JP2005143001A - Communication terminal and communication network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication terminal and a communication network in which stable communication can be ensured, radio interference can be suppressed and network resources can be effectively utilized. <P>SOLUTION: In routing control over an ad hoc network, priority is set to a plurality of paths constructed between a source terminal and a destination terminal and when a packet is received, each of relay terminals comprising a path of the highest priority, immediately relays and transmits the packet, but each of relay terminals comprising paths of the low priority, temporarily waits the relay and transmission even when a packet is received, and monitors for a fixed time whether or not the path of the high priority relays and transmits the packet. When it can not be detected within the time that the path of the high priority relays and transmits the packet, it is judged that any fault occurs on the path of the high priority. The packet waited in the present terminal is then relayed and transmitted but when it can be detected that the path of the high priority relays and transmits the packet, the packet waited in the present terminal is not relayed/transmitted but is discarded. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a communication network such as an ad hoc network constituted by a plurality of communication terminals, and a communication terminal constituting the communication network, and more particularly to a routing technique in the communication network.

  In an ad hoc network, each terminal in the network has a router function, and a communication path is formed by an appropriate terminal (relay terminal) between the source terminal and the destination terminal. By relaying the packet transmitted from the terminal to the destination terminal, communication between the source terminal and the destination terminal is performed. The routing technique in such an ad hoc network includes a single path routing technique (for example, refer to Non-Patent Document 1) for communicating by forming one communication path, and wireless instability by forming a plurality of communication paths. There is a multi-path routing technique (see Non-Patent Document 2, for example) that enables continuation of communication using another path even when a simple path is disconnected and ensures the stability of communication.

“Ad hoc On-Demand Distance Vector (AODV) Routing”, Internet URL: <http://www.ietf.org/rfc/rfc3561.txt> ([October 16, 2003 search]) “On-demand Multipath Distance Vector Routing in AD Hoc Networks”, Internet URL: <http://www.cs.sunysb.edu/~samir/Pubs/icnp-01.pdf> ([October 16, 2003 Search])

  However, in the case of performing communication using the conventional single path routing technique, there is a problem that communication is likely to be disconnected or unstable due to movement of the relay terminal. In addition, when communicating using the above-described conventional multipath routing technology, a plurality of routes are formed by running endlessly and vertically between the source terminal and the destination terminal, and packets between adjacent terminals are almost at the same timing. Since many packets from neighboring terminals will be forwarded indefinitely and horizontally at the same timing, stable communication using multiple paths should be possible, but as a result The radio waves of the terminals interfere with each other (wireless collision, Collision), and this wireless interference causes a problem of packet loss and communication delay. Furthermore, although the conventional multipath routing technique consumes a large amount of network resources, there is a problem that using the conventional multipath routing technique when the communication is stable is a waste of network resources.

  The present invention has been made to solve such a conventional problem, and provides a communication terminal and a communication network that can secure stable communication, can suppress radio interference, and can effectively use network resources. The purpose is to do.

The communication terminal of the present invention
A communication means for transmitting and receiving packets to and from other communication terminals constituting the communication network;
Analyzing means for analyzing shortest path information between the source terminal and the destination terminal from the packet received by the communication means;
It is determined whether or not the own terminal is included in the information in the shortest path, and if the own terminal is included in the shortest path information, the packet is immediately relayed from the communication means, and the own terminal If not included in the shortest path information, determination means for temporarily waiting the packet;
Standby setting means for setting a holding time for causing the terminal to wait for the packet;
The packet held by the determination unit is held until the holding time elapses, and it is monitored whether the same packet as the packet is relayed by another communication terminal until the holding time elapses. In the meantime, if the same packet is relayed and transmitted by the other communication terminal, the held packet is discarded, and the same packet is relayed and transmitted by the other communication terminal even if the holding time elapses. If not, packet monitoring means for relaying and transmitting the held packet from the communication means is provided.

In addition, another communication terminal of the present invention,
A communication means for transmitting and receiving packets to and from other communication terminals constituting the communication network;
Analysis means for analyzing a source address, a destination address, an ID of a neighboring terminal that has sent the packet, an ID of the packet, PDV information, and ODV information from the packet received by the communication means; ,
For each destination terminal ID, the ID of one PDV (Primary Distance Vector) terminal that immediately relays and transmits the packet relayed by the terminal, and one or more ODVs that temporarily wait for the packet relayed by the terminal (Other Distance Vector) DV holding means for holding the terminal ID,
Whether the packet is the first received packet is determined based on the packet ID. If the packet is the first received packet, the source address is set as the destination terminal ID and the neighborhood The DV holding means holds the terminal ID as the PDV terminal ID, and if the packet is the same packet as the packet already received, the source address is set as the destination terminal ID and the neighboring terminal ID is set as ODV. DV creation means to be held in the DV holding means as the terminal ID;
It is determined whether the own terminal is a PDV terminal included in the PDV information, an ODV terminal included in the ODV information, or neither the PDV terminal nor the ODV terminal, and the own terminal is a PDV terminal. If there is, the packet is immediately relayed from the communication means. If the terminal is an ODV terminal, the packet is temporarily held. If the terminal is neither a PDV terminal nor an ODV terminal, the packet is discarded. Determination means to perform,
Standby setting means for setting a holding time for holding the packet in the terminal;
The packet held by the determination unit is held until the holding time elapses, and it is monitored whether the same packet as the packet is relayed by another communication terminal until the holding time elapses. In the meantime, if the same packet is relayed and transmitted by the other communication terminal, the held packet is discarded, and the same packet is relayed and transmitted by the other communication terminal even if the holding time elapses. If there is no packet monitoring means for relaying the held packet from the communication means,
The destination address is set as the destination terminal ID, and for the destination terminal ID, one PDV terminal ID held in the DV holding means is set as new PDV information and held in the DV holding means. One or more ODV terminal IDs as new ODV information are used, and the previous PDV information and the previous ODV information of the packet relayed from the communication means are updated to the new PDV information and the new ODV information. And DV information updating means.

The communication network of the present invention is
In a communication network composed of a plurality of communication terminals each having a router function,
Set priorities for multiple paths built between the source and destination terminals,
The relay terminal that configures the path with the highest priority relays the received packet immediately,
In the relay terminal configuring the low priority path, the received packet is temporarily waited to monitor whether the high priority path relays the packet for a certain period of time. If the relay transmission of the high priority path cannot be detected, the received packet is relayed. If the relay transmission of the high priority path is detected, the received packet is discarded. Features.

  According to the present invention, by setting priorities to a plurality of paths, a main path is constructed by a communication terminal having the highest priority, and the main path is defined as a space by a communication terminal having a lower priority than that. Therefore, it is possible to construct a backup path separated from each other in terms of time and time, so that stable communication can be ensured, radio interference can be suppressed, and network resources can be effectively used.

  In each embodiment of the present invention described below, in routing control in an ad hoc network, priority is set for a plurality of paths established between a source terminal and a destination terminal, and the path with the highest priority is set. The relay terminal that configures relays the packet immediately after receiving the packet, and the relay terminal that configures the low priority path temporarily waits for relay transmission even after receiving the packet, and the high priority path is Whether or not the packet has been relayed is monitored for a certain period of time, and if the relay transmission of the high priority path is not detected within the time, it is determined that some failure has occurred in the high priority path. When relay transmission of a packet waiting on its own terminal is detected and relay transmission of the above high priority path is detected, the packet waiting on its own terminal is relayed and transmitted. Characterized in that it discarded without. In this way, only when the relay transmission of the highest priority path fails, the relay transmission of the low priority path can suppress radio wave interference between adjacent terminals and effectively use network resources. .

Embodiment 1
The first embodiment of the present invention is based on a source routing method (a method of transmitting a packet by adding path information designating a path to be passed at the time of data transmission), and includes a source terminal and a destination terminal. When communicating with each other, a multipath is constructed by the following procedures 1) to 5).

  1) In order to confirm that the source terminal and the destination terminal can communicate with each other, the source terminal advertises the position of its own terminal by flooding and requests communication with the destination terminal. At this time, each terminal in the network relays the flooded packet with its own terminal ID added. The destination terminal that has received the flooding packet can find the shortest path from its own terminal to the source terminal based on the ID of the added via terminal.

  2) The destination terminal that has received the flooding from the source terminal advertises the position of the terminal itself by flooding and returns a response to the source terminal. At this time, each terminal in the network adds the ID of its own terminal and relays the flood packet of the response. The source terminal receiving the reply flood packet can find the shortest path from its own terminal to the destination terminal based on the ID of the added via terminal.

  3) Through the above-described flooding transmission / reception operation, the source terminal and the destination terminal confirm that communication is possible, and the shortest path between the source terminal and the destination terminal and the terminals constituting the shortest path Get an ID.

  4) The source terminal adds the path information listing the terminal IDs on the shortest path to the packet and transmits it.

  5) The terminal that has received the packet determines whether or not the terminal is the terminal included in the path information (= the terminal that forms the shortest path), and if it is included in the path information, the received packet Is relayed immediately, and if it is not included in the path information, it waits for relay transmission for a certain period of time, monitors whether or not relay transmission has been performed by the terminal on the shortest path, and by the other terminal within the certain time If relay transmission can be detected, the waiting packet is discarded, and if the relay transmission by the other terminal cannot be detected within the predetermined time, the standby packet is relayed.

  In the above procedure 5), whether or not relay transmission is performed by the terminal on the shortest path is determined by whether or not the same packet as the waiting packet is received within the predetermined time. If the same packet as the waiting packet is received within the time, it is determined that relay transmission has been performed by the terminal on the shortest path, both packets are discarded, and the same packet as the waiting packet is received within the time. If the packet is not received at the same time, it is determined that the relay transmission has not been performed by the terminal on the shortest path, and the standby packet is relayed and transmitted.

  FIG. 1 is a configuration diagram of a radio communication terminal according to Embodiment 1 of the present invention. The terminal according to the first embodiment includes a communication unit 1, a packet analysis unit 2A, a packet generation unit 3A, a packet monitoring unit 4A, and a device 5A for shifting time.

[Communication unit 1]
The communication unit 1 wirelessly communicates with other terminals in the network, and transmits / receives packets to / from these other terminals.

[Packet analysis unit 2A]
The packet analysis unit 2A analyzes the packet received by the communication unit 1. The packet analysis unit 2A further performs the following two analysis processes a) and b).

  a) Analyzing the source address as the destination terminal ID from the packet to which the ID of the transit terminal received by the communication unit 1 is added, and analyzing the ID of the transit terminal, the ID of the destination terminal and the transit terminal Path information (terminal ID information (terminal information via the shortest path) constituting the shortest path from the local terminal to the destination terminal) is generated from the ID of the ID and sent to the packet generator 3A.

  b) The path received by the communication unit 1 that holds the terminal ID (information that can identify the terminal such as a communication interface address, IP address, MAC address, etc.) of the own terminal for distinguishing the own terminal from other terminals The path information, source address, destination address, and packet ID (information that can identify the packet, such as sequence number and port number) are analyzed from the packet to which the information is added, and the path information of the terminal is analyzed to the analyzed path information. It is determined whether or not an ID is included, and if the own terminal is included in the path information, the packet is immediately relayed using the communication unit 1. When the own terminal is not included in the path information, if the path information includes information on any peripheral terminal that can be confirmed by carrier sense by the communication unit 1, the packet is sent to the packet monitoring unit 4A. The holding time set by the time shifting device 5A is held. If the information on the peripheral terminal is not included in the path information at all, it is determined that the packet is transmitted in a direction not toward the destination terminal, and the packet is sent to the packet monitoring unit 4A to discard the packet. As for the ID of the own terminal, it is not uncommon for one terminal to have one or more addresses. For example, if the table is divided according to the address format and a plurality of pieces of information are held in each of the plurality of ID data tables, and the path information is composed of, for example, MAC addresses, the MAC among the plurality of ID tables It is determined whether or not the ID held in the ID table corresponding to the address is included in the path information.

[Packet generator 3A]
The packet generator 3 </ b> A generates a packet and transmits it using the communication unit 1. The packet generator 3A further performs the following two processes A) and B).

  A) A communication request packet is generated and transmitted, and a response packet for the received communication request packet is generated and transmitted.

  B) The path information passed from the packet analysis unit 2A is added to the generated packet and transmitted.

[Packet monitoring unit 4A]
The packet monitoring unit 4A holds the packet passed from the packet analysis unit 2A for the holding time set by the time shifting device 5A. If the same packet as the held packet is delivered from the packet analysis unit 2A within the holding time, it is determined that the other terminal on the shortest path correctly relayed the packet and holds it. Both the existing packet and the same packet passed are discarded. When the holding time elapses, it is determined that other terminals on the shortest path have not correctly relayed the held packet, and the held packet is relayed and transmitted using the communication unit 1. .

[Device 5A for shifting time]
The apparatus 5A for shifting the time sets a holding time for the packet monitoring unit 4A to hold the packet. The device 5A for shifting the time is connected to the communication unit 1, but not connected to the packet analysis unit 2A, and monitors the radio wave state (by performing wireless carrier sense), and holds the holding time. Set.

  The operation of the ad hoc network configured with the terminal according to the first embodiment will be described below.

  First, the source terminal tries to communicate with the destination terminal, transmits a communication request packet by flooding, and inquires of the destination terminal whether communication is possible. Each terminal in the network relays the communication request packet with its own terminal ID added.

  The destination terminal that has received the communication request packet from the source terminal knows that the packet is a communication request packet for its own terminal, and further transmits a response packet by flooding to reply to the source terminal. Each terminal in the network adds its own terminal ID and relays the response packet.

  The source terminal that has received the reply packet from the destination terminal knows the shortest path from its own terminal to the destination terminal and the IDs of the terminals constituting the shortest path. This completes the preparation.

  Since the source terminal knows the shortest path to the destination terminal and the IDs of the terminals constituting the shortest path by the above preparation, the packet generation unit 3A uses the shortest path for the packet to be sent to the destination terminal. A terminal ID to be configured is added as path information, and this packet is transmitted using the communication unit 1.

  FIG. 2 is a flowchart for explaining a relay procedure in the terminal according to the first embodiment of the present invention.

  When the relay terminal receives the packet with the path information added (step S1), the packet analysis unit 2A analyzes the path information (step S2).

  Further, the relay terminal determines whether or not the held ID (= own node) is included in the analyzed path information in the packet analysis unit 2A (step S3).

  If the path information includes its own terminal, the packet analysis unit 2A immediately relays and transmits the packet using the communication unit 1 (step S4).

  If the path information does not include the own terminal, the packet analysis unit 2A determines whether or not information on any peripheral terminal that can be confirmed by carrier sense is included in the path information (step S1). S5). Then, in order to perform processing according to the determination result, the packet is transferred to the packet monitoring unit 4A.

  The packet monitoring unit 4A that has received the packet from the packet analysis unit 2A determines whether or not the same packet as the received packet is already held. If the same packet is not held, the packet monitoring unit 4A uses the time shifting device 5A. The received packet is held and waits until the set holding time elapses (step S6).

  Further, the packet monitoring unit 4A determines whether the peripheral terminal holds the same packet depending on whether or not the same packet as the held packet is received again by the communication unit 1 and passed from the packet analysis unit 2A within the holding time. It is monitored whether the relayed packet is correctly relayed (step S7).

  Then, when the packet monitoring unit 4A receives the same packet as the held packet from the packet analysis unit 2A within the holding time, the packet monitoring unit 4A determines that the peripheral terminal correctly relayed the packet. Both the already held packet and the received same packet are discarded (step S8).

  Further, if the packet monitoring unit 4A does not receive the same packet as the held packet from the packet analysis unit 2A until the holding time elapses, the peripheral terminal does not relay the packet correctly. Judgment and relay transmission of the held packet using the communication unit 1 is performed.

  The determination as to whether or not the already held packet is the same as the received packet is made, for example, by the packet monitoring unit 4A from the packet analysis unit 2A and the packet ID (or Further, the packet monitoring unit 4A determines whether or not the packet is the same by determining whether or not the packet ID (or the source address and the destination address) match each other. .

  In addition, the time shifting device 5A is located on the opposite side of the own terminal with respect to the route included in the path information through the communication unit 1 and the peripheral terminal that is geographically present on the subject terminal and the target. Monitor the radio wave condition of peripheral terminals in a wider range than the own terminal's communication range (including peripheral terminals that are located and constitute a backup path in the same way as the own terminal) (perform wireless carrier sense) Thus, the communication status of the peripheral terminal is monitored, and in accordance with the communication status of the upper peripheral terminal, a time for delaying the relay transmission of the packet (= the holding time) is set in order for the terminal to wait for relay. For example, if the peripheral terminal is not communicating at all, the holding time is set short, and if the peripheral terminal is communicating frequently, the holding time is set long. In addition, in the apparatus 5A for shifting the time, the holding time can be set according to a specific algorithm. For example, it is also possible to generate a random numerical value using time information and set the holding time. In addition, determine the optimum time from multiple time shift methods (whether the retention time is set according to the communication status of the peripheral terminal or the retention time is set according to the algorithm), and the optimal time shift is performed. It is also possible to provide a device for setting the direction so that the optimal time shift method can be set for the terminal resource and the network resource.

  3 to 24 are diagrams for explaining the relay operation in the ad hoc network configured with a plurality of terminals according to the first embodiment. 3 to 24, a, b, c, d, e, f, and g in FIG. 3 each represent a terminal, and terminals a, b, and e are terminals that constitute the shortest path with the highest priority. Terminals c, d, f, and g are terminals that constitute a path having a lower priority than the shortest path.

  3 to 7 are diagrams for explaining the operation of each terminal when the relay transfer on the shortest path is successful.

  First, in FIG. 3, when the terminal a receives a packet, the terminal a immediately relays and forwards the received packet because the terminal a is a terminal on the shortest path. The packet relayed and transferred by the terminal a is received by the terminals b, c, and d.

  Next, in FIG. 4, the terminal b that has received the packet from the terminal a determines that its own terminal is a terminal on the shortest path and immediately relays and forwards the received packet, but receives the packet from the terminal a. Each of the terminals c and d is determined to be a terminal on a path whose priority is lower than that of the shortest path, and to wait for a certain time for a received packet and monitor relay transfer in the shortest path.

  In FIG. 5, terminal b immediately relays and forwards the packet received from terminal a. The packet relay-transferred at the terminal b is received by the terminals c, d, e, f, and g.

  Next, in FIG. 6, the terminals c and d that have received the same packet from the terminal b as received from the terminal a determine that the packet has been correctly relayed, and the held packet And discard the same packet received from terminal b. Also, the terminal e that has received the packet from the terminal b determines that the terminal e is the terminal on the shortest path and relays the received packet immediately, but the terminals f and g that have received the packet from the terminal b Determines that each terminal is a terminal on a path having a lower priority than the shortest path, waits for a certain time for received packets, and monitors relay transfer in the shortest path.

  In FIG. 7, terminal e immediately relays and forwards the packet received from terminal b. The packet relay-transmitted at the terminal e is received by the terminals f and g. Terminals f and g that have received from terminal e the same packet received and held from terminal b determine that the packet has been correctly relayed, and the same packet received from terminal e and the held packet Discard the packet.

  8 to 14 are diagrams for explaining the operation of each terminal when the relay transfer at the terminal b on the shortest path fails.

  First, in FIG. 8, when receiving a packet, the terminal a immediately relays and forwards the received packet because the terminal a is a terminal on the shortest path. The packet relay-transferred at the terminal a is received by the terminals c and d. However, it is unclear whether the packet relayed and transferred by the terminal a is received by the terminal b.

  Next, in FIG. 9, terminals c and d that have received a packet from terminal a are terminals on a path whose own terminal has a lower priority than the shortest path. It is determined to monitor relay transmission in the path. However, it is unclear whether or not the terminal b has received the packet from the terminal a and has determined that the terminal is the terminal on the shortest path and that the received packet is immediately relayed and forwarded.

  In FIG. 10, when the terminal b does not relay and transfer the packet from the terminal a due to a movement or a failure, and the retention time elapses in the packet at the terminal d, the terminal d is the same as the retained packet. Since the packet cannot be received within the holding time, it is determined that the packet has not been correctly relayed, and the held packet is relayed and transferred. The packet relay-transferred at the terminal d is received by the terminals c and g.

  Next, in FIG. 11, the terminal c that has received from the terminal d the same packet received and held from the terminal a determines that the packet has been relayed correctly, and determines that the held packet and terminal Discard the same packet received from d. Further, the terminal g that has received a packet from the terminal d is a terminal on a path having a lower priority than the shortest path, and waits for a certain period of time to monitor the relay transfer in the shortest path. judge.

  In FIG. 12, when the packet holding time at terminal g elapses, terminal g cannot receive the same packet as the held packet within the holding time, and therefore determines that the packet has not been relayed correctly. Then, the held packet is relayed and transferred. The packet relayed and transferred by the terminal g is received by the terminals e and f.

  Next, in FIG. 13, the terminal e that has received the packet from the terminal g determines that the terminal e is a terminal on the shortest path and relays the received packet immediately, but receives the packet from the terminal g. The determined terminal f is a terminal on a path having a lower priority than the shortest path, and determines that the received packet waits for a certain period of time and monitors relay forwarding in the shortest path.

  In FIG. 14, the terminal e immediately relays and forwards the packet received from the terminal g. The packet relay-transmitted at the terminal e is received by the terminal f. The terminal f that has received the same packet from the terminal e as received from the terminal g determines that the packet has been relayed correctly, and determines that the held packet and the same packet received from the terminal e are the same. Discard.

  8 and 9 and FIGS. 15 to 19 are diagrams for explaining other operations of each terminal when the relay transfer at the terminal b on the shortest path fails.

  After the operations of FIG. 8 and FIG. 9 are performed, in FIG. 15, the terminal b does not relay and transfer the packet from the terminal a due to movement or failure, and the packet holding time at the terminals c and d is increased. After the elapse of time, the terminals c and d cannot receive the same packet as the held packet within the holding time, and therefore determine that the packet has not been correctly relayed and relay and transfer the held packet. . The packet relayed and transferred by the terminal c is received by the terminal f, and the packet relayed and transferred by the terminal d is received by the terminal g.

  Next, in FIG. 16, the terminal f that has received the packet from the terminal c is a terminal on the path whose priority is lower than that of the shortest path, and waits for the received packet for a certain period of time. Determine that relay transfer is to be monitored. Similarly, the terminal g that has received the packet from the terminal d is a terminal on the path whose priority is lower than that of the shortest path, and waits for a certain time for the received packet to monitor the relay transfer in the shortest path. Judge that.

  In FIG. 17, when the holding time elapses for the packet at the terminal f, the terminal f cannot receive the same packet as the holding packet within the holding time, and thus determines that the packet is not correctly relayed. Then, the held packet is relayed and transferred. The packet relayed and transferred by the terminal f is received by the terminals e and g.

  Next, in FIG. 18, the terminal g that has received the same packet from the terminal f as received from the terminal d determines that the packet has been relayed correctly, and determines that the held packet and the terminal f Discard the same packet received from. Also, the terminal e that has received the packet from the terminal f determines that the terminal e is a terminal on the shortest path and that the received packet is immediately relayed and transferred.

  In FIG. 19, terminal e immediately relays and forwards the packet received from terminal f.

  8 and 9 and FIGS. 20 to 24 are diagrams for explaining the operation of each terminal when the terminal b on the shortest path recovers after failing the relay transfer.

  After the operations of FIG. 8 and FIG. 9 are performed, in FIG. 20, the terminal b does not relay and forward the packet from the terminal a due to a movement or a failure, and within the packet holding time in the terminals c and d. When the terminal b recovers and the holding time elapses for the packet at the terminal d, the terminal d cannot receive the same packet as the holding packet within the holding time, and thus the packet is not correctly relayed. Judging and relaying the held packet. The packet relay-transferred at the terminal d is received by the terminals c and g and the restored terminal b.

  Next, in FIG. 21, the terminal c that has received the same packet from the terminal d as received from the terminal a determines that the packet has been correctly relayed, and the held packet and the terminal d. Discard the same packet received from. Further, the restored terminal b that has received the packet from the terminal d determines that its own terminal is a terminal on the shortest path and immediately relays and forwards the received packet. Further, the terminal g that has received a packet from the terminal d is a terminal on a path having a lower priority than the shortest path, and waits for a certain period of time to monitor the relay transfer in the shortest path. judge.

  In FIG. 22, the restored terminal b immediately relays and forwards the packet received from the terminal d. The packet relay-transferred at the terminal b is received by the terminals e, f, and g.

  Next, in FIG. 23, the terminal g that has received from the terminal b the same packet received and held from the terminal d determines that the packet has been relayed correctly, and the held packet and the terminal b Discard the same packet received from. The terminal e that has received the packet from the terminal b determines that the terminal e is a terminal on the shortest path and that the received packet is immediately relayed and transferred. The terminal f that has received the packet from the terminal b is a terminal on the path whose priority is lower than that of the shortest path, and waits for a certain period of time to monitor the relay transfer in the shortest path. judge.

  In FIG. 24, the terminal e immediately relays and transfers the packet received from the terminal b. The packet relay-transmitted at the terminal e is received by the terminal f. The terminal f that has received the same packet from the terminal e as received from the terminal b determines that the packet has been relayed correctly, and determines that the held packet and the same packet received from the terminal e are the same. Discard.

  As described above, according to the first embodiment, path information (routed terminal information constituting the shortest path) is added to a packet transmitted from the source terminal, and the relay terminal included in this path information immediately receives the received packet. The relay terminal that is relayed and not included in the above path information waits for the received packet to monitor relay transmission by the relay terminal on the shortest path, and waits if the relay terminal on the shortest path cannot relay. By relaying the transmitted packet, the main path configured by the relay terminal on the path information and the backup path configured by the relay terminal not included in the path information are separated spatially and temporally. Since it can be constructed, stable communication can be ensured, radio interference can be suppressed, packet loss and delay can be prevented, and network resources can be effectively utilized.

  In addition, by setting the holding time for waiting for the packet according to the communication status including the local terminal and the peripheral terminal that exists geographically with respect to the route included in the path information by the device 5A for shifting the time. Since the transmission timing with the peripheral terminal existing in the target can be shifted, if the terminal included in the path information does not relay the packet correctly, two terminals existing geographically in the target are backed up simultaneously. The probability of starting communication can be lowered.

Embodiment 2
FIG. 13 is a configuration diagram of the wireless communication terminal according to the second embodiment of the present invention, and the same components as those in FIG. The terminal according to the second embodiment includes a communication unit 1, a packet analysis unit 2A, a packet generation unit 3A, a packet monitoring unit 4A, and a time shifting device 5B. That is, the terminal of the second embodiment is the same as the terminal 5 of the first embodiment (see FIG. 1), except that the device 5A for shifting the time is a device 5B for shifting the time.

[Device 5B for shifting time]
The device 5B for shifting the time sets a holding time for the packet monitoring unit 4A to hold the packet, similarly to the device 5A for shifting the time in the first embodiment. However, the device 5B for shifting the time is connected to the packet analysis unit 2A, but is not connected to the communication unit 1, and monitors the packet transmission / reception to set the holding time.

  The apparatus 5B for shifting the time monitors the transmission / reception of packets of peripheral terminals within the communication range of the own terminal through the packet analysis unit 2A, so that the terminals included in the path information analyzed by the packet analysis unit 2A are correctly ordered. The activity status of the above peripheral terminals, such as whether or not they are active, is monitored, and in accordance with this activity status, the time for delaying the relay transmission of the packet for the terminal to wait for relaying (= the above holding time) is set To do. For example, if both of the two terminals included in the path information are operating correctly and regularly, the retention time is set to be long, and if one of the top two terminals becomes irregular, Set the retention time short. In addition, in the apparatus 5B which shifts this time, it is also possible to set the holding time according to a specific algorithm. For example, it is also possible to generate a random numerical value using time information and set the holding time. In addition, determine the optimal time from multiple time shift methods (whether the retention time is set according to the activity status of the peripheral terminal or the retention time is set according to the algorithm), and the optimal time shift is performed. It is also possible to provide a device for setting the direction so that the optimal time shift method can be set for the terminal resource and the network resource.

  As described above, according to the second embodiment, when two terminals in the vicinity of the own terminal included in the path information are monitored and the relay of these two terminals is supported, the activity of the two terminals By constantly monitoring the situation, if one of the two terminals does not transmit a packet, it is determined that an abnormality has occurred in the terminal included in the path information, and the retention time is shortened. The recovery time when an abnormality occurs in the path included in the path information can be shortened.

Embodiment 3
FIG. 14 is a configuration diagram of the radio communication terminal according to the third embodiment of the present invention, and the same components as those in FIG. The terminal according to the third embodiment includes a communication unit 1, a packet analysis unit 2A, a packet generation unit 3A, a packet monitoring unit 4A, and a device 5C for shifting time. That is, the terminal of Embodiment 3 is the same as the terminal 5 of Embodiment 1 (see FIG. 1), except that the device 5A for shifting time is the device 5C for shifting time.

[Device 5C for shifting time]
The device 5C for shifting the time sets a holding time for the packet monitoring unit 4A to hold the packet, similarly to the device 5A for shifting the time in the first embodiment. However, the device 5C for shifting the time is connected to the communication unit 1 and the packet analysis unit 2A, monitors the radio wave condition (and performs wireless carrier sense), and monitors packet transmission and reception. Set the retention time.

  The device 5C for shifting the time monitors a radio wave condition of a peripheral terminal in a wider range than the communication range of the own terminal through the communication unit 1 (performs wireless carrier sense), thereby wider than the communication range of the own terminal. The terminal included in the path information analyzed by the packet analysis unit 2A is monitored by monitoring the communication status of the peripheral terminals in the range and monitoring the transmission / reception packets of the peripheral terminals within the communication range of the own terminal through the packet analysis unit 2A Monitors the activity status of peripheral terminals within the communication range of the terminal itself, such as whether or not they are operating correctly and regularly, and the communication status of peripheral terminals in a range wider than the communication range of the terminal itself and the communication of the terminal itself In accordance with the activity status of the peripheral terminals within the range, a time (= holding time) for delaying the relay transmission of the packet is set so that the own terminal waits for the relay.

  In the device 5A for shifting the time according to the first embodiment, information on the activity status of the terminal included in the path information cannot be obtained, and therefore the recovery time when an abnormality occurs cannot be shortened. Further, in the device 5B for shifting the time according to the second embodiment, information about the communication status of the peripheral terminal that is geographically targeted to the own terminal with respect to the route included in the path information cannot be obtained. Two terminals transmit relay packets for recovery at the same time, and wireless collision may occur.

  On the other hand, in the device 5C for shifting the time according to the third embodiment, it is possible to obtain information on the communication status of the peripheral terminal that is geographically targeted to the own terminal with respect to the route included in the path information. Since the information about the activity status of the terminal included in the path information can be obtained, the transmission timing with the peripheral terminal existing in the target is shifted, and the two terminals existing geographically in the target simultaneously perform backup communication. It is possible to reduce the probability that a radio collision will occur after starting, and to shorten the recovery time when an abnormality occurs in the path included in the path information. Furthermore, if it can communicate with the peripheral terminals present in the target and synchronize so that they do not move at the same time, the probability of radio collisions can be reduced to almost zero.

  In addition, in device 5C for shifting the time, similarly to device 5A for shifting the time in the first embodiment, the holding time is set in accordance with the communication status of peripheral terminals in a wider range than the communication range of the own terminal. It is also possible. Further, similarly to the device 5B for shifting the time in the second embodiment, the holding time can be set according to the communication status of the peripheral terminals within the communication range of the own terminal. It is also possible to set the holding time according to a specific algorithm. For example, it is also possible to generate a random numerical value using time information and set the holding time. Furthermore, how to shift multiple times (set the holding time according to the communication status and activity status of the peripheral terminal, set the holding time according to the communication status of the peripheral terminal, or depending on the activity status of the peripheral terminal Set the retention time or set the retention time according to the algorithm) to determine the most appropriate one and set the optimal time shift method to provide the optimal time for terminal resources and network resources. It is also possible to set the shifting method.

  As described above, according to the third embodiment, it is possible to reduce the probability that two terminals that are geographically present at the same time start backup communication at the same time to cause a radio collision, and the route included in the path information is abnormal. When this occurs, the recovery time can be shortened.

Embodiment 4
FIG. 15 is a configuration diagram of the radio communication terminal according to the fourth embodiment of the present invention, and the same components as those in FIG. The terminal according to the fourth embodiment includes a communication unit 1, a packet analysis unit 2A, a packet generation unit 3A, a packet monitoring unit 4A, and a device 5D for shifting time. That is, the terminal of the fourth embodiment is the same as the terminal 5 of the first embodiment (see FIG. 1), except that the device 5A for shifting the time is a device 5D for shifting the time.

[Device 5D for shifting time]
The device 5D for shifting the time sets a holding time for the packet monitoring unit 4A to hold the packet, similarly to the device 5A for shifting the time in the first embodiment. However, the apparatus 5D for shifting the time is not connected to either the communication unit 1 or the packet analysis unit 2A, and sets the holding time at random, for example.

  The device 5D for shifting the time delays the relay transmission of the packet so that the own terminal performs the relay standby using the specific information according to the specific algorithm without monitoring the radio wave state and the packet transmission / reception. (= The above holding time) is set. For example, a random numerical value using time information or date / time information is generated and set to the holding time.

  As described above, according to the fourth embodiment, the device 5D for shifting the time does not perform the processing as the devices 5A to 5C for shifting the time of the first to third embodiments. When it is difficult to cause a collision, it is possible to mount and use the device 5D for easily shifting the time, and to effectively use the resources of the terminal.

Embodiment 5
The fifth embodiment of the present invention is based on the distance vector method. When the source terminal and the destination terminal communicate with each other, a multipath is constructed by the following procedures 1) to 5).

  1) Each terminal in the network holds neighboring terminals that have transferred packets as DV (Distance Vector) terminals, and assigns priorities to a plurality of DV terminals that have transferred the same packets according to reception timing. deep.

  2) The source terminal adds the information of the highest priority DV terminal and the DV terminal information having a lower priority to the packet and transmits the packet.

  3) The terminal that has received the packet determines whether the terminal is the highest priority DV terminal or a lower priority DV terminal, and if it is the highest priority DV terminal, immediately relays and transmits it, If it is a DV terminal having a lower priority than that, it waits for relay transmission for a certain period of time, monitors whether or not relay transmission is performed by another terminal having the highest priority, and relays by the other terminal within the certain time. If transmission can be detected, the waiting packet is discarded, and if relay transmission by the other terminal cannot be detected within the predetermined time, information on the highest priority DV terminal of the waiting packet and Also, the DV terminal information having a low priority is updated, and the packet that has been waiting is relayed and transmitted.

  In the procedure 3), whether or not the relay transmission is performed by the highest priority terminal is determined by whether or not the same packet as the waiting packet is received within the predetermined time. If the same packet as the waiting packet is received within the time, it is determined that relay transmission has been performed by the highest priority terminal, both packets are discarded, and the same packet as the waiting packet is received within the time. If the packet cannot be received, it is determined that relay transmission has not been performed by the highest priority terminal, and the standby packet is relayed and transmitted.

  FIG. 16 is a configuration diagram of the radio communication terminal according to the fifth embodiment of the present invention, and the same components as those in FIG. The terminal according to the fifth embodiment includes a communication unit 1, a packet analysis unit 2E, a packet generation unit 3E, a packet monitoring unit 4E, a time shifting device 5E, and a DV (Distance Vector) table 6. It is configured.

[Packet analysis unit 2E]
The packet analysis unit 2E analyzes the packet received by the communication unit 1. The packet analysis unit 2E further performs the following three analysis processes a) to c).

  a) From the packet received by the communication unit 1, the source address, the terminal ID (information that can identify the terminal such as the communication interface address, IP address, MAC address) of the neighboring terminal that has sent this packet, and the packet ID ( The information such as a sequence number and a port number) is analyzed, and the destination terminal ID and the corresponding packet ID are inquired to the DV table 6 using the analyzed source address as the destination terminal ID. If the analyzed destination terminal ID and packet ID are already held in the DV table 6, the analyzed neighboring terminal ID is added to the ODV (Other Distance Vector) item of the DV table 6 for the destination terminal ID. And the DV table 6 is updated. The analyzed destination terminal ID is held in the DV table 6, but if the packet ID is different, the PDV (Primary Distance Vector) item of the DV table 6 for the destination terminal ID is analyzed in the above-described neighborhood. The terminal ID is rewritten, and if the analyzed neighboring terminal ID is held in the ODV item, it is deleted, the packet ID item is rewritten to the analyzed packet ID, and the DV table 6 is updated. If the analyzed destination terminal ID is not held in the DV table 6, the analyzed destination terminal ID is added to the destination item of the DV table 6, and the analyzed neighboring terminal ID is added to the PDV item. And the analyzed packet ID is added to the packet ID field, and the DV table 6 is updated.

  b) When the self terminal is the source terminal, the DV table 6 is inquired about the PDV terminal ID and the ODV terminal ID of the destination terminal, and one responded PDV terminal ID is set as PDV information. One or more ODV terminal IDs are used as ODV information, and these PDV information and ODV information are sent to the packet generator 3E.

  c) Similar to the packet analysis unit 2A of the first embodiment, the communication unit 1 holds the ID of the own terminal for distinguishing the own terminal from other terminals, and the own terminal is a relay terminal. From the received packet, the PDV information, the ODV information, and the destination address are analyzed to determine whether the ID of the own terminal is included in the analyzed PDV information and whether it is included in the ODV information. By doing so, it is determined whether the terminal is PDV, ODV, or neither PDV nor ODV. If the own terminal is a PDV, the analyzed destination address is used as the destination terminal ID, the PDV terminal ID and the ODV terminal ID for the destination terminal ID are inquired of the DV table 6, and one responded PDV terminal The ID is set as new PDV information, one or more responding ODV terminal IDs are set as new ODV information, and the packet, the new PDV information and the new ODV information are sent to the packet generation unit 3E, and immediately relayed using the communication unit 1 Send. If the own terminal is an ODV, the analyzed destination address is used as the destination terminal ID, the PDV terminal ID and the ODV terminal ID for the destination terminal ID are inquired of the DV table 6, and one responded PDV terminal The ID is set as new PDV information, and one or more responding ODV terminal IDs are set as new ODV information, and the packet and the new PDV information and new ODV information are sent to the packet monitoring unit 4E and set by the time shifting device 5E. Hold for the holding time. If the terminal is neither PDV nor ODV, the packet is discarded.

[DV table 6]
The DV table 6 is a data table for storing a DV (Distance Vector), and is configured as shown in FIG. 17, and includes a destination item, a PDV (Primary Distance Vector) item, and an ODV (Other (Distance Vector) item and packet ID item. In the destination item, the source address analyzed by the packet analysis unit 2E is held as the destination terminal ID. The PDV item holds the ID of the neighboring terminal that first transferred the packet among the neighboring terminal IDs analyzed by the packet analysis unit 2E as the PDV terminal, and the ODV item contains the packet analysis. Among the IDs of the neighboring terminals analyzed by the unit 2E, the IDs of all the neighboring terminals excluding the PDV terminal (the IDs of all neighboring terminals that transferred the packet after the second) are held as ODV terminals. The packet ID item holds the packet ID of the packet analyzed by the packet analysis unit 2E.

[Packet generator 3E]
The packet generation unit 3E generates a packet and transmits it using the communication unit 1. The packet generator 3E further performs the following two processes A) and B).

  A) The previous DV information (PDV information and ODV information) of the packet passed from the packet analysis unit 2E is deleted, the new DV information passed from the packet analysis unit 2E is written, and the packet with the updated DV information is transmitted. To do.

  B) The previous DV information (PDV information and ODV information) of the packet passed from the packet monitoring unit 4E is deleted, the new DV information passed from the packet monitoring unit 4E is written, and the packet with the updated DV information is transmitted. To do.

[Packet monitoring unit 4E]
The packet monitoring unit 4E holds the packet passed from the packet analysis unit 2E and new DV information about the packet for the holding time set by the time shifting device 5E. If the same packet as the held packet is delivered from the packet analysis unit 2E within the holding time, it is determined that the other terminal on the shortest path correctly relayed the packet and holds it. Discard both the existing packet and the new DV information for that packet as well as the new DV information for the same packet passed and that packet. When the holding time elapses, it is determined that other terminals on the shortest path could not correctly relay the held packet, and the packet and the new DV information about the packet are stored in the packet generator. 3E and relay transmission using the communication unit 1.

[Time shifter 5E]
The device 5E for shifting the time sets a holding time for the packet monitoring unit 4E to hold the packet, similarly to any of the devices 5A to 5D for shifting the time in the first to fourth embodiments.

  The operation of the ad hoc network configured with the terminals of the fifth embodiment will be described below.

  When each terminal in the network receives a packet transmitted from another terminal, in the packet analysis unit 2E, from the packet, the source address, the ID of the neighboring terminal that sent the packet to its own terminal, and the packet The ID is analyzed, the analyzed source address is set as the destination terminal ID, and the destination terminal ID and the corresponding packet ID are inquired to the DV table 6.

  If the analyzed destination terminal ID is already held in the DV table 6 and the packet ID held in the DV table 6 for the destination terminal ID matches the analyzed packet ID, The received packet is determined to be already received, and the analyzed neighboring terminal ID is added to the ODV item of the DV table 6 for the destination terminal ID to update the DV table 6.

  Further, the analyzed destination terminal ID is already held in the DV table 6. However, if the packet ID held in the DV table 6 is different from the analyzed packet ID for the destination terminal ID, the received terminal ID is received. It is determined that the packet is the first received packet, the PDV item of the DV table 6 for the destination terminal ID is rewritten with the analyzed neighboring terminal ID, and the analyzed neighboring terminal ID is held in the ODV item. If so, it is deleted, the packet ID item is rewritten with the analyzed packet ID, and the DV table 6 is updated.

  Even if the analyzed destination terminal ID is not held in the DV table 6, it is determined that the received packet is a packet received for the first time, and the analyzed destination is included in the destination item of the DV table 6. The terminal ID is added, the analyzed neighboring terminal ID is added to the PDV item, the analyzed packet ID is added to the packet ID item, and the DV table 6 is updated. As described above, the DV table 6 is sequentially updated every time a packet is received.

  The source terminal holds the PDV terminal ID for the destination terminal in the PDV item of the DV table 6 and the ODV terminal ID in the ODV item of the DV table 6 by updating the DV table 6. Therefore, the packet analysis unit 2E inquires the DV table 6 about the PDV terminal ID and the ODV terminal ID, sets one responded PDV terminal ID as PDV information, and sets one or more responded ODV terminal IDs as ODV information. The packet generation unit 3E adds the PDV information and ODV information to the packet to be sent to the destination terminal, and transmits the packet using the communication unit 1.

  FIG. 18 is a flowchart for explaining a relay procedure in the terminal according to the fifth embodiment of the present invention.

  When the relay terminal receives the packet to which the PDV information and the ODV information are added (step S11), the packet analysis unit 2E analyzes the PDV information, the ODV information, and the destination address, and holds the own terminal ID. Is included in PDV information and whether it is included in ODV information, whether the terminal is a PDV terminal (included in the analyzed PDV information) or an ODV terminal (analysis) Whether it is included in the analyzed ODV information) or whether it is neither the PDV terminal nor the ODV terminal (not included in any of the analyzed PDV information and ODV information) (step S12). Here, the PDV terminal is the terminal with the highest priority with standby time = 0. The DV table 6 is updated when a packet to which the PDV information and ODV information are added is received.

  If the own terminal is a PDV terminal (Yes in step S12), the packet analysis unit 2E uses the analyzed destination address as the destination terminal ID, and sets the PDV terminal ID and ODV terminal ID for the destination terminal ID. The packet generator 6 inquires and responds to the DV table 6 as a new PDV information with one responding PDV terminal ID as one of new PDV information, and sets one or more responding ODV terminal IDs as new ODV information. Send to 3E.

  The packet generator 3E that has received the packet and the new DV information from the packet analyzer 2E receives the DV information (PDV information and ODV information) of the packet passed from the packet analyzer 2E as the new PDV passed from the packet analyzer 2E. Information and new ODV information are updated (step S13), and the packet with the updated DV information is immediately relayed using the communication unit 1 (step S14). Here, the terminal included in the new PDV information is a PDV terminal newly set by this relay terminal, and is the terminal with the highest priority with standby time = 0.

  The packet analysis unit 2E discards the packet if the terminal is not a PDV terminal (No in step S12) and is not an ODV terminal.

  In addition, if the own terminal is not a PDV terminal (No in step S12) and the own terminal is an ODV terminal, the packet analysis unit 2E uses the analyzed destination address as the destination terminal ID and the destination terminal ID. The PD table 6 is inquired about the PDV terminal ID and ODV terminal ID of the received packet, and the one PDV terminal ID responded is set as new PDV information, and one or more responded ODV terminal IDs are set as new ODV information. Information and new ODV information are sent to the packet monitoring unit 4E.

  The packet monitoring unit 4E that has received the packet and the new DV information from the packet analysis unit 2E determines whether or not the same packet as the received packet is already held. The received packet and new DV information are held and waited until the holding time set by the device 5E for shifting is passed (step S15).

  Further, the packet monitoring unit 4E determines whether the peripheral terminal holds the packet depending on whether the same packet as the held packet is received again by the communication unit 1 and passed from the packet analysis unit 2E within the holding time. It is monitored whether or not the relayed packet is correctly relayed (step S16).

  When the packet monitoring unit 4E receives the same packet as the held packet from the packet analysis unit 2E within the holding time, the packet monitoring unit 4E determines that the peripheral terminal correctly relayed the packet. Both the already held packet and the new DV information for the packet and the received new DV information for the same packet and the packet are deleted (step S17).

  If the packet monitoring unit 4E does not receive the same packet from the packet analysis unit 2E as the packet held until the holding time elapses, the packet monitoring unit 4E determines that the peripheral terminal has not correctly relayed the packet. Then, the held packet and new DV information about the packet are sent to the packet generation unit 3E.

  The packet generator 3E that receives the packet and the new DV information from the packet monitor 4E receives the DV information (PDV information and ODV information) of the packet passed from the packet monitor 4E as the new PDV passed from the packet monitor 4E. Information and new ODV information are updated, and the packet with the updated DV information is relayed using the communication unit 1. Here, the terminal included in the new PDV information is a PDV terminal newly set by this relay terminal, and is the terminal with the highest priority with standby time = 0.

  The determination as to whether or not the packet already held and the received packet are the same can be made, for example, by the packet monitoring unit 4E from the packet analysis unit 2E and the packet ID (or Further, the packet monitoring unit 4E determines whether or not the packets are the same by determining whether or not the packet ID (or the source address and the destination address) match each other. .

  Similarly to the device 5A for shifting the time in the first embodiment, the device 5E for shifting the time monitors the radio wave conditions of peripheral terminals in a wider range than the communication range of the own terminal through the communication unit 1 (wireless carrier). The communication status of peripheral terminals in a range wider than the communication range of the terminal is monitored, and the relay transmission of the packet is delayed in order for the terminal to perform relay standby according to the communication status. Set time (= holding time).

  Alternatively, similarly to the device 5B for shifting time in the second embodiment, the device 5E for shifting time monitors packet transmission / reception of peripheral terminals within the communication range of its own terminal through the packet analysis unit 2E, thereby performing packet analysis. Peripherals within the communication range of the terminal itself, such as whether or not the terminal included in the PDV information analyzed by the unit 2E and the terminal included in the new PDV information generated by the packet analyzing unit 2E are operating correctly and regularly The activity status of the terminal is monitored, and in accordance with this activity status, a time (= holding time) for delaying the relay transmission of the packet is set in order for the terminal to wait for relay.

  Alternatively, similarly to the device 5C for shifting the time in the third embodiment, the device 5E for shifting the time monitors the communication status of the peripheral terminals in a wider range than the communication range of the own terminal, and automatically transmits the packet through the packet analysis unit 2E. Monitors the activity status of peripheral terminals within the communication range of the terminal, and sets the time (= holding time) for delaying the relay transmission of the packet in order for the own terminal to wait for relay according to the communication status and the activity status. .

  Or, similarly to the device 5D for shifting the time in the fourth embodiment, the device 5E for shifting the time randomly sets the time (= the holding time) for delaying the relay transmission of the packet in order for the terminal to wait for the relay. To do.

  Further, in the device 5E for shifting the time, similarly to the first to third embodiments, a device for judging the optimum one from a plurality of time shifting methods and setting the optimal time shifting method. It is also possible to set an optimal time shift method for terminal resources and network resources.

  In the fifth embodiment, unlike the first to fourth embodiments described above, the main path and the backup path are not set in the source terminal, and each terminal in the network is a DV terminal for the destination terminal. The ID (the ID of the PDV terminal and the ID of the ODV terminal) is held, and as a result, the PDV terminal held by each terminal constructs the main path. In this case, if the DV terminal has no distinction between the PDV terminal and the ODV terminal, each terminal immediately relays and transmits the packet as a terminal constituting the main path, thereby causing radio interference. Thus, by incorporating the elements PDV and ODV, only the PDV terminal relays and transfers immediately, and the ODV terminal waits for a while, so that a main path with reduced interference can be constructed.

  As described above, according to the fifth embodiment, each terminal holds a PDV terminal and an ODV terminal, and the PVD terminal immediately relays the received packet. The ODV terminal receives the received packet. , The relay transmission by the PDV terminal is monitored, and when the PDV terminal cannot perform relay transmission, the standby path is relayed and the main path configured by the PVD terminal and the backup configured by the ODV terminal are transmitted. Since the path can be constructed spatially and temporally separated, stable communication can be ensured, radio interference can be suppressed, packet loss and delay can be prevented, and network resources can be effectively utilized.

Embodiment 6
In the sixth embodiment of the present invention, in the fifth embodiment, the priority of the relay of the own terminal is set by setting the waiting time of the received packet according to the number of flows currently relayed by the own terminal. It is characterized by adjusting.

  In the fifth embodiment, the relay priority of the own terminal is set by DV information (whether it is a PDV terminal or an ODV terminal) included in the received packet, and the higher the priority, the longer the waiting time. However, a terminal that has already relayed many flows cannot process that many flows even if the priority is high. Therefore, in this sixth embodiment, the larger the number of flows being relayed, the longer the waiting time is set and the other terminals are in charge of the flow, thereby reducing the load on the own terminal, and Load balance. In this way, adjusting the relay priority according to the number of relaying flows is important in terms of load balancing.

  FIG. 31 is a configuration diagram of the radio communication terminal according to the sixth embodiment of the present invention. Components similar to those in FIG. The terminal according to the sixth embodiment includes a communication unit 1, a packet analysis unit 2F, a packet generation unit 3E, a packet monitoring unit 4E, a time shifting device 5F, and a DV (Distance Vector) table 6. It is configured. That is, the terminal of the sixth embodiment is the same as the terminal of the fifth embodiment (see FIG. 28), in which the packet analysis unit 2E is the packet analysis unit 2F, and the time shifting device 5E is the time shifting device 5F. is there.

[Packet analysis unit 2F]
The packet analysis unit 2F analyzes the packet received by the communication unit 1. The packet analysis unit 2E further performs the following four analysis processes a) to d).

  a) Similar to the procedure a) of the packet analysis unit 2E of the fifth embodiment, the packet received by the communication unit 1 is analyzed and the DV table 6 is updated.

  b) Holding the number of relay flows fn representing the number of flows currently relayed by the terminal itself, and relaying a packet between any two terminals, the IDs of the two terminals (one is the ID of the source terminal) The other holds the ID of the destination terminal) for a certain period of time, adds 1 to the number of relay flows fn, and relays the packet between the two terminals again while holding the ID of the two terminals. From that time, the IDs of the two terminals are further held for a certain period of time. When the predetermined time has passed without relaying the packet between the two terminals again, the IDs of the two terminals are deleted and 1 is subtracted from the number of relay flows fn.

  Here, the number of relaying flows means the number of relaying sessions. Further, the IDs of the two terminals are stored separately in the source terminal and the destination terminal, and when the flow for transmitting from the source terminal to the destination terminal and the flow for returning from the destination terminal to the source terminal are relayed together. The number of flows currently relayed by the terminal is two. Note that it is possible to periodically clear all of the IDs of the two held terminals and periodically clear the number of relay flows fn to zero.

  c) When the own terminal is the source terminal, the DV table 6 is inquired about the PDV terminal ID and the ODV terminal ID for the destination terminal, and one PDV terminal ID responded is set as PDV information (1stDV information). Any one or more of the responded ODV terminal IDs is used as 2ndDV information, and the other ODV terminal ID is used as 3rdDV information, and these DV information (1stDV information, 2ndDV information, 3rdDV information) is packetized. The data is sent to the generation unit 3E. One or more ODV terminal IDs that have been responded may be all 2ndDV information, and 3rdDV information may not be created.

  d) Like the packet analysis unit 2A of the first embodiment, the communication unit 1 holds the ID of the own terminal for distinguishing the own terminal from other terminals, and the own terminal is a relay terminal. From the received packet, 1stDV information, 2ndDV information, 3rdDV information, and the destination address are analyzed, and whether the ID of the own terminal is included in the analyzed 1stDV information or whether it is included in the 2ndDV information And whether the terminal is 1stDV, 2ndDV, 3rdDV, or 1stDV, 2ndDV, or 3rdDV by determining whether it is included in the 3rdDV information. judge.

  If the own terminal is 1st DV and the number of relay flows fn = 1, the analyzed destination address is the destination terminal ID, and the PDV terminal ID and ODV terminal ID for the destination terminal ID are stored in the DV table 6. One PDV terminal ID that is inquired and responded is set as new PDV information (1stDV information), one ODV terminal ID among the one or more responding ODV terminal IDs is new 2ndDV information, and the other ODV terminal IDs are new As the 3ndDV information, the packet and the new DV information (1stDV information, 2ndDV information, 3ndDV information) are sent to the packet generation unit 3E, and immediately relayed using the communication unit 1.

  In this procedure d), the number of flows currently relayed by the terminal increases by one by the reception of the packet, and 1 is added to the number of relay flows fn. Therefore, if other flows are not relayed, The number of relay flows fn = 1. For example, if two flows are not relayed in addition to the received packet flow, the number of relay flows fn = 3. That is, the number of relay flows fn in the procedure d) is the number of flows including the flow of the received packet.

  Further, if the own terminal is 1st DV and the number of relay flows fn ≧ 2, or if the own terminal is 2ndDV, 3rdDV, the analyzed destination address is the destination terminal ID, and the PDV terminal for this destination terminal ID The DV table 6 is inquired about the ID and the ODV terminal ID, and one responded PDV terminal ID is set as new PDV information (1stDV information), and one ODV terminal ID among the responded one or more ODV terminal IDs is new. 2ndDV information and other ODV terminal IDs are set as new 3ndDV information, and the DV to which the terminal belongs (whether it belongs to 1stDV, 2ndDV, or 3ndDV) and the number of relay flows fn are sent to the time shifter 5F, and the packet and the new DV information (1st DV information, ndDV information, 3NdDV information) sent to the packet monitor 4E, the holding time set by the device 5F staggering, is maintained.

  If the terminal is not any of 1stDV, 2ndDV, and 3rdDV, the packet is discarded.

[Device 5F for shifting time]
The device 5F for shifting the time has a holding time (a packet is held by the packet monitoring unit 4E) in accordance with the DV to which the terminal belongs (whether it belongs to 1stDV, 2ndDV, or 3ndDV) and the number of relay flows fn. Set the waiting time to wait for a packet. Here, when the received packet is relayed immediately (when the terminal is 1st DV and the number of relay flows fn = 1), the time from reception to transmission of the packet is defined by, for example, SIFS (IEEE802.11b) Short Inter Frame Space), and a time obtained by adding the retention time in the packet monitoring unit 4E to the SIFS is defined as the waiting time.

  The device 5E for shifting the time sets the waiting time to SIFS × 2 (holding time is SIFS) if the own terminal is 2ndDV and the number of relay flows fn = 1, and the own terminal is 3ndDV and the relay flow. If the number fn = 1, the standby time is set to SIFS × 3 (holding time is SIFS × 2), and if the terminal is 1st DV and the number of relay flows fn ≧ 2, the standby time is set to SIFS + (fn− 1) × SIFS × 3 (holding time is set to (fn−1) × SIFS × 3), and if the terminal is 2nd DV and the number of relay flows fn ≧ 2, the waiting time is set to SIFS × 2 + (fn− 1) × SIFS × 3 (holding time is set to SIFS + (fn−1) × SIFS × 3), and if the terminal is 3rdDV and the number of relay flows fn ≧ 2, the waiting time is set to SIFS × 3 + (fn -1) x SIFS x 3 Setting the retention time SIFS × 2 + (fn-1) × SIFS × 3).

  Here, the standby times of 1stDV, 2ndDV, and 3rdDV are set as SIFS, SIFS * 2, and SIFS * 3, respectively, and the standby time (holding time) is set longer for terminals with lower relay priorities. Further, when relaying a plurality of flows, it is desirable to shift SIFS × 3 after the second flow, so that the number of other relayed flows (fn−1) excluding the received packet flow Accordingly, the standby time is set longer by SIFS × 3.

  FIG. 32 is a time chart for explaining the operation of a relay terminal in an ad hoc network configured by a plurality of terminals according to the sixth embodiment of the present invention, where Src is a source terminal, 1st is the relay terminal (1stDV terminal) that becomes the above-mentioned 1stDV. ) 2nd represents a relay terminal (2ndDV terminal) serving as the 2ndDV, 3rd represents a relay terminal (3rdDV terminal) serving as the 3rdDV, and DATA represents a packet transmitted and relayed from the source terminal (Src).

  FIG. 32A shows that in any of the 1st DV terminal, 2nd DV terminal, and 3nd DV terminal, there is no flow that has already been relayed in addition to the flow of the packet (DATA) received from the source terminal (Src) (number of relay flows). This is the case of fn = 1).

  In FIG. 32A, the standby time in the 1st DV terminal is SIFS (holding time is 0), the standby time in the 2nd DV terminal is set to SIFS × 2 (holding time is SIFS), and the standby time in the 3nd DV terminal is set The time is set to SIFS × 3 (the holding time is SIFS × 2).

  Of the 1st DV terminal, 2nd DV terminal, and 3nd DV terminal, the 1st DV terminal relays and transmits the packet (DATA) immediately at the earliest standby time SIFS. The 2nd DV terminal and the 3nd DV terminal receive the packet (DATA) relayed and transmitted by the 1st DV terminal within each waiting time, and discard the packet from the 1st DV terminal and the held source terminal (Src).

  FIG. 32B shows that, in the 2nd DV terminal, there is no flow already relayed in addition to the packet (DATA) flow received from the source terminal (Src) (the number of relay flows fn = 1). However, in the 1st DV terminal and the 3nd DV terminal, there is one flow already relayed (number of relay flows fn = 2) in addition to the flow of the packet (DATA) received from the source terminal (Src).

  In FIG. 32B, the standby time in the 1st DV terminal is set to SIFS × 4 (holding time is SIFS × 3), the standby time in the 2nd DV terminal is set to SIFS × 2 (holding time is SIFS), The standby time in the 3nd DV terminal is set to SIFS × 6 (the holding time is SIFS × 5).

  Of the 1stDV terminal, 2ndDV terminal, and 3ndDV terminal, the 2ndDV terminal relays and transmits the packet (DATA) with the waiting time SIFS × 2. The 1st DV terminal and the 3nd DV terminal receive the packet (DATA) relayed and transmitted by the 2nd DV terminal within each waiting time, and discard the packet from the 2nd DV terminal and the held source terminal (Src). That is, relaying is performed by a backup path that bypasses the 1st DV terminal.

  As described above, according to the sixth embodiment, by adjusting the waiting time of the received packet according to the number of flows currently being relayed by the own terminal, the own terminal when many flows have already been relayed is adjusted. The load on the terminal can be reduced, and the load on the entire network can be distributed.

Embodiment 7
FIG. 33 is a block diagram of the radio communication terminal according to the seventh embodiment of the present invention, and the same components as those in FIG. 1 or FIG. The terminal according to the seventh embodiment includes a communication unit 1, a packet analysis unit 2G, a packet generation unit 3A, a packet monitoring unit 4A, and a device 5G for shifting time. That is, the terminal of the seventh embodiment is obtained by applying the sixth embodiment to the first to fourth embodiments. In the terminal of the first embodiment (see FIG. 1), the packet analysis unit 2A is The packet analysis unit 2G corresponding to the packet analysis unit 2F of the sixth embodiment is used, and the device 5A for shifting the time is a device 5G for shifting the time corresponding to the device 5F for shifting the time of the sixth embodiment. is there.

[Packet analysis unit 2G]
The packet analysis unit 2G analyzes the packet received by the communication unit 1. The packet analysis unit 2G further performs the following four analysis processes a) to d).

  a) Similarly to the procedure a) of the packet analysis unit 2A of the first embodiment, path information (terminal information via the shortest path) is generated and sent to the packet generation unit 3A.

  b) Similar to the procedure b) of the packet analysis unit 2F of the sixth embodiment, the number of relay flows fn is held, and the number of relay flows fn is updated.

  c) Like the packet analysis unit 2A of the first embodiment, the terminal ID of the own terminal for distinguishing the own terminal from other terminals is held, and the path information received by the communication unit 1 is added. The path information, source address, destination address, and packet ID are analyzed from the packet, and it is determined whether or not the analyzed path information includes the ID of the own terminal.

  If the own terminal is included in the path information and the number of relay flows fn = 1, the packet is immediately relayed using the communication unit 1.

  In addition, if the own terminal is included in the path information and the number of relay flows fn ≧ 2, or if the own terminal is not included in the path information, the packet is sent to the packet monitoring unit 4A and the time is shifted. Hold for the holding time set by 5G.

[Device 5G for shifting time]
The apparatus 5G for shifting the time waits for the packet monitoring unit 4A to hold the packet (waiting for the own terminal to wait for the packet) according to whether the own terminal is included in the path information and the number of relay flows fn. Set the standby time. Here, when the received packet is relayed immediately (when the own terminal is included in the path information and the number of relay flows fn = 1), the time from reception to transmission of the packet is set, for example, in SIFS (IEEE802.11b). (Short Inter Frame Space), and a time obtained by adding the retention time in the packet monitoring unit 4A to the SIFS is defined as the waiting time.

  If the own terminal is not included in the path information and the number of relay flows fn = 1, the apparatus 5G for shifting the time sets the waiting time to SIFS × 2 (the holding time is SIFS), and the own terminal Is included in the path information and the number of relay flows fn ≧ 2, the waiting time is set to SIFS + (fn−1) × SIFS × 3 (the holding time is (fn−1) × SIFS × 3) If the terminal is not included in the path information and the number of relay flows fn ≧ 2, the waiting time is SIFS × 2 + (fn−1) × SIFS × 3 (the holding time is SIFS + (fn−1) × SIFS × 3). Set to.

  Here, the waiting time at the terminal included in the path information is SIFS, the waiting time at the terminal not included in the path information is SIFS * 2, and the terminal having a lower relay priority has a longer waiting time (holding time). It is set. Further, when relaying a plurality of flows, it is desirable to shift SIFS × 3 after the second flow, so that the number of other relayed flows (fn−1) excluding the received packet flow Accordingly, the standby time is set longer by SIFS × 3.

  The operation of the relay terminal included in the path information in the ad hoc network configured by a plurality of terminals according to the seventh embodiment is the same as that of the 1st DV terminal in FIG. 32, for example, and is included in the path information in the ad hoc network. The operation of the non-relay terminal is the same as that of the 2nd DV terminal in FIG.

  As described above, according to the seventh embodiment, by adjusting the waiting time of the received packet according to the relay priority of the own terminal and the number of flows currently relayed by the own terminal, It is possible to reduce the load on the own terminal when it is already relayed, and to distribute the load on the entire network.

It is a block diagram of the radio | wireless communication terminal of Embodiment 1 of this invention. It is a flowchart explaining the relay procedure in the terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a figure explaining the relay operation | movement in the ad hoc network comprised with the some terminal of FIG. It is a block diagram of the radio | wireless communication terminal of Embodiment 2 of this invention. It is a block diagram of the radio | wireless communication terminal of Embodiment 3 of this invention. It is a block diagram of the radio | wireless communication terminal of Embodiment 4 of this invention. It is a block diagram of the radio | wireless communication terminal of Embodiment 5 of this invention. It is a block diagram of a DV table in the terminal of FIG. It is a flowchart explaining the relay procedure in the terminal of FIG. It is a block diagram of the radio | wireless communication terminal of Embodiment 6 of this invention. FIG. 32 is a time chart for explaining the operation of a relay terminal in an ad hoc network including a plurality of terminals of FIG. 31. FIG. It is a block diagram of the radio | wireless communication terminal of Embodiment 7 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication part 2A, 2E, 2F, 2G Packet analysis part 3A, 3E Packet generation part 4A, 4E Packet monitoring part 5A, 5B, 5C, 6D, 5E, 5F, 5G The apparatus which shifts time 6 DV table

Claims (12)

A communication means for transmitting and receiving packets to and from other communication terminals constituting the communication network;
Analyzing means for analyzing shortest path information between the source terminal and the destination terminal from the packet received by the communication means;
It is determined whether or not the own terminal is included in the information in the shortest path, and if the own terminal is included in the shortest path information, the packet is immediately relayed from the communication means, and the own terminal If not included in the shortest path information, determination means for temporarily waiting the packet;
Standby setting means for setting a holding time for causing the terminal to wait for the packet;
The packet held by the determination unit is held until the holding time elapses, and it is monitored whether the same packet as the packet is relayed by another communication terminal until the holding time elapses. In the meantime, if the same packet is relayed and transmitted by the other communication terminal, the held packet is discarded, and the same packet is relayed and transmitted by the other communication terminal even if the holding time elapses. And a packet monitoring unit that relays and transmits the held packet from the communication unit. It further comprises flow number monitoring means for monitoring the number of flows relayed by its own terminal,
If the terminal is included in the shortest path information and there is no flow relayed by the terminal other than the flow of the packet, the determination unit immediately relays and transmits the packet from the communication unit. If the terminal is not included in the shortest path information, or if the terminal is included in the shortest path information and there is a flow relayed by the terminal in addition to the flow of the packet, the packet is temporarily suspended. Let
The standby setting means sets the holding time according to whether or not the own terminal is included in the shortest path information and the number of flows relayed by the own terminal. The communication terminal described. A communication means for transmitting and receiving packets to and from other communication terminals constituting the communication network;
Analysis means for analyzing a source address, a destination address, an ID of a neighboring terminal that has sent the packet, an ID of the packet, PDV information, and ODV information from the packet received by the communication means; ,
For each destination terminal ID, the ID of one PDV (Primary Distance Vector) terminal that immediately relays and transmits the packet relayed by the terminal, and one or more ODVs that temporarily wait for the packet relayed by the terminal (Other Distance Vector) DV holding means for holding the terminal ID,
Whether the packet is the first received packet is determined based on the packet ID. If the packet is the first received packet, the source address is set as the destination terminal ID and the neighborhood The DV holding means holds the terminal ID as the PDV terminal ID, and if the packet is the same packet as the packet already received, the source address is set as the destination terminal ID and the neighboring terminal ID is set as ODV. DV creation means to be held in the DV holding means as the terminal ID;
It is determined whether the own terminal is a PDV terminal included in the PDV information, an ODV terminal included in the ODV information, or neither the PDV terminal nor the ODV terminal, and the own terminal is a PDV terminal. If there is, the packet is immediately relayed from the communication means. If the terminal is an ODV terminal, the packet is temporarily held. If the terminal is neither a PDV terminal nor an ODV terminal, the packet is discarded. Determination means to perform,
Standby setting means for setting a holding time for holding the packet in the terminal;
The packet held by the determination unit is held until the holding time elapses, and it is monitored whether the same packet as the packet is relayed by another communication terminal until the holding time elapses. In the meantime, if the same packet is relayed and transmitted by the other communication terminal, the held packet is discarded, and the same packet is relayed and transmitted by the other communication terminal even if the holding time elapses. If there is no packet monitoring means for relaying the held packet from the communication means,
The destination address is set as the destination terminal ID, and for the destination terminal ID, one PDV terminal ID held in the DV holding means is set as new PDV information and held in the DV holding means. One or more ODV terminal IDs as new ODV information are used, and the previous PDV information and the previous ODV information of the packet relayed from the communication means are updated to the new PDV information and the new ODV information. A communication terminal comprising: DV information updating means. It further comprises flow number monitoring means for monitoring the number of flows relayed by its own terminal,
If the terminal is the PDV terminal and the flow is not relayed by the terminal in addition to the flow of the packet, the determination means causes the packet to be relayed immediately from the communication means, and the terminal transmits the ODV. If it is a terminal, or if the terminal is the PDV terminal and there is a flow relayed by the terminal in addition to the flow of the packet, the packet is temporarily held,
The standby setting means sets the holding time according to whether the own terminal is the PDV terminal or the ODV terminal and the number of flows relayed by the own terminal. The communication terminal described in 1. A communication means for transmitting and receiving packets to and from other communication terminals constituting the communication network;
From the packet received by the communication means, the source address, the destination address, the ID of the neighboring terminal that sent the packet, the ID of the packet, and the first to nth (n is an integer of 2 or more) Analysis means for analyzing the DV information of
For each destination terminal ID, the ID of one PDV (Primary Distance Vector) terminal that immediately relays and transmits the packet relayed by the terminal, and one or more ODVs that temporarily wait for the packet relayed by the terminal (Other Distance Vector) DV holding means for holding the terminal ID,
Whether the packet is the first received packet is determined based on the packet ID. If the packet is the first received packet, the source address is set as the destination terminal ID and the neighborhood The DV holding means holds the terminal ID as the PDV terminal ID, and if the packet is the same packet as the packet already received, the source address is set as the destination terminal ID and the neighboring terminal ID is set as ODV. DV creation means to be held in the DV holding means as the terminal ID;
It is determined whether the own terminal is the k-th DV terminal included in the k-th DV information (k is any integer from 1 to n) or any of the first to n-th DV terminals. If the own terminal is the first DV terminal, the packet is immediately relayed from the communication means, and if the own terminal is one of the second to nth ODV terminals, the packet is temporarily held. If the terminal is not one of the first to n-th DV terminals, a determination unit that discards the packet;
Standby setting means for setting a holding time for holding the packet in the terminal;
The packet held by the determination unit is held until the holding time elapses, and it is monitored whether the same packet as the packet is relayed by another communication terminal until the holding time elapses. In the meantime, if the same packet is relayed and transmitted by the other communication terminal, the held packet is discarded, and the same packet is relayed and transmitted by the other communication terminal even if the holding time elapses. If there is no packet monitoring means for relaying the held packet from the communication means,
The destination address is the ID of the destination terminal, and for this destination terminal ID, one PDV terminal ID held in the DV holding means is set as new first DV information, and the DV holding means Each of the one or more ODV terminal IDs held in the above as the first to second m-th (m is an integer greater than or equal to 2) DV information, the previous first to first packets of the packet to be relayed from the communication means DV information updating means for updating the nth ODV information to the new first to mth DV information. A communication terminal, comprising: It further comprises flow number monitoring means for monitoring the number of flows relayed by its own terminal,
If the own terminal is the first DV terminal and the flow is not relayed by the own terminal in addition to the flow of the packet, the determining means causes the packet to be immediately relayed and transmitted from the communication means. Is the second to n-th DV terminals, or if the terminal is the first DV terminal and there is a flow relayed by the terminal in addition to the flow of the packet, the packet is temporarily Wait,
The standby setting means sets the holding time according to whether the own terminal is the first to n-th PDV terminals and the number of flows relayed by the own terminal. Item 6. The communication terminal according to Item 5.   6. The communication terminal according to claim 1, wherein the standby setting unit sets the holding time according to a communication status of a peripheral terminal.   6. The communication terminal according to claim 1, wherein the standby setting unit sets the holding time according to an activity situation of a peripheral terminal.   6. The communication terminal according to claim 1, wherein the standby setting unit sets the holding time according to a communication status and an activity status of a peripheral terminal.   6. The communication terminal according to claim 1, wherein the standby setting unit sets the holding time using specific information according to a specific algorithm.   A communication network comprising a plurality of communication terminals according to claim 1. In a communication network composed of a plurality of communication terminals each having a router function,
Set priorities for multiple paths built between the source and destination terminals,
The relay terminal that configures the path with the highest priority relays the received packet immediately,
In the relay terminal configuring the low priority path, the received packet is temporarily waited to monitor whether the high priority path relays the packet for a certain period of time. If the relay transmission of the high priority path cannot be detected, the received packet is relayed. If the relay transmission of the high priority path is detected, the received packet is discarded. A featured communication network.

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