JP2006197288A - Ad-hoc network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ad-hoc network system which can satisfy the request for application, by making it possible to preferentially select a planned route as a data transmission route. <P>SOLUTION: Device ID is established for each node, the planned routes specified for respective end devices 51, 55, are stored to a memory 58m built in a gateway 58, as planned route information. The end device 51 and routers 52, 53, 56, 57 transmit self device ID attaching to route discovery packets. The gateway 58 compares the received route discovery packets 64 to 67 and a planned route information 61, regarding the end device 51, and preferentially selects a planned route from among four route candidates as a data transmission route. A return packet 68 is sent to the end device 51, reversely tracing only the planned route. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ad hoc network system, and more particularly to a routing method in the system.

  Ad hoc network system routing protocols are broadly classified into reactive protocols and proactive protocols. Typical reactive protocols include AODV (Adhoc On-demand Distance Vector) and DSR (Dynamic Source Routing). Yes. In these routing protocols, a route used for transmitting data from the end device to the gateway (hereinafter referred to as “data transmission route”) is automatically constructed. At that time, there is a case where it is desired to prioritize which route is selected as a data transmission route from among a plurality of route candidates in response to a request from an application such as leveling the battery consumption of all routers.

  Patent Document 1 below discloses a technique for determining a data transmission route based on a parameter relating to quality of service (QoS).

JP 2004-56787 A

  At the time of system construction, an ideal route (hereinafter referred to as “planned route”) from each end device to the gateway is assumed based on a node arrangement plan reflecting application demands, and the arrangement location of each node is determined accordingly. . However, when a routing protocol such as DSR or AODV is used, even if each node is arranged based on the node arrangement plan, a router belonging to the planned route may fail due to ad hoc characteristics during actual operation. A situation may occur in which the planned route is not selected as the data transmission route even though it is not. As a result, there arises a problem that the request of the application cannot be satisfied.

  The present invention has been made to solve such a problem, and an object of the present invention is to obtain an ad hoc network system capable of satisfying a request of an application by making it possible to preferentially select a planned route as a data transmission route. To do.

  An ad hoc network system according to the present invention includes a data transmission source node, a data transmission destination node, and a plurality of data relay nodes that relay data between the data transmission source node and the data transmission destination node, The data transmission destination node stores a predetermined planned route from the data transmission source node to the data transmission destination node via a specific data relay node of the plurality of data relay nodes The data transmission source node has a function of transmitting a route search packet to the plurality of data relay nodes, and each of the plurality of data relay nodes includes the data transmission source node or The route search packet received from the previous data relay node is sent to the next data relay node or the data transmission destination. The data transmission destination node receives a plurality of route search packets from the plurality of data relay nodes, and a plurality of routes defined by the plurality of route search packets. It has a function of preferentially selecting the planned route as a data transmission route from the candidates.

  According to the ad hoc network system according to the present invention, the planned route is preferentially selected as the data transmission route, thereby satisfying the application request.

  Hereinafter, an ad hoc network system according to an embodiment of the present invention will be described.

  An application assumed as a target of the present invention is status monitoring and control of devices and facilities using a wireless network. FIG. 1 is a diagram illustrating an example of an ad hoc network system according to an embodiment of the present invention. A temperature sensor 50 is connected to the end device 51 as a data transmission source node. Similarly, a vibration sensor 54 is connected to an end device 55 as a data transmission source node. A personal computer 59 is connected to the gateway 58 as a data transmission destination node. An external network 60 such as the Internet is connected to the personal computer 59. However, instead of using the personal computer 59, the gateway 58 and the external network 60 may be connected using a mobile phone such as a PHS (Personal Handyphone System).

  Between the end devices 51 and 55 and the gateway 58, a plurality (four in the example shown in FIG. 1) of routers 52, 53, 56, and 57 as data relay nodes are arranged. As indicated by arrows in FIG. 1, the routers 52, 53, 56, and 57 relay data between the end devices 51 and 55 and the gateway 58 by wireless communication.

  The temperature sensor 50 measures the temperature of the device or the room, and the vibration sensor 54 measures the vibration of the device or the like. The data related to the temperature detection result by the temperature sensor 50 and the data related to the vibration detection result by the vibration sensor 54 are communicated in a multi-hop manner between the plurality of routers 52, 53, 56, and 57 and finally sent to the gateway 58. Sent.

  The gateway 58 is connected to an external power source via a power cable (not shown), and power necessary for the operation of the gateway 58 is supplied from this external power source. On the other hand, the routers 52, 53, 56, and 57 are supplied with power from dry batteries, button batteries, or the like.

  When designing an industrial application, especially an application for collecting field information, the location of the device to be measured is known. Therefore, the place where the temperature sensor 50, the vibration sensor 54, and the end devices 51 and 55 should be arranged is determined. Also, the location where the gateway 58 is arranged is often determined. Thus, the problem is where to place the routers 52, 53, 56, and 57.

  In the design of the ad hoc network system, the connection between the end devices 51 and 55 and the gateway 58 is ensured even when one of the routers 52, 53, 56, and 57 falls into an inoperable state due to a failure, a battery exhaustion, or the like. The locations of the routers 52, 53, 56, and 57 are determined. Further, in order to level the battery consumption of all the routers 52, 53, 56, and 57, the arrangement locations of the routers 52, 53, 56, and 57 are determined so that the load on the specific router is not excessive. In other words, in the design of the ad hoc network system according to the present embodiment, a planned route to reach a gateway from which end device to a gateway in accordance with a request of an application targeted by the system is provided at the location of each node. Based on this, it is predetermined for each end device. For example, as indicated by a thick arrow in FIG. 1, for the end device 51, a route from the end device 51 through the routers 52 and 53 to the gateway 58 in this order is determined as a planned route.

<Premise of routing>
When constructing the ad hoc network system according to the present embodiment, a human being performs the following operations as a premise.

  First, system design (hereinafter referred to as “node placement plan”) is performed. That is, the arrangement locations of the end devices 51 and 55 and the gateway 58 are planned, and the arrangement locations of the routers 52, 53, 56, and 57 are determined based on the request of the target application. At that time, a planned route is also determined for each end device 51, 55 based on the location of each node.

  Next, a device ID as an identification number is set for each node. As the device ID, an individual value is assigned to each node so that there is no overlap between the nodes. In the example shown in FIG. 1, the end device 51 is “100”, the end device 55 is “200”, the router 52 is “10”, the router 53 is “11”, the router 56 is “20”, The router 57 has a device ID “21” and the gateway 58 has a device ID “0”. Here, the device ID is a unique identification number assigned to each node before node placement, and is different from a network address or the like automatically assigned by a routing protocol.

  By assigning a unique device ID to each node, each node can be identified by the device ID in subsequent routing.

  The set device ID is stored in a storage unit such as a memory built in each node. For example, the device ID = 100 set in the end device 51 is stored in the storage unit 51m built in the end device 51, and the device ID = 10 set in the router 52 is built in the router 52. The device ID = 0 stored in the storage unit 52m and set in the gateway 58 is stored in the storage unit 58m built in the gateway 58. The same applies to other nodes.

  Also, the planned route determined for each end device 51, 55 is specified by a combination of device IDs, and stored as planned route information in the storage unit 58m built in the gateway 58. FIG. 2 is a diagram showing the planned route information 61. As described above, regarding the end device 51, a route from the end device 51 to the gateway 58 via the routers 52 and 53 in this order is determined as a planned route. Accordingly, the item 61a of the planned route information 61 uses the device ID = 100 of the end device 51, the device ID = 10 of the router 52, the device ID = 11 of the router 53, and the device ID = 0 of the gateway 58. Thus, the planned route (EP = 100) regarding the end device 51 is described as “100, 10, 11, 0”. For the end device 55, a route from the end device 55 to the gateway 58 via the routers 56 and 57 in this order is determined as a planned route. Therefore, in the item 61b of the planned route information 61, the planned route (EP = 200) regarding the end device 55 is described as “200, 20, 21, 0”.

  Next, by referring to a layout drawing such as a drawing or CAD, each node is placed at a place to be placed based on the node placement plan. In order to prevent misplacement of nodes, a label printed with a device ID is affixed to each node, and the device ID of each node is also attached to the layout diagram, and each node is checked while checking the device ID of both nodes. It is desirable to perform the arrangement.

  Immediately after the node arrangement, a network is automatically formed by the function of the ad hoc network. At this stage, it is uncertain what route is formed between the end devices 51 and 55 and the gateway 58.

<Routing basics>
The present invention relates to a routing method in an ad hoc network system, and can be realized only by adding (or changing a part of) the functions according to the present invention to various standard routing protocols and manufacturer-specific routing protocols. It can be done. Therefore, for the routing function other than the function according to the present invention, the function of the routing protocol to which the function according to the present invention is added is used as it is.

  In the reactive protocol, route discovery is started when data communication is required. Here, route discovery is an operation in which a data transmission source node searches for a route to a data transmission destination node. In the ad hoc network system according to the present embodiment, the data transmission source nodes are the end devices 51 and 55, and the data transmission destination node is the gateway 58.

  Route discovery is basically executed according to the routing protocol of the ad hoc network. Examples of standard reactive protocols include AODV and DSR. The basics of route discovery in these protocols are as follows. First, the route discovery packet (route search packet) sent from the end device is multi-hopped by the router and sent to the gateway. The gateway that has received the route discovery packet sends a reply packet. The reply packet sent from the gateway is sent to the end device after being multi-hopped in the reverse direction by the router via the route discovery packet. As a result, the end device receives a plurality of reply packets sent from the gateway via different routes. In many cases, the end device selects a route having the smallest number of hops among a plurality of route candidates defined by a plurality of return packets as a data transmission route to the gateway.

  By the way, in the standards such as AODV and DSR, only the basic part is defined, and when it is mounted on ZigBee or the like, it is necessary to independently mount the part not defined in the standard. In the present invention, based on a standard protocol (hereinafter referred to as “base protocol”) such as AODV or DSR, the function according to the present invention is added to a part not defined by the base protocol, thereby obtaining a desired effect. To get.

<Routing function according to the present invention>
3 to 5 are diagrams for explaining a routing function according to the present embodiment. Hereinafter, the routing between the end device 51 and the gateway 58 will be described with reference to FIGS. Referring to FIGS. 1 and 3, when data communication becomes necessary, the end device 51 creates a route discovery packet based on the function of the base protocol. Thereafter, based on the function according to the present invention, the device ID = 100 stored in the storage unit 51m is added to the route discovery packet and transmitted as the route discovery packet 62. The “XXX” portion of the route discovery packet 62 shown in FIG. 3 is the content used by the base protocol.

  When the end device 51 adds its own device ID to the route discovery packet, the other nodes that have received the route discovery packet 62 recognize that the transmission source of the route discovery packet 62 is the end device 51. be able to. The device ID = 100 added to the route discovery packet by the end device 51 will be referred to when the planned route is determined later by the gateway 58.

  Referring to FIG. 1, route discovery packet 62 is received by routers 52 and 56. Referring to FIGS. 1 and 3, the router 52 adds its own device ID = 10 stored in the storage unit 52m to the received route discovery packet 62 based on the function according to the present invention, It is transmitted as a discovery packet 63. The same applies to the router 56.

  When the router 52 adds its own device ID to the route discovery packet 62, the other nodes that have received the route discovery packet 63 receive the route discovery packet 63 from the end device 51 via the router 52. You can recognize what has happened. The device ID = 10 added to the route discovery packet 62 by the router 52 will be referred to when the planned route is determined later by the gateway 58.

  Referring to FIG. 1, route discovery packet 63 is received by routers 53 and 57. 1 and 3, the router 53 adds its own device ID = 11 stored in the storage unit 53m to the received route discovery packet 63 based on the function according to the present invention, A discovery packet 64 is transmitted. The same applies to the router 57.

  When the router 53 adds its own device ID to the route discovery packet 63, other nodes that have received the route discovery packet 64 receive the route discovery packet 64 from the end device 51 via the routers 52 and 53. You can recognize that it has been sent. The device ID = 10 added to the route discovery packet 63 by the router 53 will be referred to when the planned route is determined later by the gateway 58.

  Referring to FIG. 1, route discovery packet 64 is received by gateway 58. 1 and 4, in addition to the route discovery packet 64, the gateway 58 sends the route discovery packet 65 sent from the end device 51 through the routers 52 and 57 in this order, and the router from the end device 51 to the router. The route discovery packet 66 sent through the routers 56 and 53 in this order and the route discovery packet 67 sent from the end device 51 through the routers 56 and 57 in this order are received. That is, in the example of the present embodiment, there are four route candidates defined by the four route discovery packets 64-67.

  2 and 4, next, the gateway 58 compares the received route discovery packets 64 to 67 with the planned route information 61 (item 61a) regarding the end device 51 based on the function according to the present invention. Then, the planned route is preferentially selected from the four route candidates as the data transmission route. Specifically, the gateway 58 combines the device IDs specified in the item 61a among the device ID combinations described in the route discovery packets 64 to 67 (provided that the device ID = 0 of the gateway 58 is set). It is determined whether there is a match with (except for).

  If the system is designed correctly and there is no failure or battery exhaustion in the router that constitutes the planned route, the planned route is included in the route candidates specified by the route discovery packet. It should be. In the example of the present embodiment, the device ID combination (100, 10, 11) described in the route discovery packet 64 is changed to the device ID combination (100, 10, 11) specified in the item 61a. Match. In this case, the gateway 58 selects a planned route for the end device 51 as a data transmission route. As a result, the planned route is selected as the data transmission route with priority over the other route candidates defined by the route discovery packets 65 to 67. Since the data transmission route is selected not by the end device 51 but by the gateway 58, the load on the battery-driven end device 51 can be reduced and power consumption can be suppressed. The gateway 58 does not perform any processing for the route discovery packets 65 to 67 corresponding to the remaining three route candidates.

  On the other hand, if the router that constitutes the planned route has a failure, battery exhaustion, etc., or if there is a radio interference due to a shielding object, the route candidate specified by the route discovery packet The route should not be included. Accordingly, the device ID combinations described in the route discovery packets 64 to 67 match the device ID combination specified in the item 61a (except for the device ID = 0 of the gateway 58). Will not exist. In this case, the gateway 58 continues routing based on the base protocol. For example, as described above, the gateway 58 sends a reply packet, and the end device 51 sends a plurality of route candidates defined by a plurality of reply packets sent from the gateway 58 via the routers 52, 53, 56, and 57. For example, the route with the smallest number of hops is selected as the data transmission route. In this way, when the planned route is in an incommunicable state, a route different from the planned route is selected as the data transmission route based on the function of the base protocol, so the end device 51 and the gateway 58 The state where communication is possible is maintained.

  Processing when the planned route is selected as the data transmission route will be described subsequently. Referring to FIG. 5, gateway 58 creates a return packet based on the function of the base protocol. Thereafter, based on the function according to the present invention, a combination of device IDs (100, 10, 11, 0) constituting the planned route related to the end device 51, and information (OPT) indicating that the planned route is selected, It is added to the reply packet and transmitted as a reply packet 68. The “YYY” portion of the reply packet 68 is the content used by the base protocol.

  The reply packet 68 is sent to the end device 51 by following only the planned route in reverse. Since the reply packet 68 describes the combination of device IDs (100, 10, 11, 0) constituting the planned route, each router refers to this to identify the next transmission destination of the reply packet 68. To do. For example, the router 53 refers to the combination of device IDs (100, 10, 11, 0) described in the received reply packet 68, and the device ID described before its own device ID = 11 is “ On the basis of “10”, the reply packet 68 is transmitted only to the router 52 whose device ID is “10”. In this way, the reply packet 68 is sent from the gateway 58 to the end device 51 via the routers 53 and 52 in this order.

  Since the reply packet 68 is transmitted by following only the planned route, the routers 56 and 57 that do not constitute the planned route are not involved in the transmission process of the reply packet 68. Therefore, since the load of the routers 56 and 57 can be reduced, the power consumption of the routers 56 and 57 driven by batteries can be suppressed.

  The end device 51 that has received the reply packet 68 identifies that the route described in the reply packet 68 is a planned route by including “OPT” in the reply packet 68. Then, the end device 51 determines the planned route as the data transmission route, and transmits data to the gateway 58 via the planned route.

  A configuration may be adopted in which the end device has a cache memory capable of storing past route history, and a planned route as a data transmission route is stored in the cache memory. In this case, it is possible to communicate with the gateway via the planned route read from the cache memory without performing route discovery thereafter.

  Hereinafter, although partially overlapping with the above description, processing in the ad hoc network system according to the present embodiment will be described separately for each node.

<Processing of End Devices 51 and 55>
FIG. 6 is a flowchart showing the flow of processing in the end device. First, in step SP101, the end device creates a route discovery packet. Next, in step SP102, the self device ID is added to the route discovery packet to create the route discovery packet 62 shown in FIG. Next, in step SP103, the route discovery packet 62 is transmitted.

  Then, after waiting for a while, in step SP104, the reply packet sent from the gateway 58 is received. Next, in step SP105, the contents of the reply packet are confirmed, and it is determined whether or not the route defined by the reply packet is a planned route. Specifically, when “OPT” is included in the reply packet, it is determined that the route is a planned route. On the other hand, when “OPT” is not included, the route is a planned route. It is determined that it is not.

  If the route defined by the reply packet is a planned route, that is, if the result of determination in step SP105 is “YES”, then in step SP106, the planned route is determined as the data transmission route.

  On the other hand, if the route is not a planned route, that is, if the result of determination in step SP105 is “NO”, then in step SP107, it is determined whether or not a predetermined time has elapsed. That is, it is determined whether or not a timeout has occurred.

  If it is not time-out, that is, if the result of determination in step SP107 is “NO”, then another reply packet is received in step SP108. The end device receives the return packet until it is determined that the time is out.

  If it is time-out, that is, if the result of determination in step SP107 is “YES”, then in step SP109, based on the function of the base protocol, the data transmission route is determined based on the plurality of reply packets received so far. select. For example, as described above, a route having the smallest number of hops among a plurality of route candidates defined by a plurality of reply packets received so far is selected as a data transmission route.

<Processing of Routers 52, 53, 56, 57>
FIG. 7 is a flowchart showing the flow of processing in the router. First, in step SP201, the router receives a route discovery packet from the preceding router or end device. Next, in step SP202, its own device ID is added to the received route discovery packet. Next, in step SP203, the route discovery packet with the device ID added is transmitted to the router or gateway 58 at the next stage.

  Then, after waiting for a while, in step SP204, a reply packet sent from the gateway 58 is received. Next, in step SP205, the received reply packet is transmitted to the next router or end device. When the reply packet received in step SP204 is the reply packet 68 shown in FIG. 5, the next transmission destination of the reply packet 68 is specified based on the device ID described in the reply packet 68.

  When the planned route is selected as the data transmission route, the routers that do not belong to the planned route are not involved in the reply packet transmission processing, and thus do not execute steps SP204 and SP205.

<Processing of gateway 58>
FIG. 8 is a flowchart showing the flow of processing in the gateway. First, in step SP301, the gateway receives a route discovery packet to which device IDs of end devices and routers are added. Next, in step SP302, by comparing the received route discovery packet with the planned route information 61 shown in FIG. 2, whether or not the route specified by the received route discovery packet is a planned route. Determine.

  If the route is a planned route, that is, if the result of determination in step SP302 is “YES”, after creating a reply packet in step SP303, in step SP304, a combination of device IDs constituting the planned route; Information indicating that the planned route is adopted (OPT shown in FIG. 5) is added to the reply packet. Next, in step SP305, a reply packet to which these pieces of information are added is transmitted.

  On the other hand, if the route defined by the route discovery packet received in step SP301 is not a planned route, that is, if the result of determination in step SP302 is “NO”, then in step SP306, a predetermined constant value is set. Determine whether the time has passed. That is, it is determined whether or not a timeout has occurred.

  If it is not time-out, that is, if the result of determination in step SP306 is “NO”, another route discovery packet is received in step SP301. Thereafter, in step SP302, it is determined whether or not the route defined by the received other route discovery packet is a planned route. Until it is determined that the route is a planned route or a timeout, the gateway receives a route discovery packet.

  If it is time-out, that is, if the result of determination in step SP306 is “YES”, then in step SP307, reply packets for all received route discovery packets are generated based on the function of the base protocol. Next, in step SP305, the generated reply packet is transmitted.

  According to the ad hoc network system according to the present embodiment, the planned route transmits data except in special cases such as when a router constituting the planned route has a failure, a battery has run out, or a radio wave interference has occurred. Selected as root. The planned route is an ideal route set in advance based on the node arrangement plan reflecting the request of the application. Therefore, by selecting the planned route preferentially as the data transmission route, it is possible to satisfy a request for an application such as leveling of the battery consumption of the router.

It is a figure which shows an example of the ad hoc network system which concerns on embodiment of this invention. It is a figure which shows plan route information. It is a figure for demonstrating the routing function which concerns on embodiment of this invention. It is a figure for demonstrating the routing function which concerns on embodiment of this invention. It is a figure for demonstrating the routing function which concerns on embodiment of this invention. It is a flowchart which shows the flow of a process in an end device. It is a flowchart which shows the flow of the process in a router. It is a flowchart which shows the flow of the process in a gateway.

Explanation of symbols

51, 55 End device, 52, 53, 56, 57 Router, 58 Gateway, 51m, 52m, 53m, 55m, 56m, 57m, 58m Storage unit, 61 Planned route information, 62-67 Route discovery packet, 68 Reply packet .

Claims (5)

A data source node;
A data destination node;
A plurality of data relay nodes that relay data between the data source node and the data destination node;
The data transmission destination node stores a predetermined planned route from the data transmission source node to the data transmission destination node through a specific data relay node of the plurality of data relay nodes. Have
The data transmission source node has a function of transmitting a route search packet to the plurality of data relay nodes,
Each of the plurality of data relay nodes has a function of transmitting the route search packet received from the data transmission source node or the previous data relay node to the next data relay node or the data transmission destination node. And
The data transmission destination node receives a plurality of route search packets from the plurality of data relay nodes, and prioritizes the planned route from among a plurality of route candidates defined by the plurality of route search packets. An ad hoc network system having a function of selecting as a data transmission route.   The ad hoc network system according to claim 1, wherein each of the data transmission source node and the plurality of data relay nodes has a storage unit that stores an individually set identification number. The planned route is specified by a combination of the identification numbers,
The data transmission source node has a function of transmitting the route search packet with its identification number added thereto,
Each of the plurality of data relay nodes has a function of adding the identification number to the received route search packet and transmitting the packet.
In the data destination node, the combination of the identification numbers added to the route search packet among the plurality of received route search packets is changed to the combination of the identification numbers specified in the planned route. The ad hoc network system according to claim 2, having a function of selecting the planned route as the data transmission route when a match exists.   The ad hoc network system according to claim 3, wherein when the planned route is selected as the data transmission route, a reply packet is transmitted from the data transmission destination node to the data transmission source node only through the planned route. The planned route is an arrangement of each of the data transmission source node, the data transmission destination node, and the plurality of data relay nodes according to a request of an application targeted by the system at the time of designing the ad hoc network system. The ad hoc network system according to claim 1, which is determined based on a location.

Images