JP5312421B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system configured to include a plurality of types of nodes that use different wireless media.

  When constructing a large-scale data collection system using a wireless mesh network, considering the fact that sensor nodes are installed in various environments and requirements for transmission throughput, etc., construct a mesh network with multiple wireless media A case is assumed. For example, when a wireless LAN is used, a broadband wireless network can be realized, so that a mesh network with excellent transmission throughput can be realized. However, because of poor diffraction characteristics, a network can be constructed only in an environment with a good line of sight. On the other hand, the 430MHz band extra-small radio has a narrow band, so the transmission throughput is limited compared to when using a wireless LAN, but it can be constructed even in places with poor visibility due to its good diffraction characteristics. It becomes possible.

  However, when trying to build a system in consideration of the bandwidth and radio characteristics, in order to improve the number of terminals accommodated, it is necessary to install a large number of gateway devices for relaying between the mesh network and the upper-level center device. There is a problem that the system cost increases. In addition, when a wired transmission path is used as an upper I / F from the center device to the gateway device, there is a problem that the installation location of the gateway device is limited. In order to cope with a reduction in the number of gateway devices and an environment where gateway devices cannot be installed, it is necessary that one gateway device can accommodate a mesh network composed of different wireless media. For example, Patent Document 1 describes a technique of mutually connecting different types of wireless systems using a wireless repeater equipped with a wireless medium.

JP 2009-49644 A

  However, Patent Document 1 only discloses means (wireless repeater) for connecting to wireless devices having different systems by a single link, and means for connecting mesh networks having different corresponding wireless communication systems. Not disclosed. For this reason, it is impossible to realize connection between mesh networks having different methods. Moreover, it is not assumed about the case where a radio repeater breaks down.

  The present invention has been made in view of the above, and it is an object of the present invention to obtain a wireless communication system capable of communicating communication devices belonging to mesh networks having different wireless communication methods without using a host device. Objective. Another object of the present invention is to obtain a radio communication system with high fault tolerance.

  In order to solve the above-described problems and achieve the object, the present invention includes a first mesh network configured to include a first sensor node that performs communication using a first wireless medium, A second mesh network configured to include a second sensor node that performs communication using a second wireless medium different from the first wireless medium, a higher-level communication device, and the first mesh network. A gateway having a function of connecting and communicating directly with at least one of the first sensor nodes using the first wireless medium; and the first sensor using the first wireless medium. A wireless repeater that communicates directly with at least one of the nodes and communicates directly with at least one of the second sensor nodes using the second wireless medium, the gateway comprising: The terminal identifiers of the first sensor node, the second sensor node, and the wireless repeater are managed so that the terminal identifiers do not overlap with each other, and the route search is performed using the managed terminal identifiers. It is characterized by performing.

  Advantageous Effects of Invention According to the present invention, there is an effect that sensor nodes in each mesh network are handled as sensor nodes in the same network, and sensor nodes having different wireless media can communicate with each other without using a host device.

FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a wireless communication system. FIG. 2 is a diagram illustrating a configuration example of a gateway. FIG. 3 is a diagram illustrating a configuration example of the sensor node. FIG. 4 is a diagram illustrating a configuration example of the sensor node. FIG. 5 is a diagram illustrating a configuration example of a wireless repeater. FIG. 6 is a sequence diagram illustrating an example of a control procedure when a sensor node enters the network. FIG. 7 is a sequence diagram illustrating an example of a control procedure when a wireless repeater enters the network. FIG. 8 is a sequence diagram illustrating an example of a control procedure when a sensor node enters the network. FIG. 9 is a diagram illustrating a sequence example when searching for a route to the sensor node. FIG. 10 is a diagram illustrating a sequence example when searching for a route to the wireless repeater. FIG. 11 is a diagram illustrating a sequence example when searching for a route to a sensor node. FIG. 12 is a diagram illustrating a configuration example of a radio repeater according to the second embodiment. FIG. 13 is a sequence diagram illustrating an example of a data collection operation in the wireless communication system according to the second embodiment. FIG. 14 is a sequence diagram illustrating an example of an operation in which the gateway searches for a route to the sensor node. FIG. 15 is a diagram illustrating an encapsulation operation in the wireless communication system according to the third embodiment. FIG. 16 is a diagram illustrating an example of terminal information used for route search with an encapsulation operation.

  Embodiments of a wireless communication system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a first embodiment of a wireless communication system according to the present invention. The wireless communication system according to the present embodiment configures a center device 1, a plurality of gateways 2-1 to 2-2, sensor nodes 3A-1 to 3A-3 constituting a mesh network A, and a mesh network B. Wireless repeaters 4-1 to 4-2 for relaying signals between the sensor nodes 3B-1 to 3B-4, the sensor nodes constituting the mesh network A, and the sensor nodes constituting the mesh network B And.

  The sensor nodes 3A-1 to 3A-3 include a wireless medium A, and the sensor nodes 3B-1 to 3B-4 include a wireless medium B. That is, in the mesh network A, communication is performed by a wireless method (wireless A) supported by the wireless medium A, and in the mesh network B, communication is performed by a wireless method (wireless B) supported by the wireless medium B.

  The gateways 2-1 and 2-2 connect the mesh network A and the center device 1 and include a wireless medium A. Further, data is collected from each sensor node of the mesh network A and each sensor node of the mesh network B, and the collected data is transmitted to the center device 1. The connection between the center apparatus 1 and the gateways 2-1 and 2-2 may be either a wired connection or a wireless connection.

  The wireless repeaters 4-1 and 4-2 include a wireless medium A and a wireless medium B, use the wireless medium A for communication with the sensor nodes of the mesh network A, and communicate with the sensor nodes of the mesh network B. In communication, by using the wireless medium B, a signal received from the mesh network A side is transferred to the mesh network B side, and a signal received from the mesh network B side is transferred to the mesh network A side.

  Each gateway (gateway 2-1, 2-2), each sensor node (sensor node 3A-1 to 3A-3, sensor node 3B-1 to 3B-4) and each wireless repeater (wireless repeater 4- 1,4-2) execute a common mesh routing function and form a single mesh network starting from each gateway.

  In the following description, when the operations, functions, configurations, etc. common to the gateways 2-1 and 2-2 are described, these gateways are collectively referred to as the gateway 2. Similarly, when explaining operations, functions, configurations, etc. common to the sensor nodes constituting the mesh network A, these sensor nodes are collectively referred to as the sensor node 3A, and the mesh network B is configured. When the operation, function, configuration, etc. common to each sensor node is described, it is referred to as a sensor node 3B.

  FIG. 2 is a diagram illustrating a configuration example of the gateway 2. The gateway 2 includes a wireless unit 21, a communication processing unit 22, an upper I / F communication processing unit 23, and an upper I / F 24.

  The wireless unit 21 is configured by a wireless medium A. The communication processing unit 22 includes a wireless media processing unit 221 that controls the wireless unit 21, a mesh network construction / management unit 222 that constructs and manages a mesh network, and a mesh routing processing unit that performs route resolution and transmission / transfer processing. 223, an application processing unit 224 that performs data collection by sensors, and a higher-level I / F-wireless mesh cooperation processing unit 225 that performs cooperation processing with the center apparatus 1. The host I / F communication processing unit 23 performs I / F communication processing with the center device 1 which is a host device. The host I / F 24 is an interface for connecting to the center apparatus 1 via a transmission path.

  FIG. 3 is a diagram illustrating a configuration example of the sensor node 3A. The sensor node 3A includes a wireless unit 31A and a communication processing unit 32A.

  The wireless unit 31A is configured by the wireless medium A, like the wireless unit 21 of the gateway 2 described above. The communication processing unit 32A includes a wireless media processing unit 321A that controls the wireless unit 31A, a mesh network entry processing unit 322 that performs entry processing to the mesh network, and a mesh routing processing unit 323 that performs route resolution and transmission / transfer processing. And an application processing unit 324 that performs data collection by a sensor. The wireless media processing unit 321A, the mesh routing processing unit 323, and the application processing unit 324 are components that perform the same processing as the wireless media processing unit 221, the mesh routing processing unit 223, and the application processing unit 224 of the gateway 2 described above. is there.

  FIG. 4 is a diagram illustrating a configuration example of the sensor node 3B. The sensor node 3B includes a wireless unit 31B and a communication processing unit 32B.

  The wireless unit 31B is configured by a wireless medium B. The communication processing unit 32B is obtained by replacing the wireless media processing unit 321A of the communication processing unit 32A configuring the sensor node 3A described above with a wireless media processing unit 321B. The wireless media processing unit 321B controls the wireless unit 31B.

  FIG. 5 is a diagram illustrating a configuration example of the wireless repeater 4 (wireless repeaters 4-1 and 4-2). The wireless repeater 4 includes wireless units 41A and 41B and a communication processing unit 42.

  The wireless unit 41A is configured by the wireless medium A in the same manner as the wireless unit 21 of the gateway 2 and the wireless unit 31A of the sensor node 3A described above. The wireless unit 41B is configured by the wireless medium B in the same manner as the wireless unit 31B of the sensor node 3B described above. The communication processing unit 42 includes a wireless media processing unit 421A that controls the wireless unit 41A, a wireless media processing unit 421B that controls the wireless unit 41B, a mesh network entry processing unit 422 that performs entry processing to the mesh network, A mesh routing processing unit 423 that performs route resolution and transmission / transfer processing, and a fragment processing unit 424 for absorbing differences between the wireless medium A and the wireless medium B are configured. The wireless media processing unit 421A, the mesh network entry processing unit 422, and the mesh routing processing unit 423 are the same processes as the wireless media processing unit 321A, the mesh network entry processing unit 322, and the mesh routing processing unit 323 of the sensor node 3A described above. It is the component which performs. The wireless media processing unit 421B is a component that performs the same processing as the wireless media processing unit 321B of the sensor node 3B described above.

  In the present embodiment, the wireless medium A and the wireless medium B constituting the wireless unit of each device correspond to different wireless communication systems, and the wireless medium A has a wider bandwidth than the wireless medium B. Suppose.

  In addition, each sensor node (sensor nodes 3A-1 to 3A-3, 3B-1 to 3B-4) can acquire information such as temperature by the mounted sensor, and serial communication or infrared communication. Are assumed to be terminals that can acquire data from other devices (such as other sensor nodes). Furthermore, each sensor node transmits data (information acquired using a sensor) in response to a request from the center device 1 or the gateway 2 or autonomously transmits data to the center device 1 or the gateway 2. Assume that.

  The center device 1 collects and manages data from each sensor node, and the gateway 2 relays data between each sensor node belonging to the mesh network and the center device 1, notifies the sensor node of setting information change, and controls the route. And so on.

  In the wireless communication system of the present embodiment, it is assumed that hop-by-hop routing such as AODV (Ad hoc On-Demand Distance Vector) is used as a route search algorithm. The route table held by the gateway 2, the sensor node 3A, the sensor node 3B, and the wireless repeater 4 is the destination, the next hop terminal when transmitting to the destination, and the data transmitting to the next hop terminal It is assumed that it is composed of three elements of wireless medium information used for.

  Next, a method in which a new node enters a network included in the wireless communication system according to the present embodiment (a network formed from the gateway 2 as a starting point and including the mesh networks A and B) will be described. Here, when the node that newly enters the network managed by the gateway 2 is the sensor node 3A, when the node that newly enters is a wireless repeater, and when the node that newly enters is the sensor node 3B Separately described.

(When the newly entering node is the sensor node 3A)
FIG. 6 is a sequence diagram illustrating an example of a control procedure when a sensor node enters a network included in the wireless communication system of the present embodiment, and specifically includes the same wireless medium as that of the gateway 2. An example in which the sensor node 3A enters the mesh network A managed by the gateway 2-1. Here, in the wireless communication system shown in FIG. 1, the sensor nodes 3A-1 and 3A-2 have already entered the mesh network A, and the sensor node 3A-3 (the sensor node that wishes to enter the network). ) Will be described as being located in a place where only direct communication with the sensor node 3A-2 is possible.

  As shown in FIG. 6, when the sensor node 3A-3 to be newly entered is powered on, the mesh network entry processing unit 322 of the sensor node 3A-3 sets a temporary terminal identifier and sets the destination as the gateway 2- 1, the network entry notification message is generated, and the network entry notification message is transmitted via the wireless media processing unit 321A and the wireless unit 31A. In the following description, the terminal identifier is simply referred to as an identifier.

  The sensor nodes 3A-2 and 3A-1 serving as relay terminals point the network entry notification message transmitted from the sensor node 3A-3 to the gateway 2-1 according to the route information to the gateway 2-1 held by the sensor nodes 3A-2 and 3A-1. Forward.

  In the gateway 2-1, which has received the network entry notification message transmitted from the sensor node 3A-3, the mesh network construction / management unit 222 checks whether or not there is an identifier overlap with a node that has already joined the network (identifier). double check).

  When the identifier (temporary identifier) set in the received network entry notification message overlaps with the identifier of another node that has already entered (when there is an identifier overlap), the mesh network construction / management unit 222 may An identifier is set again for 3A-3, and adjustment is performed so that identifier duplication is eliminated. The identifier after reset is notified to the sensor node 3A-3 by an identifier setting message. When the resetting of the identifier is completed, the mesh network construction / management unit 222 generates a network entry notification response message whose destination is the sensor node 3A-3, and transmits it via the wireless media processing unit 221 and the wireless unit 21. The identifier setting message and the network entry notification response message are transferred toward the sensor node 3A-3 by the sensor nodes 3A-1 and 3A-2.

  On the other hand, when the result of the identifier duplication check is “no identifier duplication”, the mesh network construction / management unit 222 assigns the destination to the sensor node 3A− without performing the resetting of the identifier for the sensor node 3A-3. A network entry notification response message 3 is generated and transmitted.

  When the sensor node 3A-3 receives the network entry notification response message transmitted from the gateway 2-1 and relayed by the sensor nodes 3A-1 and 3A-2, the network entry of the sensor node 3A-3 is completed.

  Although FIG. 6 shows an example in which the identifier is reset only when the result of the identifier duplication check is “with identifier duplication”, the identifier is reset even when “no identifier duplication”. It does not matter as long as the control is correct.

  A method for the newly entering sensor node 3A-3 to search for the gateway 2-1 is not particularly defined. Any existing method may be used. For example, the sensor node 3A-3 transmits a gateway search request message by broadcast at the time of activation. Among the adjacent sensor nodes that have received the gateway search request message, the sensor node that has already entered the network sends the gateway 2-1 identifier and the gateway from its own terminal to the sensor node 3A-3 that is the transmission source of the gateway search request message. A gateway search request response message is transmitted to notify the number of hops up to 2-1. In the above example, since the sensor node 3A-2 is an adjacent sensor node that has already entered the mesh network A, a gateway search request response message is transmitted from the sensor node 3A-2 to the sensor node 3A-3, and the gateway 2 -1 identifier and the number of hops from the sensor node 3A-2 to the gateway 2-1. Here, when there are a plurality of adjacent sensor nodes that have already entered the mesh network A and the gateway search request response message is received from each of these adjacent sensor nodes, the sensor node 3A-3 receives the received gateway search request response message. Among them, the adjacent sensor node having the shortest number of hops to the gateway 2-1 is registered (stored) as the next hop terminal (next hop) addressed to the gateway 2-1. In the above example, since the adjacent sensor node is only the sensor node 3A-2, the sensor node 3A-2 is registered as the next hop terminal addressed to the gateway 2-1.

(When the newly entering node is the wireless repeater 4)
In the wireless communication system according to the present embodiment, the sensor node 3B having a wireless medium different from that of the gateway 2 can also communicate with both the sensor node 3A and the sensor node 3B in order to enter the network managed by the gateway 2. A wireless repeater 4 is installed at a point where direct communication is possible.

  FIG. 7 is a sequence diagram showing an example of a control procedure when the wireless repeater 4 (wireless repeaters 4-1 and 4-2) enters a network included in the wireless communication system of the present embodiment. Specifically, an example in which the wireless repeater 4 enters the mesh network A is shown. Here, in the wireless communication system shown in FIG. 1, the sensor nodes 3A-1 to 3A-3 have already entered the mesh network A, and the wireless repeaters 4-1 and 4-2 (enter the network). In the following description, it is assumed that the wireless repeater that wants to communicate with the sensor node 3A-2 is located in a location where direct communication is possible. Since the wireless repeaters 4-1 and 4-2 can directly communicate only with the sensor node 3A-2, the same sequence is performed when any wireless repeater 4 enters.

  As shown in FIG. 7, when the wireless repeater 4 that wishes to newly enter is turned on, the mesh network entry processing unit 422 of the wireless repeater 4 is similar to the above-described new entry operation of the sensor node 3A-3. Sets a temporary identifier, generates a network entry notification message with the destination being the gateway 2-1, and transmits the network entry notification message via the wireless media processing unit 421A and the wireless unit 41A.

  The sensor nodes 3A-2 and 3A-1 serving as relay terminals follow the route information to the gateway 2-1 held by the sensor nodes 3A-2 and 3A-1 toward the gateway 2-1. Forward.

  When the gateway 2-1 receives the network entry notification message transmitted from the wireless repeater 4, the mesh network construction / management unit 222 checks whether there is an identifier overlap with a node that has already joined the network (identifier). double check).

  When the result of the identifier duplication check is “with identifier duplication”, after performing identifier resetting for the wireless repeater 4 and eliminating the identifier duplication, similarly to the new entry operation of the sensor node 3A-3 described above, A network entry notification response message whose destination is the wireless repeater 4 is generated and transmitted. If the result of the identifier duplication check is “no identifier duplication”, a network entry notification response message with the destination set as the wireless repeater 4 is generated and transmitted without resetting the identifier for the wireless repeater 4. . When the wireless repeater 4 receives the network entry notification response message, the network entry of the wireless repeater 4 is completed.

  Any existing method may be used as a method for the newly entered wireless repeater 4 to search for the gateway 2-1.

(When the newly entering node is the sensor node 3B)
FIG. 8 is a sequence diagram illustrating an example of a control procedure when a sensor node enters a network included in the wireless communication system according to the present embodiment. Specifically, the wireless communication system includes a wireless medium different from the gateway 2. An example in which the sensor node 3B enters the mesh network B is shown. Here, in the wireless communication system shown in FIG. 1, the sensor nodes 3A-1 to 3A-3 and the wireless repeater 4-1 have already entered the mesh network A, and the sensor node 3B-1 (to the network) The description will be made assuming that the sensor node that wishes to enter is located at a place where direct communication is possible only with the wireless repeater 4-1.

  As shown in FIG. 8, when the sensor node 3B-1 that is desired to be newly entered is powered on, the mesh network entry processing unit 322 of the sensor node 3B-1 sets a temporary identifier and sets the destination as the gateway 2-1. The network entry notification message is generated, and the network entry notification message is transmitted via the wireless media processing unit 321B and the wireless unit 31B.

  The wireless relay device 4-1 serving as a relay terminal performs reception processing in the wireless media processing 421B, and the mesh routing processing unit 423 refers to the route table held in the own device (wireless relay device 4-1). As already described, the route table is composed of destination, next hop terminal, and wireless medium information used when data is transmitted to the next hop terminal. In this example, since the destination of the message is the gateway 2-1 having the wireless medium A, as a result of referring to the route table, the next hop terminal is the sensor node 3A-2 and the wireless medium to be used is the wireless medium A. recognize. Then, the wireless medium to be used is changed from the wireless medium B to the wireless medium A, and the wireless media processing unit 421A performs the transfer process of the network entry notification message. The network entry notification message transferred by the wireless repeater 4-1 is further transferred by the sensor node 3A-2 as the next relay terminal and the sensor node 3A-1 as the next relay terminal, and is sent to the gateway 2-1. To reach.

  In the gateway 2-1 that has received the network entry notification message transmitted from the sensor node 3 B- 1, the mesh network construction / management unit 222 confirms whether or not identifier duplication has occurred with a node that has already joined the network (identifier). double check).

  When the identifier (temporary identifier) set in the received network entry notification message overlaps with the identifier of another node that has already entered (when there is an identifier overlap), the mesh network construction / management unit 222 may An identifier is set again for 3B-1, and the identifier after the reset is notified to the sensor node 3B-1 by an identifier setting message, thereby eliminating the identifier duplication. When the resetting of the identifier is completed, the mesh network construction / management unit 222 generates a network entry notification response message with the destination being the sensor node 3B-1, and transmits it via the wireless media processing unit 221 and the wireless unit 21. The identifier setting message and the network entry notification response message are transferred toward the sensor node 3B-1 by the sensor nodes 3A-1 and 3A-2.

  On the other hand, when the result of the identifier duplication check is “no identifier duplication”, the mesh network construction / management unit 222 sets the destination to the sensor node 3B− without performing the resetting of the identifier for the sensor node 3B-1. A network entry notification response message set to 1 is generated and transmitted.

  The identifier setting message and the network entry notification response message transmitted from the gateway 2-1 and relayed to the sensor node 3B-1 by the sensor nodes 3A-1 and 3A-2 are one of the relay terminals. 4-1 is reached. In the wireless repeater 4-1, the wireless media processing unit 421A receives these messages via the wireless unit 41A, and the mesh routing processing unit 423 refers to the route table held in the own device. Since the destination of the message is the sensor node 3B-1, as a result of referring to the route table, it is recognized that the next hop terminal is the sensor node 3B-1 and the wireless medium to be used is the wireless medium B. Then, the wireless medium to be used is changed from the wireless medium A to the wireless medium B, and the wireless media processing unit 421B performs transfer processing of the received message (identifier setting message, network entry notification response message). The message transferred by the wireless repeater 4-1 reaches the sensor node 3B-1.

  When the sensor node 3B-1 receives the network entry notification response message, the network entry of the sensor node 3B-1 is completed. The control procedure when the sensor node 3B other than the sensor node 3B-1 enters the network is that the message may be transferred between the sensor nodes 3B in the mesh network B and the wireless repeater 4-2. Is the same as the network entry procedure of the sensor node 3B-1, except that there is a case where the relay is performed with the mesh network A side.

  In the above description, an example in which the identifier is reset only when the result of the identifier duplication check is “identifier duplication” is shown. However, the identifier is reset even when “identifier duplication is not present”. It does not matter as long as the control is correct.

  Any existing method may be used as a method for the newly entering sensor node 3B to search for the gateway 2-1.

  The above-described control procedure described with reference to FIGS. 6 to 8 makes it possible to manage a mesh network constructed by nodes having different wireless media as the same network, gateway 2, sensor node 3A, sensor The node 3B and the wireless repeater 4 can communicate without being aware of the medium difference.

  Next, a route solving operation in the wireless communication system of the present embodiment, specifically, an operation in which the gateway 2 searches for a route to the sensor node 3A, the wireless repeater 4, and the sensor node 3B will be described.

(Route search for sensor node 3A)
FIG. 9 is a diagram showing a sequence example when searching for a route to the sensor node 3A. Specifically, in the wireless communication system having the configuration shown in FIG. 1, the gateway 2-1 moves to the sensor node 3A-3. An example in the case of searching for a route is shown.

  When the gateway 2-1 searches for a route to the sensor node 3A-3, first, the mesh routing processing unit 223 of the gateway 2-1 selects a node to be searched (in this case, the sensor node 3A-3). An RREQ (Route Request) message storing information (identifier) is generated, and a broadcast address is set as a destination of the RREQ message. Next, the wireless media processing unit 221 transmits this RREQ message. Each terminal (sensor node) that has received the RREQ message refers to the information of the search target node stored in the RREQ message, and checks whether this information indicates the own device (whether the search target is the own device). . As a result of the confirmation, if the search target is not the own device, the process of transferring the destination of the received RREQ message as a broadcast address is repeated. As a result, the RREQ message storing the identifier of the sensor node 3A-3 reaches the sensor node 3A-3.

  In the sensor node 3A-3 that has received the RREQ message, the mesh routing processing unit 323 generates an RREP (Route Reply) message in which the destination is set to the gateway 2-1, and the wireless media processing unit 321A transmits the RREP message. To do. The RREP message is transferred toward the gateway 2-1 by the sensor nodes 3A-2 and 3A-1 which are relay terminals, and reaches the gateway 2-1. Then, the gateway 2-1 receives the RREP message, analyzes the content, and constructs a route table.

(Route search for wireless repeater 4)
FIG. 10 is a diagram illustrating a sequence example when searching for a route to the wireless repeater 4. Specifically, in the wireless communication system having the configuration illustrated in FIG. An example in the case of searching for a route is shown. Since the wireless repeaters 4-1 and 4-2 can directly communicate only with the sensor node 3A-2, the same sequence is used when searching for a route to any wireless repeater.

  When the gateway 2-1 searches for a route to the wireless repeater 4, first, the mesh routing processing unit 223 of the gateway 2-1 stores the information (identifier) of the node (wireless repeater 4) to be searched. An RREQ message is generated, and a broadcast address is set as a destination of the RREQ message. Next, the wireless media processing unit 221 transmits this RREQ message. Each terminal (sensor node) that has received the RREQ message refers to the information of the search target node stored in the message, and checks whether this information indicates the own device (whether the search target is the own device). As a result of the confirmation, if the search target is not the own device, the process of transferring the destination of the received RREQ message as a broadcast address is repeated. As a result, the RREQ message in which the identifier of the wireless repeater 4 is stored reaches the wireless repeater 4.

  In the wireless repeater 4 that has received the RREQ message, the mesh routing processing unit 423 generates an RREP message in which the destination is set to the gateway 2-1, and the wireless media processing unit 421A transmits the RREP message. The RREP message is transferred toward the gateway 2-1 by the sensor nodes 3A-2 and 3A-1 which are relay terminals, and reaches the gateway 2-1. Then, the gateway 2-1 receives the RREP message, analyzes the content, and constructs a route table.

(Route search for sensor node 3B)
FIG. 11 is a diagram showing a sequence example when searching for a route to the sensor node 3B. Specifically, in the wireless communication system having the configuration shown in FIG. 1, the gateway 2-1 moves to the sensor node 3B-1. An example in the case of searching for a route is shown.

  When the gateway 2-1 searches for a route to the sensor node 3B-1, first, the mesh routing processing unit 223 of the gateway 2-1 obtains information (identifier) of the node (sensor node 3B-1) to be searched. A stored RREQ message is generated, and a broadcast address is set as a destination of the RREQ message. Next, the wireless media processing unit 221 transmits this RREQ message. Each terminal (sensor node, wireless repeater) that has received the RREQ message refers to the information of the search target node stored in the message, and whether this information indicates the own device (whether the search target is the own device). )Check. As a result of the confirmation, if the search target is not the own device, the process of transferring the destination of the received RREQ message as a broadcast address is repeated. At this time, the wireless repeater 4 performs the following process to transfer the RREQ message. That is, in the wireless repeater 4, the wireless media processing unit 421A receives the RREQ message transferred from the sensor node 3A, but the information stored in the RREQ message does not indicate the own device, and further transfers the RREQ message. In the case of performing the transmission, the wireless media processing unit 421B performs the transfer process and broadcasts it instead of transferring it by the wireless media processing unit 421A that has received the RREQ message. As a result, the RREQ message transmitted on the mesh network A side configured by the sensor node 3A is also transferred to the mesh network B side configured by the sensor node 3B. The above operation is realized by permitting the route search only from the gateway 2.

  As a result of executing the above procedure, the RREQ message in which the identifier of the sensor node 3B-1 is stored reaches the sensor node 3B-1.

  In the sensor node 3B-1 that has received the RREQ message, the mesh routing processing unit 323 generates an RREP message with the destination set to the gateway 2-1, and the wireless media processing unit 321B transmits the RREP message. The RREP message is transferred to the gateway 2-1 by the wireless repeater 4, which is a relay terminal, and the sensor nodes 3A-2 and 3A-1, and reaches the gateway 2-1. Then, the gateway 2-1 receives the RREP message, analyzes the content, and constructs a route table.

  When the wireless repeater 4 transfers the RREP message, the wireless media processing unit 421A performs the transfer process instead of the wireless media processing unit 421B that has received the RREP message.

  Further, when transferring a signal between the mesh network A side and the mesh network B side, the wireless repeater 4 according to the present embodiment performs data fragment processing as described below as necessary before and after the transfer. Adjust the size.

(Processing in the relay processing from the mesh network A side to the B side)
When the wireless repeater 4 receives a message transmitted from the sensor node 3A, the gateway 2, or the center device 1 to the sensor node 3B, the wireless repeater 4 checks the data length of the received message. As a result of confirmation, it is confirmed that the data length of the received message exceeds the maximum data length of the message that can be handled by the wireless communication method corresponding to the wireless medium B, that is, the wireless communication method used in the mesh network B. If detected, the fragment processing unit 424 performs data fragmentation, divides the data, and transfers the data, thereby absorbing the data length difference between the media.

(Processing in relay processing from mesh network B side to A side)
On the contrary, when the wireless repeater 4 receives a plurality of messages having the same destination transmitted from the sensor node 3B to the sensor node 3A, the gateway 2 or the center device 1, the wireless repeater 4 is used in the mesh network A. The fragment processing unit 424 reassembles a plurality of data (messages) having the same destination in accordance with the maximum data length of a message that can be handled by the existing wireless communication method, and transfers the combined data. In order to realize this transfer process, when the sensor node 3B transmits a message to the sensor node 3A, the gateway 2 or the center device 1, the destination is set so that the wireless repeater 4 can reassemble the data. A plurality of identical data messages are generated and transmitted together with information indicating that the data is to be reassembled.

  As described above, the wireless communication system according to the present embodiment includes the first mesh network formed by the nodes including the wireless medium (wireless medium A) corresponding to the first wireless system, and the second wireless system. A second mesh network formed by a node including a wireless medium (wireless medium B) corresponding to the wireless medium, and a wireless repeater including first and second wireless media, Signals transmitted from the first mesh network side to the second mesh network side at positions where one or more nodes of one mesh network and one or more nodes of the second mesh network can communicate with each other In addition, a signal transmitted from the second mesh network side toward the first mesh network side is relayed. Further, the gateway of the first mesh network manages the terminal identifier so that the terminal identifiers of the nodes in the first and second mesh networks do not overlap with each other, and each node (sensor node It was decided to search for a route to 3A, 3B, the wireless repeater 4). In addition, when transferring data transmitted / received between sensor nodes with different wireless media, the wireless repeater performs fragment processing and divides the data received as one message and transfers it as a plurality of messages, or the destination is Data received as a plurality of the same messages are collected and transferred as one message.

  As a result, the signal transmitted from the node in the first mesh network and the signal transmitted from the node in the second mesh network can be transmitted / received to / from each other without going through a higher-level device of each mesh network. . That is, nodes in each mesh network can be handled as nodes in the same network, and nodes having different wireless media can communicate with each other. Further, the gateway can communicate with each sensor node without being aware of the difference in the wireless medium between the sensor nodes.

  Furthermore, since a plurality of wireless repeaters are provided, even if some of the wireless repeaters break down, another route repeater (failure occurs) by performing a reroute search from the gateway to the target terminal. It is possible to construct a route via a wireless repeater that is not.

Embodiment 2. FIG.
The configuration of the radio communication system of the present embodiment is the same as that of the radio communication system of the first embodiment. In the first embodiment, the operation when the sensor node collects data is not particularly defined. However, the wireless communication system of the present embodiment has a feature in the control at the time of data collection. Specifically, the gateway 2 is characterized by control for collecting data from each sensor node at a constant period.

  FIG. 12 is a diagram illustrating a configuration example of a radio repeater according to the second embodiment. As shown in the figure, the wireless repeater 4a of this embodiment is obtained by adding a data collection control unit 425 to the wireless repeater 4 (see FIG. 5) described in the first embodiment. The data collection control unit 425 collects data from each sensor node 3B in the mesh network B.

  FIG. 13 is a sequence diagram illustrating an example of a data collection operation in the wireless communication system according to the second embodiment.

  In the wireless communication system according to the present embodiment, since there is a large usable bandwidth in communication using the wireless medium A, each sensor node 3A autonomously transmits data to the gateway 2. On the other hand, in the communication using the wireless medium B, the usable bandwidth is small, and when each sensor node 3B autonomously transmits data, the data collection rate decreases due to message collision. Therefore, as shown in FIG. 13, the data collection control unit 425 of the wireless repeater 4a polls the sensor node 3B designated by the gateway 2-1, collects the data, and collects the collected data as the gateway. Transmit to 2-1. In FIG. 13, description of a message transmitted when the gateway 2-1 instructs the wireless repeater 4a is omitted.

  As described above, in the wireless communication system according to the present embodiment, data collection from each sensor node 3B that uses a wireless system with a small usable bandwidth is led by the wireless relay 4a. Thereby, it is possible to avoid collision between messages storing data collected by the sensor node 3B, and it is possible to prevent a decrease in the data collection rate.

Embodiment 3 FIG.
The configuration of the radio communication system of the present embodiment is the same as that of the radio communication system of the first embodiment. The wireless communication system according to the present embodiment is characterized by a route search operation from the gateway 2 to the sensor node 3B.

  FIG. 14 is a sequence diagram illustrating an example of an operation in which the gateway 2 searches for a route to the sensor node 3B.

  In the wireless communication system according to the first embodiment, when a route search from the gateway 2 to the sensor node 3B is performed, a route search request (RREQ message) is transmitted to all the sensor nodes in the mesh network. Since the message propagates to terminals that are not candidates for the route to the sensor node 3B, unnecessary traffic increases in the mesh network.

  Therefore, in the wireless communication system of the present embodiment, as shown in FIG. 14, a route search request from gateway 2 to sensor node 3B (in FIG. 14, from gateway 2-1 to sensor node 3B-2). When the (RREQ message) is transmitted, the wireless repeater 4 is transmitted by unicast. Specifically, when performing a route search, the mesh routing processing unit 223 of the gateway 2 checks whether the wireless medium included in the search target node is the wireless medium B. The request is encapsulated and unicasted to the wireless repeater. The route search request is encapsulated as shown in FIG. When receiving the encapsulated route search request, the wireless repeater 4 performs decapsulation, extracts the route search request, and transmits it by broadcast. The operation of the sensor node 3B is the same as that in the first embodiment. That is, each sensor node 3B, when the search target node indicated by the received route search request is not its own, is transferred by broadcast. Thereby, a route search request can be made to reach all sensor nodes in the mesh network B, and unnecessary messages can be prevented from propagating in the mesh network A.

  Note that the mesh routing processing unit 223 of the gateway 2 holds the terminal information as shown in FIG. When transmitting a route search request, the wireless medium included in the search target node is confirmed. If a node of a wireless medium different from the own device (gateway 2) is a search target, the route search request is encapsulated. Transmit to the wireless repeater 4. FIG. 16 is a diagram illustrating an example of terminal information used for route search with an encapsulation operation. The wireless medium information included in the terminal information includes, for example, each node (sensor nodes 3A, 3B, wireless repeater 4) storing its own wireless medium information in a network entry notification message requesting entry into the network. And transmitted to the mesh routing processing unit 223 of the gateway 2. As described above, since the route table includes wireless medium information, the route table can be used with the terminal information. FIG. 16 shows an example in which a route table is used as terminal information.

  As described above, in the wireless communication system according to the present embodiment, when performing a route search, the gateway 2 encapsulates a route search request for searching for a node having a wireless medium different from the wireless medium included in the gateway 2. When the encapsulated route search request is received, the radio repeater 4 performs decapsulation and broadcast transmission. Thereby, it is possible to prevent unnecessary traffic from occurring in the system.

  As described above, the wireless communication system according to the present invention is useful for sensor networks, and is particularly suitable for sensor networks that collect data using a plurality of types of sensor nodes having different wireless media.

1 Center device 2-1, 2-2 Gateway 3A-1 to 3A-3, 3B-1 to 3B-4 Sensor node 4-1, 4-2 Wireless repeater 21, 31A, 31B, 41A, 41B Wireless unit 22 , 32A, 32B, 42, 42a Communication processing unit 23 Upper I / F communication processing unit 24 Upper I / F
221, 321 A, 321 B, 421 A, 421 B Wireless media processing unit 222 Mesh network construction / management unit 223, 323, 423 Mesh routing processing unit 224, 324 Application processing unit 225 Host I / F-wireless mesh cooperation processing unit 322, 422 Mesh network entry processing unit 424 Fragment processing unit 425 Data collection control unit

Claims (5)

A first mesh network configured to include a first sensor node that communicates using a first wireless medium;
A second mesh network configured to include a second sensor node that communicates using a second wireless medium different from the first wireless medium;
A gateway having a function of connecting a higher-level communication device and the first mesh network, and directly communicating with at least one of the first sensor nodes using the first wireless medium;
Communicating directly with at least one of the first sensor nodes using the first wireless medium and directly with at least one of the second sensor nodes using the second wireless medium A wireless repeater for communication;
With
The gateway manages terminal identifiers of the first sensor node, the second sensor node, and the wireless repeater, adjusts so that terminal identifiers do not overlap with each other, and uses the managed terminal identifiers And performing a route search.   The wireless communication system according to claim 1, comprising a plurality of the wireless repeaters. In the signal relay from the first mesh network side to the second mesh network side and the signal relay from the second mesh network side to the first mesh network side, the wireless repeater is configured to each of the meshes. The wireless communication system according to claim 1 or 2, wherein data division processing and data combination processing based on a difference in maximum data length that can be handled by a wireless medium used in a network are executed. The wireless communication system according to claim 1, wherein the wireless repeater collects data from the second sensor node by polling and transmits the collected data to the gateway. In the route search process for the second sensor node, the gateway generates a route search request that stores a terminal identifier of the second sensor node to be searched and sets a broadcast address as a destination, and performs the route search Encapsulate the request and send it to the radio repeater,
The wireless repeater performs decapsulation when receiving an encapsulated route search request, and broadcasts the route search request after decapsulation in the second mesh network. The radio | wireless communications system as described in any one of -4.

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