JP2007251811A - Radio communication apparatus, radio communication method, and method of creating route information table - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide techniques with which improvement in communication efficiency can be attained in an ad-hoc wireless network. <P>SOLUTION: Each of nodes in the ad-hoc wireless network holds, in a route information table, the combination of an adjacent relay node for each destination node and a destination node of which the repeating route is common for two or more hops. Each of the nodes merges packets of which the repeating route is common for two or more hops, as a multi-hop merged packet and transmits it and packets of which the repeating route is common only for one hop, are merged and transmitted as a one-hop merged packet. Furthermore, in such merging determination processing, if it is determined that a node which has first created the one-hop merged packet can be notified about updating of the route, updating of the route is notified, thereby updating the route information table of that node. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for integrating and transmitting packets having overlapping routes in wireless packet communication.

  Conventionally, wireless packet communication is performed using a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) method in a wireless LAN or the like. In the CSMA / CA system, in order to communicate using a common wireless channel, packets are transmitted after confirming whether other nodes are using the wireless channel. At this time, the transmission node waits for the DIFS and the back-off time, and starts transmission of a packet if no other communication is performed during this period. Thus, since a waiting time (overhead) occurs during packet transmission, it is not efficient to send a large number of fine packets.

  In order to avoid such overhead, when a plurality of packets are transmitted continuously between the same transmission / reception nodes, there is a technique for transmitting packets continuously (in a burst) at SIFS intervals shorter than DIFS. Are known. Since packets are continuously transmitted at intervals shorter than DIFS, other nodes do not start transmission between successive packets. In addition, since the interval between successive packet transmissions is shortened, overhead can be reduced and throughput can be improved.

  Also, a technique is known in which a plurality of packets are concatenated and transmitted as multicast packets to reduce the number of packets to be transmitted (Patent Document 1). According to this technique, overhead due to waiting time can be avoided by reducing the number of packets to be transmitted.

  A technique is also known in which route information in a network is held in advance, and packets transmitted through the same route are integrated and transmitted from the destination of the packet to be transmitted (Patent Document 2). Similarly, with this technique, the number of packets to be transmitted can be reduced, so that overhead due to waiting time can be avoided.

  Incidentally, a network system in the form of an ad hoc wireless network is known. An ad hoc wireless network is an autonomous wireless network that is temporarily constructed by mobile terminals without depending on infrastructure such as a base station or a dedicated line. When direct communication (one-hop communication) is not possible, such as when the distance between nodes is long, information is exchanged by relaying nodes existing on the way and performing multi-hop communication. That is, each node not only functions as a communication device but also has a wireless communication relay function (routing function).

In a wireless communication device that configures an ad hoc wireless network, the distance between nodes changes due to movement, and the communicable nodes change. Moreover, not only movement but also a rapid fluctuation of radio wave quality due to obstacles, interference, etc. occurs. For these reasons, ad hoc wireless networks are characterized by frequent changes in the network topology.
JP 2005-57373 A JP 2005-223656 A

In the ad hoc wireless network, in order to suppress the overhead due to the waiting time as described above, the following problems occur when the above conventional technique is applied.

  First, since the technique of transmitting a plurality of packets in bursts at SIFS intervals is applied to communication performed between the same transmission / reception nodes, the scene where the effect is exhibited is limited. In addition, there is a technology that suppresses overhead by transmitting to different transmission destinations in bursts, but it improves the efficiency of communication between 1 hops. Not applicable to

  In order to realize multicast communication in an ad hoc wireless network, a multicast group must be established, but this process is complicated. Furthermore, in an ad hoc wireless network, the network topology frequently changes, so it is necessary to frequently update multicast groups. As described above, the method of Patent Document 1 that uses multicast to reduce the communication waiting time has a demerit that it requires overhead to create and update a multicast group.

  Further, the technique described in Patent Literature 2 transmits packets of common routes in an integrated manner, but it is assumed that the network topology does not change and all route information is held in advance. However, in general, the route control device (router) generally holds only the next transfer address for each destination address, and it is not realistic to have information about all routes. Moreover, in an ad hoc wireless network, since a route is dynamically established, it is difficult to hold route information in advance.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique capable of realizing efficient communication in an ad hoc wireless network.

  In order to achieve the above object, the present invention performs efficient wireless packet communication by the following means or processing.

  The wireless communication apparatus according to the present invention is a wireless communication apparatus that integrates (collectively) and transmits a plurality of packets having a common relay route in an ad hoc wireless network. In an ad hoc wireless network, a wireless communication device (node) performs wireless packet communication with another node directly or via one or more relay nodes. In this specification, a node that transmits a packet is a transmission node, a node that the transmission node wants to send a packet (information) to is a destination node, and the packet is relayed when the packet is transmitted from the transmission node to the destination node. A node is called a relay node.

  The wireless communication apparatus according to the present invention includes route information storage means, integrated packet generation means, and packet transmission means. The route information storage means stores which node to transfer the packet to among the nodes one hop ahead (hereinafter also referred to as an adjacent node) when transmitting the packet to a certain node. The route information storage means also stores information on a combination of destination nodes having a common relay route of two or more hops and to which relay node the relay route is common.

The integrated packet generation means determines whether the relay route of the plurality of packets to be transmitted matches up to a relay node that is two or more hops ahead, and if they match, integrates the plurality of packets to determine the relay node on the route. One packet (hereinafter referred to as a multi-hop integrated packet) is generated as a destination. Note that the destination of the multi-hop integrated packet is preferably the farthest (having many hops) relay node on the common relay route. The integrated packet generation means
If the relay paths of these multiple packets are not common for two or more hops, it is determined whether the relay nodes that are one hop ahead match, and if they match, the multiple packets are combined and the relay node is the destination 1 One packet (hereinafter referred to as a 1-hop integrated packet) is generated.

  The packet transmitting unit transmits the integrated packet generated by the integrated packet generating unit (refers to both a multi-hop integrated packet and a one-hop integrated packet).

  According to the wireless communication apparatus according to the present invention, packets having a common relay route can be integrated and transmitted to a relay node that is two or more hops ahead, and communication processing is performed compared to a case where a plurality of packets are individually transmitted. Is made more efficient. In particular, by integrating and transmitting packets up to two or more hops away, it is not necessary to integrate and restore packets for each hop, and thus efficient communication can be realized.

  In addition, it is easy to acquire a relay node that is one hop ahead using an existing protocol in an ad hoc wireless network. Therefore, the wireless communication apparatus according to the present invention is capable of acquiring a plurality of packets for at least one hop even when the route information is not completely acquired and the relay route to the relay node beyond two hops is unknown. It is possible to transmit in an integrated manner, thereby improving the efficiency of communication processing.

  It is preferable that the wireless communication apparatus according to the present invention further includes integrated packet restoration means for restoring the received integrated packet. The wireless communication apparatus according to the present invention preferably restores the integrated packet received by the integrated packet restoring means when the node receives the integrated packet designated as the destination. Then, the integrated packet generation means determines whether the relay routes of the restored plurality of packets are common, and if so, integrates the plurality of packets again to obtain a multi-hop integrated packet or a one-hop integrated packet as described above. It is preferable to produce similarly. According to such a configuration, a plurality of packets are individually transmitted by repeating the integration and restoration of packets even in a situation where information on a route ahead of 2 hops or more is not constructed in the route information storage unit. Communication processing can be made more efficient than the case. Further, depending on the accumulation state of the route information storage means, even if it is determined that multi-hop integration is not possible at the transmission node, it may be determined that multi-hop integration is possible at the relay node on the relay route. Even in such a case, since the multi-hop integrated packet can be formed from the middle of the relay route, the communication processing is made efficient. That is, efficient communication is realized even in a situation where not all wireless communication devices have completely acquired route information.

  In the wireless communication apparatus according to the present invention, it is preferable that an address of a node that first integrates a plurality of packets included therein is stored as an integration source node in the 1-hop integrated packet. When the relay node that has received and restored the one-hop integrated packet determines that a plurality of packets obtained by the restoration cannot be integrated and transmitted, it performs route update notification to the integration source node. That is, from the integration source node to this node, the packet is relayed by repeating generation and restoration of a 1-hop integration packet for each hop, so the relay route of these packets is common from the integration source node to this node. Can be judged. Therefore, this node notifies the integration source node to that effect. The node that has received this route update notification updates the route information based on the notification content.

In addition, when the relay node that has received and restored the 1-hop integrated packet can integrate the multiple packets obtained by the restoration into a multi-hop integrated packet, that is, there is a route from this relay node to the relay node that is two or more hops ahead If it is determined that they are common, a route update notification is sent to the integration source node included in the one-hop integration packet. In such a situation, it can be determined that it is possible to integrate and transmit the multi-hop integrated packet from the integration source node. Therefore, this node notifies the integration source node to that effect. This route information update notification includes information on addresses of a plurality of destination nodes and to which relay node the relay routes of these destination nodes are common. The node that has received this route information update notification updates the route information based on this notification.

  By such processing, the route information can be dynamically constructed by notifying the integration source node of the common routes of a plurality of destination nodes. Further, even when the network topology changes and the route is changed, new route information can be constructed in a short time.

  The route information update notification is also transmitted to the integration source node via the relay node. It is preferable that the node that relayed the route information update notification also updates the route information storage unit based on this notification. By adopting such a configuration, all the route information of the nodes on the relay route of the route information update notification is updated, so that the route information can be constructed more quickly.

  In the wireless communication apparatus according to the present invention, when the integrated packet generation unit generates a 1-hop integrated packet, if a plurality of packets to be integrated are not restored from the 1-hop integrated packet by the packet recovery unit, The address of the own node is stored as the integration source address in the generated one-hop integration packet. Conversely, when the plurality of packets to be integrated are those restored from the 1-hop integrated packet by the packet restoring means, the 1-hop integration that newly generates the integration source address included in the 1-hop integrated packet before the restoration Store in packet. In this way, when an integrated packet is generated / restored for each hop and relayed, the address of the integration source node is held in the 1-hop integrated packet and relayed.

  In addition, this invention can also be grasped | ascertained as a radio | wireless communication method including at least one part of the said process, or a program for implement | achieving this method. Moreover, it is also possible to grasp as a method for creating a route information table for storing route information by the above processing, or as a program for realizing such a method.

  According to the present invention, it is possible to improve communication efficiency in an ad hoc wireless communication network.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings.

In the present embodiment, an ad hoc wireless network is configured by a plurality of movable wireless communication devices. Each wireless communication device performs wireless packet communication using a common wireless channel. And in order to avoid the collision of a packet, each radio | wireless communication apparatus performs radio | wireless communication using a CSMA / CA system. Specifically, an IEEE802.11 wireless LAN access method is adopted. However, other wireless communication methods may be adopted. In addition, the movable wireless communication device is installed in a car or the like in addition to the portable device such as a notebook computer, a mobile phone, and a PDA (Personal Data Assistant), A wireless communication device that moves because an installed object (such as an automobile) is a moving object is also included.

In an ad hoc wireless network, all nodes (wireless communication devices) constituting the network have a relay function (router function). That is, each node has a route information table, and based on the route information table, it is possible to determine which node should be used as a relay node for each destination node to relay a packet. Note that in an ad hoc wireless network, the network topology changes frequently, so the route information table needs to be constantly updated.

  In the present embodiment, a plurality of packets having a common relay route are integrated and transmitted, thereby eliminating waste due to waiting time that occurs during packet transmission. In the present specification, multi-hop integrated transmission refers to integrating and transmitting a plurality of packets having a common relay route of 2 hops or more to a node that is 2 hops or more ahead. A packet generated by multi-hop integrated transmission and integrated with a plurality of packets is called a multi-hop integrated packet. Also, one-hop integrated transmission refers to integrating and transmitting a plurality of packets having a common next hop to the next hop. Further, a packet generated by one-hop integrated transmission and integrated with a plurality of packets is referred to as a one-hop integrated packet.

  Hereinafter, the packet integration process will be described in detail. Further, since this packet integration processing is performed based on route information, a method of creating / updating a route information table suitable for the above-described purpose will be described in detail.

<Functional configuration>
First, the wireless communication device 1 in the present embodiment will be described. The wireless communication device 1 is configured to include a CPU (Central Processing Unit), a main storage device (RAM), an auxiliary storage device (ROM), a communication interface, and the like connected via a bus as a hardware configuration. May be.

  FIG. 1 is a diagram illustrating an example of functional blocks of the wireless communication device 1. In the wireless communication device 1 according to the present embodiment, various programs (OS, applications, etc.) stored in the auxiliary storage device are loaded into the main storage device and executed by the CPU, whereby the packet reception unit 2 and the packet determination unit 3 are loaded. , Packet buffer unit 4, integrated packet generation unit 7, integrated packet restoration unit 6, route information table 5, packet transmission unit 8, and route update unit 9. In addition, all or some of the functions of the wireless communication device 1 in the present embodiment may be configured by a dedicated chip.

  The packet receiver 2 receives a packet from another node (wireless communication device). The packet received by the packet receiving unit 2 is passed to the packet determining unit 3. The packet determination unit 3 determines the processing method by determining the received packet.

  When the received packet is an integrated packet addressed to its own node, the packet determination unit 3 passes this packet to the integrated packet restoration unit 6. The integrated packet restoration unit 6 decomposes (restores) the integrated packet into individual packets, and the packet determination unit 3 determines the processing method of the restored individual packets again.

  If the received packet is a normal packet addressed to its own node (refers to a packet that is not integrated), the packet determination unit 3 transfers this packet to an upper layer.

  When the received packet is an integrated packet that is not addressed to its own node, the packet determination unit 3 buffers this packet in the packet buffer unit 4.

If the received packet is a normal packet that is not addressed to its own node, the packet determination unit 3 determines whether or not this packet is the target of integration processing. This determination process is performed based on the nature of the packet. For example, the packet determination unit 3 determines that the packet is not a target of integration processing when the allowable delay amount of the packet is small or the packet size is large. The reason why a packet with a small allowable delay amount is not subjected to integration processing is that it is necessary to perform buffering in order to integrate, but buffering increases delay. Also, the reason why large packets are not subjected to integration processing is that the effect of suppressing overhead is small even when packets with large packet sizes are integrated. In addition, since an upper limit is set for the packet size, a packet having a size close to the upper limit often cannot be integrated with other packets.

  The route information table 5 stores information related to the packet relay route. FIG. 2 is a diagram illustrating an example of the positional relationship between nodes in an ad hoc wireless network. In FIG. 2, nodes capable of direct communication (one-hop communication) are connected by a straight line. FIG. 3 is an example of the route information table 5 that the node c in FIG. 2 has. The routing information table 5 includes, for each destination node, the address of the next forwarding node (“forwarding destination”), the number of hops to the destination node (“hop count”), and the address of the node that can perform multihop integrated transmission (“multiple” Information indicating “hop integration node”) and to which node multihop integration is possible (“multihop integration transmission destination”) is stored. Referring to the route information table of FIG. 3, for example, when a packet is transmitted from node c to node h, it is understood that the next node to be transferred is node d and reaches node h in 4 hops. Further, for example, when packets are transmitted from the node c to the node h, it can be understood that packets addressed to the nodes g and i can be integrated and transmitted to the node g and packets addressed to the nodes e and f can be integrated and transmitted to the node e.

  FIG. 3 is an example of the route information table 5, and stores information on the next hop node for each destination node, a combination of destination nodes having a common relay route of two or more hops, and up to which node multihop integrated transmission is possible. As long as it is, any specific structure may be used.

  The integrated packet generation unit 7 determines whether or not the plurality of packets stored in the packet buffer unit 4 can be integrated and transmitted with reference to the path information table 5, and if the packets can be integrated and transmitted, the integrated packet generator 7 integrates the packets. Generate a packet. In this embodiment, when generating an integrated packet, a multi-hop integrated packet in which a plurality of packets having a common relay route of 2 hops or more are integrated is preferentially generated, and a packet that cannot generate a multi-hop integrated packet is set to 1 A one-hop integrated packet having a common relay route for hops is generated. Thus, by generating the multi-hop integrated packet preferentially, it is possible to effectively suppress overhead such as communication waiting time due to transmission of a plurality of packets.

  Details of packet integration processing for integrating packets based on a plurality of packet relay paths performed by the integrated packet generation unit 7 and packet configurations of integrated packets (multi-hop integrated packet and 1-hop integrated packet) generated by the integrated packet generation unit 7 Will be described in detail later.

  The packet transmitting unit 8 transmits the integrated packet generated by the integrated packet generating unit 7 and the packet determined to be transmitted without being integrated by the packet determining unit 3. The packet transmission unit 8 also transmits a packet stored in the packet buffer unit 4 for a certain period or more.

  The route update unit 9 updates the route information table 5. Specifically, a process for notifying route information to other nodes and a process for updating the route information table 5 in accordance with notifications from other nodes are performed. Details of the route update processing will be described later in detail.

<Packet structure>
[1-hop integrated packet]
FIG. 4 is a diagram for explaining the structure of a 1-hop integrated packet. The 1-hop integrated packet includes an integrated packet header 20 and subsequent normal packets 21a to 21n to be integrated.

  The integrated packet header 20 includes a control header 201, a receiver MAC address 202, a sender MAC address 203, an integrated packet number 204, an integration source address 205, a packet 1 offset value 206a,..., A packet n offset value 206n. The

  The control header 201 stores a value indicating that this packet is a 1-hop integrated packet. The receiver MAC address 202 stores the MAC address of the node that receives the one-hop integrated packet, that is, the common relay node that is one hop ahead of the integrated packets. The sender MAC address 203 stores the MAC address of the node that transmits this 1-hop integrated packet, that is, the node that generated this 1-hop integrated packet. The integrated packet number 204 stores the number of packets integrated into the one-hop integrated packet. The integration source address 205 stores the address of the node that first integrated the packets included in this one-hop integration packet. The 1-hop integrated packet may be reintegrated again as a 1-hop integrated packet after being restored as described later. In this case, the same address is used as the address stored in the integration source address 205 before and after the reintegration. The packet 1 offset value 206a stores an offset value indicating the start position of the packet 21a, and the packet n offset value 206n stores an offset value indicating the start position of the packet 21n.

  In the present embodiment, the packet structure as described above is adopted. For example, a header obtained by adding an integrated packet number 204, an integration source address 205, and a packet 1 offset value 206a to a packet n offset value 206n to a normal MAC header; A packet structure including a payload in which a plurality of packets to be integrated is connected may be used.

[Multi-hop integrated packet]
FIG. 5 is a diagram for explaining the structure of a multi-hop integrated packet. The multi-hop integrated packet includes an integrated packet header 30 and subsequent normal packets 31a to 31n to be integrated.

  The integrated packet header 30 includes a control header 301, a next hop MAC address 302, a sender MAC address 303, a transfer destination IP address 304, a transfer source IP address 305, an integrated packet number 306, a packet 1 offset value 307a,. n offset value 307n.

  The control header 301 stores a value indicating that this packet is a multi-hop integrated packet. The next hop MAC address 302 stores the address of the node that relays this multi-hop integrated packet next. The sender MAC address 303 stores the MAC address of the node that transmits or relays this multi-hop integrated packet. The transfer destination IP address 304 stores the IP address of the node to which this multi-hop integrated packet is finally delivered. The multi-hop integrated packet is transmitted without being restored to the node of the transfer destination IP address 304 without being restored. The source IP address 305 stores the IP address of the node that generated this multi-hop integrated packet. The integrated packet number 306 stores the number of packets integrated into the multi-hop integrated packet. The packet 1 offset value 307a stores an offset value indicating the start position of the packet 31a, and the packet n offset value 307n stores an offset value indicating the start position of the packet 31n.

In the present embodiment, the multi-hop integrated packet has the structure as described above, but is not limited thereto. Since the multi-hop integrated packet is to be processed in the IP layer because it is destined for a node that is two or more hops ahead, a plurality of packets 31a to 31n integrated as a payload, a conventional IP header (forwarding destination) as an IP header A structure in which the number of integrated packets and the offset value of each packet are added to the IP address and the transfer source IP address is used, and a structure in which a MAC header is further added may be used.

<Packet determination processing>
The packet received by the wireless communication device 1 is first determined by the packet determination unit 3 as to how to process it. That is, the packet determination unit 3 determines whether the received packet should be transferred to the upper layer, transferred as it is, or whether it can be integrated into an integrated packet. FIG. 6 is a flowchart illustrating a flow of packet determination processing performed by the packet determination unit 3.

  First, the packet receiving unit 2 receives a packet and passes the received packet to the packet determining unit 3 (S101). The packet determination unit 3 determines whether this packet is addressed to its own node (S102). If it is determined that the packet is addressed to the own node (S102-YES), it is determined whether this packet is an integrated packet (S103). If it is an integrated packet (S103-YES), the integrated packet restoration unit 6 restores (disassembles) this packet (S104). The processing content of the restored packet is again determined by the packet determination unit 3 (S103). When the received packet addressed to the own node is not an integrated packet (S103-NO), the packet determination unit 3 transfers this packet to the upper layer (S105) and ends the determination process.

  If the received packet is not addressed to its own node (S102-NO), it is determined whether this packet is an integrated packet (S106). If it is not an integrated packet (S106-NO), it is determined whether this packet matches the conditions for integrating the packets (S107). Here, the condition for integrating the packets is, for example, a condition as to whether or not the packet is suitable for packet integration, such as whether the allowable delay amount is smaller than a predetermined threshold or whether the packet size is smaller than the predetermined threshold. If the condition for integrating the packets is not met (S107-NO), the packet is passed to the packet transmitter 8 (S108), and transmitted by the packet transmitter 8 without being integrated. When the conditions for integrating the packets are met (S107-YES) or when this packet is an integrated packet (S106-YES), this packet is buffered in the packet buffer unit 4 (S109). The packets buffered in the packet buffer unit 4 are subjected to integration determination described later.

  In the above, it is assumed that the integrated packet is further integrated (S106-YES to S109). However, when it is determined that the integrated packet is an integrated packet (S106-YES), the packet transmission unit 8 transmits the packet as it is. It doesn't matter. If the integrated packets are further integrated, it can be considered that processing takes time, so this can be omitted to simplify the processing.

<Packet integration processing>
FIG. 7 is a flowchart illustrating a flow of processing for generating an integrated packet based on a packet relay route, which is performed by the wireless communication device 1 according to the present embodiment.

  The integrated packet generation unit 7 acquires a predetermined number of packets from the packet buffer unit 4 (S201).

  Then, the integrated packet generation unit 7 determines whether there is a packet capable of multihop integrated transmission from among the plurality of acquired packets (S202). Specifically, the determination is made based on whether or not there is a combination of destination nodes capable of multihop integrated transmission stored in the route information table 5 among the plurality of acquired packets.

If it is determined that multi-hop integrated transmission is possible (S202—YES), the integrated packet generator 7 generates a multi-hop integrated packet (S203). The structure of the multihop integrated packet is as described above. There are various methods for selecting a packet to be integrated into an integrated packet from a plurality of packets acquired from the packet buffer unit 4. For example, a method of integrating packets having a common relay route to the farthest node (having the largest number of hops) (in this case, the number of packets integrated into the integrated packet is reduced), or the most packets being integrated into one integrated packet Various algorithms can be considered for selecting packets to be integrated, such as a method of integrating packets so that the destination of the integrated packet is a close node (with a small number of hops). In this embodiment, a hop number priority algorithm is used that generates an integrated packet that can be transmitted in an integrated manner up to a node having the largest number of hops.

  When a multi-hop integrated packet is generated, it may be possible to send a route update notification to another node, so a process is performed to determine whether a route update notification is possible (S204). Details of this route update processing will be described later.

  The multi-hop integrated packet generated by the integrated packet generator 7 is sent to the packet transmitter 8 (S208), and is transmitted to the next relay node.

  When it is determined that a plurality of packets acquired from the packet buffer unit 4 cannot be integrated multi-hop transmission (S202-NO), it is determined whether the one-hop integrated transmission is possible for the plurality of packets (S205). Specifically, based on the route information table 5, it is determined whether or not there is a packet common to the relay nodes one hop ahead. If 1-hop integrated transmission is possible (S205—YES), these packets are integrated to generate a 1-hop integrated packet (S206). The structure of the 1-hop integrated packet is as described above. Then, the created one-hop integrated packet is sent to the packet transmission unit 8 (S208) and transmitted to the next relay node.

  When it is determined that a plurality of packets acquired from the packet buffer unit 4 cannot perform 1-hop integrated transmission (S205-NO), a route update notification may be made to another node. Processing for determining whether notification is possible is performed (S207). Details of this route update processing will be described later.

  The plurality of packets determined to be unable to be integratedly transmitted are sent to the packet transmission unit 8 (S208), and are transmitted as normal packets to the next relay node.

<Route update process>
As described above, in the packet integration process, there are cases where a route update notification can be made to another node. FIG. 8 is a flowchart showing the flow of the route update processing in S204 of the packet integration processing, and FIG. 9 is a flowchart showing the flow of the route update processing in S207 of the packet integration processing.

  The route update process illustrated in FIG. 8 is a process performed after a plurality of packets acquired from the packet buffer unit 4 are integrated into a multihop integrated packet. In this route update processing, first, the route update unit 9 determines whether a plurality of packets integrated into a multi-hop integrated packet are integrated into a one-hop integrated packet and transmitted to the own node ( S301). When the integrated packet is transmitted to the own node as a one-hop integrated packet (S301-YES), the route update unit 9 updates the route to the integration source node of the transmitted one-hop integrated packet. Notification is performed (S302).

The fact that a plurality of packets sent to the node as one-hop integrated packets can be integrated into a multi-hop integrated packet and transmitted from the original source node into a multi-hop integrated packet. Means that. Therefore, the route updating unit 9 acquires the integration source node of the 1-hop integrated packet from the integration source address 205 of the 1-hop integrated packet, and the addresses of the plurality of destination nodes of the integrated packets are stored in the integration source node. The destination address of the multi-hop integrated packet (the relay routes of the plurality of destination nodes are common to this node) is notified as a route update notification. The integration source node that has received this route update notification updates the route information table of its own node based on this notification.

  If the plurality of packets integrated into the multi-hop integrated packet are not transmitted as one-hop integrated packets to the own node (S301-NO), the process returns to the packet integration processing flowchart without performing route update notification.

  The route update process illustrated in FIG. 9 is a process performed after it is determined that a plurality of packets acquired from the packet buffer unit 4 cannot be integratedly transmitted (multihop integrated transmission or 1-hop integrated transmission). In this route update process, first, the route update unit 9 determines whether or not a plurality of packets transmitted as one-hop integrated packets could not be reintegrated as one-hop integrated packets (S401). That is, the path update unit 9 determines whether a plurality of packets that cannot be integrated and transmitted are integrated into a 1-hop integrated packet and transmitted to the own node (S401). When these packets are transmitted to the own node as one-hop integrated packets (S401-YES), the route update unit 9 sends a route update notification to the integration source node of the transmitted one-hop integrated packets. Perform (S402).

  The fact that a plurality of packets transmitted to the own node by repeating the one-hop integrated transmission cannot be integratedly transmitted at the own node means that the relay route to the destination node of the plurality of packets is the integration source of the one-hop integrated packet. It means that it is common from the node to its own node. Therefore, the route update unit 9 notifies the integration source node of the one-hop integrated packet that the relay routes to the plurality of destination nodes are common to the own node as a route update notification. The integration source node that has received this route update notification updates the route information table of its own node based on this notification. When the integration source node is an adjacent node of the own node, the route update notification may be omitted.

  If a plurality of packets determined not to be integrated and transmitted are not integrated into a one-hop integrated packet and transmitted to the own node (NO in S402), route update notification is not performed and the flowchart of the packet integration process is performed. Return.

  In this way, it is possible to dynamically update the route information table 5 of each node by performing route update processing while performing packet integration processing.

<Operation example>
[Operation example 1 / Route information table is complete]
Next, an operation example of packet integration processing in the case of the network topology as shown in FIG. 2 will be described. In the following description, it is assumed that the path information table is completely completed in all the nodes, and focusing on packet integration processing.

  First, an example of packet integration processing performed by the node c will be described. The path information table of node c is shown in FIG. Assume that node c receives a packet addressed to node h from node a and a packet addressed to node i from node b. In this case, by referring to the route information table, it is understood that the relay route to the node h and the node i is common to the node g. Therefore, node c integrates these packets to generate a multi-hop integrated packet addressed to node g.

  Assume that node c receives a packet addressed to node h from node a and a packet addressed to node f from node b. In this case, by referring to the route information table, it is understood that the relay route to the node h and the node f is common to the node e. Accordingly, node c integrates these packets to generate a multi-hop integrated packet addressed to node e.

  Similarly, the node c generates a packet addressed to the nodes f and g as a multi-hop integrated packet addressed to the node e, or generates a packet addressed to the nodes g and h as a multi-hop integrated packet addressed to the node g.

  Next, an example of packet integration processing performed by the node e will be described. The route information table of the node e is shown in FIG. Assume that node e receives a packet addressed to node h from node d and a packet addressed to node i from node f. It can be determined from the route information table that the relay routes of these packets are not common to two or more hops and multi-hop integrated transmission is not possible. On the other hand, since the next hop node of these packets is common to node g, a one-hop integrated packet destined for node g is generated.

[Operation example 2-When the routing information table is incomplete]
Next, the operation of packet integration processing when the route information table is incomplete and the processing for updating the route information table will be described. FIG. 11 is a diagram for explaining packet integration processing and route update processing. As shown in FIG. 11, each node in the network already has information on which node the packet should be forwarded for each destination node, but information on a route that is two or more hops ahead Is not yet held (note that FIG. 11 shows only the route information for the destination nodes h and i). In this operation example, processing for constructing (updating) a route information table while integrating and transmitting packets in such a situation will be described.

  First, the packet P addressed to the node h is transmitted from the node a to the node c. Further, the packet Q addressed to the node i is transmitted from the node b to the node c. The node c determines whether or not these packets can be transmitted in an integrated manner. First, it is determined whether multi-hop integrated transmission is possible. However, since there is no information about a node having a common path beyond two hops in the path information table of node c, it is determined that multi-hop integrated transmission is not possible. Next, it is determined whether 1-hop integrated transmission of these packets is possible. Referring to the route information table, since both nodes h and i are the node d, the next hop node is determined to be capable of 1-hop integrated transmission.

  The one-hop integrated packet I1 generated by the node c stores the MAC address of the node d as the receiver MAC address 202, the MAC address of the node c as the sender MAC address 303, and 2 as the number of integrated packets. Further, since the packet P and the packet Q are integrated for the first time at the node c, the MAC address of the node c is stored in the integration source address 205.

  The 1-hop integrated packet I1 created by the node c is received by the node d designated as the destination. Node d performs restoration processing because this one-hop integrated packet I1 is addressed to its own node. By restoring, packet P and packet Q are obtained, but since neither is a packet addressed to its own node, node d is stored in packet buffer unit 4 and is subject to integration processing.

Similarly to the case of the node c, the node d is determined that the packet P and the packet Q cannot be subjected to the multi-hop integrated transmission, but can be one-hop integrated transmission to the node e. Therefore, the node d integrates the packet P and the packet Q to generate a one-hop integrated packet I2 addressed to the node e. In the one-hop integrated packet I2, the MAC address of the node e is stored in the receiver MAC address 202, and the MAC address of the node d is stored in the sender MAC address 203.

  The packet P and the packet Q integrated into the 1-hop integrated packet I2 are transmitted as the 1-hop integrated packet I1 addressed to the node d. The MAC address of the node c is stored as the integration source address 205 in the one-hop integration packet I1. Therefore, the node d can determine that the packet P and the packet Q are integrated for the first time at the node c, and stores the MAC address of the node c in the integration source address 205 of the generated one-hop integrated packet I2.

  The one-hop integrated packet I2 generated by the node d is received by the node e designated as the destination. Also in the node e, the same processing as that of the node d is performed, and the 1-hop integrated packet I3 addressed to the node g is generated. The integration source address 205 of the 1-hop integrated packet I3 stores the MAC address of the node c that first integrated the packet P and the packet Q.

  The node g that has received the 1-hop integrated packet I3 performs a restoration process because this packet is an integrated packet addressed to itself. Since the restored packets P and Q are not addressed to the own node, they are targeted for integration processing. Referring to the path information table of node g, it can be determined that packet P and packet Q cannot be integrated into one packet because the next-hop nodes are different. Therefore, the node g transmits the packet P to the node h and the packet Q to the node i as a normal packet.

  Further, since the node g could not transmit the packet P and the packet Q obtained by disassembling the 1-hop integrated packet I3 by 1-hop integrated transmission, the node g sends a route update notification to the integration source node of the 1-hop integrated packet I3. Do it. The integration source node is identified as node c by referring to the integration source address 205 of the one-hop integration packet I3. The fact that the packet P addressed to the node h and the packet Q addressed to the node i arrived from the node c to the node g by repeating one-hop integrated transmission means that the packet P and the packet Q are originally multi-hoped to the node g at the node c. This means that it was possible to perform integrated transmission. Therefore, the node g notifies the node c that the relay route to the node h and the node i is common to the own node (node g).

  The node c receiving this route update notification updates its own route information table based on this notification. That is, the fact that the relay route of node h and node i is common to node g is stored in the route information table. The route update notification is transmitted from the node g to the node c through the nodes e and d. Nodes e and d that relay this route update notification can similarly update the route information table.

  As described above, even when the route information table for the route beyond 2 hops is not completely created, the communication efficiency is improved by repeating the 1-hop integrated transmission as compared with the case where the packets are individually transmitted. be able to. In addition, a route information table can be constructed using route update notification while performing one-hop integrated transmission. In the above description, the situation in which route information is not accumulated has been described as an example. However, even when the network topology changes in a situation in which route information is accumulated, a new route can be created in a short time using the route update notification. Information can be constructed.

[Operation example 3-When the routing information table is incomplete]
Next, another example of packet integration processing when the route information table is incomplete and another example of processing for updating the route information table will be described. FIG. 12 is a diagram for packet integration processing and route update. This operation example is different from the operation example 2 (FIG. 11) in that only the path information table of the node c is incomplete and the path information tables of other nodes are correct. FIG. 12 shows only the route information for the destination nodes h and i.

  Also in this operation example, the packet P addressed to the node h is transmitted from the node a to the node c, and the packet Q addressed to the node i is transmitted from the node b to the node c. Node c cannot perform multi-hop integrated transmission of these packets, but determines that 1-hop integrated transmission is possible up to node d.

  Since the path information table of the node d is correctly constructed, it can be determined that the packet P addressed to the node h and the packet Q addressed to the node i can be multi-hop integrated transmission to the node g. Accordingly, the node d generates and transmits a multihop integrated packet addressed to the node g. At this time, since the packet d and the packet Q, which are transmitted by being integrated into the 1-hop integrated packet, have been transmitted by the multi-hop integrated transmission, the node d sends a route update notification to the node c that is the transmission source of the 1-hop integrated packet. Do. That is, the node d can determine that the integration source node c was originally able to perform multi-hop transmission of the packet addressed to the nodes h and i to the node g, and notifies the node c of that fact.

  The node c receiving this route update notification updates its own route information table based on this notification. That is, the fact that the relay route of node h and node i is common to node g is stored in the route information table.

  Thus, when multi-hop integrated transmission is possible, the efficiency of communication processing can be improved by using multi-hop integrated transmission as much as possible. In addition, the route information table can be updated while performing efficient communication processing.

<Effect of embodiment>
In an ad hoc wireless network, by integrating and transmitting multiple packets, the overhead of transmission waiting time such as DIFS and backoff time that occurs when transmitting multiple packets is reduced, thereby improving the efficiency of communication processing. Can do. In this case, it is possible to eliminate the waste of packet restoration and integration for each hop by managing a node having a common route of 2 hops or more by the route information table and preferentially using multi-hop integrated transmission. Yes. Further, the route information table used for determining packet integration corresponds to dynamic route establishment, and it is not necessary to have all route information in the route information table in advance. The route information can be dynamically updated by performing the route update notification while performing the process of integrating and transmitting the packets.

<Modification>
In the above description, only an example in which two packets are integrated to generate an integrated packet has been described, but an integrated packet may be generated by integrating three or more packets. Further, the packets to be integrated are not limited to ordinary packets, and a plurality of integrated packets, or integrated packets and normal packets may be integrated to generate an integrated packet.

It is a figure which shows the functional block of the radio | wireless communication apparatus which concerns on this embodiment. It is a figure which shows the example of the network topology of an ad hoc wireless network. It is a figure which shows the example of a path | route information table. It is a figure explaining the structure of a 1-hop integrated packet. It is a figure explaining the structure of a multihop integrated packet. It is a flowchart which shows the flow of a packet determination process. It is a flowchart which shows the flow of a packet integration process. It is a flowchart which shows the flow of a route update process. It is a flowchart which shows the flow of a route update process. It is a figure which shows the example of a path | route information table. It is a figure for demonstrating a packet integration process and a route update process. It is a figure for demonstrating a packet integration process and a route update process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 2 Packet receiving part 3 Packet determination part 4 Packet buffer part 5 Path | route information table 6 Integrated packet decompression | restoration part 7 Integrated packet generation part 8 Packet transmission part 9 Path | route update part

Claims (11)

A wireless communication device that performs wireless packet communication directly with another node or via one or more relay nodes, and transmits a plurality of packets having a common relay route in a single packet,
Route information storage means for storing, as route information, a relay node that is one hop ahead for each destination node, and a combination of destination nodes having a common relay route of two or more hops;
When it is determined based on the route information that the relay route of a plurality of packets is common to relay nodes that are two or more hops ahead, multi-hop integration that is one packet destined for the relay node that is two or more hops ahead When a packet is generated and the relay route is not common to a relay node that is two or more hops ahead but the relay node that is one hop ahead is common based on the route information, the relay node that is one hop ahead is the destination Integrated packet generation means for generating a one-hop integrated packet that is one packet
Packet transmitting means for transmitting the integrated packet generated by the integrated packet generating means;
A wireless communication device. An integrated packet restoring means for restoring the received integrated packet;
When this node receives an integrated packet specified as the destination,
The integrated packet recovery means recovers the integrated packet;
The integrated packet generation unit reintegrates the plurality of packets again when it is determined based on the route information that the relay routes of the plurality of restored packets are common. Wireless communication device. In the one-hop integrated packet, an address of a node that first integrated a plurality of packets included in the one-hop integrated packet is stored as an integration source node,
When it is determined that the next relay node of the plurality of packets restored from the one-hop unified packet by the unified packet restoration means is different, the one-hop integration is performed on the integration source node included in the one-hop unified packet. A route notification means for notifying that a relay route to a destination node of a plurality of packets included in the packet is common to the own node;
The wireless communication apparatus according to claim 2, further comprising: In the one-hop integrated packet, an address of a node that first integrated a plurality of packets included in the one-hop integrated packet is stored as an integration source node,
When it is determined that the relay route of the plurality of packets restored from the 1-hop integrated packet by the integrated packet restoration means is common to the relay nodes that are two or more hops ahead, the integration source node included in the one-hop integrated packet A route notification means for notifying that a relay route to a destination node of a plurality of packets included in the one-hop integrated packet is common to the relay node that is two or more hops ahead;
The wireless communication apparatus according to claim 2, further comprising: The integrated packet generation means generates a one-hop integrated packet when
If a plurality of packets to be integrated are not restored from the 1-hop integrated packet by the packet recovery means, the address of the own node is stored as an integration source address in the generated 1-hop integrated packet,
When a plurality of packets to be integrated are those restored from the one-hop integrated packet by the packet restoration means, the integration source address included in the one-hop integrated packet before the restoration is stored in the generated one-hop integrated packet. The wireless communication apparatus according to claim 3, wherein the wireless communication apparatus is a wireless communication apparatus. A wireless communication method in which a plurality of packets having a common relay route are integrated into one packet and transmitted directly to another node or via one or more relay nodes,
Wireless communication device
Obtain, as route information, a relay node that is one hop ahead for each destination node and a combination of destination nodes that have a common relay route of two or more hops,
When it is determined based on the route information that the relay route of a plurality of packets is common to relay nodes that are two or more hops ahead, a multi-hop integrated packet that is one packet destined for the relay node on the route is If a relay path is not common to a relay node that is two or more hops ahead, but it is determined based on the route information that a relay node that is one hop ahead is common, the destination is the relay node that is one hop ahead Generate one-hop integrated packet that is one packet,
Send the generated integrated packet,
A wireless communication method. A program for causing a wireless communication apparatus to perform a wireless communication by integrating and transmitting a plurality of packets having a common relay route into one packet directly with another node or via one or more relay nodes,
For wireless communication devices
A relay node that is one hop ahead for each destination node and a combination of destination nodes that have a common relay route of two or more hops are acquired as route information.
When it is determined based on the route information that the relay route of a plurality of packets is common to relay nodes that are two or more hops ahead, a multi-hop integrated packet that is one packet destined for the relay node on the route is If it is determined based on the route information that the relay node is not common to the relay nodes that are two or more hops ahead, but the relay node that is one hop ahead is common, the relay node that is one hop ahead is the destination Generate one-hop integrated packet that is one packet,
Send the generated integrated packet,
A program characterized by that. Performs wireless packet communication with other nodes directly or via one or more relay nodes, and stores a relay node that is one hop ahead for each destination node and a combination of destination nodes that have a common relay route of two or more hops A method for creating a route information table in a wireless communication system including a wireless communication device that integrates and transmits packets based on a route information table,
Each node in the wireless communication system
Obtain a relay node 1 hop ahead for each destination node, store it in the route information table,
The sending node
A 1-hop integrated packet is created by integrating a plurality of packets shared by the relay nodes that are 1 hop ahead, and the address of the own node is stored as an integrated source address in the 1-hop integrated packet,
Send the generated 1-hop integrated packet,
The node that received the 1-hop integrated packet
Restore the received 1-hop integrated packet,
Determine whether the relay nodes one hop ahead of a plurality of packets obtained by restoration are common,
When the relay nodes that are one hop ahead of a plurality of packets obtained by restoration are common, the plurality of packets are merged again to generate a new one-hop unified packet and stored in the one-hop unified packet before restoration. Stored as the integration source address in the new one-hop integration packet,
When the relay nodes one hop ahead of the plurality of packets obtained by restoration are not common, the node of the integration source address included in the one-hop integration packet is directed to the destination node of the plurality of packets restored That the relay route of
The node that received the notification
A route information table creation method, wherein the route information table is updated based on the notification. Performs wireless packet communication with other nodes directly or via one or more relay nodes, and stores a relay node that is one hop ahead for each destination node and a combination of destination nodes that have a common relay route of two or more hops A program for creating a route information table in a wireless communication system composed of wireless communication devices that integrate and transmit packets based on a route information table,
Each node in the wireless communication system
Get the relay node 1 hop ahead for each destination node and store it in the route information table,
To the sending node
A plurality of packets common to one-hop destination relay nodes are integrated to create a one-hop integrated packet, and the address of the own node is stored as an integration source address in the one-hop integrated packet;
Send the generated 1-hop integrated packet,
1-hop integrated packet to receiving node,
Restore the received 1-hop integrated packet,
It is determined whether the relay nodes one hop ahead of the plurality of packets obtained by restoration are common,
When the relay nodes that are one hop ahead of a plurality of packets obtained by restoration are common, the plurality of packets are merged again to generate a new one-hop unified packet and stored in the one-hop unified packet before restoration. Stored integration source address as the integration source address in the new one-hop integration packet,
When the relay nodes one hop ahead of the plurality of packets obtained by restoration are not common, the node of the integration source address included in the one-hop integration packet is directed to the destination node of the plurality of packets restored To notify that the relay route of
To the node that received the notification,
A program for updating a route information table based on the notification. Performs wireless packet communication with other nodes directly or via one or more relay nodes, and stores a relay node that is one hop ahead for each destination node and a combination of destination nodes that have a common relay route of two or more hops A method for creating the route information table in a wireless communication system including a wireless communication device that integrates and transmits packets based on a route information table,
Each node in the wireless communication system
Obtain a relay node 1 hop ahead for each destination node, store it in the route information table,
The sending node
A 1-hop integrated packet is created by integrating a plurality of packets shared by the relay nodes that are 1 hop ahead, and the address of the own node is stored as an integrated source address in the 1-hop integrated packet,
Send the generated 1-hop integrated packet,
The node that received the 1-hop integrated packet
Restore the received 1-hop integrated packet,
It is determined whether the relay route of the plurality of packets obtained by the restoration is common to the relay node more than 2 hops ahead,
When the path of multiple packets obtained by restoration is common to relay nodes that are two or more hops away, the restoration is obtained for the node of the integration source address stored in the one-hop integration packet. The relay route to the destination node of the plurality of packets is common to the relay node more than two hops ahead,
The node that received the notification
A route information table creation method, wherein the route information table is updated based on the notification. Performs wireless packet communication with other wireless nodes directly or via one or more relay nodes, and stores a relay node that is one hop ahead for each destination node and a combination of destination nodes that have a common relay route of two or more hops A program for creating a route information table in a wireless communication system composed of wireless communication devices that integrate and transmit packets based on a route information table
For each node in the wireless communication system,
Get the relay node 1 hop ahead for each destination node and store it in the route information table,
To the sending node
A plurality of packets common to one-hop destination relay nodes are integrated to create a one-hop integrated packet, and the address of the own node is stored as an integration source address in the one-hop integrated packet;
Send the generated 1-hop integrated packet,
To the node that received the 1-hop integration packet,
Restore the received 1-hop integrated packet,
It is determined whether the relay route of the plurality of packets obtained by the restoration is common to the relay node more than 2 hops ahead,
When the path of multiple packets obtained by restoration is common to relay nodes that are two or more hops away, the restoration is obtained for the node of the integration source address stored in the one-hop integration packet. The relay route to the destination node of the plurality of packets is common to the relay node more than two hops ahead,
To the node that received the notification,
A program for updating a route information table based on the notification.

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