JP2005236764A - Route establishment method in ad hoc radio network, and radio node - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent wasteful broadcast of a control packet without impeding route establishment in an ad hoc radio network. <P>SOLUTION: The method includes the procedures of: transmitting an RREQ message from a source node; registering route information of a return path into a routing table by a relay node receiving the above RREQ; determining in the relay node whether or not relaying the RREQ is permitted, on the basis of location information of the relay node registered in the RREQ and a present location of the relay node concerned; registering in the relay node the present location of the relay node concerned into the RREQ permitted to relay, as location information; replying an RREP message from the destination node receiving the RREQ; and registering route information of the forward path into the routing table by the relay node receiving the RREP. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ad hoc wireless network route establishment method and a wireless node, and more particularly to an ad hoc wireless network route establishment method and a wireless node suitable for multi-hop communication.

There is an increasing interest in an ad hoc wireless network in which mobile terminals having a wireless communication function perform communication by autonomously configuring a network between terminals without using an infrastructure such as a wireless base station. In such an ad hoc wireless network, in order to further expand the conventional method in which only terminals located within a communicable area can participate in communication, and to enable communication with mobile terminals located outside the communicable area For example, Patent Document 1 discloses the development of an ad hoc routing technique in which a routing function is added to each mobile terminal and communication data is relayed (multi-hop communication). Various methods regarding ad hoc routing are being actively studied. Among them, AODV (RFC-3561) and DSR (draft-ietf-manet-dsr-09.txt) are ad hoc routing protocols that are attracting much attention.
JP 2003-273788 A

  In the methods proposed so far, when establishing a communication path between a transmission source node and a destination node, the transmission source node broadcasts a control packet for a path request to adjacent nodes. The adjacent node that has received this control packet establishes a reverse path to the node that transmitted the control packet, but has never received this control packet and has path information to reach the destination node. Otherwise, the received control packet is relayed and broadcast to adjacent nodes. This series of control packet broadcast operations is called flooding, and is repeated until the control packet reaches the destination node.

  When the destination node receives the control packet, a route response packet is returned from the destination node. The response packet is returned to the source node along the reverse path established by flooding the control packet. The relay node that transfers the route response control packet establishes a forward path to the destination node, and when the packet is transferred to the source node, a communication path is established between the source node and the destination node. . In addition, control packets for route maintenance are periodically transmitted and received between adjacent nodes.

  In an ad hoc wireless network in which a large number of nodes participate and connect, the number of neighboring nodes increases, and when the control packet is broadcast as described above, more nodes are involved in the route generation operation, and as a result, A large amount of control packets are generated. When a large number of control packets are flooded, there is a possibility that not only will data congestion be caused by communication congestion but also a problem of power consumption due to signaling when each relay node broadcasts a packet.

  An object of the present invention is to provide a route establishment method and a wireless node capable of preventing wasteful broadcast of control packets without causing trouble in route establishment in an ad hoc wireless network.

  To achieve the above object, the present invention provides an ad hoc wireless network route establishment method and a wireless node in which wireless nodes exchange route request messages and route response messages to generate route information on an ad hoc wireless network. This is characterized by the following procedures or measures taken.

  (1) The route establishing method of the present invention includes a procedure in which a transmission source node transmits a route request message, a procedure in which a relay node that has received the route request message registers route information of a return route, and the relay node is a local node. Detecting the current position of the route request message based on the position information registered in the route request message and the current position of the own node, and the relay node A procedure for a node to register and transmit the current position of its own node as location information in a route request message that is permitted to be relayed, a procedure for a destination node that receives the route request message to return a route response message, and a route response message The relay node that has received the message includes a procedure for registering route information of the forward route.

  (2) The wireless node of the present invention includes means for generating route information based on the received route request message and route response message, a routing table for storing the route information, and means for detecting the current position of the own node. A source function unit for functioning as a source node, a relay function unit for functioning as a relay node, and a destination function unit for functioning as a destination node, wherein the source function unit is a route request message The relay function unit extracts the position information registered in the received route request message, and based on the extracted position information and the current position of the own node, Means for determining whether or not relaying is permitted, and means for registering the current position of the own node as position information in a route request message permitted to relay. Comprising means for said destination functional unit generates a route response message.

  According to the present invention, each radio node that has received an RREQ message other than that addressed to itself is the location information of each radio node (source node, destination node, or radio node one hop ahead) registered in the RREQ message. The relay probability for the message is calculated based on the current position of the node and the current node position, and when the relay probability is low, the RREQ message is not relayed, so that unnecessary broadcast of the control packet can be prevented without hindering the route establishment. .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram of a radio node according to the present invention, in which illustration is omitted except for the configuration necessary for the description of the present invention.

  The wireless interface 10 transmits and receives various control packets or data including a route request (Route Request: RREQ) message and a route response (Route Reply: RREP) message. The route information generation unit 11 generates route information indicating the relationship between the destination wireless node and the next hop based on the received RREQ message and RREP message, and registers this in the routing table 12. The current position detection unit 13 detects the current position of the own node based on, for example, GPS signals received from a plurality of GPS satellites.

  Each wireless node further includes a source function unit 14 for the own node to function as a source node, a relay function unit 15 for the own node to function as a relay node, and a function for the own node to function as a destination node. Destination function unit 16.

  In the transmission source function unit 14, the RREQ generation unit 141 includes a current position registration unit 141a, and generates an RREQ message in which the address of the destination node is registered as the route request destination and the address of the own node is registered as the route request transmission source. To do. The current position registration unit 141a registers the current position of the own node and the current position of the destination node in the RREQ message. The current position of the destination node is registered in advance in the position information cache 17. The RREQ transmission unit 142 transmits (broadcasts) the RREQ message.

  In the relay function unit 15, the location information extraction unit 151 extracts the location information registered in the received RREQ message or RREP message and registers it in the location information cache 17. As described later in detail, the relay permission / refusal determination unit 152 is based on the position information of the transmission source node, the destination node, and the relay node one hop ahead registered in the received RREQ message, and the current position of the own node. Then, whether to relay the RREQ message is determined. The message relay unit 153 includes a current location registration unit 153a, and updates and registers the current location of the own node in the relayed RREQ message and RREP message.

  In the destination function unit 16, the RREP generation unit 161 includes a current location registration unit 161a, generates an RREP message in response to reception of the RREQ message addressed to the own node, and includes the current location and transmission source of the own node in the RREP message. The current position of the node is registered as position information. The RREP transmission unit 162 transmits (unicasts) the RREP message.

  Next, in the network topology shown in FIG. 2, a procedure for establishing a route for relaying a plurality of wireless nodes from the wireless node MN1 as the transmission source node to the wireless node MN6 as the destination node is described with reference to FIG. Description will be made along the flowchart of FIG. 7 and the sequence diagram of FIG.

  FIG. 3 is a flowchart showing the procedure of the RREQ transmission process executed by the transmission source node MN1, and when a communication request is detected in step S1, the route information reaching the destination node MN6 is displayed in the routing table 12 in step S2. It is determined whether or not already registered. If it is already registered, the process proceeds to step S7, and data communication is started using the already registered route information. If the route information to the destination node MN6 is not registered, the process proceeds to step S3.

  In step S3, the current position P1 of the current node detected by the current position detector 13 is acquired. In step S4, the RREQ generator 141 generates an RREQ message. In step S5, the current position P1 of the own node and the current position P6 of the destination node MN6 are registered in the RREQ message as position information. In step S6, the RREQ message is transmitted and received by the two relay nodes MN2 and MN3.

  FIG. 10A shows an example of the packet format of the RREQ message. The transmission source node “MN1” is registered as “packet sender”, and “ALL” means broadcast as “packet destination”. Is registered, "Request" is registered as "Packet Type", destination node "MN6" is registered as "Route Request Destination", source node "MN1" is registered as "Route Request Source", and the location As information, the current position “P1” of the source node MN1 and the current position “P6” of the destination node MN6 are registered. The current position P6 of the destination node MN6 is read from the position information cache 17.

  Next, the reception processing of the RREQ message in each wireless node will be described with reference to the flowchart of FIG.

  When the RREQ message is received, all the position information registered in the message is extracted and stored in the position information cache 17 in step S21. For example, in the case of the relay node MN2, as shown in FIG. 10A, the current position P1 of the source node MN1 and the current position P6 of the destination node are registered in the RREQ message transmitted from the source node MN1. Therefore, the two pieces of position information P1 and P6 are extracted. In the case of the relay node MN5, as shown in FIG. 10B, the RREQ message relayed by the relay node MN2 includes the current position P1 of the source node MN1, the current position P6 of the destination node, and one hop ahead. Since the current position P2 of the relay node MN2 is registered, these three pieces of position information P1, P6, and P2 are extracted. In step S22, route information (return route information) to the transmission source node MN1 is registered in the routing table 12 based on the received RREQ message.

  In step S23, based on whether the route request destination of the RREQ message is the local node, it is determined whether the destination is the local node. If it is the destination node MN6, it is determined that it is addressed to its own node, so the process proceeds to “RREQ response processing” in FIG. If it is not the destination node MN6, the process proceeds to step S24, and based on the location information of each wireless node registered in the RREQ message and the current location of the own node, whether or not to relay the RREQ message is determined.

In the present embodiment, in order to determine whether or not to relay the RREQ message, position information of each wireless node is acquired, and the relay probability is determined from the following five policies.
First policy: When the relay node moves from the wireless node one hop ahead to its own node, the relay probability increases as the distance between the transmission source node and the relay node increases.
Second policy: When the relay node moves from the wireless node one hop ahead to its own node, the relay probability increases as the distance between the destination node and the relay node decreases.
Third policy: The relay probability is increased in proportion to the distance from the wireless node before one hop to the own node.
Fourth policy: The relay probability is increased in proportion to the distance from the transmission source node to the own node.
Fifth policy: The relay probability is lowered in proportion to the distance from the own node to the destination node.

  In the present invention, these five policies can be applied singly or plural can be applied simultaneously.

  Next, with respect to the relay permission / refusal determination processing executed in step S24, as shown in FIG. 9, the relay node MNj hopped from the relay node MNi to the RREQ message transmitted from the source node MNs to the destination node MNd. The operation in FIG. 5 will be described as an example along the flowchart of FIG. Here, whether the relay is permitted or not is determined by applying the first and second policies.

  In step S41, the distance ΔLsj from the transmission source node MNs to the own node MNj is calculated by the following equation (1) using the respective current positions Ps and Pj.

    ΔLsj ＝ Pj−Ps (1)

  In step S42, the distance ΔLsi from the transmission source node MN1 to the relay node MNi one hop ahead is calculated by the following equation (2) using the respective current positions Ps and Pi.

    ΔLsi ＝ Pi−Ps (2)

  In step S43, the absolute amount A of the amount of change in the distance from the source node MN1 to the relay node due to the relay node moving from the node MNi just one hop ahead to its own node MNj is based on the following equation (3). Is calculated.

    A = | ΔLsj−ΔLsi | (3)

  In step S44, the distance ΔLjd from the own node MNj to the destination node MNd is calculated by the following equation (4) using the respective current positions Pj and Pd.

    ΔLjd = Pd−Pj (4)

  In step S45, the distance ΔLid from the node MNi one hop ahead to the destination node MNd is calculated by the following equation (5) using the respective current position information Pi and Pd.

    ΔLid = Pd−Pi (5)

  In step S46, the absolute value D of the amount of change in the distance from the relay node to the destination node MNd due to the relay node moving from the node MNi just one hop ahead to its own node MNj is based on the following equation (6). Calculated.

    D = | ΔLjd−ΔLid | ... (6)

  In step S47, the relay probability q is obtained based on the following equation (7). Here, p is a constant between (0, 1), and γ1 and γ2 are positive constants.

    q = max (0, min (p + A / γ1-D / γ2,1)) (7)

  In step S48, whether or not the message is relayed is determined based on the relay probability q. Here, for example, a random number R is separately generated in the range of 0 to 1 and compared with the relay probability q. If q ≧ R, “relay permitted” is determined, and if q <R, “relay prohibited” is determined. be able to.

  Returning to FIG. 4, in step S25, the determination result of whether or not relaying is permitted in step S48 is referred to. If relaying is prohibited, the process proceeds to step S30 and the RREQ message is discarded. If relaying is permitted, the process proceeds to step S26, and the current position of the current node detected by the current position detection unit 13 is acquired. In the present embodiment, as shown in FIG. 2, the relay nodes MN3 and MN4 are prohibited from relaying, and the relay nodes MN2 and MN5 are permitted to relay. In step S27, the packet sender of the RREQ message is updated to its own node. In step S28, the current position of the own node is added to the RREQ message. In step S29, the updated RREQ message is transmitted.

  FIG. 10B is a diagram showing a packet format of the RREQ message transmitted from the relay node MN2, where “packet sender” is rewritten to “MN2” and the current position P2 of the relay node MN2 is used as position information. Has been added. FIG. 5C shows the packet format of the RREQ message transmitted from the relay node MN5. “Packet sender” is rewritten to “MN5” and the current position P5 of the relay node MN5 is used as position information. Is registered for renewal.

  FIG. 6 is a flowchart showing the procedure of the RREQ response process executed by the destination node MN6 that has received the RREQ message addressed to its own node.

  In step S61, the current position P6 detected by the current position detection unit 13 of the own node is acquired. In step S62, an RREP message is created. FIG. 10 (d) shows an example of the packet format of the RREP message. The destination node MN6 is registered as the “packet sender” and the relay node MN5 one hop ahead is registered as the “packet destination”. , “RREP” is registered as “packet type”, destination node MN6 is registered as “route request destination”, transmission source node MN1 is registered as “route request transmission source”, and transmission source node MN1 is further registered as location information. Current position P1 and destination node current position P6 are registered. In step S63, the RREP message is transmitted.

  Next, the procedure of RREP reception processing executed in each wireless node in response to reception of the RREP message will be described with reference to the flowchart of FIG.

  In step S71, all the location information registered in the received RREP message is extracted and registered in the location information cache 17. In step S72, route information (outbound route information) to the destination node MN6 is registered in the routing table 12. In step S73, it is determined whether or not the destination of the RREP message is the local node. If it is a relay node other than the source node MN1, the process proceeds to step S74.

  In step S74, the current position detected by the current position detection unit 13 of the own node is acquired. In step S75, the packet destination of the RREP message is rewritten based on the return route information registered in the routing table, and the packet sender is rewritten to the own node. In step S76, the current position of the wireless node one hop before registered as position information is rewritten to the current position of the own node. In step S77, the updated RREP message is transmitted.

  FIG. 10 (e) is a diagram showing an example of the packet format of the RREP message transmitted from the relay node MN5, where “packet sender” is rewritten to the relay node MN5 and “packet destination” is one hop ahead. The information is rewritten to the relay node MN2, and the current position P5 of the relay node MN5 is registered as position information. FIG. 8 (f) is a diagram showing an example of a packet format of the RREP message transmitted from the relay node MN2, in which “packet sender” is rewritten to the relay node MN2 and “packet destination” is one hop ahead. The information is rewritten to the transmission source node MN1, and the current position P2 of the relay node MN2 is updated and registered as position information.

  On the other hand, if it is the transmission source node MN1, since the destination is determined to be its own node in step S73, the process proceeds to step S78 and data transmission is started.

  In the above-described embodiment, whether or not to relay the route request message is determined by applying the first policy and the second policy. However, from the wireless node one hop before the own node by applying the third policy. If the relay probability increases as the absolute distance X increases, the relay probability q can be obtained based on the following equation (8). However, p is a constant between (0, 1), and γ3 is a positive constant.

    q = max (0, min (p + X / γ3,1)) (8)

  Furthermore, the fourth and fifth policies are applied to increase the relay probability in proportion to the absolute distance Y from the source node MNs to the own node MNj, and at the same time to the distance Z from the own node MNj to the destination node MNd. If the relay probability is lowered, the relay probability q can be obtained based on the following equation (9). However, p is a constant between (0, 1), and γ4 and γ5 are positive constants.

    q = max (0, min (p + Y / γ4−Z / γ5,1)) (9)

It is a functional block diagram of the radio | wireless node which concerns on this invention. It is the figure which showed an example of the network topology to which this invention is applied. It is a flowchart of a RREQ transmission process. It is a flowchart of a RREQ reception process. It is a flowchart of a relay permission / rejection determination process. It is a flowchart of a RREQ response process. It is a flowchart of a RREP reception process. It is the sequence diagram which showed the operation | movement of this embodiment. It is a schematic diagram for demonstrating relay permission determination processing. It is the figure which showed the frame structure of the message packet.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Wireless interface, 11 ... Routing information generation part, 12 ... Routing table, 13 ... Current position detection part, 14 ... Transmission source function part, 15 ... Relay function part, 16 ... Destination function part, 17 ... Position information cache

Claims (12)

In an ad hoc wireless network route establishment method in which wireless nodes exchange route request messages and route response messages on an ad hoc wireless network to generate route information.
A procedure for the source node to send a route request message;
The relay node that has received the route request message registers the return route information.
A procedure for the relay node to detect the current position of the node;
A procedure for the relay node to determine whether or not to relay the route request message based on the location information registered in the route request message and the current location of the node;
A procedure for the relay node to register the current location of the node as location information in a route request message permitted to be relayed;
A destination node that has received the route request message returns a route response message;
A route establishment method for an ad hoc wireless network, comprising: a relay node that has received the route response message registers a route information of a forward route. A procedure for the source node to detect the current position of the node;
A step in which the transmission source node registers the current position of the own node and the position information of the destination node in the route request message;
The relay node determines whether or not to permit relaying based on each position information of a source node, a destination node, and a relay node one hop ahead registered in the received route request message and a current position of the own node. The ad hoc wireless network path establishment method according to claim 1.   3. The ad hoc according to claim 1, wherein the relay node updates the position information of the relay node one hop ahead registered in the route request message permitted to be relayed to the current position of the own node. A method for establishing a route in a wireless network.   The method for establishing a route of an ad hoc wireless network according to claim 1, wherein the relay node increases the probability of relay permission as the distance between the wireless node one hop ahead and the self node increases.   The relay node increases the probability of relay permission as the increment of the distance between the source node and the own node with respect to the distance between the source node and the wireless node one hop ahead increases. To establish a route for an ad hoc wireless network.   The relay node increases the probability of relay permission as the decrement of the distance between the destination node and the own node with respect to the distance between the destination node and the wireless node one hop ahead increases. A method for establishing a route in an ad hoc wireless network. In a wireless node that generates route information by sending and receiving route request messages and route response messages on an ad hoc wireless network,
Means for generating route information based on the received route request message and route response message;
A routing table for storing the route information;
Means for detecting the current position of the own node;
A source function unit for functioning as a source node;
A relay function unit for functioning as a relay node;
A destination function unit for functioning as a destination node,
The source function unit is
Means for generating a route request message;
The relay function unit
Means for extracting location information registered in the received route request message;
Means for determining whether or not to relay the route request message based on the extracted location information and the current location of the node;
Means for registering the current location of the node as location information in the route request message permitted to relay,
The destination function unit is
A wireless node of an ad hoc wireless network comprising means for generating a route response message for a received route request message. The means for generating the route request message registers the current position of the own node as the position information of the transmission source node, and registers the position information of the destination node,
The means for determining relay permission / rejection determines relay permission / rejection based on each position information of the source node, destination node, and relay node one hop ahead registered in the received route request message and the current position of the own node. The radio node of the ad hoc radio network according to claim 7.   The means for registering position information in the route request message permitted to relay updates the position information of the relay node one hop ahead registered in the received route request message to the current position of the own node. The wireless node of the ad hoc wireless network according to claim 7.   The wireless node of the ad hoc wireless network according to claim 7, wherein the means for determining whether or not to permit relaying increases the probability of relay permission as the distance between the wireless node one hop before and the own node increases.   The means for determining whether or not to permit relaying increases the probability of relay permission as the increment of the distance between the source node and the own node with respect to the distance between the source node and the wireless node one hop ahead increases. Item 9. A wireless node of the ad hoc wireless network according to Item 8.   The means for determining whether or not to permit relaying increases the probability of relay permission as the decrement of the distance between the destination node and the own node with respect to the distance between the destination node and the wireless node one hop ahead is larger. Item 9. A wireless node of the ad hoc wireless network according to Item 8.

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