JP6977604B2 - Wireless communication equipment, wireless communication programs, wireless communication methods, and wireless communication systems - Google Patents

Description

The present invention relates to wireless communication devices, wireless communication programs, wireless communication methods, and wireless communication systems, for example, a sensor network (for example, a large number of wireless communication devices distributed in space directly relay data. It can be applied to a system that communicates with a wireless communication device in an area where a wireless signal does not reach).

Conventionally, there is a technique described in Non-Patent Document 1 as a route control technique for a communication device that performs multi-hop communication. In the section of "7. Sequence counter" of Non-Patent Document 1, it is described that the operation is switched by comparing the sequence counters held by each communication device.

Normally, if the counter is 1 byte, the sequence counter often used in a computer system increments for each event when counting from 0, and returns to 0 again when incrementing from 255. On the other hand, in the communication device described in Non-Patent Document 1, a linear interval counting only at the time of initialization (for example, 128 to 255 in the case of 1 byte) and a circular interval counting after the linear interval (for example, 1 byte). In the case, the count is divided into 0 to 127). Further, in the communication device described in Non-Patent Document 1, when the wireless communication device is activated, counting starts from a linear section (a value of any of 128 to 255), but the last value of the linear section (a value of any of 128 to 255) is started. After 255), the value (0) at the beginning of the circular section is set, and when counting up to the last value (127) of the circular section thereafter, the count returns to the beginning (0) of the circular section again. In the communication device described in Non-Patent Document 1, by performing the counting process as described above, the counter value is returned from the circular section to the linear section by the comparison of the counter values, and the counter is within the linear section. It is possible to detect that the value of is small and notify other communication devices that the device has restarted.

IETF, "RFC6550 RPL (IPv6 Routing Protocol for Low-Power And Rossy Networks)" [Search January 27, 2018], [Online], INTERNET, <URL: https://tools.ietf.org/html/rfc6550 >

Here, in a network in which a plurality of wireless communication devices perform multi-hop communication, the technique described in Non-Patent Document 1 is used, and the sequence counters updated by the master unit of the tree-shaped route are compared by comparing the master unit of the route. It is assumed that the restart of is detected. In this case, for example, the sequence counter value is described in a control packet transmitted from the root master unit, and the control packet is propagated in the network to notify each wireless communication terminal in the wireless network of the sequence counter value. be able to. In that case, there is always a delay in the propagation of the sequence counter value in the wireless network worm, and the delay is very large especially when the transmission frequency of control packets is suppressed in order to operate each wireless communication terminal in a power-saving manner. Become.

If the propagation delay of the control packet becomes large in the conventional wireless network, the control packet may not be propagated and the old sequence counter value may be retained. Then, in the conventional wireless network, there is a restarted wireless communication terminal, and when the wireless communication terminal receives information from the wireless communication terminal holding the above-mentioned old sequence counter value, the restarted wireless communication terminal also receives information. The old sequence counter value will be retained. On the other hand, if the frequency of transmission of control packets from the root master unit is shortened, efficient communication will not be possible for the entire network.

In view of the above problems, wireless communication capable of more efficiently propagating data related to communication control (for example, the sequence counter value of the root master unit) in a network provided with a plurality of wireless communication devices. Devices, wireless communication programs, wireless communication methods, and wireless communication systems are desired.

The first wireless communication device of the present invention is a network having a tree structure, which is a wireless communication means for relaying packets received from other wireless communication devices in the network, and (2) a sequence counter value. The sequence counter updating means for updating the above, (3) the sequence counter value notifying means for causing the wireless communication means to send a packet describing the sequence counter value updated by the sequence counter updating means, and (4) the wireless communication means. However, when a packet containing the updated sequence counter value is received by the root radio communication device arranged at the root of the network, the first counter value holding means for acquiring and holding the sequence counter value and the first counter value holding means. (5) When the wireless communication means receives a packet containing a sequence counter value updated by a nearby wireless communication device capable of direct wireless communication, a second counter that acquires and holds the sequence counter value. When the value holding means and (6) the first counter value holding means newly acquired the sequence counter value, the first counter value holding means compares the newly acquired sequence counter value with the previously acquired and held sequence counter value. Based on the comparison result, the first counter value determining means for determining the presence or absence of an abnormality in the sequence counter value newly acquired by the first counter value holding means, and (7) the second counter value holding means. When the means acquires a newly acquired sequence counter value, the second counter value holding means compares the newly acquired sequence counter value with the previously acquired and held sequence counter value, and based on the comparison result, holds the second counter value. According to the determination results of the second counter value determining means for determining the presence or absence of an abnormality in the sequence counter value newly acquired by the means, (8) the first counter value determining means, and the second counter value determining means. It is characterized by having a restart determination means for determining whether or not the root wireless communication device is restarted.

The second wireless communication program of the present invention performs a routing process of relaying a packet received from another wireless communication device of the network in a network having a tree structure (1) to a computer mounted on the wireless communication device. Communication means, (2) sequence counter updating means for updating the sequence counter value, and (3) sequence counter value notification for causing the wireless communication means to send a packet describing the sequence counter value updated by the sequence counter updating means. When the means and (4) the wireless communication means receive a packet in which the sequence counter value updated by the root wireless communication device arranged at the root of the network is described, the sequence counter value is acquired and held. When the first counter value holding means and (5) the wireless communication means receive a packet in which the sequence counter value updated by a nearby wireless communication device capable of direct wireless communication is received, the sequence counter value is received. When the second counter value holding means for acquiring and holding the packet and (6) the sequence counter value newly acquired by the first counter value holding means are acquired, the first counter value holding means previously acquires the packet. The first counter value determining means for determining whether or not there is an abnormality in the sequence counter value newly acquired by the first counter value holding means based on the comparison result and the sequence counter value held in the process. (7) When the second counter value holding means acquires a newly acquired sequence counter value, it is compared with the sequence counter value previously acquired and held by the second counter value holding means, and the comparison result is obtained. Based on this, the second counter value determining means for determining the presence or absence of an abnormality in the sequence counter value newly acquired by the second counter value holding means, (8) the first counter value determining means, and the first counter value determining means. It is characterized in that it functions as a restart determination means for determining whether or not the root radio communication device is restarted according to the determination result of the counter value determination means of 2.

A third aspect of the present invention relates to a wireless communication method performed by a wireless communication device, wherein (1) a wireless communication means, a sequence counter update means, a sequence counter value notification means, a first counter value holding means, and a second counter value holding means. , A first counter value determining means, a second counter value determining means, and a restart determining means are provided. (2) The wireless communication means is a tree-structured network and is received from another wireless communication device of the network. The routing process for relaying the generated packets is performed, (3) the sequence counter updating means updates the sequence counter value, and (4) the sequence counter value notification means updates the sequence counter value updated by the sequence counter updating means. The described packet is sent to the wireless communication means, and (5) the first counter value holding means is a sequence counter in which the wireless communication means is updated by a root wireless communication device arranged at the root of the network. When a packet in which a value is described is received, the sequence counter value is acquired and held, and (6) the second counter value holding means is a wireless communication in the vicinity where the wireless communication means can directly perform wireless communication. When the device receives a packet in which the updated sequence counter value is described, the sequence counter value is acquired and held, and (7) the first counter value determining means is the first counter value holding means. When the newly acquired sequence counter value is acquired, the first counter value holding means compares it with the sequence counter value previously acquired and held, and based on the comparison result, the first counter value holding means. Determines whether or not there is an abnormality in the newly acquired sequence counter value. (8) When the second counter value determining means acquires the newly acquired sequence counter value by the second counter value holding means. Compared with the sequence counter value previously acquired and held by the second counter value holding means, and based on the comparison result, the presence or absence of an abnormality in the sequence counter value newly acquired by the second counter value holding means is determined. (9) The restart determination means determines whether or not the root radio communication device is restarted according to the determination results of the first counter value determination means and the second counter value determination means. It is characterized by.

A fourth aspect of the present invention comprises a root wireless communication device arranged at the root of a tree-structured network, and a plurality of wireless communication devices arranged under the root wireless communication device in the network, and each of the routes. It is characterized in that the first wireless communication device of the present invention is applied as a wireless communication device arranged under the wireless communication device.

According to the present invention, data related to communication control can be propagated more efficiently in a network including a plurality of wireless communication devices.

It is explanatory drawing which showed the functional configuration of the wireless communication terminal which concerns on embodiment. It is explanatory drawing which showed the whole structure of the wireless communication system which concerns on embodiment. It is explanatory drawing which showed the functional configuration of the wireless communication terminal as a root terminal which concerns on embodiment. It is explanatory drawing (the 1) which showed the state transition of the network in the wireless communication system which concerns on embodiment. It is explanatory drawing (the 2) which showed the state transition of the network in the wireless communication system which concerns on embodiment. It is explanatory drawing (the 3) which showed the state transition of the network in the wireless communication system which concerns on embodiment.

(A) Main Embodiments Hereinafter, an embodiment of a wireless communication device, a wireless communication program, a wireless communication method, and a wireless communication system according to the present invention will be described in detail with reference to the drawings. In this embodiment, an example in which the wireless communication device of the present invention is applied to a wireless communication terminal will be described.

(A-1) Configuration of First Embodiment FIG. 2 is an explanatory diagram showing an overall configuration example of the wireless communication system 1 of this embodiment.

As shown in FIG. 2, the wireless communication system 1 is a terminal (hereinafter, also referred to as a “root terminal” or a “root wireless communication device”) that serves as a route in a multi-hop wireless communication route (tree-structured route). It is assumed that the wireless communication terminal 20 and the four wireless communication terminals 10 (10-B to 10-E) participating in the network N having a tree structure starting from the root terminal are arranged, but the arranged wireless communication The number of terminals 10 is not limited. In the wireless communication system 1, the path of the packet transmitted / received between the root terminal (wireless communication terminal 20) and the other wireless communication terminal 10 is a tree-structured communication starting from the root terminal (wireless communication terminal 20). It is assumed that a route (hereinafter, also referred to as "topology") is set. In the drawings of the present specification, "A" is attached to the block (symbol) of the wireless communication terminal 20, and B to E are attached to the blocks (symbols) of the wireless communication terminals 10-B to 10-E, respectively. ing. The wireless communication terminal 10 corresponds to, for example, a sensor node in a sensor network.

In the following, the wireless communication terminals 10 and 20 on the wireless communication system 1 (network N) will be collectively referred to as "nodes".

The wireless communication terminals 10-B to 10-E perform communication control processing by using a control packet or the like in which a sequence counter value updated by the root terminal (wireless communication terminal 20) is set. Further, the control packet transmitted from the root terminal (wireless communication terminal 20) is propagated by being relayed and transferred by another wireless communication terminal 10.

Here, it is assumed that the wireless communication terminals 10-B and 10-C are arranged at positions where the wireless communication terminal 20 can directly perform wireless communication. Further, here, it is assumed that only the wireless communication terminals 20 and 10-D are arranged at positions where the wireless communication terminals 10-B can directly perform wireless communication. Further, here, it is assumed that only the wireless communication terminals 10-B, 10-C, and 10-E are arranged at positions where the wireless communication terminals 10-D can directly perform wireless communication. Furthermore, here, it is assumed that only the wireless communication terminal 10-D is arranged at a position where the wireless communication terminal 10-E can directly perform wireless communication.

Therefore, the control packet (for example, a broadcast packet such as a Hallo packet) transmitted from the wireless communication terminal 20 propagates to the wireless communication terminal 10-D via the wireless communication terminal 10-B or the wireless communication terminal 10-C. Further, it propagates to the wireless communication terminal 10-E via the wireless communication terminal 10-D.

FIG. 3 is a block diagram showing an internal functional configuration of the wireless communication terminal 20.

The wireless communication terminal 20 has a control unit 21 and a wireless communication unit 22.

The wireless communication terminal 20 is a device (not limited to one) having an execution configuration of programs such as a CPU, ROM, RAM, EEPROM, and a hard disk, and an interface for communicating with other communication devices (a plurality of devices are distributed, not limited to one). It may be configured so that it can be processed.) It may be constructed by installing a program, and even in that case, it can be functionally shown as shown in FIG. 3 above.

The wireless communication unit 22 has a function for wirelessly communicating with another node in the wireless communication terminal 20. When the wireless communication unit 22 receives a packet transmitted from another node, the wireless communication unit 22 gives the packet to at least the control unit 21. Further, the wireless communication unit 22 emits the wireless signal of the packet generated by the control unit 21 to the periphery of the wireless communication terminal 20.

The control unit 21 controls communication with the entire wireless communication terminal 20 and other nodes, and has a communication control unit 210, a sequence counter 211, and a counter update unit 212.

The sequence counter 211 holds the sequence counter value. In the following, the value of the sequence counter held by the sequence counter 211 is represented as the sequence counter value C1.

The communication control unit 210 controls the transmission / reception of packets by the wireless communication unit 22 to perform communication control processing necessary as a root terminal of a tree-structured network N (multi-hop network). Further, the communication control unit 210 also performs processing for responding to various inquiries from the wireless communication terminal 10 connected to the network N as a part of communication control for the network N. The communication control unit 210 sets the sequence counter value C1 of the sequence counter 211 when transmitting a control packet (for example, a packet related to communication control such as a Hallo packet) to a node in the network N.

The communication control unit 210 can recognize the tree structure of the network N by transmitting a control packet and receiving a response from another node (wireless communication terminal 10-B to wireless communication terminal 10-E) or the like. can. The communication control unit 210 propagates the control packet to each node (wireless communication terminal 10-B to wireless communication terminal 10-E) by, for example, a process of transmitting a broadcast control packet (so-called flooding), and propagates the control packet to each node. By selecting the parent node (establishing the topology) and receiving a packet reporting the parent node from each node, the tree structure (parent node of each node) in the network N can be recognized. At this time, each wireless communication terminal 10 retransmits the control packet only once, so that the parent node can be set in each wireless communication terminal 10 while efficiently propagating the control packet. By recognizing the tree structure of the network N, the communication control unit 210 can transmit packets to other nodes (wireless communication terminals 10-B to wireless communication terminals 10-E) by unicast. The communication control unit 210 can unicast packet transmission to other nodes (wireless communication terminal 10-B to wireless communication terminal 10-E), for example, by designating a destination communication path and transmitting a packet. .. The other nodes of the network N (wireless communication terminal 10-B to wireless communication terminal 10-E), for example, relay (forward) a packet addressed to the root terminal to the parent node, so that the packet addressed to the root terminal is relayed (forwarded). Can reach the root terminal.

The counter update unit 212 performs a process of updating the sequence counter value C1 held by the sequence counter 211. The timing at which the counter update unit 212 updates the sequence counter value C1 and the value to be added when updating are not limited. For example, the counter update unit 212 updates the sequence counter value C1 of the sequence counter 211 at a predetermined timing such as every fixed period or every packet transmission of the own node (wireless communication unit 22) (for example, a constant value is added). do. Here, it is assumed that the sequence counter 211 is a 1-byte (8-bit) counter. Then, in the sequence counter 211 (sequence counter value C1), the range of 0 to 127 is used as a linear section, and the range of 128 to 255 is used as a circular section. That is, when the own node is started (restarted), the counter update unit 212 sets the sequence counter value C1 of the sequence counter 211 to the first value (128) of the linear section. Further, the counter update unit 212 initializes the value of the sequence counter value C1 to the first value (0) of the circular section after updating the sequence counter value C1 to the final value (255) of the linear interval. .. Further, the counter update unit 212 initializes the sequence counter value C1 to the first value (0) of the circular section after the sequence counter value C1 becomes the last value (127) of the circular section.

FIG. 1 is a block diagram showing an internal functional configuration of each wireless communication terminal 10 (10-B to 10-E).

In the following, all the wireless communication terminals 10-B to 10-E will be described as having a configuration that can be shown with reference to FIG. 1.

The wireless communication terminal 10 has a control unit 11 and a wireless communication unit 12.

The wireless communication terminal 10 is a device (not limited to one) having an execution configuration for programs such as a CPU, ROM, RAM, EEPROM, and a hard disk, and an interface for communicating with other communication devices (a plurality of devices are distributed, not limited to one). It may be configured so that it can be processed.) It may be constructed by installing the wireless communication program or the like of the embodiment, and even in that case, the function is as shown in FIG. 1 above. Can be shown.

The wireless communication unit 12 has a function for wirelessly communicating with another node in the wireless communication terminal 10. When the wireless communication unit 12 receives the packet transmitted from the other wireless communication terminal 10, the wireless communication unit 12 gives the packet to at least the control unit 11. Further, the wireless communication unit 12 emits the wireless signal of the packet generated by the control unit 11 to the periphery of the wireless communication terminal 10.

The control unit 11 controls communication with the entire wireless communication terminal 10 and other nodes, and is a sequence counter 110, a root terminal counter determination unit 111, a nearby terminal counter determination unit 112, and a root terminal restart determination. It has a unit 113, a counter update unit 114, and a communication control unit 115.

The sequence counter 110 holds the sequence counter value. In the following, the value of the sequence counter held by the sequence counter 110 is represented as the sequence counter value C2.

The counter update unit 114 performs a process of updating the sequence counter value C2 held by the sequence counter 110. As for the process of updating the sequence counter value C2 by the counter update unit 114, the same process as the counter update unit 212 of the wireless communication terminal 20 can be applied, so detailed description thereof will be omitted.

Further, when the wireless communication unit 12 receives the control packet in which the sequence counter value updated by the root terminal (wireless communication terminal 20) is described, the counter update unit 114 uses the sequence counter value described in the control packet. Acquire and hold it as "root terminal counter value C3". When the counter update unit 114 acquires the newly updated sequence counter value in the root terminal (wireless communication terminal 20), the counter update unit 114 refers to the newly acquired sequence counter value (hereinafter referred to as “root terminal latest counter value C4”). Compared with the already held root terminal counter value C3, the root terminal counter value C3 to be held is changed to the root terminal latest counter value C4 only when the root terminal latest counter value C4 is ahead of the root terminal counter value C3. Update to.

Further, the counter updating unit 114 describes a packet in which the sequence counter value updated by the wireless communication unit 12 at the wireless communication terminal 10 (hereinafter, referred to as “neighboring terminal”) capable of directly wirelessly communicating with the own node is described. When it is received, the sequence counter value described in the packet is acquired and held as "neighborhood terminal counter value C5". The counter update unit 114 holds the neighborhood terminal counter value C5 in association with the address (for example, MAC address or short address) for each neighborhood terminal. That is, the counter update unit 114 holds the neighborhood terminal counter value C5 for the number of neighboring terminals. When the counter update unit 114 newly acquires the sequence counter value of the neighboring terminal (hereinafter referred to as “nearby terminal latest counter value C6”), the near terminal counter value C5 corresponding to the neighboring terminal is newly acquired. Update to the terminal latest counter value C6. In the following, it is assumed that the root terminal (wireless communication terminal 20) is excluded from the neighboring terminals.

The communication control unit 115 performs communication control processing necessary as a node on the network N by transmitting and receiving packets using the wireless communication unit 12.

For example, the communication control unit 115 performs an operation of joining the network N (an operation including a process of selecting a route for reaching the root terminal) at a timing such as at the time of initial startup. The details of the network subscription operation by the communication control unit 115 are not limited. For example, when the communication control unit 115 starts network operation, it sends out a control packet requesting network subscription to the root terminal (for example, sends a broadcast packet), and the control packet returned from the root terminal (for example, Hallo packet). Etc.), the parent node of the own node may be determined and a process of establishing a topology with the parent node may be performed. Specifically, for example, the communication control unit 115 communicates with the wireless communication terminal 20 the node of the transmission source when the control packet (broadcast packet) transmitted from the root terminal (wireless communication terminal 20) is first received. It may be selected as the parent node to do so.

Since the above-mentioned subscription operation greatly increases the traffic on the network N, the communication control unit 115 may use the communication control unit 115 when the link with the parent node is broken (for example, when a communication error or timeout occurs). May make an inquiry to a neighboring terminal and re-recognize any of the neighboring terminals as a parent node without using a broadcast packet.

Further, for example, the communication control unit 115 performs processing based on a routing function for relaying (forwarding) received packets. For example, when the communication control unit 115 receives a packet addressed to the root terminal (wireless communication terminal 20), the communication control unit 115 forwards the packet to the parent node. Further, for example, when the communication control unit 115 receives a packet addressed to another wireless communication terminal 10, the communication control unit 115 transfers the packet to the next transfer destination node set for the packet.

Further, for example, when the communication control unit 115 receives the broadcast packet (packet having the broadcast address as the destination address) transmitted from the root terminal (wireless communication terminal 20) directly or via another wireless communication terminal 10. The process of transferring (retransmitting) the control packet to the wireless communication unit 12 only once is performed.

Furthermore, for example, the communication control unit 115 performs a predetermined timing (for example, a timing based on a request from another node, a timing at regular time intervals, a restart timing, or a subscription operation to the network N). At the timing), a process may be performed in which a control packet (a packet notified to a neighboring terminal) describing the sequence counter value C2 and the root terminal counter value C3 held by the own node is sent to the wireless communication unit 12.

Further, for example, the communication control unit 115 sets each sequence counter value for neighboring nodes at predetermined timings (for example, timing at regular time intervals, timing of restarting, timing of joining network N). The wireless communication unit 12 may be made to send a transmission request of the control packet describing (sequence counter value C2 and root terminal counter value C3).

As described above, the communication control unit 115 performs various communication control processes necessary as a node on the network N.

When the counter update unit 114 newly acquires the sequence counter value of the root terminal (wireless communication terminal 20), the route terminal counter determination unit 111 already holds the latest acquired root terminal latest counter value C4. A comparison process with the root terminal counter value C3 is performed, and based on the comparison processing result, a determination process for determining the presence or absence of an abnormality regarding the latest acquired root terminal latest counter value C4 is performed.

The root terminal counter determination unit 111 determines that it is normal if the root terminal latest counter value C4 is advanced from the root terminal counter value C3, and the root terminal latest counter value C4 is a value returned from the root terminal counter value C3. If so, it is judged to be abnormal.

When the root terminal latest counter value C4 is the same as the root terminal counter value C3, the determination result by the root terminal counter determination unit 111 is the method of updating the sequence counter value in the root terminal (wireless communication terminal 20) and the method of notification. Depends on.

For example, if the root terminal (wireless communication terminal 20) updates the sequence counter value for each packet transmission and the packet is not retransmitted, the wireless communication terminal 10 (10-B to 10-E) is normally used. , The root terminal counter value C3 and the root terminal latest counter value C4 cannot usually be the same value. Therefore, in this case, the root terminal counter determination unit 111 may determine that the state where the root terminal latest counter value C4 has the same value as the root terminal counter value C3 is determined to be abnormal.

On the other hand, in the root terminal (wireless communication terminal 20), when the sequence counter value is updated at regular intervals or the control packet for transmitting the sequence counter value may be retransmitted, the root terminal latest counter value C4 is set. It may be the same as the root terminal counter value C3. Therefore, in this case, the root terminal counter determination unit 111 may determine that the root terminal latest counter value C4 is normal even if it has the same value as the root terminal counter value C3.

When the counter update unit 114 newly acquires the sequence counter value (neighborhood terminal latest counter value C6), the neighborhood terminal counter determination unit 112 already holds the neighborhood terminal latest counter value C6 and the counter update unit 114. A process of comparing with the neighborhood terminal counter value C5 corresponding to the neighborhood terminal and determining whether or not there is an abnormality regarding the latest acquired neighborhood terminal latest counter value C6 is performed. The determination process in the neighborhood terminal counter determination unit 112 can be applied in the same manner as the determination process by the route terminal counter determination unit 111 (comparison process between the root terminal counter value C3 and the root terminal latest counter value C4). Is omitted.

The root terminal restart determination unit 113 determines whether or not the root terminal (wireless communication terminal 20) has been restarted from the latest determination results of the root terminal counter determination unit 111 and the neighborhood terminal counter determination unit 112. Then, when the root terminal restart determination unit 113 determines that the root terminal (wireless communication terminal 20) has restarted, the operation of controlling the communication control unit 115 to rejoin the own node to the network N (hereinafter, "" Called "re-subscription operation") is executed.

When it is determined that the root terminal (wireless communication terminal 20) has restarted, it is considered that the information of the own node has disappeared from the root terminal (wireless communication terminal 20), so that the root terminal restart determination unit 113 communicates. By controlling the control unit 115 to execute the re-subscription operation, it is possible to notify the root terminal (wireless communication terminal 20) of the existence of the own node.

In the root terminal restart determination unit 113, for example, when the latest determination result of the root terminal counter determination unit 111 is abnormal and the latest determination result of each neighboring terminal by the neighborhood terminal counter determination unit 112 is all normal, the root terminal It is determined that (wireless communication terminal 20) has been restarted. When the root terminal (wireless communication terminal 20) is restarted, the result of the root terminal counter determination unit 111 is determined to be abnormal, but even if the neighboring terminal is restarted, the result of the root terminal counter determination unit 111 becomes abnormal. It may end up. Therefore, the root terminal restart determination unit 113 also considers the determination result of the proximity terminal counter determination unit 112, and determines that the root terminal counter determination unit 111 is abnormal and the proximity terminal counter determination unit 112 is normal (normal for all nearby terminals). It is determined that the root terminal (wireless communication terminal 20) has restarted only when it becomes, and it is determined that the root terminal (wireless communication terminal 20) has not restarted in other cases.

(A-2) Operation of the Embodiment Next, the operation of the wireless communication system 1 of this embodiment having the above configuration will be described.

4 to 6 are explanatory views showing the state transition of the network N in the wireless communication system 1.

First, here, the counter value (sequence counter value C1) of the root terminal (wireless communication terminal 20) and the respective counter values (sequence counter value C2 and root terminal) of each wireless communication terminal 10 (10-A to 10-E). It is assumed that the counter value C3) and the topology are as shown in FIG. Hereinafter, in the wireless communication system 1, the state of FIG. 4 will be referred to as an initial state.

In FIG. 4, a solid line is added between the wireless communication terminals 10 having an established topology. In FIG. 4, between the wireless communication terminal 20 and the wireless communication terminal 10-B, between the wireless communication terminal 20 and the wireless communication terminal 10-C, and between the wireless communication terminal 10-B and the wireless communication terminal 10-D. , And it is assumed that the topology has been established between the wireless communication terminal 10-D and the wireless communication terminal 10-E, respectively. Further, in the state of FIG. 4, C1 = 3 in the wireless communication terminal 20, C2 = 10 and C2 = 3 in the wireless communication terminal 10-B, and C2 = 30 in the wireless communication terminal 10-C. , C3 = 2, C2 = 40 and C3 = 3 in the wireless communication terminal 10-D, and C2 = 20 and C3 = 3 in the wireless communication terminal 10-E.

In the initial state (state of FIG. 4), the sequence counter value C1 managed by the root terminal (wireless communication terminal 20) is 3. However, in the wireless communication terminal 10-C, information is not propagated by the control packet due to poor communication with the root terminal (wireless communication terminal 20) (for example, communication delay or packet loss), so that the root terminal The counter value C3 is "2", which is one before "3".

Then, it is assumed that the power of the wireless communication terminal 10-D is turned off and then restarted in the initial state (state of FIG. 4).

FIG. 5 is an explanatory diagram showing a state of the wireless communication system 1 after the wireless communication terminal 10-D is restarted from the state of FIG.

As shown in FIG. 5, in the control unit 11 of the wireless communication terminal 10-D, the link with the wireless communication terminal 10-B is broken at the time of restart, the wireless communication terminal 10-C is selected as the parent node, and the topology is established. It shall be.

Then, after the topology with the wireless communication terminal 10-C is established, the wireless communication terminal 10-D has the root terminal counter value C3 (= 2) held by the wireless communication terminal 10-C as the wireless communication terminal 10. It is assumed that it has propagated to −D. Then, in the wireless communication terminal 10-D, "2" is held as the root terminal counter value C3.

Then, the root terminal counter value C3 (= 2) held by the wireless communication terminal 10-D is propagated to the wireless communication terminal 10-E as the root terminal latest counter value C4 (= 2). Since the wireless communication terminal 10-E already holds "3" as the root terminal counter value C3, the route is based on the root terminal latest counter value C4 (= 2) and the root terminal counter value C3 (= 3). In the terminal counter value abnormality determination process, an abnormality (abnormal because the sequence counter value has returned) is determined.

However, when the wireless communication terminal 10-D is restarted, the sequence counter value C2 managed by the wireless communication terminal 10-D is initialized and updated from 40 to 128 (updated from the circular section to the beginning of the linear section). To. As a result, the root terminal restart determination unit 113 of the wireless communication terminal 10-E can determine that the wireless communication terminal 10-D has restarted, so that the counter managed by the root terminal (wireless communication terminal 20) is inconsistent. It can be determined that the cause may be due to the restart of the wireless communication terminal 10-D. At this time, in the wireless communication terminal 10-E, the results of the determination processing (root terminal counter value abnormality determination processing and neighborhood terminal counter value or higher determination processing) of the root terminal counter determination unit 111 and the vicinity terminal counter determination unit 112 are, respectively. An abnormality occurs, and the wireless communication terminal 10-E does not re-subscribe to the network N.

FIG. 6 is an explanatory diagram showing a state of the wireless communication system 1 after the root terminal (wireless communication terminal 20) is restarted from the state of FIG.

On the other hand, when the root terminal (wireless communication terminal 20) is restarted from the initial state, the sequence counter value C2 managed by the root terminal (wireless communication terminal 20) becomes the initial value 128, and that value becomes the initial value 128 when the control packet is transmitted. It gradually propagates. Then, in the wireless communication terminals 10-B, 10-C, 10-D, and 10-E, it is detected by receiving the control packet that the sequence counter value C2 is updated in the root terminal (wireless communication terminal 20).

As a result, in the wireless communication terminals 10-B, 10-C, 10-D, and 10-E, the determination processing result of the root terminal counter determination unit 111 is abnormal, and the determination processing result of the neighboring terminal counter determination unit 112 becomes normal. The wireless communication terminals 10-B, 10-C, 10-D, and 10-E each perform a re-subscription operation to the network N.

If both the root terminal (wireless communication terminal 20) and the wireless communication terminal 10-D are restarted, the root terminal counter determination unit 111 and the neighboring terminal counter determination unit 112 will be used in the wireless communication terminal 10-E. Since both are determined to be abnormal, the detection omission of restarting the root terminal (wireless communication terminal 20) will occur. In this way, whether the wireless communication terminal 10-E determines that the root terminal (wireless communication terminal 20) has restarted when both are determined to be abnormal has priority over false detection or omission. It will be. Therefore, in such a case, the root terminal restart determination unit 113 of the wireless communication terminal 10-E does not immediately determine that the root terminal (wireless communication terminal 20) has restarted and performs a re-subscription operation. , The operation of transmitting a confirmation packet as to whether or not the system has been restarted may be performed to the root terminal (wireless communication terminal 20). Then, the root terminal restart determination unit 113 of the wireless communication terminal 10-E does nothing if there is a response that the root terminal (wireless communication terminal 20) has not restarted, and a response or response that the root terminal has been restarted is received. When the time-out occurs, the re-subscription operation to the network N can be performed to avoid unnecessary packet transmission due to the re-subscription of the network.

By the above processing, the information of the terminals participating in the network N (information about the tree structure of the network N) that has been cleared by restarting the root terminal (wireless communication terminal 20) is used as the root terminal (wireless communication). The terminal 20) can be restored to the state before it was restarted.

(A-3) Effect of Embodiment According to this embodiment, the following effects can be achieved.

In the wireless communication terminal 10 of this embodiment, the sequence counter value of the root terminal (wireless communication terminal 20) and the sequence counter value of the neighboring terminal are acquired, and the determination result of the root terminal counter determination unit 111 and the neighborhood terminal counter determination unit 112 is obtained. Is determined to restart the root terminal based on. As a result, in the wireless communication system 1 of this embodiment, it is possible to suppress the occurrence of unnecessary traffic while maintaining a more accurate sequence counter value of the root terminal.

(B) Other Embodiments The present invention is not limited to the above embodiments, and modified embodiments as illustrated below can also be mentioned.

(B-1) In the above embodiment, the wireless communication terminal 10 and the root terminal (wireless communication terminal 20) have been described using separate block diagrams, but the wireless communication terminal 10 and the root terminal (wireless communication terminal 20) have been described. A device having the configuration of both terminals may be constructed so that the function of either terminal is enabled according to the setting.

Wireless communication system 1, root terminal (wireless communication terminal 10-A), 10, 10-A to 10-E ... wireless communication terminal, 11 ... control unit, 110 ... sequence counter, 111 ... root terminal counter determination unit, 112 ... Neighborhood terminal counter determination unit, 113 ... root terminal restart determination unit, 114 ... counter update unit, 115 ... communication control unit, 12 ... wireless communication unit, 20 ... wireless communication terminal, 21 ... control unit, 210 ... communication control unit, 211 ... Sequence counter, 212 ... Counter update unit, 22 ... Wireless communication unit.

Claims (8)

In a tree-structured network, a wireless communication means that performs routing processing to relay packets received from other wireless communication devices in the network, and
A sequence counter update means for updating the sequence counter value, and
A sequence counter value notifying means for causing the wireless communication means to send a packet describing the sequence counter value updated by the sequence counter updating means, and
When the wireless communication means receives a packet in which the sequence counter value updated by the root wireless communication device arranged at the route of the network is described, the first counter value that acquires and holds the sequence counter value is obtained. Holding means and
When the wireless communication means receives a packet containing an updated sequence counter value in a nearby wireless communication device capable of direct wireless communication, a second counter value holding means that acquires and holds the sequence counter value. When,
When the first counter value holding means acquires a newly acquired sequence counter value, it is compared with the sequence counter value previously acquired and held by the first counter value holding means, and based on the comparison result, it is compared with the sequence counter value. The first counter value determining means for determining the presence or absence of an abnormality in the sequence counter value newly acquired by the first counter value holding means, and the first counter value determining means.
When the second counter value holding means acquires a newly acquired sequence counter value, it is compared with the sequence counter value previously acquired and held by the second counter value holding means, and based on the comparison result, it is compared with the sequence counter value. A second counter value determining means for determining the presence or absence of an abnormality in the sequence counter value newly acquired by the second counter value holding means, and a second counter value determining means.
The wireless communication is characterized by having the first counter value determining means and the restart determining means for determining whether or not the root wireless communication device is restarted according to the determination result of the second counter value determining means. Device. The first aspect of the present invention is that the sequence counter value updated by the sequence counter updating means includes a linear section used only at the time of initialization and a circular section used by circulating after the linear section. The wireless communication device described. The wireless communication device according to claim 1 or 2, wherein when the determination result of the first counter value determination means is abnormal, it is determined that the root wireless communication device has restarted. When the determination results of the first counter value determination means and the second counter value determination means are abnormal, the restart determination means makes an inquiry to the root wireless communication device regarding restart, and the restart determination means is described. The wireless communication device according to any one of claims 1 to 3, wherein it is determined whether or not the root wireless communication device is restarted based on the response content of the root wireless communication device. The first to fourth aspects of the present invention, wherein the wireless communication means controls the wireless communication means to execute an operation of rejoining the network when it is determined that the root wireless communication device has restarted. The wireless communication device described in any one. The computer installed in the wireless communication device,
In a tree-structured network, a wireless communication means that performs routing processing to relay packets received from other wireless communication devices in the network, and
A sequence counter update means for updating the sequence counter value, and
A sequence counter value notifying means for causing the wireless communication means to send a packet describing the sequence counter value updated by the sequence counter updating means, and
When the wireless communication means receives a packet in which the sequence counter value updated by the root wireless communication device arranged at the route of the network is described, the first counter value that acquires and holds the sequence counter value is obtained. Holding means and
When the wireless communication means receives a packet containing an updated sequence counter value in a nearby wireless communication device capable of direct wireless communication, a second counter value holding means that acquires and holds the sequence counter value. When,
When the first counter value holding means acquires a newly acquired sequence counter value, it is compared with the sequence counter value previously acquired and held by the first counter value holding means, and based on the comparison result, it is compared with the sequence counter value. The first counter value determining means for determining the presence or absence of an abnormality in the sequence counter value newly acquired by the first counter value holding means, and the first counter value determining means.
When the second counter value holding means acquires a newly acquired sequence counter value, it is compared with the sequence counter value previously acquired and held by the second counter value holding means, and based on the comparison result, it is compared with the sequence counter value. A second counter value determining means for determining the presence or absence of an abnormality in the sequence counter value newly acquired by the second counter value holding means, and a second counter value determining means.
The radio is characterized by functioning as a restart determination means for determining whether or not the root radio communication device is restarted according to the determination results of the first counter value determination means and the second counter value determination means. Communication program. In the wireless communication method performed by the wireless communication device,
Wireless communication means, sequence counter updating means, sequence counter value notifying means, first counter value holding means, second counter value holding means, first counter value determining means, second counter value determining means, and restarting. Equipped with a judgment means
The wireless communication means is a tree-structured network, and performs routing processing for relaying packets received from other wireless communication devices in the network.
The sequence counter updating means updates the sequence counter value,
The sequence counter value notification means causes the wireless communication means to send a packet describing the sequence counter value updated by the sequence counter updating means.
When the wireless communication means receives a packet containing the sequence counter value updated by the root wireless communication device arranged at the root of the network, the first counter value holding means sets the sequence counter value. Get and hold,
When the wireless communication means receives a packet containing a sequence counter value updated by a nearby wireless communication device capable of direct wireless communication, the second counter value holding means acquires the sequence counter value. Hold and hold
When the first counter value holding means acquires a newly acquired sequence counter value, the first counter value determining means together with the sequence counter value previously acquired and held by the first counter value holding means. A comparison is made, and based on the comparison result, it is determined whether or not the sequence counter value newly acquired by the first counter value holding means is abnormal.
When the second counter value holding means acquires a newly acquired sequence counter value, the second counter value determining means together with the sequence counter value previously acquired and held by the second counter value holding means. A comparison is made, and based on the comparison result, it is determined whether or not the sequence counter value newly acquired by the second counter value holding means is abnormal.
The restart determination means is characterized in that it determines whether or not the root wireless communication device is restarted according to the determination results of the first counter value determination means and the second counter value determination means. Method. A root wireless communication device arranged at the root of a network having a tree structure and a plurality of wireless communication devices arranged under the root wireless communication device in the network are provided and arranged under the respective root wireless communication devices. A wireless communication system characterized in that the wireless communication device according to any one of claims 1 to 5 is applied as the wireless communication device.

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