JP2016152533A - Program, device and method for communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve data reception and transmission efficiency.SOLUTION: A communication program is executed in a first communication device included in a network. The first communication device receives a control frame from a neighboring second communication device. The control frame includes: communication destination information capable of transmitting a frame through the second communication device; and unique information which is used when the second communication device identifies a communication destination and whose data length is shorter than an address allocated to the communication destination. The first communication device, when transmitting data to the communication destination through the second communication device, sets unique information as the destination of the data frame which includes data destined to the communication destination, to transmit the data frame to the second communication device.SELECTED DRAWING: Figure 1

Description

  The present invention relates to communication performed in a network including a plurality of communication devices.

  An ad hoc network is highly convenient because a network is dynamically formed even when communication devices forming the network are added or deleted. The ad hoc network may be used for a sensor network, a meter reading system, and the like. In this case, information obtained by a communication device in the ad hoc network is transmitted to another network including a device that processes sensor information, a meter reading result, and the like via a communication device (gateway device) that operates as a gateway. There are many cases. When each communication device in the ad hoc network provides information to another network via the gateway device, each communication device uses the Hello frame to transmit route information for transmitting a frame to the gateway device in the ad hoc network. get. Here, the Hello frame includes information on a gateway device that can transfer the frame via the communication device that is the transmission source of the Hello frame.

  A frame transmitted and received in an ad hoc network includes a final destination address of the frame, a frame transmission source address, a frame transfer destination address, and a frame transfer source address. These pieces of information are used for transfer processing. For example, when each communication device receives a frame in which the gateway device is designated as the final destination of the frame, it uses the routing table to transfer the frame from devices that can forward the frame to the gateway device designated as the final destination. Determine the destination. At the time of frame transfer, the communication device changes the frame transfer source address to the address assigned to the communication device itself, and sets the frame transfer destination address. Then, the frame is transferred to a device to which a transfer destination address in the frame is assigned. The frame transfer process is repeated until the frame reaches the gateway device designated as the final destination.

  As a related technique, a method has been proposed in which a node in which a plurality of links are set uses, as path information, a Bloom filter with a node identifier that uniquely identifies each node existing at the link destination as a key (for example, Patent Document 1).

JP 2008-11448 A

  The header of a frame transmitted / received in an ad hoc network includes the final destination, transmission source, transfer destination, and transfer source addresses of the frame, and also includes control information used for transfer processing. Furthermore, the data size of frames transmitted and received in an ad hoc network is often small compared to other networks. For this reason, the ratio of the payload data in the frames transmitted and received in the ad hoc network tends to be small, and the transmission efficiency of the payload data tends to deteriorate. Even if the data size of the control information is reduced by data compression, the data size of the control information itself is small and the control information related to the compression process is included in the frame. Therefore, it is difficult to increase the amount of payload data that can be transmitted in one frame by compressing control information.

  In one aspect, the present invention aims to improve the efficiency of data transmission / reception.

  One form is performed on a first communication device included in the network. The first communication device receives a control frame from the adjacent second communication device. The control frame is information used to identify a communication destination capable of transmitting a frame via the second communication device, and an address assigned to the communication destination, which is used when the communication destination is identified by the second communication device. Including unique information which is information having a shorter data length. When the first communication device transmits data to the communication destination via the second communication device, the first communication device sets the unique information as a destination of a data frame including data addressed to the communication destination, and the data frame Is transmitted to the second communication device.

  The efficiency of data transmission / reception can be improved.

It is a flowchart explaining the example of the communication method concerning embodiment. It is a figure explaining the example of a structure of a communication apparatus. It is a figure explaining the example of the hardware constitutions of a communication apparatus. It is a figure explaining the example of the format of a frame. It is a figure explaining the example of the process performed at the time of transmission / reception of a Hello frame. It is a flowchart explaining the example of the reception process of a Hello frame. It is a flowchart explaining the example of the transmission process of a Hello frame. It is a figure explaining the example of the transfer process of the frame addressed to a gateway apparatus. It is a figure explaining the example of the transfer process of the flame | frame transmitted from the gateway apparatus. It is a sequence diagram explaining the example of the reception process of a data frame. It is a sequence diagram explaining the example of the transmission process of a data frame. It is a figure which shows the example of a network. It is a figure explaining the example of the process performed at the time of transmission / reception of a Hello frame. It is a figure explaining the example of the process performed at the time of transmission / reception of a Hello frame. It is a figure explaining the example of the process performed at the time of transmission / reception of a Hello frame. It is a figure which shows the example of the routing table which each communication apparatus hold | maintains. It is a figure explaining the example of the transfer process of the frame addressed to a gateway apparatus. It is a figure explaining the example of the transfer process of the frame addressed to a gateway apparatus. It is a figure explaining the example of the transfer process of the frame addressed to a gateway apparatus. It is a figure explaining the example of the transfer process of the flame | frame transmitted from the gateway apparatus. It is a figure explaining the example of the transfer process of the flame | frame transmitted from the gateway apparatus. It is a figure explaining the example of the transfer process of the flame | frame transmitted from the gateway apparatus. It is a figure explaining the example of the size of the payload in a flame | frame. It is a flowchart explaining the example of the transmission process of the Hello frame performed in 2nd Embodiment. It is a figure which shows the example of the routing table which each communication apparatus hold | maintains. It is a figure explaining the example of the transfer process of a data frame. It is a figure explaining the example of the transfer process of a data frame. It is a figure explaining the example of the transfer process of a data frame.

  FIG. 1 is a flowchart illustrating an example of a communication method according to the embodiment. The communication device 10 that performs communication using the communication method according to the embodiment transmits and receives a Hello frame to and from the adjacent communication device 10. The communication device 10 may perform wired communication or wireless communication. When the communication device 10 is a device in a wireless ad hoc network, a communication device “adjacent” to a certain communication device is a communication device located within a range in which a frame transmitted from a certain communication device can be received. Shall point to. In addition, a communication device located in a range in which a frame transmitted from a certain communication device can be received may be referred to as an “adjacent node” of the communication device.

  In step S <b> 1, the communication device 10 uses the Hello frame to exchange path information and unique information attached to a communication destination that can communicate with the adjacent node. Here, the unique information is information used by an adjacent node when identifying a communication destination capable of communicating via the adjacent node, and is information having a data length shorter than an address assigned to the communication destination. is there. The communication device 10 continues the process of step S1 until a frame transmission request is made by an application or the like running on the communication device 10 (No in step S2).

  When a frame transmission request is generated by an application or the like, the communication device 10 specifies a frame transfer destination using a routing table or the like (Yes in step S2). The communication apparatus 10 determines whether the unique information set for the frame destination by the frame transfer destination has been acquired (step S3). When the transfer destination has acquired the unique information set for the final destination, the communication apparatus 10 replaces the address of the final destination of the frame with the unique information set for the final destination by the transfer destination (Yes in step S3). Step S4).

  Furthermore, the communication device 10 determines whether or not the unique information set by the node for the frame generation source has been notified to the transfer destination (step S5). If the unique information set by the node for the frame generation source has been notified to the transfer destination, the address of the frame generation source is replaced with the unique information set by the node for the generation source (step S5). Yes, step S6). Thereafter, the communication device 10 transmits the processed frame to the transfer destination (step S7).

  In step S3, when the transfer destination has not acquired the unique information set for the final destination, the communication device 10 performs the processing from step S5 onward without performing the processing in step S4. In Step S5, when it is determined that the unique information set by the node is not notified to the transfer destination with respect to the frame generation source, the communication device 10 performs the process of Step S7 without performing the process of Step S6. I do.

  Note that the processing described with reference to FIG. 1 is an example, and the processing performed in the communication device 10 can be changed according to the implementation. For example, the process of steps S5 to S6 may be modified before the processes of steps S3 to S4. As will be described later, when information other than information on the communication device 10 operating as a gateway device is not included in the Hello frame, only the information on the gateway device may be replaced with unique information. That is, as will be described later, steps S5 and S6 can be omitted in the case of processing a frame transmitted to the gateway device. For frames transmitted from the gateway device, the processes in steps S3 and S4 can be omitted.

  As described with reference to FIG. 1, the communication device 10 uses the unique information instead of the address when the final destination or the transmission source of the frame can be identified by the unique information shorter than the address at the transfer destination. The header size can be reduced. Therefore, the data size included in each frame is increased, and as a result, communication efficiency is improved. Also, the throughput is improved by increasing the payload per frame. That is, the communication speed in the ad hoc network is improved.

<Configuration of communication device and frame format example>
In the following description, the final destination of a frame may be described as a “global destination” (GD). On the other hand, a communication device designated as a transfer destination in a one-hop transfer performed to transmit a frame to a final destination may be referred to as a “local destination” (Local Destination, LD). is there. Further, relatedly, the communication device 10 that has generated the data to be transmitted to the final destination of the frame may be described as a “Global Source” (GS). In addition, the communication device 10 that is a transfer source when a frame is transferred by one hop may be referred to as a “local source” (LS).

  FIG. 2 is a diagram illustrating an example of the configuration of the communication device 10. The communication device 10 includes a reception unit 11, a header analysis unit 12, a transfer processing unit 13, an application processing unit 14, a frame generation unit 15, a transmission unit 16, a control unit 20, and a storage unit 30. The control unit 20 includes an extraction unit 21, a GDID management unit 22, a table management unit 23, a route information generation unit 24, and a timer 25. The storage unit 30 stores a link table (LT) 31, a routing table (RT) 32, and a transfer destination table 33, and also stores information indicating whether the communication device 10 operates as a gateway device. To do.

  The receiving unit 11 receives a frame from another communication device 10 and outputs the received frame to the header analyzing unit 12. The header analysis unit 12 analyzes header information in the frame and outputs a Hello frame to the extraction unit 21. In addition, the header analysis unit 12 generates the transfer destination table 33 using information on the global transmission source and the local transmission source of the data frame. The header analysis unit 12 outputs the data frame in which the own node is designated as the global destination to the application processing unit 14 and outputs the data frame in which the node other than the own node is designated as the global destination to the transfer processing unit 13. The transfer processing unit 13 uses the routing table 32 and the transfer destination table 33 to determine a transfer destination (local destination) for transferring the input frame toward the global destination. The transfer processing unit 13 outputs the specified local destination information to the frame generation unit 15 together with information such as data in the frame, global destination, and global transmission source. The application processing unit 14 processes input frame data. In addition, data to be transmitted to another device is output to the frame generation unit 15 together with information such as a destination. The frame generation unit 15 generates a frame including data input from any one of the transfer processing unit 13, the application processing unit 14, and the route information generation unit 24. The frame generation unit 15 outputs the generated frame to the transmission unit 16. The transmission unit 16 transmits a frame toward another device.

The extraction unit 21 extracts information notified in the Hello frame and outputs the information to the table management unit 23. The GDID management unit 22 manages a value that can be used as unique information (global destination ID, GDID) used by the communication device 10 for the communication destination notified of the route information by the Hello frame. The table management unit 23 updates the routing table 32 using the information input from the extraction unit 21. When the route information related to the new communication destination is notified by the Hello frame, the table management unit 23 uses the value selected from the values held by the GDID management unit 22 as the unique information used for identifying the communication destination. 32. The timer 25 measures the transmission period of the Hello frame. The route information generation unit 24 extracts information to be included in the Hello frame from the routing table 32 and outputs the information to the frame generation unit 15.

  The link table 31 stores, for each communication device 10 adjacent to the communication device 10, a value indicating the address of the communication device 10, the status of the link between the device and the own device, and the like. The transfer destination table 33 records the path information obtained by replacing the global transmission source of the received data frame with the global destination and replacing the local transmission source with the local destination. That is, the transfer destination table 33 records the route information reaching the communication device 10 that has transmitted the frame to the own node.

  FIG. 3 is a diagram illustrating an example of a hardware configuration of the communication device 10. The communication device 10 includes a processor 100, a bus 101 (101a to 101c), a timer IC 104, a dynamic random access memory (DRAM) 106, a flash memory 107, and a wireless module 108. The communication device 10 can optionally include a PHY chip 102. The buses 101a to 101c connect the processor 100, the PHY chip 102, the timer IC 104, the DRAM 106, the flash memory 107, and the wireless module 108 so that data can be input and output.

  The processor 100 is an arbitrary processing circuit such as a Micro-Processing Unit (MPU). The processor 100 reads a program such as firmware stored in the flash memory 107 and performs processing. At this time, the processor 100 can use the DRAM 106 as a working memory. In the communication device 10, the processor 100 operates as a header analysis unit 12, a transfer processing unit 13, an application processing unit 14, a frame generation unit 15, an extraction unit 21, a GDID management unit 22, a table management unit 23, and a path information generation unit 24. To do. In the communication device 10, the DRAM 106 operates as the storage unit 30. In the communication device 10, the wireless module 108 operates as the reception unit 11 and the transmission unit 16. The PHY chip 102 is used for wired communication. In the communication device 10 that operates as a gateway that relays communication between an ad hoc network and devices in other networks, communication via a line can be performed via the PHY chip 102. The timer IC 104 operates as the timer 25.

  Note that a program such as firmware may be provided by being stored in a computer-readable storage medium and installed in the communication apparatus 10. The program may be installed in the communication device 10 by being downloaded from the network via the PHY chip 102 or the wireless module 108. Furthermore, other types of storage devices other than the DRAM 106 and the flash memory 107 may be used depending on the embodiment. The communication device 10 may be realized by a computer.

  FIG. 4 is a diagram illustrating an example of a frame format. A frame F101 is an example of a format of a data frame transmitted and received in an ad hoc network, and a frame F102 is an example of a format of a Hello frame.

  As shown in a frame F101, the data frame includes a physical header, a MAC (Media Access Control) header, an ad hoc header, a payload, a signature, and an FCS (Frame Check Sequence), and appropriately includes padding. The MAC header includes a local destination address (LD) and a local transmission source address (LS). The ad hoc header includes a global destination address (GD), a global source address (GS), and a direction flag. The direction flag is information indicating whether the data frame is transmitted to the gateway device. In the following description, it is assumed that the direction flag is set to 1 in a frame transmitted toward the gateway device. On the other hand, the direction flag is set to 0 in the frame transmitted from the gateway device to the other communication device 10.

  As shown in the frame F102, the Hello frame also includes a physical header, a MAC header, an ad hoc header, a payload, a signature, and an FCS, and appropriately includes padding. The physical header, MAC header, and ad hoc header are the same as the data frame. However, in the Hello frame, both the local transmission source address and the global transmission source address are set to addresses assigned to the device that generated the Hello frame. Further, the local destination address and the global destination address of the Hello frame are set to a broadcast address (BC).

  The payload of the Hello frame includes a Hello message header and a Hello header. The Hello message header includes information such as the number of Hello headers included in the Hello frame. Each Hello header includes global destination information that can be communicated via the communication device 10 that is the transmission source of the Hello frame. In the example of FIG. 4, the Hello header includes a global destination address, GDID, hop count, and route quality weight that can be communicated from the transmission source of the Hello frame. The GDID is a value of GDID set by the sender of the Hello frame with respect to the global destination whose address is recorded in the Hello header. The number of hops is the number of hops from the transmission source of the Hello frame to the global destination in the Hello header. The route quality weight is information indicating the quality of the route from the transmission source of the Hello frame to the global destination whose information is recorded in the Hello header.

<First Embodiment>
Hereinafter, the first embodiment will be described by dividing it into a Hello frame process, a data frame transfer process, and an application example to a complicated network. In the first embodiment, information on the communication device 10 that operates as a gateway device is propagated in a Hello frame, but information on the communication device 10 that does not operate as a gateway device is not notified to other devices by the Hello frame. Describe the case. In the first embodiment, the number of communication devices 10 that do not operate as gateways, such as a meter reading system, is larger than the number of communication devices 10 that operate as gateways, and the amount of information in the routing table of each communication device 10 is reduced. It is easy to apply when is required.

[Hello frame processing]
FIG. 5 is a diagram illustrating an example of processing performed when transmitting and receiving a Hello frame. In the following description, in order to make it easy to distinguish each communication device 10, description will be made using identifiers of the communication devices 10 such as the node A and the gateway GW 1. Hereinafter, in order to clarify the node device 10 performing the operation, an alphabet assigned to the node device 10 performing the operation may be described at the end of the code. For example, the receiving unit 11 in the node A may be referred to as a receiving unit 11a, and the transfer destination table 33 in the GW1 may be referred to as a transfer destination table 33gw1. Furthermore, in order to make the figure easy to see, some information of the frame such as a MAC header, an ad hoc header, and a Hello header among the information included in the frame is illustrated, and other information may be omitted.

Hereinafter, for each GDID, which communication device 10 is used to identify which communication device 10 is used is represented by a GDID suffix. The subscript of the GDID indicates a character string in which the communication device 10 indicated by the GDID, the hyphen, and the communication device 10 in which the GDID is set are continuously described by subscript characters. For example, the GDID that the node A sets for the gateway GW1 in order to identify the gateway GW1 is expressed as GDID _GW1-A . As for the GDID assigned to the communication device 10 itself by the communication device 10 identified by the GDID, the device set by the GDID is the same as the device identified by the GDID. Sometimes omitted from subscripts. For example, “GDID _GW1 ” represents the value of GDID set by the gateway GW1 for the gateway GW1 itself. In the first embodiment, each gateway device sets a GDID for identifying its own device to 0, and a device other than the gateway device sets a value other than 0 to the GDID.

  The network shown in FIG. 5 includes two gateway devices, gateway GW1 and gateway GW2. Node A is adjacent to both gateway GW1 and gateway GW2. Node B is adjacent to node A.

First, it is assumed that the gateway GW1 generates a Hello frame shown in the frame F1. The MAC header included in the frame F1 records that the local transmission source is the gateway GW1, and the Hello header 1 includes information on the gateway GW1. The gateway GW1 includes GDID _GW1 = 0 in the Hello header 1 as information used when identifying the gateway GW1 itself. The gateway GW1 transmits a Hello frame shown in the frame F1. Note that LD = BC in the MAC header indicates that the local destination address is a broadcast address.

  The reception unit 11a of the node A receives the frame F1 and outputs it to the header analysis unit 12a. Since the frame F1 is a Hello frame, the header analysis unit 12a outputs the frame F1 to the extraction unit 21a. The extraction unit 21a extracts information on the local generation source (LS) specified in the MAC header of the frame F1 as information on the transmission source of the Hello frame, and further extracts information on the Hello header 1. The extraction unit 21a outputs the extracted information to the table management unit 23a. The table management unit 23a updates the information in the routing table 32a using the information input from the extraction unit 21a. At this time, the table management unit 23a replaces the transmission source of the Hello frame with the local transfer destination for the global destination notified by the Hello frame.

  In the routing table 32a, for each global destination, the address of the global destination, the GDID used by the own node to identify the global destination, and information on the local forwarding destination that can be used when forwarding a frame to the global destination are stored. included. The local transfer destination information includes the address assigned to the local transfer destination and the GDID used to identify the global destination communication device 10 in the communication device 10 that is the local transfer destination.

The table management unit 23a uses the information held by the GDID management unit 22a to use the value used for identifying the newly notified global destination from the GDID value that is not set in any device by the node A. Select. In the following example, it is assumed that the table management unit 23a selects GDID = 2 for GW1. The GDID management unit 22a deletes the value selected by the table management unit 23a from the selectable values. On the other hand, the table management unit 23a records the following information in the routing table 32a using information obtained from the Hello header 1 or the like.
Global destination (GD): GW1
GDID used by own node for GD: GDID _GW1-A = 2
Local destination (LD): GW1
GDID LD set to GD: GDID _GW1 = 0
For this reason, information related to “transfer destination 1” in the routing table 32a is generated by the processing of the table management unit 23a.

Next, it is assumed that the gateway GW2 generates a Hello frame shown in the frame F2. The MAC header included in the frame F2 records that the local transmission source is the gateway GW2, and the Hello header 1 includes the address of the gateway GW2 and GDID _GW2 = 0. The gateway GW2 transmits a Hello frame shown in the frame F2.

  Node A receives frame F2. The extraction unit 21a acquires the frame F2 via the reception unit 11a and the header analysis unit 12a. The extraction unit 21a specifies that the frame F2 is a Hello frame transmitted from the gateway GW2, using the MAC header of the frame F2. Further, the extraction unit 21a extracts the information of the Hello header 1 and outputs it to the table management unit 23a.

The table management unit 23a determines the GDID used by the node A when identifying the gateway GW2, using information included in the GDID management unit 22a and information input from the extraction unit 21a. It is assumed that the information for the gateway GW2 is as follows by the processing of the table management unit 23a.
Global destination (GD): GW2
GDID used by own node for GD: GDID _GW2-A = 1
Local destination (LD): GW2
GDID set by LD to GD: GDID _GW2 = 0
The table management unit 23a also records information regarding the gateway GW2 in the routing table 32a. For this reason, information indicated by “transfer destination 2” in the routing table 32a is recorded.

  Thereafter, it is assumed that the timer 25a of the node A detects that it is time for the node A to generate the Hello frame. The route information generation unit 24a extracts the global destination information included in the routing table 32a and the GDID set by the node A for each global destination as information to be included in the Hello frame. The route information generation unit 24a determines whether the node A is operating as a gateway device. Since the node A is not operating as a gateway device, the route information generation unit 24 determines not to notify the other device of the information of the node A with the Hello frame.

  The route information generation unit 24 a outputs information to be included in the Hello frame to the frame generation unit 15. The frame generation unit 15 uses the information input from the route information generation unit 24 to generate a Hello frame indicated by a frame F3 in FIG. The transmission unit 16 transmits the frame F3.

Node B receives frame F3. The extraction unit 21b acquires the frame F3 via the reception unit 11b and the header analysis unit 12b. The extraction unit 21b specifies that the frame F3 is a Hello frame transmitted from the node A using the MAC header of the frame F3. When the table management unit 23b acquires the information of the Hello header 1 and the Hello header 2 from the extraction unit 21b, the table management unit 23b determines the GDID used in the node B for the gateways GW1 and GW2. Further, the table management unit 23b records the information notified in the frame F3 in the routing table 32b. For this reason, the following information is recorded in the routing table 32b.
Forwarding destination 1
Global destination (GD): GW1
GDID used by own node for GD: GDID _GW1-B = 1
Local destination (LD): A
GDID set by LD to GD: GDID _GW1-A = 2
Forwarding destination 2
Global destination (GD): GW2
GDID used by own node for GD: GDID _GW2-B = 2
Local destination (LD): A
GDID set by LD to GD: GDID _GW2-A = 1
An example of the routing table 32b is shown in FIG.

  Since the gateway GW1 and the gateway GW2 are also adjacent to the node A, the frame F3 transmitted from the node A is processed, and the routing table 32 is updated similarly to the node B. However, neither the gateway GW1 nor GW2 uses the information in the Hello header with the local node as the global destination for updating the routing table 32. Thereafter, each communication device 10 in the ad hoc network transmits a Hello frame at a predetermined cycle. In addition, when receiving a Hello frame from the adjacent communication device 10, the communication device 10 appropriately updates the routing table 32 using the received Hello frame.

  FIG. 6 is a flowchart illustrating an example of a reception process of a Hello frame. Note that FIG. 6 is an example of processing, and the order of processing can be changed according to implementation. For example, the order of steps S14 to S16 can be arbitrarily changed.

  When the communication device 10 receives the Hello frame, the extraction unit 21 extracts information on the global destination (GD) of each Hello header in the Hello frame (Steps S11 and S12). The table management unit 23 determines whether registration for the extracted global destination already exists in the routing table 32 (step S13).

  If there is no registration for the extracted global destination in the routing table 32, the table management unit 23 records the transmission source (LS) of the Hello frame as the transfer destination (LD) of the frame addressed to the global destination (step S13). No, step S14). Further, the table management unit 23 records the GDID assigned to the global destination by the transmission source of the Hello frame in association with the transmission source of the Hello frame (Step S15). Furthermore, the table management unit 23 uses the information held by the GDID management unit 22 to assign a GDID used by the own node to identify the global destination to the global destination (step S16). The table management unit 23 registers the GDID assigned to the global destination in the routing table 32 in association with the global destination (step S17).

  On the other hand, it is assumed that the extracted global destination is already registered in the routing table 32 (Yes in step S13). In this case, the table management unit 23 determines whether the transmission source (LS) of the Hello frame is registered as the local destination (LD) with respect to the global destination (step S18). When the transmission source of the Hello frame is not registered for the global destination, the table management unit 23 records the transmission source of the Hello frame as the transfer destination (LD) of the frame addressed to the global destination (No in step S18). Step S19). Thereafter, the table management unit 23 records the GDID assigned to the global destination by the transmission source of the Hello frame in the routing table 32 in association with the transmission source of the Hello frame (Step S20).

  If it is determined in step S18 that the transmission source (LS) of the Hello frame is registered as a local destination (LD) for the global destination, the table management unit 23 performs the process of step S20 (in step S18). Yes, step S20).

  FIG. 7 is a flowchart illustrating an example of a transmission process of a Hello frame. In the flowchart shown in FIG. 7, a variable n and a constant N are used. The constant N is the total number of global destinations recorded in the routing table 32 when the Hello frame is generated. The variable n is a variable used for counting the number of global destinations extracted from the routing table 32 as a target to be notified in the Hello frame.

  The path information generation unit 24 uses the timer 25 to determine whether it is the transmission time of the Hello frame, and waits until the transmission time of the Hello frame is reached (No in step S31). When it is time to transmit the Hello frame, the path information generation unit 24 sets the value of the variable n to 1 (Yes in Step S31, Step S32). The route information generation unit 24 determines whether the variable n exceeds a constant N (step S33). When the variable n is less than or equal to the constant N, the global destination included in the nth entry and the GDID assigned to the global destination by the own node are added to the information notified in the Hello frame (No in step S33, step S34). The route information generation unit 24 increments the variable n by one and returns to the process of step S33 (step S35).

  When the variable n exceeds the constant N, the path information generation unit 24 determines whether the own node is operating as a gateway device (Yes in step S33, step S36). When the own node is operating as a gateway device, the route information generating unit 24 adds the GDID for identifying the own node to the information notified by the Hello frame in association with the information of the own node (Yes in step S36). Step S37). Thereafter, the frame generation unit 15 generates a Hello frame including information selected as information notified by the route information generation unit 24 using the Hello frame (step S38). The transmission unit 16 transmits a Hello frame (Step S39). On the other hand, when it is determined in step S36 that the own node is not operating as a gateway device, the communication device 10 performs the processing after step S38 (No in step S36).

[Data frame transfer processing]
FIG. 8 is a diagram for explaining an example of processing for transferring a frame addressed to the gateway device. An example of communication processing performed when the node B transmits data to the gateway GW1 will be described with reference to FIG.

  In the following description, when the communication device 10 that is not operating as a gateway acquires route information to a gateway device that has not had route information so far, the communication device 10 is directed toward the gateway device that newly acquired the route information. A data frame shall be transmitted. Further, the information of the routing table 32a held by the node A and the routing table 32b held by the node B are as shown in FIG. In a frame transmitted to any gateway device, the direction flag is set to 1 (upward direction).

It is assumed that the application processing unit 14b of the node B has generated data to be transmitted to the gateway GW1. The application processing unit 14b outputs the generated data and information indicating that the destination is the gateway GW1 to the frame generation unit 15b. The frame generation unit 15b refers to the routing table 32b to specify that the node A is a local destination (LD) when transmitting a frame to the gateway GW1. Further, the frame generation unit 15b also specifies from the routing table 32b that the information for identifying the gateway GW1 by the node A is GDID _GW1-A = 2. In other words, the frame generation unit 15b specifies that the node A, which is the transfer destination of the frame addressed to the gateway GW1, can notify the global destination by notifying the value of the GDID _GW1-A instead of the address of the global destination. To do. Accordingly, the frame generation unit 15b includes the data input from the application processing unit 14b in the header having the following information in the payload of the frame.
Local destination address: Node A address Local source address: Node B address Global destination address: 2
Global source address: Node B address Direction flag: 1 (upward direction)

  A data frame generated by the frame generation unit 15b is shown in a frame F11. Here, 8 bytes are used to describe the address of each communication device 10, but GDID is represented by 1 byte. For this reason, the length of the ad hoc header is 7 bytes shorter than when both the global destination and the global transmission source are represented by addresses. Therefore, the frame generation unit 15 can increase the payload length in a range up to the amount of shortening of the ad hoc header. The frame generation unit 15b outputs the generated frame F11 to the transmission unit 16b. The transmission unit 16b transmits the frame F11 to the node A.

  Assume that node A receives frame F11. Since the frame F11 is a data frame in which the direction flag = 1 is set, the header analysis unit 12a specifies the global destination identified by the GDID value notified in the global destination address field of the frame F11. 2 is recorded in the global destination address field of the frame F11. On the other hand, as shown in the routing table 32a, GDID = 2 set by the node A indicates the gateway GW1. Therefore, the header analysis unit 12a replaces the global destination address of the frame F11 with the address of the gateway GW1, and then outputs the payload information of the frame F11 and the header information of the frame F11 to the transfer processing unit 13a.

  Furthermore, since the header analysis unit 12a has received the frame F11 from the node B and the global transmission source of the frame F11 is the node B, the local destination can be set to the node B when the global destination is the node B. recognize. The header analysis unit 12a records information obtained from the global transmission source and the local transmission source of the frame F11 in the transfer destination table 33a (FIG. 9).

The transfer processing unit 13a refers to the routing table 32a to specify that the gateway GW1 is a local destination (LD) when transferring data to the gateway GW1. The transfer processing unit 13b outputs the data included in the frame F11 to the frame generation unit 15a, with the global destination of the data being the gateway GW1 and the local destination being the gateway GW1. Since the information for identifying the gateway GW1 itself by the gateway GW1 is GDID _GW1 = 0, the frame generation unit 15a generates a frame including a header having the following information.
Local destination address: Node GW1 address Local source address: Node A address Global destination address: 0
Global source address: Node B address Direction flag: 1 (upward direction)
A data frame generated by the frame generation unit 15a is shown in a frame F12. Note that the frame F12 includes data included in the frame F11. The transmission unit 16a transmits the frame F12 to the gateway GW1.

  The gateway GW1 receives the frame F12. The header analysis unit 12gw1 determines that the frame F12 is addressed to the gateway GW1 because the value of the GDID notified using the global destination address field of the frame F12 is 0. The header analysis unit 12gw1 outputs the frame F12 to the application processing unit 14gw1. The header analysis unit 12gw1 updates the transfer destination table 33gw1 using the header information of the frame F12.

  FIG. 9 is a diagram for explaining an example of transfer processing of a frame transmitted from the gateway device. An example of communication processing performed when the gateway GW1 transmits data to the node B will be described with reference to FIG.

The application processing unit 14gw1 of the gateway GW1 outputs data addressed to the node B to the frame generation unit 15gw1 together with information indicating that the global destination of the data is the node B. The frame generation unit 15gw1 uses the transfer destination table 33gw1 to specify that the local destination is set to the node A when the global destination is the node B. Here, since the gateway GW1 has already transmitted the Hello frame, the GWID used when the gateway GW1 identifies the gateway GW1 itself has been notified to the adjacent communication device 10. For this reason, the frame generation unit 15gw1 reduces the size of the ad hoc header and increases the payload length by replacing the value of the global transmission source with GDID _GW1 = 0. An example of the frame F21 generated by the processing in the frame generation unit 15gw1 is shown in FIG. Since the frame F21 is a frame transmitted from the gateway device, the direction flag of the frame F21 is 0. The transmission unit 16gw1 transmits the frame F21 to the node A.

  Assume that node A receives frame F21. Since the frame F21 is a data frame in which the direction flag = 0 is set, the header analysis unit 12a identifies the global transmission source of the frame F21 using the GDID value notified in the global transmission source address field of the frame F21. To do. That is, the header analysis unit 12a specifies the communication device 10 specified by GDID = 0 in the local transmission source (GW1) of the frame F21. At this time, the header analysis unit 12a has the GDID value and the value notified as the global transmission source in the frame F21 among the entries in which the local transmission source of the frame F21 is registered as the local destination in the routing table 32a. Search for a match. In the routing table 32a shown in FIG. 9, the global destination of the entry whose GDID value is 0 among the entries of LD = GW1 is the gateway GW1. Therefore, the header analysis unit 12a outputs the data of the frame F21 and the information of the global destination of the frame F21 to the transfer processing unit 13a together with information indicating that the global transmission source of the frame F21 is the gateway GW1.

The transfer processing unit 13a uses the transfer destination table 33a to specify that the local destination is the node B when the global destination is the node B. The transfer processing unit 13a notifies the frame generation unit 15a of information such as data and global destinations input from the header analysis unit 12a and a local destination. The frame generation unit 15a notifies the adjacent communication apparatus 10 that the node A identifies the gateway GW1 with GDID _GW1-A = 2 because the node A has already transmitted the Hello frame including the information of the gateway GW1. It is determined that it has been completed. Therefore, the frame generation unit 15a generates a frame F22 (FIG. 9) by reducing the size of the ad hoc header by replacing the global transmission source value with GDID _GW1-A = 2. Note that the direction flag of the frame F22 is 0 because the global transmission source of the frame F22 is also a gateway device. The transmission unit 16a transmits the frame F22 to the node B.

  Node B receives frame F22. Since the direction flag of the frame F22 is 0, the header analysis unit 12b specifies the global transmission source of the frame F22 using the GDID value notified in the global transmission source address field of the frame F22. That is, the header analysis unit 12b uses the routing table 32b to specify that the communication device 10 specified by GDID = 2 is the gateway GW1 at the local transmission source (node A) of the frame F22. Further, the header analysis unit 12b determines that the frame F22 is addressed to the node B because the node B is designated as the global destination address of the frame F22. The header analysis unit 12b outputs the data of the frame F22 and the global transmission source information of the frame F22 to the application processing unit 14b. The application processing unit 14b appropriately processes the input information.

  FIG. 10 is a sequence diagram illustrating an example of data frame reception processing. 10 and 11, the GDID determined by the node for the global destination is described as “internal GDID”, and the GDID determined by the local destination associated with the global destination is described as “GDID set by LD”. . Note that FIG. 10 is an example of reception processing, and the procedure may be changed depending on the implementation. For example, the processes in steps S54 to S57 may be performed before the processes in steps S58 to S60.

  When the header analysis unit 12 acquires the received frame, the header analysis unit 12 determines whether the frame is a data frame (steps S51 and S52). If the received frame is not a data frame, the header analysis unit 12 outputs the frame to the control unit 20 (No in step S52, step S53).

  When the received frame is a data frame, the header analysis unit 12 determines whether the frame is transmitted (upward) to the gateway (step S54). First, a case where the received frame is a data frame transferred in the upstream direction will be described (Yes in step S54). In this case, the header analysis unit 12 acquires from the routing table 32 an entry in which the internal GDID and the GDID notified as the global destination address by the received frame are equal (step S55). The header analysis unit 12 converts the GDID in the frame into a global destination address using the acquired entry (step S56). Further, the header analysis unit 12 registers the combination of the global transmission source and the local transmission source of the received frame in the transfer destination table 33 as a combination of the global destination and the local destination (step S57). In step S57, the global transmission source is replaced with a global destination, and the local transmission source is replaced with a local destination when the global transmission source of the frame becomes the global destination. On the other hand, when the received frame is a data frame transferred in the downlink direction, the processing from step S55 to S57 is not performed (No in step S54).

  Next, the header analysis unit 12 determines whether the received frame is a frame transmitted from the gateway (downward) (step S58). If the received frame is a data frame transferred in the downlink direction, the header analysis unit 12 acquires the combination of the GDID notified as the global transmission source of the received frame and the information of the local transmission source (Yes in step S58). Further, the header analysis unit 12 acquires, from the routing table 32, an entry in which the combination of the local destination in the routing table 32 and the GDID set by the local destination matches the combination of information acquired from the received frame (step S59). That is, through the process of step S59, the header analysis unit 12 specifies that the global destination in the obtained entry matches the global transmission source of the received frame. The header analysis unit 12 converts the global transmission source information of the received frame into the address of the global destination in the entry acquired from the routing table 32 (step S60). If the received frame is a data frame transferred in the upstream direction, the processes in steps S59 and S60 are not performed (No in step S58).

  Furthermore, the header analysis unit 12 determines whether the received frame is a frame addressed to the own node (step S61). When the received frame is a frame addressed to the own node, the header analysis unit 12 outputs the data in the frame together with the header information and the like to the application processing unit 14 (Yes in step S61, step S62). On the other hand, when the received frame is not a frame addressed to the own node, the header analysis unit 12 outputs the data in the frame together with the header information and the like to the transfer processing unit 13 (No in step S61, step S63).

  FIG. 11 is a sequence diagram illustrating an example of a data frame transmission process. Note that FIG. 11 is an example of transmission processing, and the procedure may be changed depending on the implementation. For example, the processes of steps S72 to S75 may be performed after the processes of step S76 and subsequent steps.

  When a frame transmission is requested from the application processing unit 14 or the transfer processing unit 13, the frame generation unit 15 determines whether the frame to be transmitted is a frame transmitted in the uplink direction (steps S71 and S72). When transmitting a frame forwarded in the uplink direction, the frame generation unit 15 acquires an entry in which the combination of the global destination and the local destination is equal to the transmission frame from the routing table 32 (Yes in Step S72, Step S73). The frame generation unit 15 converts the global destination address into the GDID set by the local destination in the acquired entry (step S74). Further, the value of the local destination of the acquired entry is set in the frame (step S75). If the direction in which the transmission frame is transferred is not the uplink direction, the processes in steps S73 to S75 are not performed (No in step S72).

  Next, when transmitting a frame in the downlink direction, the frame generation unit 15 acquires an entry from the routing table 32 whose global destination in the routing table 32 is equal to the global transmission source of the transmission frame (Yes in step S76, step S77). ). The frame generation unit 15 converts the global transmission source address of the transmission frame into an internal GDID for the global destination in the acquired entry (step S78). The frame generation unit 15 refers to the transfer destination table 33, determines the local transfer destination of the transmission frame, and sets it as the transmission frame (step S79). Note that if the direction in which the frame to be transmitted is transferred is the uplink direction, the processing after step S77 is not performed (No in step S76).

[Example of network application]
FIG. 12 is a diagram illustrating an example of a network to which the communication method according to the first embodiment can be applied. In FIG. 12 and subsequent figures, a description will be given of an embodiment in a network that is more complex and has a larger number of communication devices 10 than the network used in the description in FIGS. An example of processing when there are a plurality of local destinations for a certain global destination will be described with reference to FIG.

  The network shown in FIG. 12 includes gateways GW1 and GW2 and nodes A to D. In the network shown in FIG. 12, it is assumed that the node A is adjacent to the gateway GW1, the gateway GW2, and the node C. Node B is adjacent to gateway GW2 and node C. Assume that node D is adjacent to node C.

(1) Formation of Ad Hoc Network Using Hello Frame FIG. 13 is a diagram illustrating an example of processing performed when transmitting and receiving a Hello frame. Note that as an example, none of the nodes A to D has received a Hello frame in the past at the time of FIG. It is assumed that the Hello frame H1 is transmitted from the gateway GW1 and the Hello frame H2 is transmitted from the gateway GW2. When the node A receives both the Hello frame H1 and the Hello frame H2, the node A updates the routing table 32a by the same processing as the procedure described with reference to FIG. For this reason, the information shown in the routing table 32a of FIG.

On the other hand, the Node B also receives the Hello frame H2. The node B records GW2, which is the local transmission source of the Hello frame H2, as a local destination for the GW2, which is the global destination notified in the Hello frame H2. Further, the information of local GDID _GW2 = 0 notified in the Hello frame H2 is recorded in the routing table 32b in association with GW2 as a local destination when GW2 is a global destination. For this reason, the routing table 32b of the node B is as shown in FIG.

  FIG. 14 is a diagram illustrating an example of processing performed when transmitting and receiving a Hello frame. An example of processing performed when the node A transmits the Hello frame H3 will be described with reference to FIG. The process performed by the node A when transmitting the Hello frame H3 is the same as the process described as the process when generating the frame F3 in FIG. 5 and the process described with reference to FIG.

When the node C receives the Hello frame H3, the node A, which is a local transmission source of the Hello frame H3, is registered as a local destination for each of the global destinations notified by the Hello frame H3. Further, the GDID notified from the node A is recorded in the routing table 32c in association with the case where LD = node A for each global destination. Further, the node C sets a GDID for each notified global destination. For this reason, the following information is recorded in the routing table 32c when the node C receives the Hello frame H3.
Forwarding destination 1
Global destination (GD): GW1
GDID used by node C for GD: GDID _GW1-C = 1
Local destination (LD): A
GDID set by LD to GD: GDID _GW1-A = 1
Forwarding destination 2
Global destination (GD): GW2
GDID used by node C for GD: GDID _GW2-C = 2
Local destination (LD): A
GDID LD set to GD: GDID _GW2-A = 2

Thereafter, it is assumed that the Node B transmits a Hello frame H4. As shown in FIG. 14, the Hello frame H4 includes route information regarding the gateway GW2. When the node C receives the Hello frame H4, the extraction unit 21c acquires the Hello frame H4 via the header analysis unit 12c and the like. The extraction unit 21c notifies the table management unit 23c that the information of the Hello header including information regarding the gateway GW2 and that the local transmission source of the Hello frame H4 is the Node B. Since the entry for the gateway GW2 exists in the routing table 32c, the table management unit 23c determines whether the node B is registered in the routing table 32c as a local destination to the gateway GW2. Here, the node B is not registered as a local destination to the gateway GW2. For this reason, the table management unit 23c registers the node B in the routing table 32c as a local destination to the gateway GW2. Furthermore, the table management unit 23c also registers the GDID (GDID _GW2-B = 1) used when the node B identifies the gateway GW2 in the routing table 32c. Here, for node C, it is assumed that the communication status of the route to node GW2 via node A is better than the communication status of the route to node GW2 via node B. In this case, the table management unit 23c routes the local transfer destination (LD1) having the highest priority during transfer processing to the gateway GW2 as the node A, and the local transfer destination (LD2) used preferentially as the node B. Record in table 32c. Therefore, the routing table 32c held by the node C after processing the Hello frame H4 is as shown in FIG. Note that the processing of the Hello frame H4 at the node C corresponds to the processing of steps S18 to S20 in FIG.

  FIG. 15 is a diagram illustrating an example of processing performed when transmitting and receiving a Hello frame. The node C notifies the adjacent node of the information on the global destination recorded in the routing table 32c using the Hello frame H5 together with the GDID used by the node C to identify each global destination.

  Assume that the node D receives the Hello frame H5. The node D records the node C that is the local transmission source of the Hello frame H5 as the local destination for the global destinations GW1 and GW2 that are notified in the Hello frame H5. Further, the GDID used when the node C identifies each of GW1 and GW2 is recorded, and the GDID used by the node D to identify these global destinations is determined. For this reason, the routing table 32d of the node D is as shown in FIG.

  FIG. 16 is a diagram illustrating an example of the routing table 32 held by each communication device 10. FIG. 16 shows an example of the routing table 32 held by each communication device 10 of the nodes A to D when the processing of the Hello frames H1 to H5 is completed. Although not explicitly shown in FIG. 15, the node A and the node B also receive the Hello frame H5 transmitted from the node C. For this reason, both the node A and the node B hold information on the route reaching the gateways GW1 and GW2 via the node C in the routing table 32. The process of the Hello frame H5 at the node A and the node B is the same as the process described as an example when the node C processes the Hello frame H4.

(2) Processing of data frame transferred in upstream direction Hereinafter, when a frame is transmitted from node D to gateway GW1 in a state where routing table 32 held by each communication device 10 in the ad hoc network is shown in FIG. An example of the transfer process will be described. In FIG. 17 and subsequent figures, a part of the routing table 32 held by each communication device 10 may be extracted and shown for easy understanding of the drawing. In the following, the description will be given with an emphasis on the designation of the global destination and the local destination in each communication device 10, but details of processing performed in the control unit 20 of each communication device 10 will be described with reference to FIGS. It is the same.

FIG. 17 is a diagram illustrating an example of a transfer process of a frame addressed to the gateway device. First, it is assumed that the node D generates data to be transmitted to the gateway GW1. Next, using the routing table 32d, the node D uses GDID _GW1-C = 1 to identify the gateway GW1 as the local destination when transmitting a frame to the gateway GW1, and to identify the gateway GW1 in the node C. Identify that. Therefore, the node D generates a frame F31 in which the local transfer destination (LD) of the frame addressed to the gateway GW1 is designated as the node C, and a value of GD = 1 is designated instead of the address of the global destination, and the frame F31 is transmitted to the node C. To do. FIG. 17 shows local destination information and global destination information specified in the frame F31.

The node C that has received the frame F31 determines that the device whose GDID value attached to the node C is 1 is the global destination of the frame F31 because 1 is designated as the global destination (GD) of the frame F31. . As illustrated in FIG. 17, since GDID _GW1-C = 1, the node C determines that the gateway GW1 is the global destination of the frame F31.

FIG. 18 is a diagram for explaining an example of a process for transferring a frame addressed to the gateway device. The transfer process performed at the node C will be described with reference to FIG. Since the global destination of the frame F31 is the gateway GW1, the node C determines that the local destination for transmitting the transfer frame F32 is the node A. Further, since GDID _GW1-A = 1 is used for identifying the gateway GW1 in the node A, the node C designates a value of GD = 1 in the forwarding frame F32 instead of the address of the global destination. The data in the transfer frame F32 is the data in the frame F31. FIG. 18 shows local destination information and global destination information specified in the frame F32. Node C transmits frame F32 to node A.

The node A that has received the frame F32 determines that the device whose GDID value attached to the node A is 1 is the global destination of the frame F32 because 1 is designated as the global destination (GD) of the frame F32. . As illustrated in FIG. 18, since GDID _GW1-A = 1, the node A determines that the gateway GW1 is the global destination of the frame F32.

FIG. 19 is a diagram for explaining an example of a process for transferring a frame addressed to the gateway device. The transfer process performed at the node A will be described with reference to FIG. Since the global destination of the frame F32 is the gateway GW1, the node A determines the local destination when transmitting the transfer frame F33 as the gateway GW1. Further, since GDID _GW1 = 0 is used to identify the gateway GW1 in the gateway GW1, the node A designates a value of GD = 0 as the global destination address of the transfer frame F33. The data in the transfer frame F33 is data included in the frame F31. FIG. 19 shows local destination information and global destination information specified in the frame F33. Node A transmits frame F33 to gateway GW1.

  The gateway GW1 that has received the frame F33 determines that the frame addressed to the gateway GW1 has been received because 0 is designated as the global destination (GD) of the frame F33, and processes the frame F33.

(3) Processing of Data Frames Forwarded Downward Next, a frame is transmitted from the gateway GW 2 to the node D while the routing table 32 held by each communication device 10 in the ad hoc network is shown in FIG. An example of transfer processing in this case will be described. The method for generating the transfer destination table 33 in each communication apparatus 10 is also as described with reference to FIGS.

  FIG. 20 is a diagram for explaining an example of transfer processing of a frame transmitted from the gateway device. First, it is assumed that the gateway GW2 generates data to be transmitted to the node D. Next, the gateway GW2 specifies that the local destination when transmitting the frame to the node D is the node B by using the transfer destination table 33gw2. Since the gateway GW2 has transmitted the Hello frame, the GDID used when the gateway GW2 identifies the gateway GW2 itself has been notified to the adjacent communication device 10. Accordingly, the local transfer destination (LD) of the frame addressed to the node D is set as the node B, the frame F41 in which the value of GS = 0 is specified instead of the address of the global transmission source is generated, and the frame F41 is transmitted to the node B. FIG. 20 shows information on the address specified in the frame F41.

Since 0 is designated as the global transmission source (GS) of the frame F41, the node B determines that the device whose GDID value notified from the gateway GW2 is 0 is the global transmission source of the frame F41. As illustrated in FIG. 20, since GDID _GW2 = 0, the node B determines that the gateway GW2 is the global transmission source of the frame F41.

FIG. 21 is a diagram illustrating an example of transfer processing of a frame transmitted from the gateway device. With reference to FIG. 21, the transfer process performed at the node B will be described. Since the global destination of the frame F41 is the node D, the node B determines the local destination when transmitting the transfer frame F42 to the node C using the transfer destination table 33b. Since the node B has transmitted the Hello frame, the node B has notified the adjacent communication device 10 that GDID _GW2-B = 1 is used when identifying the gateway GW2. Therefore, the local transfer destination (LD) of the frame addressed to the node D is set as the node C, the frame F42 in which the value of GS = 1 is specified instead of the address of the global transmission source is generated, and the frame F42 is transmitted to the node C. FIG. 21 shows information on the address specified in the frame F42.

Since node C is designated as 1 in the global transmission source (GS) of frame F42 and the local transmission source of frame F42 is node B, a device whose GDID value notified from node B is 1 It is determined that it is the global transmission source of F42. As illustrated in FIG. 21, since GDID _GW2-B = 1, the node C determines that the gateway GW2 is the global transmission source of the frame F42.

FIG. 22 is a diagram illustrating an example of transfer processing of a frame transmitted from the gateway device. The transfer process performed at the node C will be described with reference to FIG. Since the global destination of the frame F42 is the node D, the node C determines the local destination for transmitting the transfer frame F43 to the node D using the transfer destination table 33c. The node C has notified the adjacent communication device 10 that the node C uses GDID _GW2-C = 2 when the node C identifies the gateway GW2, using the Hello frame including the information of the gateway GW2. Therefore, node D is generated as the local transfer destination (LD) of the frame addressed to node D, and frame F43 in which a value of GS = 2 is designated instead of the address of the global transmission source is generated, and frame F43 is transmitted to node D. FIG. 22 shows information on the address specified in the frame F43.

Since node D is designated as 2 in the global transmission source (GS) of frame F43 and the local transmission source of frame F43 is node C, a device whose GDID value notified from node C is 2 It is determined that it is the global transmission source of F43. As illustrated in FIG. 22, since GDID _GW2-C = 2, the node D determines that the gateway GW2 is the global transmission source of the frame F43. In addition, since the final destination of the frame F43 is the node D itself, the node D appropriately processes the data in the frame F43.

  FIG. 23 is a diagram for explaining an example of the size of the payload in the frame. The frame F111 is an example of a data frame format when the first embodiment is not applied. In the frame F111, the device address is used for both the global destination and the global transmission source. Therefore, in the frame F111, 8 bytes are respectively used for the global destination address and the global transmission source address. Since the control information is 20 bytes and 8 bytes are used for both the local destination address and the local transmission source address, 8 × 4 + 20 = 52 bytes are used for the address information and the control information in the frame F111. If the frame size used in the ad hoc network is 127 bytes, the payload length is 75 bytes.

  A frame F112 shows an example of a format of a frame transferred in the uplink direction using the first embodiment. In the frame F112, the global destination address is set to a GDID that can be processed at the local transfer destination of the frame. Here, if 1 byte is used for the description of GDID, the global destination address field can be 1 byte. Therefore, in the frame F112, 8 × 3 + 1 + 20 = 45 bytes are used for address information and control information in the frame. For this reason, in the frame F112, even if the size of the frame used in the ad hoc network is 127 bytes, 82 bytes can be used for the payload. In the case of a frame transmitted in the downlink direction, the global destination is not converted to GDID, but the global transmission source is converted to GDID. For this reason, a 82-byte payload can be secured even in a frame transmitted in the downlink direction, as shown in the frame F112. Therefore, when one frame is 127 bytes, the payload in one frame can be increased from 75 bytes to 7 bytes by using the method according to the first embodiment. In other words, when one frame is 127 bytes, the payload in one frame can be increased by about 10% by using the method according to the first embodiment.

  As described above, according to the first embodiment, each communication device 10 has unique path information used by the communication device 10 when identifying the gateway device, along with route information in the direction toward the communication device 10 operating as a gateway. Exchange information (GDID) with neighboring devices. For this reason, in a frame transferred in the upstream direction, the size of the area used for the header in the frame is reduced by replacing the gateway device serving as the global destination with the GDID recognized by the transfer destination. be able to. On the other hand, in the frame forwarded in the downlink direction, the header in the frame can be reduced by replacing the information of the gateway serving as the global transmission source with the GDID that has been notified to the communication device 10 of the forwarding destination. . Therefore, the amount of data included in each frame increases, and as a result, the throughput improves. That is, the communication speed in the ad hoc network can be improved, and the communication efficiency can be improved.

  In the network to which the first embodiment is applied, when data is exchanged between the communication apparatuses 10 not operating as a gateway, the communication apparatus 10 operating as a gateway serves as a data relay point. For this reason, even in communication between devices other than the gateway device, the amount of data in one frame can be increased by applying the first embodiment.

  By the way, when a GDID is assigned as an identifier of a gateway device, it may be considered that a GDID allocated to each gateway device is managed by a coordinator so that a common value is set for a certain gateway in the entire network. However, when a common value for the entire network is assigned to the gateway device using the coordinator, the processing performed when the communication device 10 joins or leaves the network becomes complicated, and a large amount of memory is stored in the communication device 10. There is a risk of consumption. However, the communication device 10 applied to the ad hoc network often has a small memory capacity. In addition, an unspecified number of communication devices 10 may join or leave the ad hoc network.

  On the other hand, as described in the first embodiment, when each communication device 10 freely holds the gateway information notified to the communication device 10 and notifies the adjacent node of the GDID used by the own node The burden on the communication device 10 is relatively small. Furthermore, even if the communication device 10 joins or leaves the ad hoc network, the communication device 10 is not burdened by the processing caused by the GDID processing.

<Second Embodiment>
In the second embodiment, transfer processing in a case where both information on the communication device 10 that operates as a gateway device and information on the communication device 10 that does not operate as a gateway device are notified to other devices by a Hello frame will be described. To do. Note that the processing performed by each communication device 10 when a Hello frame is received is the same as in the first embodiment.

  FIG. 24 is a flowchart illustrating an example of a transmission process of a Hello frame performed in the second embodiment. When the generation time of the Hello frame is reached, the route information generation unit 24 selects communication destination information that can be communicated via the own node as information to be notified to the adjacent node through the Hello frame by the processing of Steps S91 to S95. In addition, the process of step S91-S95 is the same as the process performed by step S31-S35 of FIG.

  Next, the path information generation unit 24 adds the GDID used by the own node to identify itself in association with the information of the own node to the information notified by the Hello frame (step S96). The frame generation unit 15 generates a Hello frame including the information selected as information to be notified by the Hello frame by the route information generation unit 24 (Step S97). The transmission unit 16 transmits a Hello frame (Step S98).

  In the Hello frame transmission process described with reference to FIG. 24, the process of step S96 is also performed by the communication apparatus 10 that is not operating as a gateway apparatus. Therefore, the route to the device other than the gateway device is also exchanged between adjacent nodes. Moreover, since the process at the time of reception of a Hello frame is as having demonstrated with reference to FIG. 6 also in 2nd Embodiment, each communication apparatus 10 is about each of the communication destination notified by the Hello frame. Assign a GDID. Information exchanged in the Hello frame is recorded in the routing table 61.

  FIG. 25 is a diagram illustrating an example of a routing table held by each communication device. In FIG. 25, in order to make the drawing easier to see, a part of the routing table 61 held by each communication device 10 is extracted and shown. However, in the second embodiment, by exchanging the Hello frame, each communication device 10 in the network can hold route information reaching all the communication devices 10 in the network. Also, each communication device 10 sets the GDID used by its own node for all devices in the network and notifies the adjacent nodes, so that the transmission source and final destination of any frame are replaced with the GDID and transferred. You can notify first.

  Hereinafter, an example of transfer processing when a frame is transmitted from the node E to the node D will be described with reference to FIGS. Note that the routing table 61 held by each communication device 10 in the ad hoc network includes the information shown in FIG. Further, when there are a plurality of local destinations, it is assumed that a local destination having a smaller number following the LD indicates a transfer destination having a better transfer path to the global destination.

FIG. 26 is a diagram illustrating an example of data frame transfer processing. First, it is assumed that the node E generates data to be transmitted to the node D. Next, the node E uses the routing table 61e, and the most conditions good destination as the local destination when transmitting a frame to the node D is a node B, node B to Gdid D-B _{= 1} To identify that node D is being identified. Further, since the node E has already transmitted the Hello frame, the node E can notify the node B that the global transmission source is the node E by using the GDID _E−E = 0 assigned to the node E itself. judge. Accordingly, node E, _{GDID D-B} = 1 in the global destination (GD), using _{Gdid E-E} = 0 in the global source (GS), generates a frame F51 including the data of the node D addressed. FIG. 26 shows address information included in the frame F51.

The node B that has received the frame F51 determines that the device having the GDID value 1 attached to the node B is the global destination of the frame F51 because 1 is designated as the global destination (GD) of the frame F51. . As shown in FIG. 26, it is determined that for a _{Gdid D-B} = 1, the node B, the node D is global destination of the frame F51. Furthermore, since 0 is designated as the global transmission source (GS) of the frame F51, the device having the GDID value attached by the node E, which is the local transmission source (LS), is the global transmission source of the frame F51. Is determined. In the routing table 61b, it is recorded that GDID _E−E = 0 in the field when the node E is a global destination. For this reason, the node B determines that the global transmission source of the frame F51 is the node E.

FIG. 27 is a diagram illustrating an example of data frame transfer processing. An example of transfer processing performed at the node B will be described with reference to FIG. The node B uses the routing table 61b to determine that the transfer destination having the best condition as a local destination when transmitting a frame to the node D is the node C, and that the node C uses GDID _D−C = 2. Specify that D is identified. Furthermore, since the node B has already transmitted the Hello frame, it is determined that the node B can notify the node C that the global transmission source is the node E by using GDID _E−B = 2 allocated to the node E. To do. Therefore, node B, _{GDID D-C} = 2 in global destination (GD), using _{GDID E-B} = 2 the global source (GS), generates a frame F52 including the data of the node D addressed. FIG. 27 shows information on addresses included in the frame F52.

The node C that has received the frame F52 determines that the device having the GDID value 2 attached to the node C is the global destination of the frame F52 because 2 is designated as the global destination (GD) of the frame F52. . As shown in FIG. 27, since it is _{Gdid D-C} = 2, node C determines that node D is a global destination of the frame F52. Furthermore, since 2 is designated as the global transmission source (GS) of the frame F52, a device having a GDID value of 2 assigned by the node B that is the local transmission source (LS) is the global transmission source of the frame F52. Is determined. In the routing table 61c, it is recorded that GDID _E−B = 2 in the field when the node E is a global destination. For this reason, the node C determines that the global transmission source of the frame F52 is the node E.

FIG. 28 is a diagram illustrating an example of data frame transfer processing. An example of transfer processing performed at the node C will be described with reference to FIG. The node C uses the routing table 61c to determine that the transfer destination having the best condition as a local destination when transmitting a frame to the node D is the node D, and that the node D uses GDID _DD = 0. Specify that D is identified. Further, since the node C has already transmitted the Hello frame, it is determined that the node C can notify the node D that the global transmission source is the node E using GDID _E−C = 1 assigned to the node E. To do. Therefore, node C, _{Gdid D-D} = 0 to the global destination (GD), using _{GDID E-C} = 1 globally source (GS), generates a frame F53 including the data of the node D addressed. FIG. 28 shows address information included in the frame F53.

The node D that has received the frame F53 determines that its own node in which the value of GDID attached to the node D is 0 is the global destination of the frame F53 because 0 is designated as the global destination (GD) of the frame F53. To do. Further, since 1 is designated as the global transmission source (GS) of the frame F53, a device having a GDID value of 1 attached by the node C as the local transmission source (LS) is the global transmission source of the frame F53. Is determined. In the routing table 61d, it is recorded that GDID _E−C = 1 in the field when the node E is a global destination. For this reason, the node C determines that the global transmission source of the frame F53 is the node E.

  As described above, according to the second embodiment, each communication apparatus 10 can notify a frame transmitted in any direction by replacing the global destination with a GDID recognized by the transfer destination. Further, each communication apparatus 10 can notify the global transmission source by replacing the global transmission source with the GDID notified to the transfer destination communication apparatus 10 in any frame transmitted in any direction. Therefore, both the global destination and the global transmission source can make the header in the frame small by notifying using the GDID. Therefore, the amount of data included in each frame increases, and as a result, the throughput improves. That is, the communication speed in the ad hoc network can be improved, and the communication efficiency can be improved.

<Others>
The embodiment is not limited to the above, and can be variously modified. Some examples are described below.

  As described in the second embodiment, when information other than the gateway device is also transmitted and received in the Hello frame, each communication device 10 does not need to generate the transfer destination table 33. When the transfer destination table 33 is not generated, the communication apparatus 10 searches the routing table 32 for transfer destination information regardless of the frame transfer direction. In this case, the direction flag may not be included in the ad hoc header.

  The frame formats and tables shown in the above description are examples, and the information elements included therein and the data length of each element can be changed according to the implementation. For example, the GDID may have a length other than 1 byte.

With respect to the embodiments including the above-described first and second embodiments, the following additional notes are disclosed.
(Appendix 1)
In the first communication device included in the network,
Used when identifying the communication destination by the second communication device and information on a communication destination capable of transmitting a frame from the adjacent second communication device via the second communication device. Receiving a control frame including unique information, which is information whose data length is shorter than the address assigned to
When transmitting data to the communication destination via the second communication device, the unique information is set as a destination of a data frame including data addressed to the communication destination,
A communication program for executing a process of transmitting the data frame to the second communication device.
(Appendix 2)
As information used when the third communication device adjacent to the first communication device has a data length shorter than the address assigned to the communication destination, and the first communication device identifies the communication destination. Notifying other determined unique information in association with the communication destination,
If the transmission source of the first frame transferred to the third communication device is the communication destination, generate a second frame in which the other unique information is set as the transmission source of the first frame,
The program according to appendix 1, wherein the first communication device is caused to execute a process of transferring the second frame to the third communication device.
(Appendix 3)
When the first frame is received from the second communication device, since the transmission source address of the first frame is the unique information, the transmission source of the first frame is the communication destination. Identify,
Note that the first communication device is caused to execute the process of generating the second frame by changing the unique information in the header of the first frame to the other unique information. 2. The program according to 2.
(Appendix 4)
The data length is shorter than the information of the target device to be communicated using the path from the first communication device to the third communication device, and the address assigned to the target device, and the first communication A setting value used by the device to identify the target device is notified to the second communication device;
When the target device receives the third frame transmitted to the communication destination, the setting value is set as the transmission source of the third frame, and the unique information is set as the destination of the third frame. Generate 4 frames,
The program according to appendix 2 or 3, characterized by causing the first communication device to execute a process of transferring the fourth frame to the second communication device.
(Appendix 5)
From the third communication device, the data length is shorter than the address assigned to the target device, and the third communication device obtains another setting value used for identifying the target device,
When the communication destination receives the fifth frame transmitted to the target device, the other unique information is set as the transmission source of the fifth frame, and the other setting value is set as the destination of the fifth frame. Generate a sixth frame with
The program according to appendix 4, wherein the first communication device is caused to execute a process of transmitting the sixth frame to the third communication device.
(Appendix 6)
In the first communication device,
When the control frame is received, the address of the communication destination, the address of the second communication device, the unique information, and the other unique information are transmitted as route information to the device with which the first communication device can communicate. Are stored in association with each other.
In another control frame for notifying a device adjacent to the first communication device of a device capable of communicating via the first communication device, the address of the communication destination and the other unique information are included.
The program according to any one of appendices 2 to 5, wherein a process of transmitting the other control frame is executed.
(Appendix 7)
A communication device that operates as a first communication device included in a network,
Used when identifying the communication destination by the second communication device and information on a communication destination capable of transmitting a frame from the adjacent second communication device via the second communication device. A receiving unit that receives a control frame including unique information that is information whose data length is shorter than the address assigned to
A controller configured to set the unique information as a destination of a data frame including data addressed to the communication destination when transmitting data to the communication destination via the second communication device;
A communication apparatus comprising: a transmission unit that transmits the data frame to the second communication apparatus.
(Appendix 8)
The control unit has a data length shorter than an address assigned to the communication destination, determines other unique information as information used when the first communication device identifies the communication destination,
The transmission unit transmits a frame in which the other unique information is associated with the communication destination to a third communication device adjacent to the first communication device,
When the transmission source of the first frame transferred to the third communication device is the communication destination, the control unit sets the second unique information as the transmission source of the first frame. Control to generate
The communication apparatus according to appendix 7, wherein the transmission unit transfers the second frame to the third communication apparatus.
(Appendix 9)
The controller is
When the receiving unit receives the first frame from the second communication device, since the transmission source address of the first frame is the unique information, the transmission source of the first frame is the communication Identify it as a destination,
The communication apparatus according to appendix 8, wherein the second frame is generated by changing the unique information in the header of the first frame to the other unique information.
(Appendix 10)
The control unit has a data length shorter than an address assigned to the target device for a target device that is a target of communication using a path from the first communication device to the third communication device, Determining a setting value used by the first communication device to identify the target device;
The transmission unit transmits a frame in which the information on the target device is associated with the set value to the second communication device,
When the receiving unit receives the third frame transmitted from the target device to the communication destination, the control unit sets the set value as a transmission source of the third frame, and the third frame To generate a fourth frame in which the unique information is set as the destination of
The communication apparatus according to appendix 8 or 9, wherein the transmission unit transfers the fourth frame to the second communication apparatus.
(Appendix 11)
The receiving unit receives, from the third communication device, another setting value that is shorter than the address assigned to the target device and that the third communication device uses to identify the target device. Receive a frame containing
When the receiving unit receives the fifth frame transmitted from the communication destination to the target device, the control unit sets the other unique information as a transmission source of the fifth frame, and Performing control for generating a sixth frame in which the other setting value is set as a frame destination;
The communication device according to appendix 10, wherein the transmission unit transmits the sixth frame to the third communication device.
(Appendix 12)
A storage unit for storing route information to a device with which the first communication device can communicate;
The controller is
When the receiving unit receives the control frame, the address of the communication destination, the address of the second communication device, the unique information, and the other unique information are associated with each other and stored in the storage unit,
In another control frame used for notifying a device communicable via the first communication device to a device adjacent to the first communication device, the other unique frame is associated with the address of the communication destination. Including information,
The communication device according to any one of appendices 8 to 11, wherein the transmission unit executes a process of transmitting the other control frame.
(Appendix 13)
In the first communication device included in the network,
Used when identifying the communication destination by the second communication device and information on a communication destination capable of transmitting a frame from the adjacent second communication device via the second communication device. Receiving a control frame including unique information, which is information whose data length is shorter than the address assigned to
When transmitting data to the communication destination via the second communication device, the unique information is set as a destination of a data frame including data addressed to the communication destination,
A communication method, comprising: executing a process of transmitting the data frame to the second communication device.
(Appendix 14)
As information used when the third communication device adjacent to the first communication device has a data length shorter than the address assigned to the communication destination, and the first communication device identifies the communication destination. Notifying other determined unique information in association with the communication destination,
If the transmission source of the first frame transferred to the third communication device is the communication destination, generate a second frame in which the other unique information is set as the transmission source of the first frame,
14. The communication method according to appendix 13, wherein the first communication device is caused to execute processing for transferring the second frame to the third communication device.

DESCRIPTION OF SYMBOLS 10 Communication apparatus 11 Receiving part 12 Header analysis part 13 Transfer processing part 14 Application processing part 15 Frame generation part 16 Transmission part 20 Control part 21 Extraction part 22 GDID management part 23 Table management part 24 Path information generation part 25 Timer 30 Storage part 31 Link table 32, 61 Routing table 33 Transfer destination table 100 Processor 101 Bus 102 PHY chip 104 Timer IC
106 DRAM
107 Flash memory 108 Wireless module

Claims (8)

In the first communication device included in the network,
Used when identifying the communication destination by the second communication device and information on a communication destination capable of transmitting a frame from the adjacent second communication device via the second communication device. Receiving a control frame including unique information, which is information whose data length is shorter than the address assigned to
When transmitting data to the communication destination via the second communication device, the unique information is set as a destination of a data frame including data addressed to the communication destination,
A communication program for executing a process of transmitting the data frame to the second communication device. As information used when the third communication device adjacent to the first communication device has a data length shorter than the address assigned to the communication destination, and the first communication device identifies the communication destination. Notifying other determined unique information in association with the communication destination,
If the transmission source of the first frame transferred to the third communication device is the communication destination, generate a second frame in which the other unique information is set as the transmission source of the first frame,
The program according to claim 1, wherein the program causes the first communication device to execute a process of transferring the second frame to the third communication device. When the first frame is received from the second communication device, since the transmission source address of the first frame is the unique information, the transmission source of the first frame is the communication destination. Identify,
The first communication device is caused to execute processing for generating the second frame by changing the unique information in the header of the first frame to the other unique information. Item 3. The program according to item 2. The data length is shorter than the information of the target device to be communicated using the path from the first communication device to the third communication device, and the address assigned to the target device, and the first communication A setting value used by the device to identify the target device is notified to the second communication device;
When the target device receives the third frame transmitted to the communication destination, the setting value is set as the transmission source of the third frame, and the unique information is set as the destination of the third frame. Generate 4 frames,
4. The program according to claim 2, wherein the program causes the first communication device to execute a process of transferring the fourth frame to the second communication device. 5. From the third communication device, the data length is shorter than the address assigned to the target device, and the third communication device obtains another setting value used for identifying the target device,
When the communication destination receives the fifth frame transmitted to the target device, the other unique information is set as the transmission source of the fifth frame, and the other setting value is set as the destination of the fifth frame. Generate a sixth frame with
5. The program according to claim 4, wherein the program causes the first communication apparatus to execute a process of transmitting the sixth frame to the third communication apparatus. In the first communication device,
When the control frame is received, the address of the communication destination, the address of the second communication device, the unique information, and the other unique information are transmitted as route information to the device with which the first communication device can communicate. Are stored in association with each other.
In another control frame for notifying a device adjacent to the first communication device of a device capable of communicating via the first communication device, the address of the communication destination and the other unique information are included.
The program according to any one of claims 2 to 5, wherein a process of transmitting the other control frame is executed. A communication device that operates as a first communication device included in a network,
Used when identifying the communication destination by the second communication device and information on a communication destination capable of transmitting a frame from the adjacent second communication device via the second communication device. A receiving unit that receives a control frame including unique information that is information whose data length is shorter than the address assigned to
A controller configured to set the unique information as a destination of a data frame including data addressed to the communication destination when transmitting data to the communication destination via the second communication device;
A communication apparatus comprising: a transmission unit that transmits the data frame to the second communication apparatus. In the first communication device included in the network,
Used when identifying the communication destination by the second communication device and information on a communication destination capable of transmitting a frame from the adjacent second communication device via the second communication device. Receiving a control frame including unique information, which is information whose data length is shorter than the address assigned to
When transmitting data to the communication destination via the second communication device, the unique information is set as a destination of a data frame including data addressed to the communication destination,
A communication method, comprising: executing a process of transmitting the data frame to the second communication device.

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