JP2008135914A - Route control method and communication node - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish a suitable route according to characteristics of an application. <P>SOLUTION: When a route entry corresponding to the destination of a packet is not present, a transmission node 11 generates a route request message including metric calculation weight information for calculating metrics being the cost for transfer between a transfer node and a transfer link, and the metrics and then transmits the message to an adjacent node. A relay node selects the best route request on the basis of the metrics included in the route request message, updates the route request message according to the selection result, and transmits the route request message having been updated to the adjacent node. A destination node 12 sets route request reception procedures for selecting the best route requests on the basis of the metrics included in the route request message and the metric calculation weight information for applications of the transmission node 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless multi-hop network, and more particularly to an application adaptive route control method and a communication node that can dynamically search and construct a route suitable for each application.

  Conventionally, in a wireless network, not only the nodes communicate directly by radio, but also communicate beyond the radio communication range by passing other nodes existing within the communication range where their own radio signals reach as relay nodes. Wireless multi-hop networks that make it possible to transmit and receive data between nodes are known.

  This wireless multi-hop network is composed of a plurality of communication nodes, and each communication node has a packet transfer function for transferring a packet not addressed to itself. With this packet transfer function, each node can deliver a packet via a relay node to a destination node that does not reach the radio directly. In wireless multi-hop networks, communication nodes that send and receive and transfer packets frequently move, and accordingly, wireless reachability between each communication node (whether direct communication is possible) changes, and packets are transmitted to the destination node. The transfer path of the network also changes frequently.

  The routing protocol that controls the packet transfer route autonomously and decentrally includes a reactive protocol that searches for a route at the start of communication, and a proactive method that regularly exchanges messages with other communication nodes to maintain the latest route. A type protocol is adopted. Typical reactive routing protocols are disclosed in Non-Patent Literature 1 to Non-Patent Literature 5 and the like. In these routing protocols, the best route from the transmission node to the destination node is determined by the number of hops (the number of nodes to be transferred). However, in reality, a route with a short hop count is not always a good route. This is because there are various factors that hinder communication such as distance between nodes, obstacles, interference with adjacent nodes, and movement in wireless.

Non-Patent Document 3 discloses a method for improving communication quality by measuring a wireless reception strength between communication nodes and constructing a route for transferring between nodes having a strong reception strength.
Non-Patent Document 4 discloses a method for constructing a transfer route having the longest communicable time by estimating the communicable time from the relative speed of the nodes.
Non-Patent Document 5 discloses a method of constructing a route while avoiding nodes where communication is concentrated by considering the number of routes held by the own node.
Patent Document 1 combines the characteristics of a wireless multi-hop network by adopting a QoS metric that integrates metrics (judgment criteria) disclosed in Non-Patent Documents 3 to 5 and other metrics. A method of constructing the best route based on judgment is disclosed.

JP 2004-56787 A C. Perkins et al., “Ad hoc On-Demand Distance Vector (AODV) Routing”, IETF RFC3561, 2003 David B. Jhonson et al., “The Dynamic Source Routing Protocol for Mobile Ad hoc Networks (DSR)”, IETF draft-ietf-manet-dsr-09.txt, 2003 R. Dube et al., “Signal Stability-Based Adaptive Routing (SSA) for Ad Hoc Mobile Networks”, Proc. Of ACM / IEEE MobiCom '98, 1999 W.Su et al., “IPv6 FLOW HANDOFF IN AD HOC WIRELESS NETWORKS USING MOBILITY PREDICTION”, Proc. Of IEEE GlobeCom'99, 1999 H. Hassanein et al., “Routing with Load Balancing in Wireless Ad hoc Networks”, Proc. Of MSWiM, 2001

  In the conventional methods disclosed in Patent Literature 1 and Non-Patent Literature 1 to Non-Patent Literature 5, in a wireless multi-hop network, hop count, signal strength, remaining battery capacity, mobility (link life), communication error rate, bandwidth Based on various metrics (criteria) such as width and number of routes, the best route can be constructed. All of these schemes calculate metrics in a preset way. Therefore, the same route is selected regardless of which application communicates. For example, an inappropriate route such as selecting a route based on the estimated lifetime of the route for an application that does not continue communication for a long time, or selecting a route based on the traffic concentration for an application with little traffic A selection is made.

  In reality, the optimal route varies depending on the characteristics of the application. For example, if you want to deliver very small data quickly, route lifetime is not a big issue, and routes with low hop counts are best. In communication that consumes a fixed band for a relatively long time such as a voice call, a path with a long path survival time, a free band, and a small delay is a good path. How much priority is given to bandwidth or route survival time depends on the voice quality and call duration. In the conventional method, there is a problem in that it is impossible to select a detailed route according to the characteristics of the application, and as a result, it is not possible to provide the user with high-quality communication for each application.

  An object of the present invention is to provide a high-quality wireless multi-hop communication environment for a user by constructing an optimum route according to application characteristics in end-to-end communication in a wireless multi-hop network.

  The present invention relates to a route control method for a wireless multi-hop network in which a multi-hop network is wirelessly formed between a plurality of communication nodes and a route request message is broadcasted in the network to search for a communication route. When there is no route entry corresponding to the transmission node, the transmission node creates a route request message including the metric calculation weight information for calculating the metric that is the transfer cost of the transfer node and the transfer link, and the metric. A route request creation and transmission procedure to be transmitted to the node, a metric calculation procedure in which the relay node calculates a metric based on metric calculation weight information included in the received route request message, and the relay node in the route request message Metrics included and the metric meter A route request update transfer procedure for selecting the best route request based on the metric calculated in the procedure, updating the route request message according to the selection result, and transmitting the updated route request message to the adjacent node; A route request reception procedure for selecting a best route request based on a metric included in the received route request message, and a route response message after a predetermined time from when the destination node first receives the route request message. A route response creation / transmission procedure for transmitting a message to an adjacent node, a first route setting procedure in which the destination node creates a route entry based on the selected route request and sets a route, and the relay node receives A second route setting procedure for creating a route entry based on the route request corresponding to the route response message and setting the route; The relay node creates a route entry based on a route response transfer procedure in which the received route response message is forwarded to an adjacent node, and the transmission node sets a route based on a route request corresponding to the received route response message. And a third route setting procedure.

In one configuration example of the route control method of the present invention, the metric calculation weight information is set for each application of the transmission node.
Further, in one configuration example of the route control method of the present invention, the application of the transmission node sets the metric calculation weight information optimum for itself prior to communication.
Further, in one configuration example of the route control method of the present invention, the metric includes a node metric total value on the route, a link metric total value on the route, a worst node metric, and a worst link metric.
Also, in one configuration example of the route control method of the present invention, the relay node and the destination node hold a plurality of route request messages in the order of good metrics, and the destination node transmits the plurality of route response messages. Thus, a plurality of routes are constructed.
In the configuration example of the route control method of the present invention, the transmission node and the relay node perform packet forwarding based on a packet destination address, an upper protocol, and a destination port.
Further, in one configuration example of the route control method of the present invention, the transmission node and the relay node transfer packets based only on the destination address when the upper layer protocol and the destination port are not registered in the route entry. It is.
In the configuration example of the route control method of the present invention, the route request message includes information on a time-up time for designating the predetermined time.

  Further, when the communication node of the present invention is a transmission node, when there is no route entry corresponding to the packet destination, metric calculation weight information for calculating a metric that is a transfer cost between the transfer node and the transfer link; A route request creation / transmission unit that creates a route request message including the metric and transmits the message to an adjacent node, and a best route request based on a metric included in the received route request message when the node is a relay node. Included in the received route request message when it is a destination node and route request update transfer means for updating the route request message according to the selection result and transmitting the updated route request message to the adjacent node. A route request receiving means for selecting the best route request based on a metric, and the destination node Route response creation / transmission means for sending a route response message to an adjacent node after a predetermined time from the first reception of the route request message, and creation of a route entry based on the selected route request in the case of the destination node The first route setting means for setting the route and the second route setting for setting the route by creating a route entry based on the route request corresponding to the received route response message when the relay node is the relay node. And a route response transfer unit that transfers the received route response message to an adjacent node when the relay node is the relay node, and a route based on the route request corresponding to the received route response message when the node is the transmission node. And a third route setting means for creating an entry and setting a route.

In one configuration example of the communication node according to the present invention, the metric calculation weight information is set for each application of the transmission node.
In one configuration example of the communication node according to the present invention, the application of the transmission node sets the metric calculation weight information optimum for itself prior to communication.
In the configuration example of the communication node according to the present invention, the route request message includes time-up time information for designating the predetermined time.

  According to the present invention, in a wireless multi-hop network controlled by a reactive route control method, by storing metric calculation weight information and route metric information in a route request message, a route suitable for an application is constructed, Quality communication can be realized.

  Also, according to the present invention, it is possible to construct a route optimal for the characteristics of the application by allowing the application of the transmission node to set metric calculation weight information optimum for itself prior to communication.

  Also, in the present invention, by setting the time-up time information from when the destination node first receives the route request message to when the route response message is transmitted to the adjacent node in the route request message, the sending node can immediately It is possible to explicitly tell the destination node whether it is desired to construct a route or to search for a route that may take a little time.

[First Embodiment]
Hereinafter, the best mode of a route control method for a wireless multi-hop network according to the present invention will be described with reference to the accompanying drawings. Here, description will be made assuming that the method of the present invention is extended based on the AODV (Ad hoc On-Demand Distance Vector) disclosed in Non-Patent Document 1.
FIG. 1 is a block diagram showing a configuration example of a wireless multi-hop network according to the first embodiment of the present invention. The wireless multi-hop network of the present embodiment is composed of a plurality of communication nodes 11-17. In the example of FIG. 1, the communication node 11 is described as a transmission node, and the communication node 12 is described as a destination node.

  FIG. 2 is a block diagram illustrating an internal configuration example of each of the communication nodes 11 to 17. Each of the communication nodes 11 to 17 receives a route control unit 31 that establishes a packet transfer route, an application 32 that transmits and receives data, data generated by the application 32 and the route control unit 31, a route request message, a route response message, and the like. An IP communication unit 33 that transmits / receives or transfers IP packets, a metric calculation weight table 34 that stores metric calculation weight information 45 that is optimal for the application 32, and an IP route table 35 that records transfer routes of IP packets to be transmitted / received or transferred The route request cache 36 for temporarily recording the route request message and the packet buffer 37 for temporarily storing data packets from the application 32 until the route construction is completed.

The route control unit 31 and the IP communication unit 33 constitute route request creation / transmission means, route request update / transfer means, route request reception means, route response creation / transmission means, route setting means, and route response transfer means. is doing.
In FIG. 2, the internal configuration is shown only for the communication node 11, but the internal configurations of the other communication nodes 12 to 17 are the same.

  Next, the operation of the wireless multi-hop network of this embodiment will be described. Here, a case where the application 32 operating on the transmission node 11 in FIG. 1 attempts to transmit data will be described. FIG. 3 is a flowchart showing the operation of the transmission node.

  When the application 32 operating on the transmission node 11 attempts to transmit data, the path control unit 31 receives the data to be transmitted (transmission / reception data 44) (step S100 in FIG. 3). The route control unit 31 searches the IP route table 35 based on the destination address and the destination port of the received transmission / reception data 44. When the application 32 communicates for the first time with a partner corresponding to the destination address and the destination port, the IP route table 35 does not have route information corresponding to the destination address and the destination port. When there is no corresponding IP route entry in the IP route table 35 (NO in step S101), the route control unit 31 stores the transmission / reception data 44 received from the application 32 in the packet buffer 37 (step S102), Start building.

  The path control unit 31 first acquires the metric calculation weight information 45 of the application 32 from the metric calculation weight table 34 of its own node (step S103). The metric calculation weight table 34 stores standard metric calculation weight information 45 that matches the characteristics of the application 32 in advance. The application 32 can set appropriate metric calculation weight information 45 prior to communication. FIG. 4 shows a configuration example of the metric calculation weight table 34. The metric calculation weight information 45 includes information on the transport layer protocol of the application 32, a destination port number, a transmission port number, and metric calculation weights W1 to WN.

There are two types of metrics calculated using the metric calculation weights W1 to WN: node metrics and link metrics.
The node metric is a value that represents a cost when the communication node performs packet transfer, and the larger the value, the higher the transfer cost. The node metric Mn is calculated as follows, for example.
Mn = Mnb + W1 × Tr + W2 × (Emax−E) / Emax + W3 × V / Vmax
... (1)

  In equation (1), Mnb is a basic node metric, which is a basic value determined by the type of communication node. For example, the basic node metric Mnb is set to a small value in a communication node with high capability such as an antenna or an in-vehicle router, and the basic node metric Mnb is set to a large value in a communication node with low capability such as a mobile phone or PDA (Personal Digital Assistant). Is done. Vmax is the maximum moving speed assumed in all nodes.

W1 is a metric calculation weight with respect to the packet transfer processing load, and Tr is the number of effective routes that the communication node has. Note that Tr may be another value representing the packet transfer processing load of the communication node, such as an average transmission queue length.
W2 is a metric calculation weight for the remaining battery level. Emax is the maximum capacity of the communication node battery, and E is the remaining battery capacity of the communication node.
W3 is the metric calculation weight for the moving speed of the communication node, and V is the moving speed of the communication node.

The link metric is a value representing the cost for transferring a packet between two communication nodes, and the larger the value, the higher the packet transfer cost between the nodes. For example, the link metric Ml is calculated as follows.
Ml = Mlb + W4 × (Qmax−Q) / Qmax
+ W5 × (Rmax−R) / Rmax (2)

In Equation (2), Mlb is a basic link metric, and its value is normally set to 1.
W4 is a metric calculation weight for link quality. Qmax is the maximum quality information value (fixed value), and Q is the signal reception strength between nodes. Note that Q may be other values representing link quality such as S / N ratio and error rate. As Qmax, the best value that the quality corresponding to Q can take is set.

  W5 is a metric calculation weight for the relative speed between the two communication nodes. Rmax is an estimated maximum relative speed that can occur between the two communication nodes, or an estimated maximum lifetime (fixed value) of the link between the two communication nodes, and R is a relative speed between the two communication nodes, or a relative speed. Is the link lifetime calculated from.

  The path control unit 31 includes an IP address and a port number of a destination node to be transmitted by the application 32, a protocol used by the application 32 (for example, TCP (Transmission Control Protocol), UDP (User Datagram Protocol)), and a transmission node address. Route request from the transmission port number, the metric calculation weight information 45 acquired from the metric calculation weight table 34, the position information of the own node acquired from GPS (Global Positioning Systems), the velocity vector information of the own node acquired from the sensor, etc. A message 42 is created (step S104).

  FIG. 5 shows the configuration of the route request message 42. 5, 0, 1, 2,..., 9, 0, 1, 2,. From the Type field at the head of the route request message 42 to the Originator Sequence Number field is the same as AODV. That is, 1 is always entered in the Type field. Hop Count is the number of hops indicating how many times the packet has been transferred from the transmission source. In the Request ID, a value obtained by adding one to the Request ID used in the route request message 42 transmitted last by the own node is set.

Destination IP Address is the IP address of the destination node, and Destination Sequence Number is the destination sequence number. In the destination sequence number, the sequence number that is last known about the destination is set.
Originator IP Address is the IP address of the sending node. Originator Sequence Number is a sender sequence number, and the sequence number of its own node is set. At this time, the route control unit 31 increases the sender sequence number of the own node immediately before creating the route request message 42.

  In the present embodiment, the following field is further added to the route request message 42. Application Protocol No. Is a number identifying the transport layer protocol (upper protocol UDP, TCP, etc.) of the application 32, Destination Port No. Indicates the destination port number of the packet, Originator Port No. Is the transmission port number of the packet.

Position Information is the position information of the own node acquired from the GPS or the like, and Velocity Information is the velocity vector information of the own node calculated from an acceleration sensor, a gyro sensor, or the like.
Sum of node metric is the total value of the node metric in the route followed by the route request message 42, Sum of link metric is the total value of the link metric in the route followed by the route request message 42, and Worst node metric is the route request message 42 The worst node metric value in the route, Worst link metric, is the worst link metric value in the route followed by the route request message 42.

Weight # is the number of metric calculation weights, Weight Type (x) is the xth (x is an arbitrary value) type of metric calculation weight, and Weight Value (x) is the value of the xth metric calculation weight. The metric calculation weight acquired from the metric calculation weight table 34 is set in the Weight Value (x). A metric calculation weight having a value of 0 can be omitted.
In the case of the transmitting node 11, the path control unit 31 sets 0 in the Sum of node metric, Sum of link metric, worst node metric, and worst link metric fields.

The route control unit 31 passes the created route request message 42 to the IP communication unit 33. The IP communication unit 33 broadcasts the route request message 42 to an adjacent communication node (that is, capable of communication without relay) (step S105).
It is also possible to include the time-up time of the route response timer set by the destination node described later in the route request message. Thereby, the application 32 of the transmission node can explicitly tell the destination node whether it is desired to construct a route immediately or to search for a route that may take a little time.

  FIG. 6 is a flowchart showing the operation of the relay node. When the route control unit 31 of the relay node receives the route request message 42 from the adjacent node (determination YES in step S200 in FIG. 6), the metric calculation weight information included in the received route request message 42, the basic link metric Mlb, the quality Using the information maximum value Qmax, the value Q representing the quality between nodes, the estimated maximum relative speed Rmax between nodes, and the relative speed R, the link metric with the adjacent node that is the transfer source of the route request message 42 is calculated. Calculate (step S201).

  Subsequently, the route control unit 31 determines whether there is a route request entry in which the combination of the received route request message 42 and the destination node address, the destination port number, the transmission node address, the transmission port number, and the protocol is identical. A search is performed from 36 (step S202).

  FIG. 7 shows a configuration example of the route request cache 36. The route request entry stored in the route request cache 36 includes a destination node address, information for identifying a protocol, a destination port number, a destination sequence number, a transmission node address, a transmission port number, and a sender sequence number. , Adjacent node address, received IF (interface) number, total node metric, total link metric, worst node metric, worst link metric, hop count, and link lifetime information It is out.

When there is no corresponding route request entry in the route request cache 36, the route control unit 31 of the relay communication node performs the following processing.
First, the route control unit 31 newly adds a route request entry corresponding to the route request message 42 to the route request cache 36 (step S203). At this time, the route control unit 31 sets the node metric total value of the route request message 42 as the node metric total value of the route request entry, and adds the link metric calculated in step S201 to the link metric total value of the route request message 42. The value is the link metric total value of the route request entry. Further, the route control unit 31 sets the worst node metric of the route request message 42 as the worst node metric of the route request entry, compares the worst link metric of the route request message 42 with the link metric calculated in step S201, and determines the larger one. The value is the worst link metric of the route request entry.

  Subsequently, the route control unit 31 updates the route request message 42 (step S204). At this time, the route control unit 31 adds 1 to the number of hops and the Request ID of the received route request message 42, respectively. The path control unit 31 also includes the metric calculation weight information included in the received path request message 42, the basic node metric Mnb of the own node, the value Tr indicating the packet transfer processing load, the maximum capacity Emax of the battery, the remaining capacity of the battery. The node metric of the own node is calculated using E and the moving speed V, and the node metric total value of the received route request message 42 is added with the calculated node metric to update the node of the route request message 42 after the update. The metric total value.

  Further, the route control unit 31 sets the value obtained by adding the link metric calculated in step S201 to the link metric total value of the received route request message 42 as the link metric total value of the updated route request message 42. Further, the route control unit 31 compares the worst node metric of the received route request message 42 with the calculated node metric, sets the larger value as the worst node metric of the updated route request message 42, and receives the received route. The worst link metric of the request message 42 is compared with the calculated link metric, and the larger value is set as the worst link metric of the updated route request message 42.

  Next, the route control unit 31 passes the updated route request message 42 to the IP communication unit 33. The IP communication unit 33 broadcasts the route request message 42 to the adjacent communication node (step S205).

On the other hand, when the route request entry corresponding to the route request cache 36 already exists, the route control unit 31 of the relay communication node performs the following processing.
First, the route control unit 31 compares the corresponding route request entry in the route request cache 36 with the received route request message 42 (step S206). This comparison method will be described later.
If the existing route request entry is better, the route control unit 31 discards the route request message 42 (step S207) and returns to step S200.

  If the route request message 42 is better, the route control unit 31 updates the corresponding route request entry (step S208), and proceeds to step S204. In step S208, the route control unit 31 sets the node metric total value of the route request message 42 as the node metric total value of the route request entry, and adds the link metric calculated in step S201 to the link metric total value of the route request message 42. This value is used as the link metric total value of the route request entry. Further, the route control unit 31 sets the worst node metric of the route request message 42 as the worst node metric of the route request entry, compares the worst link metric of the route request message 42 with the link metric calculated in step S201, and determines the larger one. The value is the worst link metric of the route request entry.

  Next, a method for comparing the route request message 42 and the route request entry in the route request cache 36 will be described. The route requests are compared by comparing the conditions in the order of the route request comparison rules (a) to (h) below, and it is determined that one of the route request message 42 and the route request entry should be given priority. When done, the comparison ends.

(A) First, when the route request message 42 is compared with the route request entry, if there is a route request having both a good node metric total value and a link metric total value, the route request having the better total value is given priority. .
In comparison of metric values, it is determined that a smaller value is better. However, since the node metric total value and the link metric total value are large, they are regarded as the same value if they are within ± 5% from the average value of both the total value of the route request message 42 and the total value of the route request entry. For example, when the node metric total value of the route request message 42 is 10,000 and the node metric total value of the route request entry is 10500, the average value of both is 10250, so the tolerance is 10250 × 0.05 = 512.5. It is. Since both the node metric total value of the route request message 42 and the node metric total value of the route request entry are within the range of 10250 ± 512.5, it is determined that both values are equal.

(B) If there is a route request having a good total value of one of the node metric total value and the link metric total value and the other total value is the same in the route request message 42 and the route request entry, the total value is Give preference to the better route request.
(C) When there is a route request having a good sum of either the node metric total value or the link metric total value and the other total value is bad in this route request, the route request message 42 and the route request entry Priority is given to the comparison result of the total value with the larger difference. For example, the node metric total value of the route request message 42 is 10,000, the node metric total value of the route request entry is 9000, the link metric total value of the route request message 42 is 9000, and the link metric total value of the route request entry is 11000. In this case, since the difference in the node metric total value is 1000 and the difference in the link metric total value is 2000 between the route request message 42 and the route request entry, the comparison result of the link metric total value is prioritized. Here, since the route request message 42 has a better link metric total value, it is determined that the route request message 42 should be prioritized.

(D) When the route request message 42 is compared with the route request entry, if there is a route request having both the worst node metric value and the worst link metric value, the route request having the better worst value is prioritized.
(E) If there is a route request in which one of the worst node metric value and the worst link metric value is good, and the other worst value is the same in the route request message 42 and the route request entry, the worst value is Give preference to the better route request.
(F) When there is a route request in which one of the worst node metric value and the worst link metric value is good and the other worst value is bad in this route request, the route request message 42 and the route request entry Priority is given to the comparison result of the worst value with the larger difference.
(G) Prioritize route requests with a small number of hops.
(H) The route request received earlier (that is, the route request entry in the route request cache 36) is given priority.

As described above, the route request message 42 is transferred via the relay node.
FIG. 8 is a flowchart showing the operation of the destination node 12. When the destination node 12 receives the route request message 42 (YES in Step S300 in FIG. 8), the route control unit 31 of the destination node 12 searches the route request cache 36 of its own node in the same manner as the relay communication node (Step S300). S301).
When there is no route request entry corresponding to the route request message 42 in the route request cache 36, the route control unit 31 of the destination node performs the following processing.

  First, the route control unit 31 includes the metric calculation weight information included in the received route request message 42, the basic link metric Mlb, the quality information maximum value Qmax, the value Q indicating quality between nodes, and the estimated maximum relative speed between nodes. Using Rmax and the relative speed R, a link metric with the adjacent node that is the transfer source of the route request message 42 is calculated (step S302).

  Subsequently, the route control unit 31 updates the link metric total value by adding the calculated link metric to the link metric total value of the received route request message 42. If the calculated link metric is worse (larger value) than the worst link metric of the route request message 42, the path control unit 31 updates the calculated link metric as the worst link metric (step S303).

  The route control unit 31 newly creates a route request entry in the route request cache 36 based on the route request message 42 after updating the link metric total value and updating the worst link metric as necessary (step S304). ). Then, the route control unit 31 sets a route response timer for returning a route response message after a certain time (step S305).

On the other hand, when the corresponding route request entry already exists in the route request cache 36, the route control unit 31 of the destination node performs the following processing.
First, the route control unit 31 calculates a link metric as in step S302 (step S306), updates the link metric total value of the route request message 42 as in step S303, and, if necessary, the route request message 42. The worst link metric is updated (step S307).

Subsequently, the route control unit 31 compares the corresponding route request entry in the route request cache 36 with the updated route request message 42 (step S308). The comparison method at this time is as described above.
When the existing route request entry is better, the route control unit 31 discards the route request message 42 (step S309). If the updated route request message 42 is better, the route control unit 31 also updates the corresponding route request entry in the route request cache 36 in response to the route request message 42 (step S310).

  Next, the route control unit 31 of the destination node 12 creates a route response message 43 when a certain time-up time has elapsed since the time when the route response timer was set (step S311). FIG. 9 shows the configuration of the route response message 43. From the Type field at the head of the route response message 43 to the LifeTime field is the same as that of AODV. That is, 2 is entered in the Type field. In the Hop Count field, 0 is stored as the number of hops.

  In the Destination IP Address and Originator IP Address fields, values copied from the received route request message 42 are stored as they are. In addition, before creating the route response message 43, the route control unit 31 determines that the sequence number of the own node is the sender if the sequence number of the own node is smaller than the sender sequence number written in the route request message 42. After rewriting with the sequence number, this sequence number is written in the Destination Sequence Number field. Lifetime is the lifetime of a link between adjacent nodes. Application Protocol No. Destination Port No. Originator Port No. In the field, the value copied from the route request message 42 is stored as it is.

  The route control unit 31 of the destination node 12 passes the created route response message 43 to the IP communication unit 33. The IP communication unit 33 transmits the route response message 43 to the adjacent node address registered in the corresponding route request entry of the route request cache 36 by unicast (step S312).

  At the same time, based on the corresponding route request entry, the route control unit 31 creates an IP route entry addressed to the transmission node address and transmission port number registered in this route request entry in the IP route table 35 of the own node (step) S313). FIG. 10 shows a configuration example of the IP route table 35. The IP route entry includes a destination node address (transmission node address of the route request entry), information for identifying a protocol, a destination port number (transmission port number of the route request entry), an adjacent node address, a transmission IF number, It contains information on the number of hops and the link lifetime. The valid time indicates the time from when this route is no longer used until it becomes invalid, and is a preset value. The valid time of the route entry used for packet transmission / reception and transfer is updated.

  When the protocol and the destination port number are not registered in the IP route entry (that is, when the protocol and the transmission port number are not registered in the route request entry), the route control unit 31 matches only the destination address. The route response message 43 is transmitted.

  Next, when the route control unit 31 of the relay node receives the route response message 43 (determination YES in step S209 in FIG. 6), it determines whether there is a route request entry corresponding to the route response message 43 or not. Search from 36 (step S210). When there is a corresponding route request entry, the route control unit 31 transmits the IP route entry addressed to the destination node address and the destination port number registered in the route request entry, the transmission node address and the transmission registered in the route request entry. An IP route entry addressed to the port number is created in the IP route table 35 of the own node (step S211).

  Then, the route control unit 31 of the relay node transfers the route response message 43 to the adjacent node registered in the route request entry (step S212). When the protocol and the destination port number are not registered in the IP route entry (that is, when the protocol and the transmission port number are not registered in the route request entry), the route control unit 31 matches only the destination address. Transfer route response message.

  Finally, when receiving the route response message 43 (determination YES in step S106 in FIG. 3), the route control unit 31 of the transmission node 11 determines whether there is a route request entry corresponding to the route response message 43. A search is performed from the cache 36 (step S107). When the corresponding route request entry exists, the route control unit 31 creates an IP route entry addressed to the destination node address and destination port number registered in the route request entry in the IP route table 35 of the own node (step S108). ).

  Then, the path control unit 31 of the transmission node 11 starts transferring the application data stored in the packet buffer 37 (step S109). At this time, the application data is transferred to the adjacent node address according to the IP route entry created in step S108.

  Next, the operation of the relay node after creating the IP route entry will be described with reference to FIG. First, the route control unit 31 of the relay node determines whether there is an IP route entry whose valid time has expired (step S400). When the route control unit 31 receives application data when the valid time of the IP route entry has not expired (determination YES in step S401), the combination of the application data, the destination node address, the destination port number, and the protocol matches. Whether there is an IP route entry is searched from the IP route table 35 (step S402). When the corresponding IP route entry exists, the route control unit 31 transfers the application data to the adjacent node address registered in the IP route entry (step S403), and returns to step S400. If the corresponding IP route entry does not exist, the route control unit 31 discards the received application data (step S404) and returns to step S400.

  Further, when the route control unit 31 of the relay node determines in step S400 that there is an IP route entry whose valid time has expired, it deletes the IP route entry whose valid time has expired from the IP route table 35 (step S405). . Then, the route control unit 31 determines whether the number of IP route entries in the IP route table 35 has become zero. If the number of IP route entries is not 0, the process returns to step S400, and if the number of IP route entries is 0, the processing in FIG.

  Next, an example of actual operation of the present embodiment will be described with reference to FIG. The transmission node 11 acquires metric calculation weight information and the like corresponding to the application 32 along with the data transmission of the application 32 of its own node, and broadcasts the route request message 51. The route request message 51 includes the number of hops 1, the address of the destination node 12, the destination sequence number 3, the protocol TCP, the destination port number 80, the address of the transmission node 11, the sender sequence number 9, the transmission port number 4335, and the total node metric. Value 0, link metric total value 0, worst node metric 0, worst link metric 0, metric calculation weights W1 = 30, W2 = 40, W3 = 0, W4 = 10, W5 = 30, location information (X, Y, Z ), Velocity vector information (dX, dY, dZ) is set.

  The route request message 51 is received by the relay nodes 13 and 14, respectively. The relay nodes 13 and 14 measure the message reception intensity, the position information and speed of the own node, the remaining battery level, the relative speed with respect to the transmission node 11, and the like. The relay nodes 13 and 14 calculate the link metric and the node metric from the measured information and the metric calculation weight information included in the route request message 51. In the example of FIG. 12, the node metric of the relay node 13 is 10, the link metric between the relay node 13 and the transmission node 11 is 20, the node metric of the relay node 14 is 40, and the link metric between the relay node 14 and the transmission node 11 is 10 is assumed.

  The relay nodes 13 and 14 update the node metric total value and link metric total value by adding the calculated link metric and node metric to the node metric total value and link metric total value of the route request message 51, respectively. In response, the worst node metric and worst link metric of the route request message 51 are updated. Then, the relay nodes 13 and 14 broadcast the updated route request messages as route request messages 53 and 52, respectively.

  In the example of FIG. 12, the node metric total value of the route request message 53 is updated to 10, the link metric total value is 20, the worst node metric is 10, and the worst link metric is 20. Further, the node metric total value of the route request message 52 is updated to 40, the link metric total value is 10, the worst node metric is 40, and the worst node metric is 10. Since the relay nodes 13 and 14 are added as nodes that transfer the route request message, the hop count of the route request messages 52 and 53 is updated to 2.

  Further, the relay node 13 registers the route request entry in the route request cache 36 of its own node. In this route request entry, the address of the destination node 12, the protocol TCP, the destination port number 80, the destination sequence number 3, the address of the transmission node 11, the transmission port number 4335, the sender sequence number 9, the address of the adjacent node 11, the reception IF number IF # 1, node metric total value 10, link metric total value 20, worst node metric 10, worst link metric 20, hop count 1, link valid time 30 seconds are registered.

  Similarly, the relay node 14 registers the route request entry in the route request cache 36 of its own node. In this route request entry, the address of the destination node 12, the protocol TCP, the destination port number 80, the destination sequence number 3, the address of the transmission node 11, the transmission port number 4335, the sender sequence number 9, the address of the adjacent node 11, the reception IF number IF # 1, node metric total value 40, link metric total value 10, worst node metric 40, worst link metric 10, hop count 1, link valid time 30 seconds are registered.

  The destination node 12 receives the route request message 53 from the relay node 13 and the route request message 52 from the relay node 14. The destination node 12 compares the route request messages 53 and 52 received from the relay nodes 13 and 14 according to the comparison method described above. In this case, the following two route requests are compared. First, in the route request based on the route request message 53, the adjacent node address is the address of the node 13, the node metric total value is 10, the link metric total value is 50, the worst node metric is 10, the worst link metric is 30, and the hop count is 2 In the route request based on the route request message 52, the adjacent node address is the address of the node 14, the node metric total value is 40, the link metric total value is 30, the worst node metric is 40, the worst link metric is 20, and the hop count is 2 Here, the route request based on the route request message 53 is prioritized by the route request comparison rule (c) described above.

  Note that the link metric total value and the worst link metric at this time are updated by the processing in steps S302 and S303 or steps S306 and S307. That is, when one of the route request messages 53 and 52 is received first, this route request message is updated by the processing of steps S302 and S303 to create a route request entry, and then the other route request message is received. Then, this route request message is updated by the processing of S306 and S307 and compared with the route request entry.

  The destination node 12 creates and transmits a route response message to the relay node 13. At the same time, the IP route entry is registered in the IP route table 35 of the own node. In this IP route entry, the address of the node 11 is registered as the destination node address, the address of the node 13 is registered as the NextHop address, and the protocol TCP, the destination port number 4335, the transmission IF number IF # 1, the number of hops 2, the valid time 30 Seconds are registered.

  When the relay node 13 receives the route response message from the destination node 12, the corresponding route request entry from the route request cache 36 of its own node, that is, the received route response message, the destination node address, the destination port number, the transmission node address, the transmission A route request entry having a matching port number and protocol pair is searched, an IP route entry is created in the IP route table 35 of the own node, and addressed to the node 11 which is an adjacent node registered in the searched route request entry. Forward the route response message.

  At this time, the relay node 13 creates an IP route entry addressed to the node 11 and an IP route entry addressed to the node 12. In the IP route entry addressed to the node 11, the address of the node 11 is registered as the destination node address and the NextHop address, and the protocol TCP, the destination port number 4335, the transmission IF number IF # 1, the number of hops 1, and the valid time 30 seconds. be registered. In the IP route entry addressed to the node 12, the address of the node 12 is registered as the destination node address and the NextHop address, and the protocol TCP, the destination port number 80, the transmission IF number IF # 1, the hop number 1, and the valid time 30 seconds are included. be registered.

  When receiving the route response message from the node 13, the sending node 11 creates an IP route entry in the IP route table 35 of the own node. In this IP route entry, the address of the node 12 is registered as the destination node address, the address of the node 13 is registered as the NextHop address, and the protocol TCP, the destination port number 80, the transmission IF number IF # 1, the number of hops 2, the valid time 30 Seconds are registered. Then, the transmission node 11 starts transmission of the packet stored in the packet buffer 37 and the packet received from the application 32.

  In a reactive route control method in a conventional wireless multi-hop network, a route is selected only by a predetermined criterion. The conventional standard is the number of hops, signal strength, estimated survival time, traffic concentration, remaining battery level, or a composite standard thereof. However, with a fixed selection criterion, it is not possible to select a route according to characteristics that differ for each application. For this reason, an inappropriate route is constructed, such as selecting a route for an application that does not continue communication for such a long time based on the estimated lifetime, or selecting a route for an application with little traffic based on the traffic concentration level. .

  In this embodiment, the metric calculation weight information for calculating a metric that is a reference for route selection is included in the route request message, and the metric calculation weight information is set for each application. Allows route selection. In the present embodiment, since the metric calculation weight is registered in the metric calculation weight table 34 for each application 32, different metric calculation weights are used in different applications 32. For this reason, the link metric and the node metric calculated at each relay node are different for each application, and as a result, the selected route may be different. The application 32 registers the optimal metric calculation weight in the metric calculation weight table 34 prior to communication, so that the application 32 can cause the path control unit 31 to construct a path based on the evaluation criteria desired by the application 32. Thus, in this embodiment, it is possible to provide a comfortable communication environment for the user.

[Second Embodiment]
In the first embodiment, the relay node and the destination node hold only the best route request entry in the route request cache 36. However, when a plurality of the same route request messages are received from different adjacent nodes, It is also possible to hold the route request entries up to the top N of them in the route request cache 36.

In this case, when a certain time-up time elapses from the time when the route response timer is set, the destination node sets an adjacent node registered in the top N route request entries held in the route request cache 36 of the own node. In response, a route response message is transmitted.
When the relay node receives the route response message, it searches the route request cache 36 of its own node for the top N route request entries corresponding to the route response message, and selects the best (highest) route request entry. Then, an IP route entry is created in the IP route table 35 of the own node, a route response message is transferred to the adjacent node address registered in the selected route request entry, and the selected route request entry is deleted.

  When the relay node receives a plurality of route response messages for the same route, as long as the route request entry corresponding to the route response message exists, the relay node selects the best route request entry, creates an IP route entry, and selects the selected route. The route response message is transferred to the adjacent node address registered in the request entry, and the selected route request entry is deleted. When the route request entry corresponding to the route response message disappears in the route request cache 36, the relay node discards the route response message. Note that route request entries that are not used are automatically discarded after a predetermined time.

  The present invention can also be applied based on DSR (Dynamic Source Routing) disclosed in Non-Patent Document 2. In the case of DSR, since the route followed by the message is stored in the route request message, the destination node can explicitly indicate the route for returning the response. Therefore, it is possible to return a plurality of responses along non-overlapping routes.

  Each communication node of the first and second embodiments can be realized by a computer having a CPU, a storage device, and an external interface, and a program for controlling these hardware resources. In such a computer, a program for realizing the path control method of the present invention is provided in a state of being recorded on a recording medium such as a flexible disk, a CD-ROM, a DVD-ROM, or a memory card. The CPU writes the program read from the recording medium into the storage device, and executes the above-described processing according to the program.

  The present invention can be applied to a wireless multi-hop network.

It is a block diagram which shows the structural example of the radio | wireless multihop network which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the internal structural example of the communication node of the radio | wireless multihop network which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the transmission node in the 1st Embodiment of this invention. It is a figure which shows the structural example of the metric calculation weight table of the communication node in the 1st Embodiment of this invention. It is a figure which shows the structure of the route request message in the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement of the relay node in the 1st Embodiment of this invention. It is a figure which shows the structural example of the path | route request | requirement cache of the communication node in the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the destination node in the 1st Embodiment of this invention. It is a figure which shows the structure of the path | route response message in the 1st Embodiment of this invention. It is a figure which shows the structural example of the IP routing table in the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the relay node after IP route entry creation in the 1st Embodiment of this invention. It is a figure explaining the operation example of the 1st Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11-17 ... Communication node, 31 ... Path control part, 32 ... Application, 33 ... IP communication part, 34 ... Metric calculation weight table, 35 ... IP path table, 36 ... Path request cache, 37 ... Packet buffer.

Claims (12)

In a route control method for a wireless multi-hop network in which a multi-hop network is formed wirelessly between a plurality of communication nodes and a route request message is broadcasted in the network to search for a communication route.
When there is no route entry corresponding to the packet destination, the transmission node creates a route request message including the metric calculation weight information for calculating the metric that is the transfer cost between the transfer node and the transfer link and the metric. Route request creation and transmission procedure to be transmitted to adjacent nodes,
A metric calculation procedure in which the relay node calculates a metric based on metric calculation weight information included in the received route request message;
The relay node selects the best route request based on the metric included in the route request message and the metric calculated in the metric calculation procedure, updates the route request message according to the selection result, and updates the updated route. A route request update transfer procedure for sending a request message to an adjacent node;
A route request reception procedure in which a destination node selects a best route request based on a metric included in the received route request message;
A route response creation and transmission procedure in which the destination node transmits a route response message to an adjacent node after a predetermined time since the route request message was first received;
A first route setting procedure in which the destination node creates a route entry based on the selected route request and sets a route;
A second route setting procedure in which the relay node creates a route entry and sets a route based on a route request corresponding to the received route response message;
A route response transfer procedure in which the relay node transfers the received route response message to an adjacent node;
A route control method comprising: a third route setting procedure in which the transmission node creates a route entry based on a route request corresponding to the received route response message and sets a route. The route control method according to claim 1,
The metric calculation weight information is set for each application of the transmission node. The route control method according to claim 2, wherein
The routing control method, wherein the application of the transmission node sets the metric calculation weight information optimum for itself before communication. The route control method according to any one of claims 1 to 3,
The metric includes a node metric total value on a route, a link metric total value on a route, a worst node metric, and a worst link metric. The route control method according to claim 1,
The relay node and the destination node hold a plurality of the route request messages in order of good metrics, and the destination node constructs a plurality of routes by transmitting the plurality of route response messages. Routing method. The route control method according to claim 1,
The routing control method, wherein the transmission node and the relay node perform packet forwarding based on a packet destination address, a higher-level protocol, and a destination port. The route control method according to claim 6, wherein
The route control method according to claim 1, wherein the transmission node and the relay node transfer a packet based only on a destination address when an upper protocol and a destination port are not registered in the route entry. The route control method according to claim 1,
The route control method, wherein the route request message includes information on a time-up time for designating the predetermined time. In a communication node that forms a multi-hop network wirelessly with other communication nodes and broadcasts a route request message in the network to search for a communication route,
In the case of a transmission node, when there is no route entry corresponding to the destination of the packet, a route request message including metric calculation weight information for calculating a metric that is a transfer cost of the transfer node and the transfer link, and the metric A route request creation and transmission means for creating and transmitting to a neighboring node;
Metric calculation means for calculating a metric based on metric calculation weight information included in the received route request message when it is a relay node;
In the case of the relay node, the best route request is selected based on the metric included in the route request message and the metric calculated by the metric calculation means, and the route request message is updated according to the selection result and updated. A route request update transfer means for transmitting a subsequent route request message to an adjacent node;
Route request receiving means for selecting the best route request based on a metric included in the received route request message when it is a destination node;
In the case of the destination node, route response creation and transmission means for transmitting a route response message to an adjacent node after a predetermined time after first receiving the route request message;
A first route setting means for creating a route entry based on the selected route request and setting a route when the destination node is the destination node;
A second route setting means for creating a route entry and setting a route based on a route request corresponding to the received route response message in the case of the relay node;
In the case of the relay node, route response transfer means for transferring the received route response message to an adjacent node;
A communication node comprising: a third route setting unit configured to create a route entry and set a route based on a route request corresponding to the received route response message in the case of the transmission node. The communication node according to claim 9, wherein
The metric calculation weight information is set for each application of the transmission node. The communication node according to claim 10, wherein
Prior to communication, the application of the transmission node sets the metric calculation weight information that is most suitable for the communication node. The communication node according to claim 9, wherein
The communication node according to claim 1, wherein the route request message includes time-up time information for designating the predetermined time.

Images