JP6016646B2 - node - Google Patents

Description

  The present invention relates to a node constituting a wireless mesh network.

  Conventionally, a number of routing protocols (ad hoc routing protocols) have been proposed in a wireless mesh (ad hoc) network that enables communication between wireless communication devices without using an existing network infrastructure (for example, the following non-patent document). 1-3).

  In the ad hoc routing protocol, it is simple and general to use the number of hops as a metric (evaluation measure) for path construction. By minimizing the number of hops from the start point to the end point, the aim is to minimize the network resources required for packet relay and to shorten the transmission time. However, reducing the number of hops agrees that the distance between the nodes is increased, and there is a problem of reducing the arrival rate of the radio link.

  Therefore, in Non-Patent Document 3 below, an index called Objective Function is adopted as a metric for path construction, and OF0 (see Non-Patent Document 4 below) or MRHOF (Minimum Rank with Hysteresis Objective Function) (see Non-Patent Document 5 below). The use of is being considered.

  Specifically, OF0 shown in Non-Patent Document 4 below employs a metric based on the number of hops called Rank. In the wireless communication device, each link is digitized with an index set in advance by the operator, an addition is performed by multiplying the weight of the number of hops every time a link is hopped, and a path that ultimately decreases the Rank is selected.

  In MRHOF shown in Non-Patent Document 5 below, a wireless communication device determines Rank using a metric based on a packet loss rate in each link called ETX (Expected Transmission Count).

DSR (Dynamic Source Routing): RFC4728 AODV (Ad Hoc On Demand Distance Vector Routing): RFC3561 RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks: RFC 6550 Objective Function Zero for the Routing Protocol for Low-Power and Lossy Networks (RPL): RFC6552 The Minimum Rank with Hysteresis Objective Function: RFC6719

  However, according to the above-described conventional technique, in the ad hoc routing protocol, a method of minimizing the number of hops of a radio link, a radio link is quantified by a metric mixed with RSSI, BER, PER, etc., and every time a link is hopped. The route is selected by a method of adding metrics (or weighted addition) and minimizing the metric value to the destination. Therefore, the terminal that selects the route can obtain detailed information about the immediately preceding link metric, but the link on the subsequent route can be grasped only by the addition value, and the route satisfies the desired communication quality. There was a problem that it was difficult to determine whether or not.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a node capable of selecting a route satisfying desired communication quality in the entire route in an ad hoc routing protocol.

  In order to solve the above-described problems and achieve the object, the present invention is a node in a wireless mesh network composed of a gateway and a plurality of nodes, and is based on a signal or message received from another node or the gateway. Link quality determination means for determining whether the quality of the radio link of the route between the other node or the gateway and the own node is divided into any of a plurality of quality levels using one or more threshold values; The route statistics information, which is information on the quality of the radio link of the route from the other node to the gateway, and the information on the number of hops to the gateway are included in the message received from the other node, and the obtained other Node path statistics information and quality level information determined by the link quality determination means are integrated. And message processing means for performing control to transmit the message transmitted from the own node including the route statistical information of the own node and the information on the number of hops to the gateway, and after the integration integrated by the message processing means Route statistical information recording means for recording the route statistical information as route statistical information from its own node to the gateway, route table recording means for recording information on the number of hops to the gateway and information on the next hop destination, Routing processing means for determining a route of a signal or message to be transmitted based on information recorded in the routing table recording means, and the message processing means, when receiving a message from a plurality of other nodes, Based on post-integration route statistical information, one post-integration route statistical information is selected. And wherein the door.

  According to the present invention, in the ad hoc routing protocol, it is possible to select a route that satisfies a desired communication quality in the entire route.

FIG. 1 is a diagram illustrating a configuration example of a wireless mesh network according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of a node. FIG. 3 is a diagram illustrating the route statistical information held in each route statistical information recording unit by the node according to the first embodiment. FIG. 4 is a diagram illustrating route tables held in the route table recording unit by the nodes according to the first embodiment. FIG. 5 is a diagram illustrating a configuration example of a gateway. FIG. 6 is a diagram illustrating an operation of the joining node when the node joins the wireless mesh network. FIG. 7 is a diagram illustrating an operation of an already-entered node when a node enters the wireless mesh network. FIG. 8 is a flowchart showing a registration process of a route statistical information recording unit and a route table recording unit in a node entering the wireless mesh network. FIG. 9 is a diagram showing the contents of the route statistical information recording unit and the route table recording unit stored in the joining node that has selected the node already entered as the next hop node. FIG. 10 is a diagram illustrating an operation in which an entry node entering the wireless mesh network transmits a registration request message addressed to a gateway. FIG. 11 is a diagram illustrating an operation in which a gateway transmits a registration response message to a node entering the wireless mesh network. FIG. 12 is a diagram illustrating a configuration example of a wireless mesh network according to the second embodiment. FIG. 13 is a diagram illustrating route statistical information held by each node in the route statistical information recording unit according to the second embodiment. FIG. 14 is a flowchart showing registration processing of the route statistical information recording unit and the route table recording unit in the nodes of the wireless mesh network. FIG. 15 is a diagram illustrating a state in which a downlink route search message is transferred from a gateway in a wireless mesh network. FIG. 16 is a diagram showing the route statistical information held by each node in the route statistical information recording unit according to the present embodiment. FIG. 17 is a diagram illustrating a state in which a downlink route search response message is transferred from a node in a wireless mesh network. FIG. 18 is a diagram showing the route statistical information held in the respective route statistical information recording units by the nodes according to the present embodiment. FIG. 19 is a diagram illustrating a configuration example of a wireless mesh network according to the third embodiment. FIG. 20 is a diagram illustrating a state of the wireless mesh network after the node changes the parent after the link error occurs.

  Embodiments of a node 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 illustrating a configuration example of a wireless mesh network according to the present embodiment. The wireless mesh network 1000 includes a plurality of nodes 101-a to 101-k and a gateway 201. The wireless links 301-a to 301-k are connected between the nodes and between the gateway 201 and the nodes. Connected by. Here, the nodes 101-a to 101-k autonomously configure a network. In the following description, when each node is not distinguished, it may be simply referred to as a node 101, and when each wireless link is not distinguished, it may be simply referred to as a wireless link 301.

  Next, the configuration of each device will be described. FIG. 2 is a diagram illustrating a configuration example of a node. The node 101 includes an antenna unit 102, a wireless communication unit 103, a link quality determination unit 104, a message processing unit 105, a routing processing unit 106, a route statistical information recording unit 107, and a route table recording unit 108. Prepare.

  The antenna unit 102 is connected to another node 101 or the gateway 201 via the wireless link 301, and transmits and receives signals and messages. The wireless communication unit 103 demodulates a signal / message received from the antenna unit 102 from the other node 101 or the gateway 201 and modulates a signal / message transmitted from itself. The link quality determination unit 104 determines the quality of the radio link 301 connected to the own node for signals / messages received from the antenna unit 102 and the wireless communication unit 103 from the other node 101 or the gateway 201. The link quality determination unit 104 divides the quality of the wireless link 301 between the adjacent node 101 or the gateway 201 into one of a plurality of quality levels based on one or more preset threshold values. The message processing unit 105 determines a process to be executed based on the received message. In addition, the message processing unit 105 acquires the route link quality (route statistical information) from the other node 101 to the gateway 201 included in the message received from the other node 101. The routing processing unit 106 determines a destination and a route when a message is transmitted / transferred. The route statistical information recording unit 107 integrates the quality of the wireless link 301 determined by the link quality determination unit 104 and the route link quality (route statistical information) to the gateway 201 in the other node 101 acquired by the message processing unit 105. Recorded route statistics. The route table recording unit 108 records the next hop for transmitting the message to the destination (gateway 201) and the number of hops to the destination.

  Here, the configuration of each recording unit will be described. FIG. 3 is a diagram showing the route statistical information that the nodes 101-a to 101-k of the present embodiment hold in the respective route statistical information recording units 107. In the route statistical information, the statistical number of quality levels of the wireless link 301 existing on the route from each node 101 to the gateway 201 is described. For example, the node 101-g has one wireless link 301 of quality level A, one wireless link 301 of quality level B, and one wireless link 301 of quality level C on the route to the gateway 201. It is shown that. The temporary area (tmp) is an area for temporarily storing route statistical information received from other nodes 101. In addition, although FIG. 3 demonstrated the case where the quality level was four (A, B, C, D), it is an example and it does not limit to this.

  FIG. 4 is a diagram illustrating a route table held in the route table recording unit 108 by each of the nodes 101-a to 101-k according to the present embodiment. The route table describes the number of hops from each node 101 to the gateway 201 and the next hop node 101 when a message is transmitted toward the gateway 201.

  Next, the configuration of the gateway 201 will be described. FIG. 5 is a diagram illustrating a configuration example of the gateway 201. The gateway 201 includes an antenna unit 202, a wireless communication unit 203, a message processing unit 204, a downlink routing processing unit 205, a database 206, and a downlink route table recording unit 207.

  The antenna unit 202 is connected to the node 101 via the wireless link 301 and transmits and receives signals and messages. The wireless communication unit 203 demodulates the signal / message from the node 101 received by the antenna unit 202 and modulates the signal / message transmitted from itself. The message processing unit 204 determines a process to be executed based on the received message. The downlink routing processing unit 205 determines the destination node 101 and the transit node 101 of the message to be transmitted. The database 206 holds data collected from each node 101. The downlink route table recording unit 207 holds the route to the destination node 101 of the message to be transmitted.

  Next, operations of the node 101 and the gateway 201 when the node 101-n newly enters the wireless mesh network 1000 will be described. FIG. 6 is a diagram illustrating an operation of the node 101-n when the node 101-n enters the wireless mesh network 1000. First, when the node 101-n enters the wireless mesh network 1000, the message processing unit 105 creates an entry request message, and sends an entry request message to the adjacent node 101 via the wireless communication unit 103 and the antenna unit 102. Broadcast transmission. Note that the configuration of the node 101-n is the same as the configuration of the other nodes 101-a to 101-k.

  FIG. 7 is a diagram illustrating operations of the (existing) nodes 101-i, 101-j, and 101-k when the (entering) node 101-n enters the wireless mesh network 1000. In the nodes 101-i, 101-j, and 101-k, when the entry request message is received via the antenna unit 102 and the wireless communication unit 103, the message processing unit 105 creates an entry response message that is a response to the entry request message. If it is determined that, it acquires its own route statistical information from the route statistical information recording unit 107, and also acquires information on the number of hops from the route table recording unit 108, and the route statistical information and the number of hops from the gateway 201 to itself. An entry response message including information is created, and the entry response message is unicast transmitted to the node 101-n via the wireless communication unit 103 and the antenna unit 102.

  When the node 101-n receives the entry response message from the nodes 101-i, 101-j, and 101-k via the antenna unit 102 and the wireless communication unit 103, the message processing unit 105 and the like follow the flowchart shown in FIG. Process the entry response message. FIG. 8 is a flowchart showing a registration process of the route statistical information recording unit 107 and the route table recording unit 108 in the node 101-n entering the wireless mesh network 1000.

  In the node 101-n, the link quality determination unit 104 determines the link quality when receiving the entry response message, and ranks it (step S101). Specifically, in the example illustrated in FIG. 7, the quality level of the radio link 301 to the node 101-i is C, the quality level of the radio link 301 to the node 101-j is B, and the node 101-k is The quality level of the wireless link 301 between is A.

  The message processing unit 105 acquires the route statistical information of the adjacent node 101 that is the transmission source of the participation response message described in the participation response message, and the acquired route statistical information and the quality level ranked by the link quality determination unit 104 Are integrated (step S102). The route statistical information generated by the integration is used as the route statistical information about the adjacent node 101 of the entry response message transmission source.

  The message processing unit 105 refers to the route table recording unit 108 (step S103). If no route is registered (step S103: Yes), the message processing unit 105 adds 1 to the number of hops to the gateway 201 included in the entry response message to obtain the number of hops from itself to the gateway 201, The adjacent node 101 of the entry response message transmission source is registered in the route table recording unit 108 as parent. In addition, the message processing unit 105 registers the route statistical information generated for the adjacent node 101 that is the transmission source of the entry response message in the route statistical information recording unit 107 (step S104).

  On the other hand, when the route is already registered in the route table recording unit 108 (step S103: No), the message processing unit 105 acquires the current route statistical information recorded in the route statistical information recording unit 107 (step S103). S105), the number of each quality level of the route statistical information generated for the adjacent node 101 of the entry response message transmission source and the current (existing) route statistical information is compared (steps S106 to S113).

  First, the message processing unit 105 checks whether or not the number of quality levels D of the route statistical information generated from the entry response message is smaller than the number of quality levels D of the existing route statistical information (step S106). When the number of quality levels D is smaller in the route statistical information generated from the entry response message (step S106: Yes), the message processing unit 105 adds 1 to the number of hops to the gateway 201 included in the entry response message. The number of hops from itself to the gateway 201, the adjacent node 101 of the entry response message transmission source as the parent, is registered in the route table recording unit 108, and the route statistical information generated from the entry response message is stored in the route statistical information recording unit It registers in 107 (step S104).

  When the number of quality levels D of the route statistical information generated from the entry response message is greater than or equal to the number of quality levels D of the existing route statistical information (step S106: No), the message processing unit 105 generates the route statistics generated from the entry response message. It is confirmed whether the number of information quality levels D is the same as the number of quality levels D of existing route statistical information (step S107).

  When the number of quality levels D of the route statistical information generated from the entry response message is the same as the number of quality levels D of the existing route statistical information (step S107: Yes), the message processing unit 105 then starts from the entry response message. It is confirmed whether the number of quality levels C of the generated route statistical information is less than the number of quality levels C of the existing route statistical information (step S108). When the number of quality levels C is smaller in the route statistical information generated from the entry response message (step S108: Yes), the message processing unit 105 adds 1 to the number of hops to the gateway 201 included in the entry response message. The number of hops from itself to the gateway 201, the adjacent node 101 of the entry response message transmission source as the parent, is registered in the route table recording unit 108, and the route statistical information generated from the entry response message is stored in the route statistical information recording unit It registers in 107 (step S104).

  Note that the message processing unit 105 determines that the number of quality levels D of the route statistical information generated from the entry response message is not the same as the number of quality levels D of the existing route statistical information, that is, the route statistical information generated from the entry response message. If the number of quality levels D is greater (step S107: No), the process is terminated.

  When the number of quality levels C of the route statistical information generated from the entry response message is equal to or higher than the number of quality levels C of the existing route statistical information (step S108: No), the message processing unit 105 generates the route statistics generated from the entry response message. It is confirmed whether or not the number of quality levels C of information is the same as the number of quality levels C of existing route statistical information (step S109).

  When the number of quality levels C of the route statistical information generated from the entry response message is the same as the number of quality levels C of the existing route statistical information (step S109: Yes), the message processing unit 105 then starts from the entry response message. It is checked whether or not the total number of quality levels A and quality levels B of the generated route statistical information is less than the total number of quality levels A and quality levels B of the existing route statistical information (step S110). When the route statistical information generated from the entry response message has a smaller total number of quality levels A and B (step S110: Yes), the message processing unit 105 proceeds to the gateway 201 included in the entry response message. 1 is added to the number of hops to determine the number of hops from itself to the gateway 201, and the adjacent node 101 of the entry response message transmission source is registered as the parent in the route table recording unit 108, and the route statistics generated from the entry response message Information is registered in the route statistical information recording unit 107 (step S104).

  Note that the message processing unit 105 determines that the number of quality levels C of the route statistical information generated from the entry response message is not the same as the number of quality levels C of the existing route statistical information, that is, the route statistical information generated from the entry response message. If the number of quality levels C is larger (step S109: No), the process is terminated.

  When the sum of the number of quality levels A and quality levels B of the route statistical information generated from the entry response message is greater than or equal to the sum of the number of quality levels A and quality levels B of the existing route statistical information (step S110: No) ), The message processing unit 105 adds the total number of quality levels A and quality levels B of the route statistical information generated from the entry response message, and the total number of quality levels A and quality levels B of the existing route statistical information. Are equal to each other (step S111).

  When the total number of quality levels A and quality levels B of the route statistical information generated from the entry response message is the same as the total number of quality levels A and quality levels B of the existing route statistical information (step S111: Next, the message processing unit 105 checks whether or not the number of quality levels A of the route statistical information generated from the entry response message is greater than the number of quality levels A of the existing route statistical information (step S112). When the route statistical information generated from the entry response message has a higher number of quality levels A (step S112: Yes), the message processing unit 105 adds 1 to the number of hops to the gateway 201 included in the entry response message. The number of hops from itself to the gateway 201, the adjacent node 101 of the entry response message transmission source as the parent, is registered in the route table recording unit 108, and the route statistical information generated from the entry response message is stored in the route statistical information recording unit It registers in 107 (step S104).

  Note that the message processing unit 105 adds the total number of quality levels A and quality levels B of the route statistical information generated from the entry response message, and the total number of quality levels A and quality levels B of the existing route statistical information. Are not the same number, that is, when the route statistics information generated from the entry response message has a larger total number of quality levels A and B (step S111: No), the process is terminated.

  When the number of quality levels A of the route statistical information generated from the entry response message is less than or equal to the number of quality levels A of the existing route statistical information (step S112: No), the message processing unit 105 generates the route statistics generated from the entry response message. Check whether the number of information quality levels A is the same as the number of quality levels A of the existing route statistical information, and enter the received power level RSSI (Received Signal Strength Indication) registered in the route table recording unit 108 The received power level RSSI when the response message is received is compared (step S113).

  The number of quality levels A of the route statistical information generated from the entry response message is the same as the number of quality levels A of the existing route statistical information, and the received power level RSSI and the entry response message registered in the route table recording unit 108. As a result of comparing the reception power level RSSI at the time of reception, if the power level RSSI at the time of reception of the entry response message is larger (step S113: Yes), the message processing unit 105 hops to the gateway 201 included in the participation response message. 1 is added to the number to obtain the number of hops from itself to the gateway 201, and the adjacent node 101 of the entry response message transmission source is registered as the parent in the route table recording unit 108, and the route statistical information generated from the entry response message is Registered in the route statistics information recording unit 107 (step S104).

  The message processing unit 105 determines that the number of quality levels A of the route statistical information generated from the entry response message is not the same as the number of quality levels A of the existing route statistical information, that is, the route statistical information generated from the entry response message. When the number of quality levels A is smaller, or / and the power level RSSI at the time of receiving the entry response message is equal to or lower than the received power level RSSI registered in the route table recording unit 108 (step S113: No), The process ends.

  The node 101-n repeatedly executes the above processing (steps S101 to S113) as many times as the number of entry response messages received, and after a certain period of time has passed since it transmitted the entry request message, the node 101-n closes reception of the entry response message. At that time, the parent described in the route table recording unit 108 is set as the uplink next hop node 101 of the wireless mesh network 1000. Then, the node 101-n unicasts the registration request message addressed to the gateway 201 to the uplink next hop node 101 described in the route table recording unit 108.

  In the node 101-n of the wireless mesh network 1000 shown in FIG. 7, the quality level of the entry response message received from the node 101-i is C, and the statistical route information in the entry response message is quality level A: 2, quality level B: 1 and the quality level of the entry response message received from the node 101-j is B, and the statistical route information in the entry response message is quality level A: 2 and quality level B: 1 and is received from the node 101-k. The quality level of the entry response message is A, and the statistical route information in the entry response message is quality level A: 2 and quality level C: 1. When the node 101-n repeatedly executes the above processing (steps S101 to S113) shown in FIG. 8 for the entry response message received from the nodes 101-i, 101-j, and 101-k, the node 101-n becomes the next hop node 101. j will be selected.

  FIG. 9 is a diagram illustrating the contents of the route statistical information recording unit 107 and the route table recording unit 108 stored in the (entry) node 101-n that has selected the (existing) node 101-j as the next hop node. In the node 101-n, the quality obtained by adding quality level B information between itself and the node 101-j to the statistical route information acquired from the entry response message from the node 101-j in the route statistical information recording unit 107. Statistical route information of level A: 2 and quality level B: 2 is recorded, and the route table recording unit 108 adds 1 to the number of hops acquired from the entry response message from the node 101-j. A route table in which the number of hops is 4 and the node 101-j is parent is recorded. As described above, the node 101-n selects the node 101-j as the upstream next hop node 101, so that the path can be constructed only by the wireless links 301 of the quality ranks A and B.

  FIG. 10 is a diagram illustrating an operation of transmitting a registration request message addressed to the gateway 201 from the node 101-n when the (entry) node 101-n enters the wireless mesh network 1000. In the node 101-n, the routing processing unit 106 acquires the information of the parent node 101-j recorded in the route table recording unit 108, and the message processing unit 105 generates an entry registration message addressed to the gateway 201. Then, unicast transmission is performed to the node 101-j via the wireless communication unit 103 and the antenna unit 102.

  In the node 101-j, when the message processing unit 105 confirms that the registration request message received from the node 101-n is addressed to the gateway 201, the node 101-j adds its own node ID to the source route described in the registration request message. Then, the registration request message is transferred via the wireless communication unit 103 and the antenna unit 102 to the parent node 101-e recorded in the own route table recording unit 108 acquired by the routing processing unit 106.

  In the node 101-e, when the message processing unit 105 confirms that the registration request message received from the node 101-j is addressed to the gateway 201, the node 101-e adds its own node ID to the source route described in the registration request message. Then, the registration request message is transferred via the wireless communication unit 103 and the antenna unit 102 to the parent node 101-b recorded in its own route table recording unit 108 acquired by the routing processing unit 106.

  In the node 101-b, when the message processing unit 105 confirms that the registration request message received from the node 101-e is addressed to the gateway 201, the node 101-b adds its own node ID to the source route described in the registration request message. Then, the registration request message is transferred via the wireless communication unit 103 and the antenna unit 102 to the parent gateway 201 recorded in its own route table recording unit 108 acquired by the routing processing unit 106.

  When the gateway 201 receives the registration request message from the node 101-n, the message processing unit 204 registers the node 101-n in its own downlink route table recording unit 207, and further described in the registration request message. The downlink route table is updated based on the existing source route.

  FIG. 11 is a diagram illustrating an operation in which the gateway 201 transmits a registration response message to the node 101-n when the node 101-n enters the wireless mesh network 1000. The gateway 201 transmits a registration response message addressed to the node 101-n to permit entry into the wireless mesh network 1000. In the gateway 201, the downlink routing processing unit 205 creates a source route designating the node 101 to hop to the node 101-n based on the contents of its own downlink route table recording unit 207, and the message processing unit 204 A registration response message describing the route is created, and the registration response message is unicast transmitted to the node 101-b via the wireless communication unit 203 and the antenna unit 202.

  The node 101-b that has received the registration response message refers to the source route described in the registration response message and transfers the registration response message to the node 101-e.

  The node 101-e that has received the registration response message refers to the source route described in the registration response message and transfers the registration response message to the node 101-j.

  The node 101-j that has received the registration response message refers to the source route described in the registration response message and transfers the registration response message to the node 101-n.

  When the node 101-n receives the registration response message, the node 101-n finishes the entry process because it can register itself with the gateway 201.

  As described above, according to the present embodiment, the nodes constituting the wireless mesh network rank the wireless link quality level to the gateway, record it as route statistical information, and newly enter the wireless mesh network. When a node enters, it acquires route statistical information from each adjacent node. As a result, the joining node acquires not only the quality of the wireless link between adjacent nodes but also the state of the wireless link from the transmission source to the destination as the route statistical information, so that the entire route in the wireless mesh network can be obtained. Since the route considering the quality of the wireless link can be selected, the route satisfying the desired communication quality in the entire route can be selected.

  In the present embodiment, the joining node 101 selects a route based on the processing of the flowchart of FIG. 8, but the present invention is not limited to this. One with a small number of wireless links may be selected, or one having a higher number of wireless links among a plurality of quality levels may be selected.

  In this embodiment, RSSI at the time of reception is used to determine the rank of the route. However, other indicators such as BER (Bit Error Rate), PER (Packet Error Rate), and the number of message retransmissions may be used. . Two or more of these indices may be used in combination.

Embodiment 2. FIG.
In the first embodiment, when the node 101 enters the wireless mesh network 1000, the joining node 101 obtains the route statistical information from the adjacent node 101 to the gateway 201, so that the link quality of the entire route is considered. Route selection was performed. In the present embodiment, when searching for the existing node 101 from the gateway 201, a route search is performed in consideration of the link quality of the entire route. A different part from Embodiment 1 is demonstrated.

  FIG. 12 is a diagram illustrating a configuration example of a wireless mesh network according to the present embodiment. The wireless mesh network 1001 includes a plurality of nodes 101-a to 101-f and a gateway 201. The wireless links 301-a to 301 are connected between the nodes 101 and between the gateway 201 and the node 101. Connected by -f. Here, the nodes 101-a to 101-f autonomously configure a network. The configurations of the nodes 101-a to 101-f and the gateway 201 are the same as those in the first embodiment.

  FIG. 13 is a diagram illustrating the route statistical information that the nodes 101-a to 101-f of the present embodiment hold in the respective route statistical information recording units 107. The format is the same as in the first embodiment.

  Next, operations of the node 101 and the gateway 201 when the gateway 201 performs a route search in the wireless mesh network 1001 will be described. In the wireless mesh network 1001, the wireless link 301 may cause a link error due to changes in the surrounding environment. The gateway 201 can detect the link error of the node 101 because the link error report from each node 101 or the data collected periodically has not reached as in the conventional case. Here, a case where the gateway 201 detects a link error of the wireless link 301-e to the node 101-e will be described.

  When the gateway 201 detects a link error of the node 101-e, the message processing unit 204 updates the node connection information of the downlink route table recording unit 207 to a link error, creates a downlink route search message, and performs wireless communication. A downlink route search message is broadcasted via unit 203 and antenna unit 202.

  When the nodes 101-a, 101-b, and 101-d receive the downlink route search message from the gateway 201 via the antenna unit 102 and the wireless communication unit 103, the message processing unit 105 or the like downloads according to the flowchart shown in FIG. Process the route search message. FIG. 14 is a flowchart showing registration processing of the route statistical information recording unit 107 and the route table recording unit 108 in the nodes 101-a to 101-f of the wireless mesh network 1001.

  In the node 101 that has received the downlink route search message, the link quality determination unit 104 determines the link quality when the downlink route search message is received and ranks it (step S201). Specifically, in the example illustrated in FIG. 12, the quality level of the radio link 301-a is A in the node 101-a, the quality level of the radio link 301-b is A in the node 101-b, and the radio link is in the node 101-d. The quality level of 301-d is C.

  When the downlink route search message is transferred from another node 101, the message processing unit 105 acquires the route statistical information of the adjacent node 101 that is the downlink route search message transfer source described in the downlink route search message. Then, the acquired route statistical information and the quality level information ranked by the link quality determination unit 104 are integrated (step S202). The integrated route statistical information is used as the route statistical information about the adjacent node 101 that is the forward route search message transfer source. For the nodes 101-a, 101-b, and 101-d that have directly received the downlink route search message from the gateway 201, the link quality determination unit 104 does not include route statistical information in the received downlink route search message. The quality level information ranked in the above is used as route statistical information.

  The message processing unit 105 refers to the temporary area of the route statistical information recording unit 107 (step S203). If no information is registered (step S203: Yes), the message processing unit 105 adds 1 to the number of hops to the gateway 201 included in the downlink route search message to obtain the number of hops from itself to the gateway 201. Then, the adjacent gateway 201 or the adjacent node 101 that is the transmission source of the downlink route search message is registered in the route table recording unit 108 as a parent. Further, the message processing unit 105 registers the route statistical information generated for the adjacent gateway 201 or the adjacent node 101 that is the transmission source of the downlink route search message in the temporary area of the route statistical information recording unit 107 (step S204).

  On the other hand, when information has already been registered in the temporary area of the route statistical information recording unit 107 (step S203: No), the message processing unit 105 stores the route statistical information recorded in the temporary area of the route statistical information recording unit 107. (Step S205), and the number of each quality level recorded in the temporary area of the route statistical information generated for the adjacent gateway 201 or the adjacent node 101 of the downlink route search message transmission source and the current (existing) route statistical information. Are compared (steps S206 to S213).

  First, the message processing unit 105 checks whether or not the number of quality levels D of the route statistical information generated from the downlink route search message is smaller than the number of quality levels D of the temporary area of the existing route statistical information (step S206). When the number of quality levels D is smaller in the route statistical information generated from the downlink route search message (step S206: Yes), the message processing unit 105 sets 1 to the number of hops to the gateway 201 included in the downlink route search message. The number of hops from itself to the gateway 201 is added, and the adjacent gateway 201 or adjacent node 101 that is the transmission source of the downlink route search message is registered as the parent in the route table recording unit 108, and the route generated from the downlink route search message Statistical information is registered in the temporary area of the route statistical information recording unit 107 (step S204).

  When the number of quality levels D of the route statistical information generated from the downlink route search message is equal to or greater than the number of quality levels D of the temporary area of the existing route statistics information (step S206: No), the message processing unit 105 displays the downlink route search message. Whether the number of quality levels D of the route statistical information generated from the number of quality levels D of the temporary area of the existing route statistical information is the same (step S207).

  When the number of quality levels D of the route statistical information generated from the downlink route search message is the same as the number of quality levels D of the temporary area of the existing route statistical information (step S207: Yes), the message processing unit 105 then It is confirmed whether or not the number of quality levels C of the route statistical information generated from the downlink route search message is smaller than the number of quality levels C of the temporary area of the existing route statistical information (step S208). When the number of quality levels C is smaller in the route statistical information generated from the downlink route search message (step S208: Yes), the message processing unit 105 sets 1 to the number of hops to the gateway 201 included in the downlink route search message. The number of hops from itself to the gateway 201 is added, and the adjacent gateway 201 or adjacent node 101 that is the transmission source of the downlink route search message is registered as the parent in the route table recording unit 108, and the route generated from the downlink route search message Statistical information is registered in the temporary area of the route statistical information recording unit 107 (step S204).

  The message processing unit 105 determines that the number of quality levels D of the route statistical information generated from the downlink route search message is not the same as the number of quality levels D of the temporary region of the existing route statistics information, that is, from the downlink route search message. If the generated route statistical information has a higher number of quality levels D (step S207: No), the process is terminated.

  When the number of quality levels C of the route statistics information generated from the downlink route search message is equal to or greater than the number of quality levels C of the temporary area of the existing route statistics information (step S208: No), the message processing unit 105 displays the downlink route search message. It is checked whether the number of quality levels C of the route statistical information generated from the number of quality levels C in the temporary area of the existing route statistical information is the same (step S209).

  When the number of quality levels C of the route statistical information generated from the downlink route search message is equal to the number of quality levels C of the temporary area of the existing route statistical information (step S209: Yes), the message processing unit 105 then Whether the sum of the number of quality levels A and quality levels B of the route statistical information generated from the downlink route search message is less than the sum of the number of quality levels A and quality levels B in the temporary area of the existing route statistical information Is confirmed (step S210). When the route statistical information generated from the downlink route search message has a smaller total number of quality levels A and B (step S210: Yes), the message processing unit 105 includes the gateway included in the downlink route search message. 1 is added to the number of hops up to 201 to obtain the number of hops from itself to the gateway 201, and the adjacent gateway 201 or the adjacent node 101 of the downlink route search message transmission source is registered as a parent in the route table recording unit 108. The route statistical information generated from the downlink route search message is registered in the temporary area of the route statistical information recording unit 107 (step S204).

  Note that the message processing unit 105 determines that the number of quality levels C of the route statistical information generated from the downlink route search message is not the same as the number of quality levels C of the temporary region of the existing route statistical information, that is, from the downlink route search message. If the generated route statistical information has a higher number of quality levels C (step S209: No), the process ends.

  When the sum of the number of quality levels A and quality levels B of the route statistical information generated from the downlink route search message is equal to or greater than the sum of the number of quality levels A and quality levels B in the temporary area of the existing route statistical information ( In step S210: No), the message processing unit 105 sums the number of quality levels A and quality levels B of the route statistical information generated from the downlink route search message, and the number of quality levels A of the temporary area of the existing route statistical information. And whether the total number of quality levels B is the same (step S211).

  When the total number of quality levels A and quality levels B of the route statistical information generated from the downlink route search message is the same as the total number of quality levels A and quality levels B of the temporary area of the existing route statistical information (Step S211: Yes) Next, the message processing unit 105 determines whether the number of quality levels A of the route statistical information generated from the downlink route search message is greater than the number of quality levels A of the temporary area of the existing route statistical information. Is confirmed (step S212). If the route statistical information generated from the downlink route search message has a higher number of quality levels A (step S212: Yes), the message processing unit 105 sets 1 to the number of hops to the gateway 201 included in the downlink route search message. The number of hops from itself to the gateway 201 is added, and the adjacent gateway 201 or adjacent node 101 that is the transmission source of the downlink route search message is registered as the parent in the route table recording unit 108, and the route generated from the downlink route search message Statistical information is registered in the temporary area of the route statistical information recording unit 107 (step S204).

  The message processing unit 105 adds the number of quality levels A and quality levels B of the route statistical information generated from the downlink route search message, the number of quality levels A and the quality level B of the temporary area of the existing route statistical information. If the sum of the numbers is not the same, that is, if the route statistical information generated from the downlink route search message has a larger total number of quality levels A and B (step S211: No), the process is terminated. To do.

  When the number of quality levels A of the route statistical information generated from the downlink route search message is equal to or less than the number of quality levels A of the temporary area of the existing route statistics information (step S212: No), the message processing unit 105 displays the downlink route search message. Whether the number of quality levels A of the route statistical information generated from the number of quality levels A in the temporary area of the existing route statistical information is the same, and the received power level RSSI registered in the route table recording unit 108 And the received power level RSSI when the downlink route search message is received (step S213).

  The number of quality levels A of the route statistical information generated from the downlink route search message is equal to the number of quality levels A of the temporary area of the existing route statistical information, and the received power level RSSI registered in the route table recording unit 108. As a result of comparing the received power level RSSI at the time of receiving the downlink route search message and the power level RSSI at the time of receiving the downlink route search message is larger (step S213: Yes), the message processing unit 105 sets the downlink route search message to 1 is added to the number of hops to the included gateway 201 to obtain the number of hops from itself to the gateway 201, and the adjacent gateway 201 or the adjacent node 101 that is the source of the downlink route search message is registered as a parent in the route table recording unit 108 And the downstream route search message The generated route statistics from registers in the temporary area of the path metrics memory 107 (step S204).

  Note that the message processing unit 105 determines that the number of quality levels A of the route statistical information generated from the downlink route search message is not the same as the number of quality levels A of the temporary area of the existing route statistics information, that is, from the downlink route search message. When the generated route statistical information has a smaller number of quality levels A, and / or when the power level RSSI when the downlink route search message is received is equal to or lower than the received power level RSSI registered in the route table recording unit 108 ( Step S213: No), the process ends.

  Each node 101 repeatedly executes the above-described processing (steps S201 to S213) as many times as the number of downlink route search messages received, and accepts the downlink route search message after a predetermined time has elapsed after receiving the first downlink route search message. And the information of the temporary area is determined by the information registered in the temporary area of the route statistics information recording unit 107 at that time. In each node 101, the message processing unit 105 adds a route created from the downlink route search message to the received downlink route search message corresponding to the route statistical information registered in the temporary area of the route statistical information recording unit 107. The statistical information is added, and the node ID of the node is added to the source route for broadcast transfer.

  FIG. 15 is a diagram illustrating a state in which a downlink route search message is transferred from the gateway 201 in the wireless mesh network 1001. In nodes 101-a, 101-b, and 101-d, the reception of the downlink route search message is closed when a predetermined time has elapsed since the reception of the first downlink route search message, and the downlink route search message is created from the message. The route statistical information is added, and the node ID of the node is added to the source route for broadcast transfer.

  The nodes 101-c to 101-f also perform the same operation as the above processing (steps S201 to S213). As a result, the wireless mesh network 1001 can flood the downlink route search message from the gateway 201 and reach the downlink route search message to the node 101-e in which the link error has occurred.

  When the node 101-e receives the downlink route search message targeting itself, the node 101-e performs the processing of the flowchart shown in FIG.

  FIG. 16 is a diagram illustrating the route statistical information that the nodes 101-a to 101-f according to the present embodiment hold in the respective route statistical information recording units 107. This shows the route statistics information that each node 101 after flooding the downlink route search message holds in the route statistics information recording unit 107. Compared with the route statistical information of FIG. 13, it can be seen that the quality information of the radio link based on the received downlink route search message is added to each temporary region (tmp).

  Further, in the node 101-e, when a predetermined time has elapsed since the message processing unit 105 first received the downlink route search message, the temporary area information of the route statistical information recording unit 107 is used as route information to the gateway 201. Register, create a downlink route search response message describing the source route (node 101-b / 101-d / node 101-e) described in the downlink route search message, and search for the downlink route destined for the gateway 201 The response message is unicast transmitted to the node 101-d via the wireless communication unit 103 and the antenna unit 102. FIG. 17 is a diagram illustrating a state in which a downlink route search response message is transferred from the node 101-e in the wireless mesh network 1001. Here, the node 101-e and the node 101-f are connected by a wireless link 301-e, and the node 101-d and the node 101-b are connected by a wireless link 301-d ′.

  In the node 101-d, when the message processing unit 105 receives the downlink route search response message described in the source route, the message processing unit 105 stores the temporary area information of the route statistical information recording unit 107 created when the downlink route search message is received. A downlink route search response message is forwarded via the wireless communication unit 103 and the antenna unit 102 to the next hop node 101-b registered in the route information and described in the source route determined by the routing processing unit 106 as the next hop. To do.

  In the node 101-b, when the message processing unit 105 receives the downlink route search response message described in the source route, the message processing unit 105 stores the temporary region information of the route statistical information recording unit 107 created when the downlink route search message is received. A downlink route search response message is transferred via the wireless communication unit 103 and the antenna unit 102 to the destination gateway 201 registered as route information and determined as the next hop by the routing processing unit 106.

  In the gateway 201 that has received the downlink route search response message, the message processing unit 204 refers to the source route described in the downlink route search response message, acquires route information to the node 101-e, and records the downlink route table. The unit 207 is updated.

  Note that the nodes 101-a, 101-c, and 101-f that have not received the downlink route search response message receive a temporary area from the route statistics information recording unit 107 after a predetermined time has passed since the downlink route search message was transferred. Delete information. FIG. 18 is a diagram illustrating the route statistical information that the nodes 101-a to 101-f according to the present embodiment hold in the respective route statistical information recording units 107. Compared to FIG. 16, the nodes 101-b, 101-d, and 101-e update the route statistical information based on the temporary information, and the nodes 101-a, 101-c, and 101-f are in the temporary area. It shows how information has been deleted. As shown in FIG. 17, for the transmission source node 101-e of the downlink route search response message and the forwarding nodes 101-b and 101-d, the route statistical information is updated based on the temporary information.

  As described above, according to the present embodiment, when a gateway that configures a wireless mesh network detects a link error for a node that already configures the wireless mesh network, the gateway transmits a downlink route search message, The node that received the downlink route search message decided to forward it including the route statistical information. As a result, the node serving as the destination of the downlink route search message can select a route in consideration of the quality of the wireless link of the entire route in the wireless mesh network, as in the first embodiment. A route that satisfies the conditions can be selected.

  In the present embodiment, the node that has entered has selected a route based on the processing of the flowchart of FIG. 14, but this is not a limitation, and simply the lower quality level among a plurality of quality levels. You may select the thing with few radio links, and you may select the thing with many radio links with a higher quality level among several quality levels.

Embodiment 3 FIG.
In the first and second embodiments, the method of considering the link quality of the entire route when constructing / searching the route from the node 101 or the gateway 201 has been described. In the present embodiment, the route table held by the node 101 is updated by adding route statistical information to the message from the gateway 201. A different part from Embodiment 1, 2 is demonstrated.

  FIG. 19 is a diagram illustrating a configuration example of a wireless mesh network according to the present embodiment. The wireless mesh network 1002 includes a plurality of nodes 101-a to 101-f and a gateway 201. The wireless links 301-a to 301 are connected between the nodes 101 and between the gateway 201 and the node 101. Connected by -f. Here, the nodes 101-a to 101-f autonomously configure a network. The configurations of the nodes 101-a to 101-f and the gateway 201 are the same as those in the first and second embodiments.

  In FIG. 19, the node 101-b uses the gateway 201 as the parent, but since a link error has occurred, the parent 101 stores the parent information recorded in the route table recording unit 108 based on the method of the second embodiment. The route statistics information recorded in the route statistics information recording unit 107 is updated by changing from 201 to the node 101-a. FIG. 20 shows a state of the wireless mesh network after the node 101-b changes the parent after the link error occurs. It can be seen that the parent of the node 101-b is changed from the gateway 201 to the node 101-a. The node 101-b and the node 101-a are connected by a wireless link 301-b ′.

  Here, since the parent of the node 101-b is changed from the gateway 201 to the node 101-a, the nodes 101-d, 101-e, and 101-f existing downstream of the node 101-b in the path table record. The number of hops to the gateway 201 recorded in the unit 108 and the contents of the route statistical information recorded in the route statistical information recording unit 107 are different from the actual route, resulting in inconsistency.

  In such a case, when the gateway 201 detects that the route of the node 101-b has changed, the gateway 201 adds an area of route statistical information to the message for the nodes 101-d, 101-e, and 101-f. Then send.

  The intermediate node 101-d that has received the message to which the region of the route statistical information is added determines the link quality at the time of receiving the message, integrates it with the route statistical information described in the message, and obtains a route statistical information recording unit 107 is overwritten.

  Also, the intermediate node 101-d that has received the message with the route statistics information area acquires the number of hops from the gateway 201 to itself by following the source route described in the message, The table recording unit 108 is updated.

  The intermediate node 101-d overwrites the route statistical information area of the message with its own route statistical information, and forwards the message to the next hop node described in the source route.

  By repeating the message transfer up to the message destination nodes 101-e and 101-f, the route tables and routes of the downstream nodes 101-d, 101-e, and 101-f generated by the route change of the upstream node 101-b. Inconsistencies in statistical information can be corrected.

  As described above, in this embodiment, it is possible to always keep the route state of the wireless mesh network 1002 in the latest state by always describing the route statistical information in the message transmitted from the gateway 201.

  Note that the gateway 201 may transmit the route statistical information in an arbitrary message only when the connection change of the wireless mesh network 1002 is detected. Thereby, it is possible to reduce the normal message transmission overhead as compared with the case where the path statistical information is always described.

  In the first to third embodiments, the route statistical information is a value obtained by accumulating the link quality up to the gateway 201 by rank. However, the present invention is not limited to this, and for example, it is combined with the source route for each link. You may notify the information which matched the quality, ie, the hop position of each node, and the quality level of the radio link.

  As described above, the node according to the present invention is useful for wireless communication, and is particularly suitable for a wireless mesh network.

  101-a to 101-k, 101-n node, 102 antenna unit, 103 wireless communication unit, 104 link quality determination unit, 105 message processing unit, 106 routing processing unit, 107 route statistical information recording unit, 108 route table recording unit , 201 gateway, 202 antenna unit, 203 wireless communication unit, 204 message processing unit, 205 downlink routing processing unit, 206 database, 207 downlink route table recording unit, 301-a to 301-k, 301-b ′, 301-d ´ Wireless link.

Claims (15)

A node in a wireless mesh network composed of a gateway and a plurality of nodes,
Based on a signal or message received from another node or the gateway, the quality of the radio link of the route between the other node or the gateway and the own node is determined using one or more thresholds. Link quality determination means for determining whether to divide the crab,
Acquires route statistical information, which is information on the quality of the radio link of the route from the other node to the gateway, and information on the number of hops to the gateway included in the message received from the other node, and acquires the other node And the quality level information determined by the link quality determination means are integrated, and the message transmitted from the own node includes the route statistical information of the own node and the number of hops to the gateway. Message processing means for controlling transmission;
Route statistical information recording means for recording the integrated route statistical information integrated by the message processing means as route statistical information from the own node to the gateway;
Route table recording means for recording information on the number of hops to the gateway and information on the next hop destination;
Routing processing means for determining a route of a signal or message to be transmitted based on information recorded in the route table recording means;
With
The message processing means, when receiving messages from a plurality of other nodes, selects one post-integration route statistical information based on the post-integration route statistical information of each node.
A node characterized by that. The quality level of the radio link includes at least one of RSSI, BER, PER, and number of retransmissions of a received signal or message.
The node according to claim 1. The route statistical information is information indicating how many wireless links are included for each of a plurality of quality levels for a route from the self-node to the gateway.
The node according to claim 1 or 2, characterized in that The route statistical information is information in which the hop position of each node is associated with the quality level of the radio link,
The node according to claim 1 or 2, characterized in that In an entry node that requests entry into the wireless mesh network,
The message processing means performs control to transmit an entry request message for requesting entry into the wireless mesh network of the own node, to an already joined node that has entered the wireless mesh network,
In the existing nodes,
The message processing means performs control to include the route statistical information of the own node and the information on the number of hops in an entry response message that is a response to the entry request message.
The node according to any one of claims 1 to 4, wherein: In the entry node,
The link quality determination means determines the quality level of the radio link with the existing node based on the participation response message received from the existing node,
The message processing means obtains the route statistical information of the already-entered node included in the entry response message received from the already-joined node, and the obtained route statistical information of the already-joined node and the link quality determination means Integrating the determined quality level information, and recording the integrated route statistical information in the route statistical information recording means;
The node according to claim 5. When an entry response message is received from multiple existing nodes,
In the entry node,
The message processing means selects, from the integrated route statistical information integrated for each existing node, one having a lower number of wireless links having a lower quality level among a plurality of quality levels.
The node according to claim 6. When an entry response message is received from multiple existing nodes,
In the entry node,
The message processing means selects, from the integrated route statistical information integrated for each existing node, one having a higher number of wireless links with a higher quality level among a plurality of quality levels.
The node according to claim 6. When the gateway performs route search of the wireless mesh network,
In the node that received the route search message by flooding from the gateway,
The link quality determination means determines a quality level of a radio link with the gateway or a route search message transfer source node based on the received route search message,
The message processing means acquires route statistical information of the route search message transfer source node included in the route search message received from the route search message transfer source node, and acquires the route of the acquired route search message transfer source node When the statistical information and the quality level information determined by the link quality determination unit are integrated and a plurality of the route search messages are received, one integration is performed based on the integrated route statistical information for each route search message. Select post-route statistical information and record it in a temporary area of the route statistical information recording means.
The node according to any one of claims 1 to 8, characterized in that: In a node that receives a plurality of the route search messages,
The message processing means selects, from the integrated route statistical information for each route search message, one having a lower number of wireless links having a lower quality level among a plurality of quality levels.
The node according to claim 9. In a node that receives a plurality of the route search messages,
The message processing means selects, from the integrated route statistical information for each route search message, one having a higher number of radio links having a higher quality level among a plurality of quality levels.
The node according to claim 9. In the node that is the destination of the route search message,
The message processing means updates the route statistical information of its own node based on the information recorded in the temporary area after a predetermined time has elapsed since receiving the first route search message, and responds to the route search message. Control to send a route search response message to the gateway;
The node according to claim 9, 10 or 11. In the node that has received the route search response message,
The message processing means updates the route statistical information of its own node based on the information recorded in the temporary area, and performs control to transmit the route search response message to the gateway.
The node according to claim 12. When the gateway sends a normal message with an area of route statistics information,
In the node that received the route statistics information area addition message,
The link quality determination means determines a quality level of a radio link between the gateway or the route statistics information area addition message transfer source node based on the route statistics information area addition message,
The message processing means acquires the route statistical information of the gateway or the route statistical information region additional message transfer source node included in the route statistical information region additional message, and acquires the acquired gateway or the route statistical information region additional message. Integrating the route statistical information of the transfer source node and the information of the quality level determined by the link quality determining unit, and recording the integrated route statistical information in the route statistical information recording unit;
The node according to any one of claims 1 to 13, characterized in that: The gateway adds an area of route statistical information as an option to a normal message, so that the message sender can update the route information at an arbitrary timing.
The node according to claim 14, wherein:

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