the other terminal that adds and relays a bandwidth information notification message to the other terminal sends a message that notifies the other terminal of information related to a radio band around the other terminal that is monitored by the other terminal. Including transmitting information, and providing the terminal with bandwidth information about a route from another terminal to the gateway.

  In another embodiment of the present invention, when the other terminal monitors a radio band around the other terminal, the other terminal transmits information on the band change to the terminal as the message. including. By immediately notifying the terminal of information regarding the change in the bandwidth monitored by the relay terminal, the latest bandwidth information on the route from the relay terminal to the gateway is provided to the terminal.

  In another embodiment of the invention, the other terminal periodically transmits the message to the terminal. By periodically notifying the terminal of information regarding the bandwidth monitored by the relay terminal, the latest bandwidth information of the route from the relay terminal to the gateway is provided to the terminal.

  In another embodiment of the present invention, the other terminal includes unicasting the message to the terminal. By notifying the terminal of information related to the band monitored by the relay terminal using unicast, the terminal is provided with the band information of the route to the gateway via the relay terminal.

  In another embodiment of the present invention, the other terminal broadcasts the message to the terminal, and the terminal that receives the message broadcast by the other terminal transmits to the terminal group around the terminal. In addition, the method further includes the step of further broadcasting and relaying the message, and the step of the terminal selecting an optimum gateway based on the bandwidth information notification message includes a plurality of the relay broadcast messages. Receiving, selecting an optimal gateway based on these messages, and selecting an optimal route to the optimal gateway. By transmitting information about the bandwidth monitored by the relay terminal to the terminal through a plurality of routes, when the bandwidth in the route to the gateway that the terminal already knows changes, a plurality of routes to the gateway, that is, Band information of the gateway use path that can be used as an alternative is provided to the terminal.

  In another embodiment of the present invention, when each gateway creates and transmits a bandwidth information notification message when the other terminal is in a state of performing communication using the gateway, Creating a bandwidth information notification message describing information on the bandwidth monitored by the gateway, and the gateway periodically sending the bandwidth notification message to the terminal. By notifying the terminal in communication with the public network of information related to the band monitored by the gateway, the latest band information on the route to the gateway is provided to the terminal.

  As described above, according to the present invention, a terminal in an ad hoc network trying to connect to a public network discovers a plurality of gateways and obtains information on the bandwidth of a route in the ad hoc network that reaches these gateways. The terminal can select the gateway on the route having the best bandwidth condition and can connect to the public network. In addition, when a terminal in an ad hoc network trying to connect to a public network receives information about the bandwidth of the route to the gateway as needed or periodically, the terminal responds to changes in the bandwidth situation in the ad hoc network. The gateway and the route to the gateway can be selected.

  Next, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a configuration diagram of an ad hoc network according to a first embodiment of this invention.

  In FIG. 1, A to G and X to Z are terminals belonging to the ad hoc network 110, and only the terminals X to Z are gateways having a function of connecting to the public network 111. N is a terminal belonging to the public network 111, X can connect to N using the route 17 and perform communication, and Y can connect to N and communicate using the route 18. It is possible that Z can communicate by connecting to N using the path 19. The connection group 16 in the ad hoc network 110 in FIG. 1 is a set of the connections 15 in FIG. 7, thereby forming the ad hoc network 110. Terminals that are not connected 16 to each other are not adjacent to each other and cannot directly communicate with each other by transmitting radio waves. However, direct wireless coverage is achieved by having other terminals relay transmission packets, that is, by multihop. Even terminals that are not present can communicate with each other.

  FIG. 2 is a diagram showing a public network connection path in the first embodiment, and FIG. 3 is a sequence showing an operation flow of the first embodiment.

  In FIG. 1, when a terminal A belonging to the ad hoc network 110 first tries to connect to a terminal N belonging to the public network 111, the terminal A creates a gateway request message in order to search for a gateway belonging to the ad hoc network 110. The message is broadcasted to a terminal group adjacent to terminal A (step 101). If the gateway request message broadcast by the terminal A in step 101 is received by the adjacent terminal B of the terminal A in step 102, the terminal B relays the received gateway request message to the terminal group adjacent to the terminal B. Broadcast transmission is performed. If the gateway request message relayed and broadcasted by the terminal B in step 102 is received by the adjacent terminal C of the terminal B in step 103, the terminal C relays the received gateway request message, so that the terminal group adjacent to the terminal C Broadcast transmission to. The gateway request message relayed and broadcasted by the terminal C in step 103 is received by the gateway X adjacent to the terminal C in step 104, and the gateway X notifies the terminal A of the existence of the gateway X itself. Create a gateway advertisement message as the destination. In this gateway advertisement message created by the gateway X, information on the bandwidth monitored by the gateway X is described. The gateway X then transmits the gateway advertisement message to the terminal A as a destination by unicasting, and the shortest path from the gateway X to the terminal A (that is, from the gateway X to the terminal C and the terminal B to the terminal A). The gateway advertisement message is unicast transmitted to the terminal C that exists on the route 51) and is adjacent to the gateway X. In step 105, the terminal C that has received the gateway advertisement message appends information on the radio band around the terminal C monitored by the terminal C to the received gateway advertisement message, and adds the appended gateway advertisement message to the terminal. For the purpose of unicast relay transmission to A, the gateway advertisement message additionally written is transmitted to terminal B on the shortest path from terminal C to terminal A and adjacent to terminal C. The gateway advertisement message relay-transmitted by terminal C in step 105 is received by terminal B adjacent to terminal C in step 106, and similarly to step 105, terminal B transmits information around terminal B monitored by terminal B. The information about the radio band is added to the received gateway advertisement message, and the added gateway advertisement message is unicast relayed to terminal A for the purpose of unicast relay transmission to terminal A. Send. The gateway advertisement message relayed by terminal B in step 106 is received by terminal A in step 107. Here, in the gateway advertisement message received by the terminal A, information on the band related to all the relay terminals on the route 51 from the terminal A to the gateway X in steps 104, 105, and 106 is described. By using this information, the bandwidth value of the route 51 from the terminal A to the gateway X via the terminals B and C can be calculated as the bandwidth information 61. Note that, as a method of calculating the band information 61 that is the band value of the path 51, as described in the related art, the band information 61 is obtained by using the minimum value among the radio band values monitored by each terminal on the path 51. There are methods.

  Since the gateway X can be connected to the terminal N via the route 17, at this stage, the terminal A knows that it can connect to the terminal N using the gateway X using the route 51. At the same time, as described above, terminal A obtains band information 61 relating to route 51 (FIG. 2).

  The gateway request message broadcast by the terminal A in step 101 is relayed by the terminals D and E, F and G as well as the terminals B and C, and is received by the gateway Y and the gateway Z. In gateway Y and gateway Z, each gateway advertisement message is created through the same procedure as in step 104 in gateway X, and is unicasted toward terminal A. The gateway advertisement message transmitted by gateway Y is received by terminal A via relay terminal E that has performed the same procedure as step 105 in terminal C and relay terminal D that has performed the same procedure as step 106 in terminal B. Is done. Similarly to step 107, the terminal A knows that it can connect to the terminal N by using the gateway Y using the path 52 to the gateway Y through the terminal D and the terminal E, and at the same time, obtains the band information 62 of the path 52. obtain. Similarly, the gateway advertisement message transmitted by the gateway Z is transmitted to the terminal via the relay terminal G that has performed the same procedure as Step 105 in the terminal C and the relay terminal F that has performed the same procedure as Step 106 in the terminal B. Similar to step 107, terminal A knows that it can connect to terminal N by using gateway Z using terminal 53 via terminal F and terminal G to gateway Z, and at the same time, Is obtained.

  Through the above steps, the terminal A discovers gateways X, Y, and Z that can be used for the purpose of connecting to the terminal N belonging to the public network 111, and routes 51, 52 leading to the respective gateways X, Y, Z. , 53 is known. At the same time, since the gateway advertisement message acts as the bandwidth information notification message described in [Means for Solving the Problems] through a series of steps 104, 105, and 106, the terminal A uses the bandwidth of each route 51, 52, and 53. Information is obtained, ie 61, 62, 63. The terminal A compares the band information 61, the band information 62, and the band information 63, and uses the path having the largest band value in the band information and the gateway belonging to the path to connect to the terminal N. Steps 109 to 110 in FIG. 3 show an example in which the band value in the band information 61 is the largest value compared to the band information 62 and 63. The terminal A that has selected the route 51 having the bandwidth information can connect to the connection to the terminal N belonging to the public network 111 through the gateway X that can be used via the route 51 having the largest bandwidth value through the step 110. Is possible.

  Through the series of operations described above, a terminal attempting to connect to the public network 111 finds a plurality of gateways existing in the ad hoc network 110, and selects a gateway on a route having the best bandwidth condition from among them. It becomes possible to select.

[Second Embodiment]
FIG. 1 shows a configuration diagram of an ad hoc network according to the second embodiment, and FIG. 2 shows a public network connection route in the second embodiment.

  In FIG. 1, gateways X and Y and Z each periodically create a gateway advertisement message. However, in each gateway advertisement message, information on the bandwidth monitored by each gateway is described as in step 104 in the first embodiment. On that basis, the gateways X, Y, and Z send the gateway advertisement messages created by the gateways X, Y, and Z to the ad hoc network for the purpose of notifying all terminals belonging to the ad hoc network 110 of their existence. Broadcast to all terminals existing in 110. As described in [Background Art], relay transmission is performed using a multi-hop function for terminals that do not receive direct radio waves during broadcasting. At the time of relaying, as in step 105 or 106 in the first embodiment, the relay terminal adds information on the radio band around the relay terminal monitored by the relay terminal to the received gateway advertisement message. By relaying, the gateway advertisement message describes bandwidth information regarding the route through which the gateway advertisement message has passed. That is, the gateway advertisement message acts as the bandwidth information notification message described in the section [Means for Solving the Problems].

  With the above operation, all terminals belonging to the ad hoc network 110 know the existence of all gateways that can be reached from the terminals using the multi-hop function, as in step 107 in the first embodiment, and the gateways. To know the intra-ad hoc route leading to, and obtain the bandwidth information of that route.

  With this operation, when the terminal A belonging to the ad hoc network 110 attempts to connect to the terminal N belonging to the public network 111, the terminal A has already passively recognized the existence of the gateways X and Y and Z, and A route 51 to the gateway X and its bandwidth information 61, a route 52 to the gateway Y and its bandwidth information 62, and a route 53 to the gateway Z and its bandwidth information 63 are acquired (FIG. 2). Therefore, the terminal A that has selected the optimum route 51 from the routes 51 to 53 by the operation similar to that in Step 109 in the first embodiment is performed by the route 51 having the largest bandwidth value through the same operation as Step 110. It connects to a terminal N belonging to the public network 111 via an available gateway X.

  Through the above series of operations, all terminals belonging to the ad hoc network 110 periodically receive gateway advertisement messages issued from the gateways X, Y, and Z, so that routes to the gateways X, Y, and Z and their bandwidths are obtained. It becomes possible to grasp the information regarding Therefore, a terminal attempting to connect to the public network 111 can immediately select a gateway on a route having the best bandwidth condition without performing an operation related to discovery and selection of a new gateway. Become. Also, unlike the first embodiment, the gateway periodically sends a gateway advertisement message, so that the route to the gateway is lost due to movement of the terminals in the ad hoc network 110, communication status, changes in the radio propagation environment, and the like. Even if the route is changed or the bandwidth of the route is changed, the change is reflected and the new route to the gateway or the latest bandwidth information of the route can be periodically notified to all terminals in the ad hoc network 110. .

[Third Embodiment]
FIG. 4 is a configuration diagram of an ad hoc network according to the third embodiment, FIG. 5 is a diagram showing a route for connecting to a public network in the third embodiment, and FIG. 6 shows an operation flow of the third embodiment. It is a sequence. In FIG. 4, a terminal H is added to FIG.

  In FIG. 4, when the terminal A belonging to the ad hoc network 110 first tries to connect to the terminal N belonging to the public network 111, the terminal A selects the optimum gateway X based on the first embodiment. However, the relay terminal B, the relay terminal C, and the gateway X that exist on the path 51 from the terminal A to the gateway X are connected to the public network terminal N by the terminal A. The fact that it exists above and plays the role of packet relay is stored for a certain period of time. During this period, when a change occurs in the radio band monitored by the terminal storing the above, for example, the terminal C, the terminal C intends to notify the terminal A of information related to the band change. C creates a band information notification message, which is a message describing information on the radio band monitored by terminal C, and broadcasts it to terminals adjacent to terminal C (step 201). However, in this broadcast, the terminal C does not transmit to the gateway X that exists in the opposite direction to the terminal A on the route 51. The bandwidth information notification message broadcast by terminal C in step 201 is received by terminal B and terminal H adjacent to terminal C. In step 202, the terminal B appends information about the wireless band around the terminal B monitored by the terminal B to the received band information notification message, and the terminal B's neighboring terminal (excluding the terminal C) is added. Broadcast. Similar to step 202 in terminal B, in step 203, terminal H appends information related to the radio band around terminal H monitored by terminal H to the received band information notification message, and adds an adjacent terminal ( However, broadcast transmission is made to (except for terminal C). The bandwidth information notification message broadcasted by terminal B in step 202 is received by terminal A adjacent to terminal B, and terminal A uses step 107 in the first embodiment based on the received bandwidth information notification message. Similarly, the bandwidth information 61 relating to the path 51 is updated to newly calculate the bandwidth information 361 (step 204). On the other hand, the bandwidth information notification message broadcasted by the terminal H in step 203 is received by the terminal A adjacent to the terminal H as in step 204, and the terminal A is based on the received bandwidth information notification message. A new route 354 reaching the gateway X via the terminal H and the terminal C is newly recognized, and the bandwidth information 364 related to the route 354 is calculated based on the received bandwidth information notification message (step 205).

  With the above operation, the terminal A has recognized the paths 51, 52, 53, and 354 as the paths that use the gateway to connect to the terminal N, and the latest band information 361 and 62 corresponding to the respective paths. , 63, 364 are obtained. Then, terminal A can select the route with the largest bandwidth as in step 110 in the first embodiment (step 206), and can connect to terminal N via the gateway using this route. For example, when the band information 361, 62, 63, and 364 are compared with each other and the band information 63 has the maximum band value, in step 206, the terminal A uses the route 51 and gateway that have been used so far. Stop using X and switch to using gateway Z via route 53. Or, for example, when the bandwidth information 361, 62, 63, 364 is compared, and the bandwidth information 364 is the maximum bandwidth value, the terminal A does not change that the gateway X is used in step 206, The route to the gateway X is switched from the route 51 to the route 354.

  As described above, in addition to the features of the first embodiment, the terminal A connected to the public network 111 changes this change when the bandwidth of the route to the gateway changes due to the action of steps 201 to 205. It is possible to recognize immediately, and it becomes possible to reselect the gateway according to the situation for the changed new band. In addition, since the bandwidth information notification message is broadcast around the terminal where the bandwidth change has occurred and reaches the public network connection terminal A through a plurality of routes, the terminal A sends a plurality of routes and bandwidths to the same gateway. Since information can be obtained, it is possible to connect to the public network via a new route while avoiding a terminal in which the bandwidth deterioration has changed without changing the already selected gateway.

  As a modification of the present embodiment, in step 201, terminal C does not create and transmit a band information notification message triggered by a change in the radio band monitored by terminal C, but terminal C monitors terminal C. In some cases, information on a wireless band to be broadcast is periodically broadcast to adjacent terminals. Further, as a modification of the present embodiment, in step 201, the terminal C may unicast transmit to the terminal A instead of broadcasting the band information notification message to the peripheral terminals.

[Fourth Embodiment]
FIG. 1 is a configuration diagram of an ad hoc network according to the fourth embodiment, and FIG. 2 is a diagram illustrating a public network connection according to the fourth embodiment.

  In FIG. 1, when the terminal A belonging to the ad hoc network 110 first tries to connect to the terminal N belonging to the public network 111, the terminal A selects the optimum gateway X based on the first embodiment. The gateway X on the route 51 used for the purpose of connecting the terminal A to the terminal N periodically performs the band information during the relay period for performing communication between the terminal N and the terminal A. A notification message is created, and this message is periodically unicasted to terminal A. The bandwidth information notification message transmitted by the gateway X is received by the terminal A through the same operations as in Step 104 to Step 107 in the first embodiment. The terminal A periodically receives this bandwidth information notification message, thereby updating the bandwidth information 61 related to the route 51 and obtaining new bandwidth information 61. Then, the terminal A compares the band information 61, the band information 62, and the band information 63, selects the path having the band with the largest value among the three band information, and selects the gateway on the path. Connect to terminal N via For example, when the band information 61, 62, and 63 are compared, and the band information 63 is the maximum band value, the terminal A stops using the route 51 and the gateway X that have been used so far, Switch to use of gateway Z via route 53.

  Through the above series of operations, in addition to the features of the first embodiment, when the terminal A is communicating with the terminal N belonging to the public network 111, the latest state of the bandwidth of the route to the gateway is immediately recognized. The gateway can be selected again according to the new bandwidth situation.

  In the first to fourth embodiments, the terminal A broadcasts a gateway request message to the ad hoc network 110, receives a gateway advertisement message, and receives a gateway advertisement message or relay broadcast. Means for selecting an optimum gateway based on the bandwidth information notification message. Terminals B to H are means for adding information about a wireless band around the terminal that is monitored by the terminal and transmitting the information in a gateway advertisement message, information about the wireless region around the terminal monitored by the terminal Means for transmitting a bandwidth information notification message for notifying the terminal A to the terminal A, and means for broadcasting and relaying the message. The gateways X, Y, and Z have means for creating a gateway advertisement message and means for transmitting the gateway advertisement message to the terminal A.

It is a block diagram of the ad hoc network in the 1st, 2nd embodiment of this invention. It is a figure showing a mode that it connects to a public network from an ad hoc network in 1st Embodiment. It is a sequence diagram which shows operation | movement of 1st Embodiment. It is a block diagram of the ad hoc network in the 3rd Embodiment of this invention. It is a figure showing a mode that it connects to a public network from an ad hoc network in 3rd Embodiment. It is a sequence diagram which shows operation | movement of 3rd Embodiment. It is a figure showing the relationship of two adjacent terminals which belong to an ad hoc network. It is a block diagram of the ad hoc network assumed in the prior art.

Explanation of symbols

A ~ H Terminals belonging to an ad hoc network
X to Z A gateway that belongs to an ad hoc network and has a function of connecting to a public network
N Terminal 11 belonging to the public network, 12 Adjacent terminal belonging to the ad network 13 Terminal 11 radio wave reach 14 Terminal 12 radio wave reach 15 The terminal 11 and the terminal 12 are adjacent to each other and directly transmit and receive radio waves 16 A group of connections indicating a state in which terminals are adjacent to each other and can directly communicate with each other in an ad hoc network 17 A gateway in the public network 111 Route from X to terminal N 18 Route from gateway Y to terminal N in public network 111 19 Route from gateway Z to terminal N in public network 111 110 Ad hoc network 111 Public network 51 From terminal A to B, C, Route via X to public network 52 Terminal A via D, E, Y to public network Route 53 Route from terminal A via F, G, Z to public network 61 Information on bandwidth of route 51 62 Information on bandwidth of route 52 63 Information on bandwidth of route 53 354 From terminal A, H, C, X Route 361 to route to public network 361 Latest information on bandwidth from route 51 364 Information on bandwidth of route 354 101-109, 201-206 Steps

Claims (18)

One or more terminals having a wireless transceiver having a function of relaying a wireless signal packet transmitted from another terminal, and two or more terminals having a communication function with the terminal and a function of connecting to a public network In an ad hoc network composed of gateways,
When there is a terminal trying to connect to the public network,
Each gateway creates a bandwidth information notification message describing information about the bandwidth monitored by the gateway itself, and the gateway sends a bandwidth information notification message to the terminal;
Adding other information about the wireless band around the other terminal, which is monitored by the other terminal on the route from the gateway to the terminal, and relaying the information to the band information notification message; and
A gateway selection method comprising: a step in which the terminal that has received the bandwidth information notification message selects an optimal gateway based on the bandwidth information notification message.   The terminal broadcasts a gateway request message in the ad hoc network for the purpose of discovering a gateway, and each gateway creates and transmits the bandwidth information notification message from the terminal. The gateway selection method according to claim 1, further comprising: transmitting the bandwidth information notification message to the terminal when the gateway request message is received.   2. The method according to claim 1, wherein each gateway generates and transmits a bandwidth information notification message, and includes periodically generating the bandwidth information notification message and periodically transmitting the bandwidth information notification message. Gateway selection method.   The step of creating and transmitting each gateway bandwidth information notification message detects that the bandwidth monitored by each gateway has changed, and transmits the bandwidth information notification message triggered by this change. The gateway selection method according to claim 1, further comprising:   The said other terminal which adds and relays to the said band information notification message includes transmitting the message which notifies the information regarding the radio | wireless band of the periphery of this other terminal which this other terminal monitors to the said terminal. 5. The gateway selection method according to any one of items 1 to 4.   The said other terminal is that the said other terminal monitors, When the radio | wireless band of the circumference | surroundings of this other terminal changes, the information regarding this band change is transmitted to the said terminal as the said message, The said terminal is included. Gateway selection method.   The gateway selection method according to claim 5, wherein the other terminal periodically transmits the message to the terminal.   The gateway selection method according to claim 5, wherein the other terminal includes unicasting the message to the terminal.   The other terminal broadcasts the message to the terminal, and the terminal that has received the message broadcast by the other terminal further broadcasts the message to a terminal group around the terminal. Relaying, wherein the terminal selects an optimum gateway based on the bandwidth information notification message, and receives a plurality of relay broadcast messages, and based on these messages 6. The gateway selection method according to claim 5, comprising selecting an optimum gateway and selecting an optimum route to the optimum gateway.   When each of the gateways creates and transmits a bandwidth information notification message and the terminal is in communication using the gateway, information on the bandwidth monitored by the gateway 2. The gateway selection method according to claim 1, further comprising: generating a bandwidth information notification message in which the gateway is described, and the gateway periodically transmitting the bandwidth information notification message to the terminal. A terminal having a wireless transceiver having a function of relaying a wireless signal packet transmitted from another terminal, together with two or more gateways having a function of communicating with the terminal and a function of connecting to a public network In terminals that make up an ad hoc network,
When attempting to connect to the public network, each gateway describes and creates information related to the bandwidth monitored by the gateway itself, and other terminals existing on the route from the gateway to its own terminal A means for receiving a band information notification message monitored by the other terminal and relayed by adding information about a radio band around the other terminal, and selecting an optimum gateway based on the band information notification message A terminal comprising means.   The terminal according to claim 11, further comprising means for broadcasting a gateway request message in the ad hoc network for the purpose of discovering a gateway.   The means for selecting the optimal gateway sends a message to the terminal group around the terminal that has received the message notifying the information about the radio area around the other terminal that is broadcast by the other terminal. The terminal according to claim 11 or 12, further comprising: selecting an optimal gateway based on a plurality of broadcasted and relayed messages and selecting an optimal route to the optimal gateway. In a gateway having an ad hoc network together with a terminal having a wireless transceiver having a function of relaying a radio signal packet transmitted from another terminal, a communication function with the terminal, and a connection function with a public network,
When there is a terminal trying to connect to the public network, a means for creating a band information notification message describing information on a band monitored by the gateway itself, and transmitting the band information notification message to the terminal A gateway characterized by comprising means for:   The means for transmitting the bandwidth information notification message transmits the bandwidth information notification message to the terminal when the terminal receives a gateway request message broadcasted in the ad hoc network for the purpose of discovering a gateway. The gateway according to claim 14.   15. The means for creating the bandwidth information notification message periodically creates the bandwidth information notification message, and the means for sending the bandwidth information notification message periodically sends the bandwidth information notification message. gateway.   The gateway according to claim 14, wherein the means for transmitting the bandwidth information notification message transmits the bandwidth information notification message when a bandwidth monitored by the gate itself has changed. The means for creating the bandwidth information notification message creates a bandwidth information notification message describing information relating to a bandwidth monitored by the gateway when the terminal is in communication using the gateway. The gateway according to claim 14, wherein the means for transmitting the bandwidth information notification message periodically transmits the bandwidth information notification message to the terminal.

Images