JP2012205295A - Radio communication terminal and path construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimally narrow down a transmission range of a path search packet in constructing a communication path.SOLUTION: A node 100 determines whether an address of a node corresponding to a GD of a communication path search packet is registered in a GD in a communication path table 140b or not, when receiving the communication path search packet. The node 100 broadcasts the communication path search packet when the address of the node corresponding to the GD of the communication path search packet is registered in the GD in the communication path table 140b. The node 100 performs subtraction on a value of a search range of the communication path search packet when the address of the node corresponding to the GD of the communication path search packet is not registered in the GD in the communication path table 140b, and broadcasts the communication path search packet when the subtracted value of the search range is equal to or larger than 0.

Description

  The present invention relates to a wireless communication terminal and the like.

  In recent years, research on an ad hoc network in which a plurality of wireless communication terminals are interconnected in an autonomous distributed manner has been advanced. The ad hoc network includes, for example, a fixed multi-hop network such as a smart net. Hereinafter, the wireless communication terminal is referred to as a node. In an ad hoc network, no access point is set, and each node transmits a packet received from an adjacent node to another node based on a communication path, thereby transmitting the packet to a destination.

  Each node of the ad hoc network can construct a communication path by transmitting and receiving Hello Packets (see, for example, Patent Document 1). Here, when constructing a communication route (downward direction) from a gateway (Gateway: hereinafter referred to as “GW” as appropriate) to each node, consider performing route construction under the following preconditions 1 and 2. .

  Precondition 1 is a condition that an upstream communication path has been created. The uplink direction is a direction from the node to the GW. When an upstream communication path has been created, one or more transfer destination nodes for transmitting packets to the destination “GW” are registered in the communication path. The communication path can be created using the technique described in Patent Document 1 above.

  Precondition 2 is that each node transmits a packet to the GW a plurality of times and uses the upstream communication path to perform the downstream communication. This is a condition that a transfer destination node is registered for each destination node in the direction communication path table. However, the destination node of the communication path of the GW is the source node that transmitted the packet to the GW.

  In the above preconditions 1 and 2, the number of route candidates is limited, and the followability to changes in the network becomes a problem. Therefore, it is conceivable as a solution to use a reactive method in which a transmission request is generated and a routing table is dynamically created later. In the Reactive method, when a transmission request is generated, a request packet for searching for a destination is simultaneously transmitted (flooded) to its neighbor nodes. For example, the GW broadcasts a route search packet in which a node included in the communication route is set as a destination in all directions. The GW receives a response from the destination node that has received the route search packet, and creates a plurality of communication routes to the destination node. In this way, if there are multiple communication paths to the destination node, even if a certain communication path cannot be used due to a change in the network, it is possible to use another communication path to Can send packets.

  Note that, when a route search packet is broadcast in all directions, the load on the entire network increases, so there is a technique that limits the number of hops of a route search packet (see, for example, Patent Document 2). By limiting the number of hops of the search request packet, the propagation range of the route search packet is narrowed down, and the load on the entire network can be suppressed.

JP 2009-267532 A JP 2007-184827 A

  However, the above-described conventional technique has a problem that the transmission range of the route search packet cannot be narrowed down optimally when a communication route is constructed.

  For example, in the conventional Reactive method, since the route search packet spreads in a circle around the GW, the route search packet is transmitted in a direction different from the destination node. In addition, when there is only a detour route to reach the destination node, the route search packet transmission range is exceeded, and the route search packet does not reach the destination node, and communication reaches the destination node. In some cases, the route could not be constructed.

  The disclosed technology has been made in view of the above, and an object of the present invention is to provide a wireless communication terminal and a route construction method capable of optimally narrowing a transmission range of a route search packet when a communication route is constructed. And

  The disclosed wireless communication terminal includes a determination unit and a transmission control unit. When the determination unit receives a packet having information on the wireless communication terminal to be searched and a value indicating the search range, the determination unit refers to the communication route table including the route of the destination and sets the destination of the communication route table. Then, it is determined whether or not a wireless communication terminal to be searched is included. Based on the determination result of the determination unit, the transmission control unit transmits a packet to an adjacent wireless communication terminal when the destination of the communication route table includes a wireless communication terminal to be searched. On the other hand, if the destination of the communication path table does not include the wireless communication terminal to be searched, the transmission control unit subtracts a predetermined value from the value indicating the search range, and the value indicating the search range is If it is equal to or greater than the predetermined threshold, the packet is transmitted to the adjacent wireless communication terminal.

  According to the disclosed wireless communication terminal, there is an effect that the transmission range of the route search packet can be narrowed down optimally when a communication route is constructed.

FIG. 1 is a diagram illustrating a configuration of an ad hoc network. FIG. 2 is a diagram illustrating a configuration of a node. FIG. 3 is a diagram illustrating an example of a data structure of a hello packet. FIG. 4 is a diagram illustrating an example of the data structure of the work table. FIG. 5 is a diagram illustrating an example of the data structure of the communication path table. FIG. 6 is a diagram illustrating an example of the data structure of the path construction packet. FIG. 7 is a diagram illustrating an example of a data structure of a route search packet. FIG. 8 is a diagram illustrating a processing procedure for path construction using hello packets. FIG. 9 is a diagram (1) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 10 is a diagram (2) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 11 is a diagram (3) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 12 is a diagram (4) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 13 is a diagram (5) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 14 is a diagram (6) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 15 is a diagram (7) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 16 is a diagram (8) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 17 is a diagram (9) illustrating an example of the data structure of the hello packet and the data structure of the communication path table of each node. FIG. 18 is a diagram (1) illustrating a route construction process using a route construction packet. FIG. 19 is a diagram (2) for explaining the route construction processing by the route construction packet. FIG. 20 is a diagram (3) for explaining the route construction processing by the route construction packet. FIG. 21 is a diagram (4) illustrating the route construction processing by the route construction packet. FIG. 22 is a diagram (1) for explaining the routing packet transfer process. FIG. 23 is a diagram (2) for explaining the routing packet transfer process. FIG. 24 is a diagram (3) illustrating the route search packet transfer process. FIG. 25 is a diagram (4) for explaining the route search packet forwarding process. FIG. 26 is a diagram (5) for explaining the transfer process of the route search packet. FIG. 27 is a diagram (6) for explaining the routing packet transfer process. FIG. 28 is a diagram (7) for explaining the routing packet transfer process. FIG. 29 is a diagram (8) for explaining the routing packet transfer process. FIG. 30 is a flowchart illustrating the processing procedure of the hello packet reception processing. FIG. 31 is a flowchart showing the processing procedure of the hello packet transmission processing. FIG. 32 is a flowchart illustrating a processing procedure of a route construction packet transmission process. FIG. 33 is a flowchart of a process procedure of a path construction packet reception process. FIG. 34 is a flowchart showing the processing procedure of the route search packet. FIG. 35 is a diagram illustrating a hardware configuration of a computer constituting the node.

  Embodiments of a wireless communication terminal and a route construction method disclosed in the present application will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  The configuration of the ad hoc network according to the present embodiment will be described. FIG. 1 is a diagram illustrating a configuration of an ad hoc network. As shown in FIG. 1, this ad hoc network includes nodes 100a to 100g and 100x to 100z. The nodes 100a to 100g and 100x to 100z are examples of wireless communication terminals. The node 100g corresponds to a GW (Gate Way).

  The nodes 100a to 100g and 100x to 100z are wirelessly connected to adjacent nodes. For example, the node 100g is connected to the nodes 100a, 100b, and 100x. The node 100a is connected to the nodes 100g, 100c, and 100d. The node 100b is connected to the nodes 100g, 100d, 100e, and 100y. The node 100c is connected to the nodes 100a, 100d, and 100f. The node 100d is connected to the nodes 100a, 100b, 100c, 100e, and 100f. 100e is connected to the nodes 100b, 100d, and 100f. The node 100f is connected to the nodes 100c, 100d, and 100e. The node 100x is connected to the nodes 100g, 100b, and 100y. The node 100y is connected to the nodes 100b, 100x, and 100z. The node 100z is connected to the node 100y. In this embodiment, the nodes 100a to 100g and 100x to 100y are collectively referred to as a node 100.

  Next, the configuration of the node 100 according to the present embodiment will be described. FIG. 2 is a diagram illustrating a configuration of a node. As illustrated in FIG. 2, the node 100 includes a wireless communication unit 110, an input unit 120, a display unit 130, a storage unit 140, and a control unit 150.

  The wireless communication unit 110 is a device that performs wireless data communication with adjacent nodes. For example, the wireless communication unit 110 corresponds to a wireless link module or the like. The control unit 150 transmits / receives a hello packet or the like to / from adjacent nodes via the wireless communication unit 110.

  The input unit 120 is an input device for inputting various types of information to the node 100. For example, the input unit 120 corresponds to a keyboard, a mouse, a touch panel, and the like. The display unit 120 is a display device that displays various types of information. For example, the display unit 130 corresponds to a display, a touch panel, or the like.

  The storage unit 140 stores, for example, a work table 140a, a communication path table 140b, and a data management table 140c. The storage unit 140 corresponds to, for example, a semiconductor memory device such as a random access memory (RAM), a read only memory (ROM), and a flash memory, or a storage device such as a hard disk or an optical disk.

  The work table 140a is a table that temporarily holds hello packet information. Here, an example of the data structure of the hello packet and an example of the data structure of the work table 140a will be described.

  FIG. 3 is a diagram illustrating an example of a data structure of a hello packet. As shown in FIG. 3, the hello packet has GS, LS, and E. Among these, GS stores the address of the destination node. For example, the address of the node 100g serving as the GW is stored in the GS. The LS stores the address of the node that transferred the hello packet. In E, for example, the number of hops of the hello packet is stored.

  FIG. 4 is a diagram illustrating an example of the data structure of the work table. As shown in FIG. 4, this work table 140a has GD, LD, and E. The address of the destination node is stored in the GD. The LD stores a transfer destination address. In E, for example, the number of hops of the hello packet is stored. The GS, LS, and E of the hello packet shown in FIG. 3 are stored in GD, LD, and E of the work table 140a of FIG. 4, respectively.

  The communication path table 140b indicates to which adjacent node the packet should be transferred when the packet is transmitted to the destination node. FIG. 5 is a diagram illustrating an example of the data structure of the communication path table. The description regarding GD, LD, and E in FIG. 5 is the same as the description regarding GD, LD, and E in FIG. As illustrated in FIG. 5, for example, the communication path table 140 b stores a plurality of communication paths for the destination node “GD”. The communication path table 140b indicates that when a packet is transmitted to the node 100g, the packet may be transferred to any one of the nodes 100a to 100e. In FIG. 5, for convenience of explanation, the name of the node is shown, but the address of the node may be registered.

  The data management table 140c is a table that stores a packet transmission history. This data management table 140c is used by the downstream path construction unit 150b described later.

  The control unit 150 includes a hello packet control unit 150a, a downlink route construction unit 150b, a route search packet transmission unit 150c, and a route search packet reception unit 150d. The control unit 150 corresponds to an integrated device such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). Moreover, the control part 150 respond | corresponds to electronic circuits, such as CPU and MPU (Micro Processing Unit), for example.

  The hello packet control unit 150a is a processing unit that registers the relationship between the destination “GD”, the transfer destination “LD”, and the number of hops “E” in the communication path table 140b by transmitting and receiving hello packets to and from adjacent nodes. .

  A process when the hello packet control unit 150a receives a hello packet will be described. The hello packet control unit 150a stores the GS and LS information of the hello packet in the GD and LD of the work table 140a. In addition, the hello packet control unit 150a stores the value obtained by adding 1 to the value of E of the hello packet in E of the work table 140a. The hello packet control unit 150a registers the record of the work table 140a in the communication path table 140b.

  A process when the hello packet control unit 150a transmits a hello packet will be described. For example, the hello packet control unit 150a generates a hello packet when a clock event occurs.

  The hello packet control unit 150a stores the GS information of the communication path table 140b in the GS of the hello packet. For example, the hello packet control unit 150a may store the address of the node 100g corresponding to the gateway in the GS of the hello packet. The hello packet control unit 150a stores the address of the own node 100 in the LS of the hello packet. The hello packet control unit 150a stores E in the communication path table 140b in E of the hello packet.

  The downlink path construction unit 150b transmits a packet to a destination node in the upstream direction, and cooperates with the downstream path construction unit 150b of another node reaching the destination to construct a downstream path. Part. A packet transmitted to an upstream destination node for the purpose of constructing a downstream route is referred to as a route construction packet for convenience.

  FIG. 6 is a diagram illustrating an example of the data structure of the path construction packet. As shown in FIG. 6, this path construction packet has GD, GS, LS, LD, E, and FID. Among these, GD indicates a destination, and GD information of the communication path table 140b is stored. GS stores the address of the transmission source of the route construction packet. In LS, the address of the node from which the path construction packet is transferred is stored. The LD stores the address of the adjacent node that is the transfer destination of the path construction packet. E stores the number of hops. The FID stores a value that uniquely identifies the route construction packet. The downlink path construction unit 150b stores information on the transmitted path construction packet in the data management table 140c as a transmission history.

  The route search packet transmission unit 150c is a processing unit that transmits a route search packet to a destination node for the purpose of increasing route information reaching a destination node. FIG. 7 is a diagram illustrating an example of a data structure of a route search packet. As shown in FIG. 7, the route search packet has GS, GD, and search range. The GS stores the address of the node from which the route search packet is transmitted. The address of the destination node is stored in the GD. The search range stores a value indicating whether or not to transfer a route search packet. The route search packet transmitter 150c substitutes a predetermined numerical value for the search range and broadcasts the route search packet.

  When the route search packet transmission unit 150c does not receive a response from the destination node of the route search packet, the route search packet transmission unit 150c retransmits the route search packet by increasing the value assigned to the search range. For example, the route search packet transmission unit 150c retransmits the route search packet when a response is not received within a predetermined time after broadcasting the route search packet.

  The route search packet receiving unit 150d is a processing unit that, when receiving a route search packet, transmits the route search packet based on the search range of the route search packet. The route search packet receiving unit 150d includes a determination unit 151 and a transmission control unit 152.

  The determination unit 151 determines whether or not the node stored in the GD of the route search packet is included in the GD of the communication route table 140b, and outputs the determination result to the transmission control unit 152.

  The transmission control unit 152 is a processing unit that performs transmission control of a route search packet based on the determination result of the determination unit 151.

  A process of the transmission control unit 152 when the determination result of the determination unit 151 includes information indicating that the node stored in the GD of the route search packet is included in the GD of the communication route table 140b will be described. . In this case, the transmission control unit 152 returns the value of the search range of the route search packet to the original initial value and broadcasts the route search packet.

  On the other hand, the transmission control unit 152 when the determination result of the determination unit 151 includes information indicating that the node stored in the GD of the route search packet is not included in the GD of the communication route table 140b. The process will be described. In this case, the transmission control unit 152 subtracts 1 from the value of the search range of the route search packet. Then, the transmission control unit 152 broadcasts a route search packet when the subtracted search range value is larger than a predetermined threshold value. On the other hand, the transmission control unit 152 broadcasts a route search packet when the subtracted search range value is equal to or smaller than a predetermined threshold value. For example, the predetermined threshold value compared with the value of the search range is set to 0.

  By the way, when the GD of the route search packet is the own node, the transmission control unit 152 may transmit the response data to the node from which the route search packet is transmitted.

  Next, a process in which the nodes 100a to 100g and 100x to 100z of the ad hoc network transmit and receive hello packets to update the communication path table will be described. FIG. 8 is a diagram illustrating a processing procedure for path construction using hello packets. 9 to 17 are diagrams illustrating examples of the data structure of the hello packet and the data structure of the communication path table of each node.

  In FIG. 8, the node 100g transmits a hello packet to the nodes 100a, 100b, and 100x (step S10). The node 100a receives the hello packet and updates the communication path table (step S11). The node 100b receives the hello packet and updates the communication path table (step S12). The node 100c receives the hello packet and updates the communication path table (step S13).

  In FIG. 9, the hello packet 10 is a hello packet transmitted in step S10. The communication path tables 10a, 10b, and 10x are communication path tables of the nodes 100a, 100b, and 100x, respectively. “100 g” is registered in the GD of the hello packet 10, “100 g” is registered in the LS, and “0” is registered in the E.

  When the node 100a receives the hello packet 10 from the node 100g, the node 100a registers “100g” in the GD and “100g” in the LD of the communication path table 10a. Further, the node 100a stores a value “1” obtained by adding 1 to the value of E of the hello packet 10 in the communication path table 10a. The node 100b registers “100g” in the GD and “100g” in the LD of the communication path table 10b. Further, the node 100b stores a value “1” obtained by adding 1 to the value of E of the hello packet 10 in the communication path table 10b. The node 100x registers “100g” in the GD and “100g” in the LD of the communication path table 10x. Further, the node 100x stores a value “1” obtained by adding 1 to the value of E of the hello packet 10 in the communication path table 10x.

  In FIG. 8, the node 100a transmits a hello packet to the nodes 100c and 100d (step S20). The node 100c receives the hello packet and updates the communication path table (step S21). The node 100d receives the hello packet and updates the communication path table (step S22).

  In FIG. 10, the hello packet 20 is a hello packet transmitted in step S20. The communication path tables 10c and 10d are communication path tables of the nodes 100c and 100d, respectively. “100 g” is registered in the GD of the hello packet 20, “100 a” is registered in the LS, and “1” is registered in the E.

  When the node 100c receives the hello packet 20 from the node 100a, the node 100c registers “100g” in the GD of the communication path table 10c and “100a” in the LD. Further, the node 100c stores a value “2” obtained by adding 1 to the value of E of the hello packet 20 in the communication path table 10c. Further, when the node 100d receives the hello packet 20 from the node 100a, the node 100d registers “100g” in the GD of the communication path table 10d and “100a” in the LD. In addition, the node 100d stores a value “2” obtained by adding 1 to the value of E of the hello packet 20 in the communication path table 10d.

  In FIG. 8, the node 100b transmits a hello packet to the nodes 100d, 100e, and 100y (step S30). The node 100d receives the hello packet and updates the communication path table (step S31). The node 100e receives the hello packet and updates the communication path table (step S32). The node 100y receives the hello packet and updates the communication path table (step S33).

  In FIG. 11, the hello packet 30 is a hello packet transmitted in step S30. The communication path tables 10d, 10e, and 10y are communication path tables of the nodes 100d, 100e, and 100y, respectively. “100 g” is registered in the GS of the hello packet 30, “100b” is registered in the LS, and “1” is registered in the E.

  When the node 100d receives the hello packet 30 from the node 100b, the node 100d additionally registers “100g” in the GD of the communication path table 10d and “100b” in the LD. In addition, the node 100d stores a value “2” obtained by adding 1 to the value of E of the hello packet 30 in the communication path table 10d. When the node 100e receives the hello packet 30 from the node 100b, the node 100e stores “100g” in the GD of the communication path table 10e and “100b” in the LD. Further, the node 100e stores a value “2” obtained by adding 1 to the value of E of the hello packet 30 in the communication path table 10e. When the node 100y receives the hello packet 30 from the node 100b, the node 100y stores “100g” in the GD of the communication path table 10y and “100b” in the LD. Further, the node 100y stores a value “2” obtained by adding 1 to the value of E of the hello packet 30 in the communication path table 10y.

  In FIG. 8, the node 100x transmits a hello packet to the node 100y (step S35). The node 100y receives the hello packet and updates the communication path table (step S36).

  In FIG. 12, the hello packet 35 is a hello packet transmitted in step S35. The communication path table 10y is a communication path table of the node 100y. “100 g” is registered in the GS of the hello packet 35, “100x” is registered in the LS, and “1” is registered in the E.

  When the node 100y receives the hello packet 35 from the node 100x, the node 100y additionally registers “100g” in the GD of the communication path table 10y and “100x” in the LD. Further, the node 100y stores a value “2” obtained by adding 1 to the value of E of the hello packet 35 in the communication path table 10y.

  In FIG. 8, the node 100c transmits a hello packet to the nodes 100a, 100d, and 100f (step S40). The node 100a receives the hello packet and updates the communication path table (step S41). The node 100d receives the hello packet and updates the communication path table (step S42). The node 100f receives the hello packet and updates the communication path table (step S43).

  In FIG. 13, the hello packet 40 is a hello packet transmitted in step S40. The communication path tables 10a, 10d, and 10f are communication path tables of the nodes 100a, 100d, and 100f. “100 g” is registered in the GS of the hello packet 40, “100 c” is registered in the LS, and “2” is registered in the E.

  When the node 100a receives the hello packet 40 from the node 100c, the node 100a additionally registers “100g” in the GD of the communication path table 10a and “100c” in the LD. Further, the node 100a stores a value “3” obtained by adding 1 to the value of E of the hello packet 40 in the communication path table 10y. When the node 100d receives the hello packet 40 from the node 100c, the node 100d additionally registers “100g” in the GD of the communication path table 10d and “100c” in the LD. In addition, the node 100d stores a value “3” obtained by adding 1 to the value of E of the hello packet 40 in the communication path table 10d.

  When the node 100f receives the hello packet 40 from the node 100c, the node 100f additionally registers “100g” in the GD of the communication path table 10f and “100c” in the LD. Further, the node 100f stores a value “3” obtained by adding 1 to the value of E of the hello packet 40 in the communication path table 10f.

  In FIG. 8, the node 100d transmits a hello packet to the nodes 100a, 100b, 100c, 100e, and 100f (step S50). The node 100a receives the hello packet and updates the communication path table (step S51). The node 100b receives the hello packet and updates the communication path table (step S52). The node 100c receives the hello packet and updates the communication path table (step S53). The node 100e receives the hello packet and updates the communication path table (step S54). The node 100f receives the hello packet and updates the communication path table (step S55).

  In FIG. 14, the hello packet 50 is a hello packet transmitted in step S50. The communication path tables 10a, 10b, 10c, 10e, and 10f are communication path tables of the nodes 100a, 100b, 100c, 100e, and 100f. “100 g” is registered in the GS of the hello packet 50, “100 d” is registered in the LS, and “2” is registered in the E.

  When the node 100a receives the hello packet 50 from the node 100d, the node 100a additionally registers “100g” in the GD of the communication path table 10a and “100d” in the LD. Further, the node 100a stores the value “3” obtained by adding 1 to the value of E of the hello packet 50 in the communication path table 10a. When receiving the hello packet 50 from the node 100d, the node 100b additionally registers “100g” in the GD of the communication path table 10b and “100d” in the LD. Also, the node 100b stores a value “3” obtained by adding 1 to the value of E of the hello packet 50 in the communication path table 10b.

  When the node 100c receives the hello packet 50 from the node 100d, the node 100c additionally registers “100g” in the GD of the communication path table 10c and “100d” in the LD. Further, the node 100c stores a value “3” obtained by adding 1 to the value of E of the hello packet 50 in the communication path table 10c. When the node 100e receives the hello packet 50 from the node 100d, the node 100e additionally registers “100g” in the GD of the communication path table 10e and “100d” in the LD. Further, the node 100e stores a value “3” obtained by adding 1 to the value of E of the hello packet 50 in the communication path table 10e. When the node 100f receives the hello packet 50 from the node 100d, the node 100f additionally registers “100g” in the GD of the communication path table 10f and “100d” in the LD. In addition, the node 100f stores a value “3” obtained by adding 1 to the value of E of the hello packet 50 in the communication path table 10f.

  In FIG. 8, the node 100e transmits a hello packet to the nodes 100b, 100d, and 100f (step S60). The node 100b receives the hello packet and updates the communication path table (step S61). The node 100d receives the hello packet and updates the communication path table (step S62). The node 100f receives the hello packet and updates the communication path table (step S63).

  In FIG. 15, the hello packet 60 is a hello packet transmitted in step S60. The communication path tables 10b, 10c, and 10f are communication path tables of the nodes 100b, 100c, and 100f. “100 g” is registered in the GS of the hello packet 60, “100 e” is registered in the LS, and “3” is registered in the E.

  When the node 100b receives the hello packet 60, the node 100b additionally registers “100g” in the GD of the communication path table 10b and “100e” in the LD. Further, the node 100b stores a value “4” obtained by adding 1 to the value of E of the hello packet 60 in the communication path table 10b. When the node 100c receives the hello packet 60, the node 100c additionally registers “100g” in the GD of the communication path table 10c and “100e” in the LD. Further, the node 100c stores a value “4” obtained by adding 1 to the value of E of the hello packet 60 in the communication path table 10c. When the node 100f receives the hello packet 60, the node 100f additionally registers “100g” in the GD and “100e” in the LD of the communication path table 10f. Further, the node 100f stores a value “4” obtained by adding 1 to the value of E of the hello packet 60 in the communication path table 10f.

  In FIG. 8, the node 100y transmits a hello packet to the nodes 100b, 100x, and 100z (step S70). The node 100b receives the hello packet and updates the communication path table (step S71). The node 100x receives the hello packet and updates the communication path table (step S72). The node 100z receives the hello packet and updates the communication path table (step S73).

  In FIG. 16, a hello packet 70 is a hello packet transmitted in step S70. The communication path tables 10b, 10x, and 10z are communication path tables of the nodes 100b, 100x, and 100z. “100g” is registered in the GS of the hello packet 70, “100y” is registered in the LS, and “2” is registered in the E.

  When the node 100b receives the hello packet 70, the node 100b additionally registers “100g” in the GD and “100y” in the LD of the communication path table 10b. Further, the node 100b stores a value “3” obtained by adding 1 to the value of E of the hello packet 70 in the communication path table 10b. When the node 100x receives the hello packet 70, the node 100x additionally registers “100g” in the GD and “100y” in the LD of the communication path table 10x. Further, the node 100x stores a value “3” obtained by adding 1 to the value of E of the hello packet 70 in the communication path table 10x. When the node 100z receives the hello packet 70, the node 100z additionally registers “100g” in the GD of the communication path table 10z and “100y” in the LD. Further, the node 100z stores a value “3” obtained by adding 1 to the value of E of the hello packet 70 in the communication path table 10z.

  In FIG. 8, the node 100f transmits a hello packet to the nodes 100c, 100d, and 100e (step S80). The node 100c receives the hello packet and updates the communication path table (step S81). The node 100d receives the hello packet and updates the communication path table (step S82). The node 100e receives the hello packet and updates the communication path table (step S83).

  In FIG. 17, a hello packet 80 is a hello packet transmitted in step S80. The communication path tables 10c, 10d, and 10e are communication path tables of the nodes 100c, 100d, and 100e. “100g” is registered in the GS of the hello packet 80, “100f” is registered in the LS, and “3” is registered in the E.

  When the node 100c receives the hello packet 80, the node 100c additionally registers “100g” in the GD of the communication path table 10c and “100f” in the LD. Further, the node 100b stores a value “4” obtained by adding 1 to the value of E of the hello packet 80 in the communication path table 10c. When the node 100d receives the hello packet 80, the node 100d additionally registers “100g” in the GD of the communication path table 10d and “100f” in the LD. In addition, the node 100d stores a value “4” obtained by adding 1 to the value of E of the hello packet 80 in the communication path table 10d. When the node 100e receives the hello packet 80, the node 100e additionally registers “100g” in the GD and “100f” in the LD of the communication path table 10e. Also, the node 100e stores a value “4” obtained by adding 1 to the value of E of the hello packet 80 in the communication path table 10e.

  As described above, each of the nodes 100a to 100g and 100x to 100z executes the process as shown in FIG. 8, thereby updating each communication path table as shown in FIGS. The communication path tables shown in FIGS. 9 to 17 correspond to the communication path table 140b shown in FIG.

  Next, a process in which the nodes 100a to 100g and 100x to 100z of the ad hoc network transmit / receive a path construction packet and update the communication path table will be described. FIG. 18 to FIG. 21 are diagrams for explaining route construction processing using a route construction packet.

  First, as shown in FIG. 18, a case where a route construction packet is transmitted from the node 100f and transferred in the order of the nodes 100d, 100a, and 100g will be described. Further, FIG. 19 shows the contents of the path construction packet and the path construction packet of each node at that time. In FIG. 19, 10f, 10d, 10a, and 10g are communication path tables of the nodes 100f, 100d, 100a, and 100g.

  For example, the node 100f selects the second level of the communication path table 10f. The node 100f stores the GD “100g” and the LD “100d” of the communication path table 10f in the GD and LD of the path construction packet 85a. Further, the node 100f stores the address of its own node in the GS and LS of the path construction packet 85a. Further, the node 100f stores “0” in E, and registers a value “1” for identifying the path construction packet 85a in the FID.

  The node 100f transmits the path construction packet 85a to the node 100d. The node 100d registers the GS and LS of the path construction packet 85a in the GD and LD of the communication path table 10d. Further, the node 100d registers a value “1” obtained by adding 1 to E of the route construction packet 85a in E of the communication route table 10d (step S85a).

  The node 100d stores the GD “100g” and the GS “100f” of the route construction packet 85a in the GD and GS of the route construction packet 85b. Further, the node 100d stores its own node in the LS of the path construction packet 85b. The node 100d stores “100a” as the transfer destination in the LD of the path construction packet 85b. Further, the node 100d stores a value “1” obtained by adding 1 to E of the previous route construction packet 85a in E of the route construction packet 85b. The node 100d registers the value “1” in the FID.

  The node 100d transmits the path construction packet 85b to the node 100a. The node 100a registers the GS and LS of the path construction packet 85b in the GD and LD of the communication path table 10a. Further, the node 100a registers a value “2” obtained by adding 1 to E of the route construction packet 85b in E of the communication route table 10a (step S85b).

  The node 100a stores the GD “100g” and the GS “100f” of the route search packet 85b in the GD and GS of the route construction packet 85c. Further, the node 100a stores its own node in the LS of the path construction packet 85c. The node 100a stores “l00g” as the transfer destination in the LD of the path construction packet 85c. Also, the node 100a stores a value “2” obtained by adding 1 to E of the previous route construction packet 85a in E of the route construction packet 85c.

  The node 100a transmits the path construction packet 85c to the node 100g. The node 100g registers the GS and LS of the path construction packet 85c in the GD and LD of the communication path table 10g. Further, the node 100g registers a value “3” obtained by adding 1 to E of the route construction packet 85c in E of the communication route table 10g (step S85c).

  Thus, by executing the processing of steps S85a to 85c, the node 100g can obtain a communication path for the destination “100f”.

  Next, as shown in FIG. 20, a case where a path construction packet is transmitted from the node 100f and transferred in the order of the nodes 100e, 100d, 100b, and 100g will be described. However, since the transfer of the path construction packet from the node 100e to the node 100b has failed, the path construction packet is transferred from the node 100e to the node 100b via the node 100d.

  In FIG. 21, 10f, 10e, 10d, 10b, and 10g are communication path tables of the nodes 100f, 100e, 100d, 100b, and 100g. For example, the node 100f selects the third level of the communication path table 10f. The node 100f stores the GD “100g” and the LD “100e” of the communication path table 10f in the GD and LD of the path construction packet 86a. Further, the node 100f stores the address of its own node in the GS and LS of the path construction packet 86a. Further, the node 100f stores 0 in E, and registers a value “2” for identifying the path construction packet 85a in the FID.

  The node 100f transmits the path construction packet 86a to the node 100e. The node 100e registers the GS and LS of the path construction packet 86a in the GD and LD of the communication path table 10e. Further, the node 100f registers a value “1” obtained by adding 1 to E of the route construction packet 86a in E of the communication route table 10e (step S86a).

  The node 100e stores the GD “100g” and the GS “100f” of the route construction packet 86a in the GD and GS of the route construction packet 86b. Further, the node 100e stores its own node in the LS of the path construction packet 86b. The node 100e stores “l00b” as the transfer destination in the LD of the path construction packet 86b. Further, the node 100e stores a value “1” obtained by adding 1 to E of the previous route construction packet 86a in E of the route construction packet 86b.

  The node 100e transfers the path construction packet 86b to the node 100b, but the transfer fails. Thus, when the transfer fails, the communication path is switched. For example, the node 100e creates a route construction packet 86c in which the LD of the route construction packet 86b is changed to “100d”, and transmits the route construction packet 86c to the node 100d.

  The node 100d receives the route construction packet 86c, and registers the GS and LS of the route construction packet 86c in the GD and LD of the communication route table 10d. Further, the node 100d registers a value “2” obtained by adding 1 to E of the route construction packet 86c in E of the communication route table 10d (step S86b).

  The node 100d stores the GD “100g” and the GS “100f” of the route search packet 86c in the GD and GS of the route construction packet 86d. Further, the node 100d stores its own node in the LS of the path construction packet 86d. The node 100d stores “100b” as the transfer destination in the LD of the path construction packet 86c. Further, the node 100d stores a value “2” obtained by adding 1 to E of the previous route construction packet 86c in E of the route construction packet 86d. The node 100d transmits the path construction packet 86d to the node 100b.

  The node 100b receives the path construction packet 86d, and registers the GS and LS of the path construction packet 86d in the GD and LD of the communication path table 10b. Further, the node 100b registers a value “3” obtained by adding 1 to E of the route construction packet 86b in E of the communication route table 10b (step S86c).

  The node 100b stores the GD “100g” and the GS “100f” of the route search packet 86d in the GD and GS of the route construction packet 86e. Further, the node 100b stores its own node in the LS of the path construction packet 86e. The node 100b stores “100 g” as the transfer destination in the LD of the path construction packet 86e. Further, the node 100b stores a value “3” obtained by adding 1 to E of the previous path construction packet 86d in E of the path construction packet 86e. The node 100b transmits a route construction packet 86e to the node 100g.

  The node 100g receives the route construction packet 86e, and registers the GS and LS of the route construction packet 86e in the GD and LD of the communication route table 10g. Further, the node 100g registers a value “4” obtained by adding 1 to E of the route construction packet 86e in E of the communication route table 10g (step S86d).

  Thus, by executing the processing of steps S86a to 86d, the node 100g can obtain a new communication accounting for the destination “100f”.

  Next, a process in which the nodes 100a to 100g and 100x to 100z of the ad hoc network transmit a route search packet will be described. However, the process of transmitting the route search packet is executed after the transmission / reception of the hello packet shown in FIG. 8 and the transmission / reception of the route construction packet shown in FIG.

  Next, a route search packet transfer process will be described. 22 to 29 are diagrams for explaining the route search packet forwarding process. Here, as an example, a case will be described in which the node 100g broadcasts a route search packet by storing the address of the node 100f in the GD of the route search packet. In FIG. 22, the node 100g broadcasts a route search packet, and the nodes 100a, 100b, and 100x receive the route search packet (step S90).

  The route search packet transmitted in step S91 will be described. As illustrated in FIG. 23, the node 100g stores the address of the node 100g in the GS of the route search packet 90, and stores the address of the node 100f in the GD. Further, the node 100g sets the initial value 1 to the search range of the route search packet 90 and broadcasts the route search packet 90.

  In FIG. 22, the node 100a broadcasts a route search packet, and the nodes 100c and 100d receive the route search packet (step S91).

  The route search packet transmitted in step S91 will be described. As shown in FIG. 24, the GD of the communication path table 10a includes the address of the node 100f. For this reason, the node 100a sets the search range of the route search packet 90 to an initial value of 1, and broadcasts the route search packet 90.

  In FIG. 22, the node 100b broadcasts a route search packet, and the nodes 100d, 100e, and 100y receive the route search packet (step S92).

  The route search packet transmitted in step S92 will be described. As shown in FIG. 25, the GD of the communication path table 10b includes the address of the node 100f. For this reason, the node 100b sets the search range of the route search packet 90 to an initial value of 1, and broadcasts the route search packet 90.

  In FIG. 22, the node 100x broadcasts a route search packet, and the node 100y receives the route search packet (step S93).

  The route search packet transmitted in step S93 will be described. As illustrated in FIG. 26, the GD of the communication path table 10x does not include the address of the node 100f. Therefore, the node 100x subtracts 1 from the search range of the route search packet. Since the value of the search range is 0 or more, the node 100x broadcasts the route search packet 90.

  Further, as shown in FIG. 26, the GD of the communication path table 10y does not include the address of the node 100f. For this reason, the node 100y subtracts 1 from the search range of the route search packet. Since the value of the search range is less than 0, the node 100f stops forwarding the route search packet 90.

  In FIG. 22, the node 100y broadcasts the route search packet received from the node 100b, and the node 100z receives the route search packet (step S94).

  The route search packet transmitted in step S94 will be described. As shown in FIG. 27, the GD of the communication path table 10y does not include the address of the node 100f. For this reason, the node 100y subtracts 1 from the search range of the route search packet. Since the value of the search range is 0 or more, the node 100y broadcasts the route search packet 90.

  As shown in FIG. 27, the GD of the communication path table 10z does not include the address of the node 100f. Therefore, the node 100z subtracts 1 from the search range of the route search packet. Since the value of the search range is less than 0, the node 100z stops forwarding the route search packet.

  In FIG. 22, the node 100d broadcasts the route search packet received from the node 100a, and the nodes 100c, 100e, and 100f receive the route search packet (step S95).

  The route search packet transmitted in step S95 will be described. As shown in FIG. 28, the address of the node 100f is included in the GD of the communication path table 10d. For this reason, the node 100d sets the search range of the route search packet 90 to an initial value of 1, and broadcasts the route search packet 90.

  In FIG. 22, the node 100c broadcasts the route search packet received from the node 100d, and the node 100f receives the route search packet. The node 100e broadcasts the route search packet received from the node 100d, and the node 100f receives the route search packet (step S96).

  The route search packet transmitted in step S96 will be described. As shown in FIG. 29, the GD of the communication path table 10e includes the address of the node 100f. For this reason, the node 100e sets the search range of the route search packet 90 to an initial value of 1, and broadcasts the route search packet 90.

  As shown in FIG. 29, the GD of the communication path table 10c does not include the address of the node 100f. Therefore, the node 100c subtracts 1 from the search range of the route search packet. Since the value of the search range is 0 or more, the node 100c broadcasts the route search packet 90.

  In step S96, the node 100f receives the route search packet addressed to itself. In this case, the node 100f transmits a response packet addressed to the node 100g.

  Next, a processing procedure when the node 100 receives a hello packet will be described. FIG. 30 is a flowchart illustrating the processing procedure of the hello packet reception processing. The process shown in FIG. 30 is executed when a hello packet is received, for example. The process shown in FIG. 30 corresponds to the process of the hello packet control unit 150a.

  As illustrated in FIG. 30, when the node 100 has not received a hello packet (No in step S101), the process ends. On the other hand, when the node 100 receives the hello packet (step S101, Yes), the node 100 determines whether information is included in the hello packet (step S102).

  If the information is not included in the hello packet (step S102, No), the node 100 ends the process. On the other hand, when information is included in the hello packet (step S102, Yes), the node 100 determines whether the GS or LS is its own address (step S103).

  If the GS or LS is the self address (step S103, Yes), the node 100 ends the process. On the other hand, when GS or LS is not its own address (step S103, No), the node 100 creates a new record in the work table 140a (step S104).

  The node 100 sets the GS of the hello packet in the GD of the work table 140a (step S105), and sets the LS of the hello packet in the LD of the work table 140a (step S106). The node 100 sets a value obtained by adding 1 to E of the hello packet to E of the work table 140a (step S107).

  When the same GS and LD records do not exist in the communication path table 140b (No at Step S108), the node 100 newly adds the record created in the work table to the communication path table (Step S110), and performs processing. finish. On the other hand, when the same GS and LD records do not exist in the communication path table 140b (step S108, No), the node 100 newly adds the record created in the work table 140a to the communication path table 140b (step S110). ). On the other hand, when the same GS and LD records exist in the communication path table 140b (step S108, Yes), the node 100 overwrites it (step S109).

  Next, a processing procedure when the node 100 transmits a hello packet will be described. FIG. 31 is a flowchart showing the processing procedure of the hello packet transmission processing. The process illustrated in FIG. 31 is executed, for example, when a clock event occurs. The process shown in FIG. 31 corresponds to the process of the hello packet control unit 150a.

  As illustrated in FIG. 31, when the clock event has not occurred (No in step S150), the node 100 ends the process. On the other hand, when a clock event has occurred (step S150, Yes), the node 100 determines whether information exists in the communication path table 140b (step S151).

  If no information exists in the communication path table (step S151, No), the node 100 ends the process. On the other hand, when information exists in the communication path table (step S151, Yes), the node 100 extracts a record in which GS is the address of the GW from the communication path table 140b (step S152). If the GW is the node 100g, the node 100 extracts a record in which the GS is the address of the node 100g.

  The node 100 sets the GD of the communication path table 140b to the GS of the hello packet (step S153), and sets the LD of the communication path table 140b to the LS of the hello packet (step S154).

  The node 100 sets E of the communication path table to E of the hello packet (step S155), and transmits the hello packet (step S156).

  Next, transmission processing of a route construction packet when the node 100 constructs a downlink route will be described. FIG. 32 is a flowchart illustrating a processing procedure of a route construction packet transmission process. The process illustrated in FIG. 32 is executed, for example, when a clock event occurs. The process illustrated in FIG. 32 corresponds to the process of the downlink path construction unit 150b.

  As illustrated in FIG. 32, when the desired GD does not exist in the communication path table 140b (No in Step S201), the node 100 ends the process. On the other hand, when the desired GD exists (step S201, Yes), the node 100 determines whether there is a transfer destination that can be transmitted to the communication path table 140b based on the data management table 140c (step S201). Step S202).

  If there is no transfer destination that can be transmitted to the communication path table 140b based on the data management table 140c (step S202, No), the node 100 ends the process. On the other hand, when there is a transfer destination that can be transmitted in the communication path table 140b (Yes in step S202), the node 100 extracts an unsent upper record in the communication path table (step S203).

  If the node 100 is not GS (No at Step S204), the node 100 sets the GD of the record to the GD of the route construction packet (Step S205). The node 100 sets the GS of the record to the GS of the route construction packet (step S206), sets the E of the record to E of the route construction packet (step S207), and proceeds to step S211.

  On the other hand, when the node 100 is GS (step S204, Yes), the node 100 sets the address of the destination node in the GD of the route construction packet (step S208). The node 100 sets the address of the node itself in the GS of the route construction packet (step S209), and sets the upper E of the communication route table 140b to E of the route construction packet (step S210).

  The node 100 sets the upper LD of the communication path table 140b to the LD of the path construction packet (step S211), and sets a unique numerical value to the FID of the path construction packet (step S212). The node 100 sets the address of the node itself in the LS of the path construction packet (step S213), records the contents of the path construction packet in the data management table 140c (step S214), and transmits the path construction packet (step S215). .

  Next, the route construction packet reception process when the node 100 constructs a downlink route will be described. FIG. 33 is a flowchart of a process procedure of a path construction packet reception process. The process illustrated in FIG. 33 is executed, for example, when a route construction packet is received. The process shown in FIG. 33 corresponds to the process of the downlink path construction unit 150b.

  As illustrated in FIG. 33, when the node 100 has not received the route construction packet (No in step S250), the process ends. On the other hand, when the node 100 receives the route construction packet (step S250, Yes), the node 100 newly creates a record in the work table 140a (step S251).

  The node 100 sets the GS of the path construction packet in the GD of the work table 140a (step S252), and sets the LS of the path construction packet in the LD of the work table 140a (step S253).

  The node 100 sets a value obtained by adding 1 to E of the route construction packet in E of the work table 140a (step 254). If the same GS and LD records exist in the communication path table 140b (step S255, Yes), the node 100 overwrites them (step S256). On the other hand, when the same GS and LD records do not exist in the communication path table 140b (step S255, No), the node 100 newly adds the record created in the work table 140a to the communication path table (step S257). .

  Next, the process performed by the node 100 for the route search packet will be described. FIG. 34 is a flowchart showing the processing procedure of the route search packet. The process shown in FIG. 34 is executed when a route search request is received or a route search packet is received, for example. The process illustrated in FIG. 34 corresponds to the process of the route search packet transmission unit 150c and the route search packet reception unit 150d.

  As shown in FIG. 34, when there is a route search request (step S301, Yes), the address of the own node is set in the GS of the route search packet (step S302). The node 100 sets the target node in the GD of the route search packet (step S303).

  The node 100 sets an initial value of the search range in the search range of the route search packet (step S304). For example, the node 100 sets 1 as the initial value of the search range. When the search range is 0 or more (step S305, Yes), the node 100 transmits a route search packet (step S306). On the other hand, when the search range is less than 0 (step S305, No), the node 100 ends the process.

  By the way, when there is no route search request (No in step S301), the node 100 determines to transfer the route search packet (step S307). The node 100 uses the GD and GS of the route search packet as they are (step S308), and when the GD exists in the communication route table 140b (step S309, Yes), the node 100 proceeds to step S304.

  On the other hand, when the GD does not exist in the communication route table 140b (No at Step S309), the node 100 sets a value obtained by subtracting 1 from the existing search range value in the search range of the route search packet (Step S309). S310), the process proceeds to step S305.

  Next, the effect of the node 100 according to the present embodiment will be described. When the node 100 receives the communication route search packet, the node 100 determines whether the address of the node corresponding to the GD of the communication route search packet is registered in the GD of the communication route table 140b. The node 100 broadcasts the communication route search packet when the address of the node corresponding to the GD of the communication route search packet is registered in the GD of the communication route table 140b. On the other hand, when the node address corresponding to the GD of the communication path search packet is not registered in the GD of the communication path table 140b, the node 100 subtracts the value of the search range of the communication path terminal packet. . The node 100 broadcasts a communication route search packet when the value of the subtracted search range is 0 or more. For this reason, the communication route search packet is not transferred in the direction other than the destination, but is transferred in the direction of the destination. Therefore, the node 100 can narrow down the transmission range of the route search packet optimally when constructing the communication route.

  Further, the node 100 resets the search range of the communication route search packet to the initial value when the address of the node corresponding to the GD of the communication route search packet is registered in the GD of the communication route table 140b. For this reason, the communication route search packet can be reached even when the communication route to the destination node has only a detour route.

  If the node 100 does not receive a response from the destination node of the communication route search packet after transmitting the communication route search packet, the node 100 increases the search range of the communication route search packet by a predetermined value and retransmits it. For this reason, the communication route search packet can be more reliably reached the destination node.

  By the way, each component of the node 100 is functionally conceptual and does not necessarily need to be physically configured as illustrated. That is, the specific form of the node 100 is not limited to the illustrated one, and can be configured to be functionally or physically distributed / integrated in arbitrary units according to various loads and usage conditions. For example, the functions of the processing units 150a to 150d in FIG.

  The functions of the node 100 shown in the above embodiment can be realized by mounting each function corresponding to the node in an information processing apparatus such as a known PC (Personal Computer) or PDA (Personal Digital Assistants). FIG. 35 is a diagram illustrating a hardware configuration of a computer constituting the node.

  As shown in FIG. 35, the computer 300 includes a CPU 301 that executes various arithmetic processes, an input device 302 that receives input of data from the user, and a display 303. The computer 300 also includes a reading device 304 that reads a program and the like from a storage medium, and an interface device 305 for connecting to other devices. The computer 300 also includes a wireless communication device 306 that is wirelessly connected to other devices, a RAM 307 that temporarily stores various types of information, and a hard disk device 308. Each device 301 to 308 is connected to a bus 309.

  The hard disk device 308 stores various programs such as a determination program and a transmission control program.

  The CPU 301 reads each program stored in the hard disk device 308, develops it in the RAM 307, and performs various processes. Also, these programs can cause the computer to function as the determination unit 151 and the transmission control unit 152 in FIG.

  Note that the above program need not necessarily be stored in the hard disk device 308. For example, the computer 300 may read and execute a program stored in a storage medium such as a CD-ROM. Each program may be stored in a storage device connected to a public line, the Internet, a LAN (Local Area Network), a WAN (Wide Area Network), or the like. In this case, the computer 300 may read and execute each program from these.

100a, 100b, 100c, 100d, 100e, 100f, 100g, 100x, 100y, 100z Node 110 Wireless communication unit 120 Input unit 130 Display unit 140 Storage unit 150 Control unit

Claims (6)

When a packet having information on a wireless communication terminal to be searched and a value indicating a search range is received, a communication route table including a route of the destination is referred to, and the search target is set at the destination of the communication route table. A determination unit that determines whether or not a wireless communication terminal is included;
Based on the determination result of the determination unit, when the wireless communication terminal to be searched is included in the destination of the communication path table, the packet is transmitted to an adjacent wireless communication terminal,
If the destination of the communication path table does not include the wireless communication terminal to be searched, a predetermined value is subtracted from the value indicating the search range, and the value indicating the search range is equal to or greater than a predetermined threshold value In this case, a wireless communication terminal comprising: a transmission control unit that transmits the packet to an adjacent wireless communication terminal.   When the destination of the communication path table includes the wireless communication terminal to be searched, the transmission control unit resets the value of the search range included in the packet to an initial value, The wireless communication terminal according to claim 1, wherein the packet is transmitted to an adjacent wireless communication terminal. A path construction method executed by a computer,
When a packet having information on a wireless communication terminal to be searched and a value indicating a search range is received, a communication route table including a route of the destination is referred to, and the search target is set at the destination of the communication route table. If the wireless communication terminal is included, the packet is transmitted to the adjacent wireless communication terminal,
If the destination of the communication path table does not include the wireless communication terminal to be searched, a predetermined value is subtracted from the value indicating the search range, and the value indicating the search range is equal to or greater than a predetermined threshold value In the case of (1), a route construction method characterized by transmitting the packet to an adjacent wireless communication terminal.   When the destination of the communication path table includes the wireless communication terminal to be searched, the search range value included in the packet is reset to the initial value, and the packet is adjacent to the wireless communication terminal. The route construction method according to claim 3, wherein the route construction method transmits to a terminal. The first wireless communication terminal transmits a packet having information on the wireless communication terminal to be searched and a value indicating the search range,
When the second wireless communication terminal receives the packet, the communication route table including the route of the destination is referred to, and the wireless communication terminal to be searched is included in the destination of the communication route table If so, send the packet to the adjacent wireless communication terminal,
If the destination of the communication path table does not include the wireless communication terminal to be searched, a predetermined value is subtracted from the value indicating the search range, and the value indicating the search range is equal to or greater than a predetermined threshold value In the case of (1), a route construction method characterized by transmitting the packet to an adjacent wireless communication terminal.   When the first wireless communication terminal does not receive the packet response from the wireless communication terminal to be searched, the first wireless communication terminal adds a predetermined value to the search range value of the packet, and retransmits the packet. The route construction method according to claim 5.

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