JP2018164154A - Radio relay device, radio communication device, and radio communications system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication device that can autonomously control a communication path such that an amount of communication is not biased to a specific node in consideration of traffic of each node.SOLUTION: A radio communication device that can be wirelessly connected to a plurality of radio relay device includes a second radio communication unit that transmits and receives a packet between with each of the radio relay devices, a priority information storage unit that stores priority information that defines a priority of the radio relay devices that are wirelessly connected to the radio communication device, a connection destination management unit that selects one radio relay device from among the respective radio relay devices as a connection destination on the basis of the priority information, and a priority information management unit that updates the priority information on the basis of at least link quality information indicating the link quality between the radio communication device and the respective radio relay devices and communication amount information on a communication amount within a predetermined period of each of the radio relay devices at a predetermined timing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless relay device, a wireless communication device, and a wireless communication system, and can be applied to, for example, a multi-hop wireless network.

  In a multi-hop sensor network composed of a sink node that collects sensing packets, a sensing node (child node) that acquires and transmits sensing packets to the sink node, and a relay node (parent node) that transfers the sensing packets to the sink node, there are many In this case, when a node is arranged and the power is turned on, an appropriate network topology is automatically constructed. In this network topology, each node autonomously calculates link quality based on packets including link information such as Hello packets received from neighboring nodes, and determines a node with good link quality as a parent node. Built.

  By the way, in the network topology construction method as described above, since each node autonomously determines a parent node based only on link quality, a situation occurs in which many child nodes are biased toward a specific parent node. As a result, a bias in power consumption occurs at the parent (relay) node that relays the packet. In recent years, the use of multi-hop sensor networks in infrastructure monitoring systems has increased, but such systems require a battery life of several years to a decade level. Therefore, the bias in power consumption at the relay node may cause a serious problem that the actual lifetime becomes shorter than the designed lifetime.

  As an example of the path control method for eliminating the bias of the child node with respect to the specific parent node as described above, for example, a technique described in Patent Document 1 is cited. In the technique described in Patent Document 1, a specific route control device grasps the total number of descendants of each node in a certain number of hops based on the received packet. By instructing the node with the total number of descendants with a large bias among the total number of descendants to intentionally change the packet containing link information to be transmitted to the neighbor so that the link quality is deteriorated. This is to eliminate the bias in the total number of descendants.

JP 2013-65957 A

  However, even if the bias is eliminated based on the number of child nodes as in the technique described in Patent Document 1, the bias of the power consumption of each node is not necessarily suppressed. This is because the actual problem is the packet transmission frequency and data amount of the child node. If the packet transmission frequency and the amount of data are constant, the technique described in Patent Document 1 has a certain effect. For example, when the number of child nodes of node A is 5 and the number of child nodes of node B is 10, In some cases, the amount of data relayed by node A in one minute is 50 and node B is 20. In this case, when the node A is in a busy state and the child node of the node B changes the parent to the node A, the busy state of the node 200A is further deteriorated, which may promote a bias in power consumption. There is.

  Therefore, a wireless relay device, a wireless communication device, and a wireless communication system that can autonomously control a communication path so that the communication amount is not biased to a specific node in consideration of the communication amount of each node is desired.

  According to a first aspect of the present invention, in the wireless relay device that relays a packet received from the first wireless communication device to the second wireless communication device, (1) itself and the first wireless communication device or the second wireless communication device. A first wireless communication unit that transmits and receives packets to and from a communication device; and (2) a packet cumulative value that is a cumulative value of packets received from all wireless communication devices that are relayed to itself within a predetermined period. A cumulative packet amount management unit that holds and determines whether the packet cumulative value obtained by adding the packet newly received from the first wireless communication device exceeds a first threshold; (3) the cumulative When the packet amount management unit determines that the packet accumulated value exceeds the first threshold, the packet accumulated value exceeds the first threshold using the first wireless communication unit. Information indicating that A notification packet including the Packet cumulative abnormal information, and having a first packet transceiver which performs control to transmit to the radio communication device.

  According to a second aspect of the present invention, in a wireless communication device that can be wirelessly connected to a plurality of wireless relay devices, (1) a second wireless communication unit that transmits and receives packets between itself and each of the wireless relay devices; ) A priority information storage unit that stores priority information that defines the priority order of each wireless relay device that is wirelessly connected to itself; and (3) one wireless relay device from among the wireless relay devices based on the priority information. (4) at a predetermined timing, at least, link quality information indicating the link quality between itself and each of the wireless relay devices, and a predetermined period of each of the wireless relay devices And a priority information management unit that updates the priority information based on the traffic amount information related to the traffic amount.

  According to a third aspect of the present invention, in the wireless communication system having a plurality of wireless relay devices and a plurality of wireless communication devices, the wireless relay device of the first aspect of the present invention is the second wireless communication device. The wireless communication apparatus of the present invention is applied.

  According to the present invention, it is possible to autonomously control a communication path so that the communication amount is not biased toward a specific node in consideration of the communication amount of each node.

It is a block diagram which shows the structure of the radio | wireless communication apparatus (child node) which concerns on 1st Embodiment. 1 is a block diagram illustrating an overall configuration of a wireless communication system according to a first embodiment. It is a block diagram which shows the structure of the radio | wireless communication apparatus (parent node) which concerns on 1st Embodiment. It is explanatory drawing which shows an example of the coefficient determination table which concerns on 1st Embodiment. It is explanatory drawing which shows an example of the parent candidate table which concerns on 1st Embodiment. It is a flowchart which shows the characteristic operation | movement of the radio | wireless communication apparatus (parent node) which concerns on 1st Embodiment. It is a flowchart which shows the characteristic operation | movement of the radio | wireless communication apparatus (child node) which concerns on 1st Embodiment. It is explanatory drawing (the 1) which imaged the procedure which changes the communication path which concerns on 1st Embodiment (changes a parent node). It is explanatory drawing (the 2) which imaged the procedure which changes the communication path which concerns on 1st Embodiment (changes a parent node). It is explanatory drawing (the 3) which imaged the procedure which changes the communication path which concerns on 1st Embodiment (changes a parent node). It is explanatory drawing (the 4) which imaged the procedure which changes the communication path which concerns on 1st Embodiment (changes a parent node). It is explanatory drawing (the 5) which imaged the procedure which changes the communication path which concerns on 1st Embodiment (changes a parent node). It is a block diagram which shows the structure of the radio | wireless communication apparatus (child node) which concerns on 2nd Embodiment. It is explanatory drawing (the 1) which imaged the procedure which changes the communication path which concerns on 2nd Embodiment (changes a parent node). It is explanatory drawing (the 2) which imaged the procedure which changes the communication path which concerns on 2nd Embodiment (changes a parent node). It is explanatory drawing (the 3) which imaged the procedure which changes the communication path which concerns on 2nd Embodiment (changes a parent node).

(A) First Embodiment Hereinafter, a first embodiment of a wireless relay device, a wireless communication device, and a wireless communication system according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of the First Embodiment (A-1-1) Overall Configuration FIG. 2 is a block diagram showing the overall configuration of the wireless communication system according to the first embodiment. 2, the wireless communication system 1 includes a wireless communication device 10, wireless communication devices 200 (200-1, 200-2), and wireless communication devices 100 (100-1 to 100-4). In FIG. 2, for ease of explanation, the wireless communication system 1 includes two wireless communication devices 200-1 and 200-2 and four wireless communication devices 100-1 to 100-4. Although the case is illustrated, of course, the number of each device is not particularly limited.

  In the wireless communication system 1, it is assumed that a wireless multihop network is configured by the wireless communication device 10, the wireless communication devices 200-1, 200-2, and the wireless communication devices 100-1 to 100-4 (network The structure is not particularly limited). Hereinafter, the wireless communication device 10, the wireless communication devices 200-1, 200-2, and the wireless communication devices 100-1 to 100-4 are collectively referred to as “nodes”. In addition, a node may be given a reference numeral to refer to each device (for example, the node 200-2).

  The communication system of each node is not particularly limited, and for example, various wireless LAN interfaces can be applied. For example, each node can adopt a wireless communication scheme of IEEE 802.15.4 / ZigBee.

  The wireless communication device 100 is a node belonging to the end in the wireless communication system 1 (multi-hop network). The wireless communication device 100 is mounted (or connected) with a predetermined sensor, and transmits sensing data (sensing packet) to the wireless communication device 10 via the wireless communication device 200. Various types of sensors can be applied depending on the service to be provided. For example, sensor types include sensors such as a temperature sensor, a humidity sensor, an illuminance sensor, a human sensor, and a power sensor. Hereinafter, the wireless communication device 100 is also referred to as a “sensing node (child node)”.

  The wireless communication device 200 is a node that relays a packet from a sensing node to the wireless communication device 10 in the wireless communication system 1 (multi-hop network). Hereinafter, the wireless communication device 200 is also referred to as a “relay node (parent node)”. Note that the relay node may have a function as a sensing node.

  The wireless communication device 10 is a node located at the highest level in the wireless communication system 1 (multi-hop network). The wireless communication device 10 collects packets transmitted from each sensing node. Hereinafter, the wireless communication device 10 is also referred to as a “sink node”.

(A-1-2) Detailed Configuration of Radio Communication Device 200 (Parent Node) FIG. 3 is a block diagram showing the configuration of the radio communication device (parent node) according to the first embodiment. The wireless communication apparatus according to the first embodiment may be configured as hardware such as a dedicated IC chip on which the components illustrated in FIG. 3 are mounted, or the CPU and a program executed by the CPU are mainly described. May be configured as software, but can be functionally represented in FIG. In FIG. 3, only a portion related to communication path control (management of cumulative transfer amount), which is a characteristic portion of the present embodiment, is illustrated, and other configurations are omitted.

  The radio communication unit 201 performs demodulation processing on the radio signal from the antenna 250, converts the radio signal into digital data (packet), and gives the packet to the packet transmitting / receiving unit 202. The wireless communication unit 201 converts the transmission data (packet) given from the packet transmitting / receiving unit 202 into a radio signal (modulation processing) and gives it to the antenna 250.

  The packet transmission / reception unit 202 performs processing related to packet transmission / reception. Further, the packet transmitting / receiving unit 202 has a function of analyzing a packet received by the wireless communication unit 101 (a function of analyzing whether or not the packet is taken into the own apparatus). The packet transmitting / receiving unit 202 notifies the cumulative transfer amount management unit 203 of the data amount of the packet obtained by analyzing the packet. Further, the packet transmitting / receiving unit 202 creates a packet including the cumulative transfer amount S notified from the cumulative transfer amount management unit 203.

  The accumulated transfer amount management unit 203 manages the accumulated transfer amount S of packets transferred (relayed) to other nodes within a predetermined period (set time of a timer T1 described later). When the newly transferred packet is received, the accumulated transfer amount management unit 203 has a transfer allowable amount L in which the accumulated transfer amount S of the packet (a value obtained by adding the data of the newly transferred packet) is a predetermined threshold. Is exceeded, the packet transfer amount S is returned to the transmission source node (child node) together with ACK (reception completion notification). The cumulative transfer amount management unit 203 simply returns an ACK (reception completion notification) when the cumulative transfer amount S of the packet does not exceed the transfer allowable amount L. When the cumulative transfer amount management unit 203 receives a timer out notification from the timer management unit 204, the cumulative transfer amount management unit 203 initializes the cumulative transfer amount S of the packet. Then, the cumulative transfer amount management unit 203 performs control to transfer the received packet after transmitting the cumulative transfer amount S (or simply ACK) of the packet.

  The timer management unit 204 manages a timer T <b> 1 for setting a time (a fixed time) for accumulating the cumulative transfer amount S of packets in the cumulative transfer amount management unit 203. In addition, the timer management unit 204 starts counting the timer T1 at a predetermined timing (for example, when the power is turned on or when the network is joined). When the timer T1 times out (the set time has elapsed), the timer management unit 204 notifies the cumulative transfer amount management unit 203 to that effect. After the timer T1 times out, the timer management unit 204 resets the timer T1 and starts counting again.

(A-1-3) Detailed Configuration of Radio Communication Device 100 (Child Node) FIG. 1 is a block diagram showing the configuration of the radio communication device (child node) according to the first embodiment. The wireless communication apparatus according to the first embodiment may be configured as hardware such as a dedicated IC chip on which each component shown in FIG. 1 is mounted, or the CPU and a program executed by the CPU are mainly used. May be configured as software, but can be functionally represented in FIG.

  In FIG. 1, the wireless communication device 100 includes a wireless communication unit 101, a packet transmission / reception unit, a parent node management unit 103, a parent candidate table management unit 104, a storage unit 105, and an antenna 150. In FIG. 1, only the part related to the control of the communication path (selection of the parent node), which is a characteristic part of the present embodiment, is illustrated, and the other configuration is omitted.

  The radio communication unit 101 performs demodulation processing on the radio signal from the antenna 150, converts it into digital data (packet), and provides the packet transmission / reception unit 102. The wireless communication unit 101 converts transmission data (packets) given from the packet transmission / reception unit 102 into a radio signal (modulation processing) and gives it to the antenna 150.

  The packet transmitting / receiving unit 102 performs processing (control) related to packet transmission / reception. Further, the packet transmitting / receiving unit 102 has a function of analyzing a packet received by the wireless communication unit 101 (a function of analyzing whether or not the packet is taken into the own apparatus). The packet transmitting / receiving unit 102 notifies the parent candidate table management unit 104 of information related to link quality (such as an RSSI (Received Signal Strength Indication) value) included in the analyzed packet and the cumulative transfer amount S of the parent node packet.

  The parent candidate table management unit 104 updates the parent candidate table D2 based on the link quality information obtained by the packet transmitting / receiving unit 102 and the cumulative transfer amount S of the parent node packet. Further, the parent candidate table management unit 104 calculates the priority of each parent candidate (a node that can be a parent node) from the acquired link quality and information on the cumulative transfer amount S of the parent node packet, and calculates the calculated priority. Is stored (updated) in the parent candidate table D2.

  For example, the parent candidate table management unit 104 calculates the priority of each parent candidate according to the following equation (1).

Priority = Cumulative transfer amount × α (1)
In the above equation (1), “coefficient α” is a coefficient determined according to the link cost (link quality). The link cost is an evaluation value for evaluating the link quality between itself and another node based on information such as the RSSI value, and is determined by various existing calculation methods. FIG. 4 is an explanatory diagram illustrating an example of a coefficient determination table according to the first embodiment. In FIG. 4, the coefficient determination table D1 has items of “link cost” and “coefficient α”. In FIG. 4, “link cost” is set to a value from 1 (best link quality) to MAX (worst link quality). Further, the “coefficient α” is set to a value of 1.0 to 100 in accordance with the link cost value (within the link cost value range). For example, when the link cost is “1”, the coefficient α is determined as “1.0”.

  In the above equation (1), the “cumulative transfer amount” is set to the cumulative transfer amount S of the packet received from the parent node. Note that when the cumulative transfer amount S is not received from the parent node, an initial value k (for example, k = 1) that is a value other than “0” is set in advance as the cumulative transfer amount.

  In addition, according to the above formula (1), the calculated priority values of the parent candidates may be used as they are, or the calculated priority values of the respective parent candidates are 1, 2, A positive integer such as 3 ... may be reset.

  The storage unit 105 stores the parent candidate table D2. The parent candidate table D2 is a table that holds the link cost for each parent candidate, the cumulative transfer amount S of packets of the parent node, priority information, and the like. FIG. 5 is an explanatory diagram illustrating an example of a parent candidate table according to the first embodiment. In FIG. 5, the parent candidate table D2 includes items of “priority”, “address”, “link cost”, and “cumulative transfer amount”. The “priority” is an item in which the value calculated by the above equation (1) is stored (updated). “Address” is an item in which the node address of the parent candidate (wireless communication apparatus 200) is stored. For example, the address “0x0001” indicates the destination of the wireless communication apparatus 200-1, “0x0002” indicates the destination of the wireless communication apparatus 200-2, and “0x0003” indicates a node (not shown). Indicates the destination. “Link cost” is an item in which a value indicating the quality of the link between itself and each parent candidate is stored. The “cumulative transfer amount” is an item in which the above-described cumulative transfer amount S (or initial value k) is stored. The “cumulative transfer amount” is updated to the value of the received cumulative transfer amount S every time the cumulative transfer amount is received from the parent node, and is updated to the initial value k every time an ACK is received from the parent node. .

  The parent candidate table D2 in FIG. 5 shows data sorted in the ascending order of priority items. That is, in FIG. 5, the top data (first data) among the parent candidate data is data that becomes its parent node.

  When the parent node management unit 103 receives notification from the parent candidate table management unit 104 that the parent candidate table D2 has been updated, the parent node management unit 103 refers to the updated parent candidate table D2 and needs to change its parent node. In other words, the parent node is changed. That is, if the priority of the current parent node is not the best (lowest value) in the parent candidate table D2, the parent candidate having the best priority is determined as a new parent node.

(A-2) Operation of the First Embodiment Next, the operation of the wireless communication system 1 of the first embodiment having the above configuration will be described with reference to the drawings. In this embodiment, since there are features for each of the processing of the wireless communication device 200 (parent node) and the wireless communication device 100 (child node) constituting the wireless communication system 1, the processing of the parent node will be described below. And the process of child nodes will be described separately. The parent node described below is the parent candidate with the highest priority in the parent candidate table D2 of the child node.

(A-2-1) Operation of Parent Node FIG. 6 is a flowchart showing the characteristic operation of the wireless communication apparatus (parent node) according to the first embodiment.

  The parent node (timer management unit 204) starts (starts counting) the timer T1 at a predetermined timing (ST101).

  After the timer T1 is started, the parent node (wireless communication unit 201) enters a standby state (ST102). When the parent node receives the packet from the child node, the packet transmitting / receiving unit 202 analyzes the packet, and then executes the process of the next step ST103. On the other hand, when the timer T1 times out while waiting for reception, the parent node executes a process of step ST108 described later.

  The accumulated transfer amount management unit 203 adds the data amount of the packet obtained by the analysis to the accumulated transfer amount S of the packet (step ST103).

  The cumulative transfer amount management unit 203 compares the cumulative transfer amount S of the added packets with the transfer allowable amount L by the process of step ST103, and the cumulative transfer amount S of the added packets exceeds the transfer allowable amount L. It is determined whether or not (step ST104). When the accumulated transfer amount management unit 203 determines that the accumulated transfer amount S of the added packet exceeds the transfer allowable amount L, the process of the next step ST105 is performed. Performs the process of step ST106 described later.

  If the cumulative transfer amount management unit 203 determines in step ST104 that the added cumulative transfer amount S exceeds the transfer allowable amount L, the cumulative transfer amount S ( Control is performed to transmit an ACK including information indicating the added cumulative transfer amount S of the current packet (ST105). The packet to be transmitted is not limited to this. For example, a command packet other than ACK may be used. When it is desired to reduce the amount of data to be transmitted, information indicating that the cumulative transfer amount S of the packet exceeds the transfer allowable amount L (information of 1 bit at a minimum) is replaced with the cumulative transfer amount. Also good.

  Further, if the cumulative transfer amount S of the added packet is equal to or smaller than the transfer allowable amount L by the process of step ST104 described above, the cumulative transfer amount management unit 203 determines that the traffic load is small, and the child of the transmission source A normal ACK is transmitted to the node (ST106).

  The accumulated transfer amount management unit 203 performs a process of transferring the packet received from the child node to the sink node (directly to the sink node or via another relay node) after the process of step ST105 (or step ST106) described above. Perform (ST107).

  On the other hand, when the set timer T1 times out in the processing of step ST101 described above, the timer management unit 204 notifies the cumulative transfer amount management unit 203 that time-out has occurred. Receiving the notification, the accumulated transfer amount management unit 203 returns the accumulated transfer amount S of packets to the initial state (ST108).

  The timer management unit 204 returns the timer T1 to the initial state, and starts (restarts) counting of the timer T1 again by the process of step ST101 described above (ST109).

(A-2-2) Operation of Child Node FIG. 7 is a flowchart showing the characteristic operation of the wireless communication apparatus (child node) according to the first embodiment.

  When a reason for transmitting the packet from the standby state (for example, timing for transmitting the sensing packet to the sink node) occurs, the child node transmits the packet to the parent node having the highest priority in the parent candidate table D2 (ST201). -ST203).

  After the process of step ST203, the child node (wireless communication unit 101) enters a standby state (ST204). When the child node receives the packet from the parent node, the packet transmitting / receiving unit 102 analyzes the packet, and if it is an ACK, the child node executes a process of step ST209 described later. On the other hand, if the child node includes information indicating the accumulated transfer amount S of the packet (or information indicating that the accumulated transfer amount S of the packet exceeds the allowable transfer amount L) in the analyzed packet, the child node performs the next step. The process of ST205 is executed.

  When receiving the notification of the cumulative transfer amount S of the packet from the packet transmitting / receiving unit 102, the parent candidate table management unit 104 recalculates the priority of the parent candidate based on the value of the cumulative transfer amount S and the link cost (for example, as described above) Recalculate according to the equation (1) and update the parent candidate table D2 (ST206).

  The parent candidate table management unit 104 checks whether or not the parent candidate with the highest priority has changed due to the update of the parent candidate table D2 (ST207). If there is no change in the parent candidate with the highest priority, the parent candidate table management unit 104 does nothing and moves to the above-described step ST201 (standby state). On the other hand, if there is a change in the parent candidate with the highest priority, the parent candidate table management unit 104 notifies the parent node management unit 103.

  The parent node management unit 103 changes the parent node to the parent candidate with the highest priority (ST208).

  On the other hand, when the parent candidate table management unit 104 receives the notification that the ACK is received from the packet transmission / reception unit 102 after the processing of step ST204 described above, the transmission source (parent node) stored in the parent candidate table D2 Is returned to the initial state (ST209, ST210). Also, the parent candidate table management unit 104 initializes (transfer permission) even when the parent candidate table D2 is managed not in the cumulative transfer amount of packets but in a transfer allowable amount excess state (1 is exceeded, 0 is not exceeded). Set the capacity excess state to 0).

(A-2-3) Description of Specific Example Next, a specific example of the process of changing the communication path (changing the parent node) among the processes of the parent node and the child node (FIGS. 6 and 7) described above. I will give you a description. 8 to 12 are explanatory diagrams illustrating the procedure for changing the communication path (changing the parent node) according to the first embodiment.

  First, it is assumed that the node 100-1 newly participates in the wireless communication system 1 (already constructed multi-hop network) with the node 200-1 as a parent. In the parent candidate table D2 of the node 100-1 at this time, all the accumulated transfer amounts are initial values k (values other than 0). Therefore, the priority order is equal to the order in which the link quality is good. For convenience of explanation, only the node 200-1 and the node 200-2 are described in the parent candidate table D2 in FIGS. 8 to 12 (in the address item, the destination is indicated by the node code). Also, the sink node 10 is omitted in the wireless communication system 1 of FIGS.

  As illustrated in FIG. 8, the node 100-1 transmits the transmission packet having the packet data amount “5” to the parent node 200-1. After the transmission, the node 100-1 waits for a response from the node 200-1. At this time, the cumulative transfer amount S of the packet of the node 200-1 is “97”, and the set transfer allowable amount L is “100”.

  As illustrated in FIG. 9, when the node 200-1 receives a packet having a packet data amount of 5, the node 200-1 adds the packet data amount (5) to the cumulative transfer amount S (97) of the packet to obtain a transfer allowable amount L (100 ). Then, the cumulative transfer amount S (102) of the packet> the transfer allowable amount L (100), and the cumulative transfer amount S exceeds the transfer allowable amount L. Therefore, the node 200-1 ACK with the accumulated transfer amount added is transmitted.

  As illustrated in FIG. 10, the node 200-1 transfers the packet received from the node 100-1 to the sink node 10.

  As illustrated in FIG. 11, when the node 100-1 receives the ACK to which the information indicating the cumulative transfer amount S of the packet is added, the node 100-1 updates the parent candidate table D2. Specifically, the cumulative transfer amount of the node 200-1 is rewritten from k to 102 in the parent candidate table. Here, when the node 100-1 recalculates the priority of the parent candidate node, the node 200-1 having the priority “1” has the priority “2”. At the same time, the priority of the node 200-2 whose priority is “2” is “1”. When the node 100-1 cannot receive the ACK from the node 200-1 and an ACK timeout occurs, for example, the cumulative transfer amount of the node 200-1 is maximized in the parent candidate table D2. It is also good.

  As shown in FIG. 12, as a result of the update of the parent candidate table D2, the parent candidate having the priority 1 in the node 100-1 changes from the node 200-1 to the node 200-2. The parent is changed to the node 200-2 having the priority 1.

(A-3) Effect of First Embodiment According to the first embodiment, each node distributes the load on the entire network in order to avoid each node autonomously having a node with a high traffic load as a parent. be able to. In addition, in order to distribute the load by observing the actual traffic volume over time, nodes that frequently transmit packets temporarily and nodes that regularly transmit a certain amount of packets are mixed in the network. Also, the load on each node can be distributed.

(B) Second Embodiment Hereinafter, a second embodiment of the wireless relay device, the wireless communication device, and the wireless communication system according to the present invention will be described in detail with reference to the drawings.

(B-1) Configuration of Second Embodiment The radio communication system 1 of the second embodiment is basically the same as each configuration shown in FIG. 2, but instead of the radio communication device 100, a radio communication device The difference is that 100A is applied. The wireless communication device 200 of the wireless communication system 1 of the second embodiment is the same as that of the first embodiment. Hereinafter, only the wireless communication device 100A different from the first embodiment will be described.

  FIG. 13 is a block diagram illustrating a configuration of a wireless communication device (child node) according to the second embodiment. The wireless communication apparatus according to the second embodiment may be configured as hardware such as a dedicated IC chip on which the components illustrated in FIG. 13 are mounted, or the CPU and a program executed by the CPU are mainly used. May be configured as software, but can be functionally represented in FIG.

  In FIG. 13, a wireless communication device 100A is obtained by adding a timer management unit 106 to each configuration of the wireless communication device 100A (wireless communication unit 101, packet transmission / reception unit, parent node management unit 103, storage unit 105, and antenna 150). It is. However, the wireless communication device 100A is different in that a parent candidate table management unit 104A is applied instead of the parent candidate table management unit 104 of the first embodiment. Hereinafter, only the parent candidate table management unit 104A replaced with the added timer management unit 106 will be described.

  The timer management unit 106 manages a timer T2 that indicates the timing for initializing the cumulative transfer amount value in the parent candidate table D2. The timer management unit 106 starts the timer T2 at a predetermined timing, and notifies the parent candidate table management unit 104A when time-out occurs.

  When the parent candidate table management unit 104A receives the notification due to the timeout of the timer T2, the parent candidate table management unit 104A initializes the value of the cumulative transfer amount of each parent candidate in the parent candidate table D2, and recalculates the priority of each parent candidate.

(B-2) Operation | movement of 2nd Embodiment Next, operation | movement of the radio | wireless communications system 1 of 2nd Embodiment which has the above structures is demonstrated, referring drawings. Note that the operations of the wireless communication device 200 (parent node) and the wireless communication device 100A (child node) constituting the second embodiment perform the same operations as those described above with reference to FIGS. . Only operations unique to the wireless communication device 100A of the second embodiment will be described below.

  The child node timer management unit 106 starts (starts counting) the timer T2 at a predetermined timing. When the timer T2 times out, the timer management unit 106 notifies the parent candidate table management unit 104 that the timer T2 has timed out. The timer management unit 106 resets the timer T2 and starts counting again. Receiving the notification from the timer management unit 106, the parent candidate table management unit 104 returns the accumulated transfer amount of the parent candidate table D2 to the initial value, and recalculates the priority of each parent candidate.

  Next, a process for changing the communication path (changing the parent node) by the process of the child node described above will be described with a specific example. FIG. 14 to FIG. 16 are explanatory diagrams illustrating the procedure for changing the communication path according to the second embodiment. The state of FIG. 14 is a continuation from FIG. 12 described above (the state in which the node 100-1 changes the parent of the node 200-2 from the node 200-1).

  In FIG. 14, the node 100-1 has the node 200-2 as a parent. At this time, in the item of the cumulative transfer amount of the data of the node 200-1 in the parent candidate table D2 of the node 100-1, the cumulative transfer amount S (102) of the packet received when the node 200-1 is the parent. ) Is stored.

  In FIG. 15, the node 100-1 resets the accumulated transfer amount in the parent candidate table D2 of the node 100-1 to the initial value (k) after a certain time (timer T2) has elapsed.

  In FIG. 16, with the resetting of the accumulated transfer amount in the parent candidate table D2, the node 200-1 with the highest link quality is the best priority. As a result, the node 100-1 changes the parent from the node 200-2 to the node 200-1. Thereby, the node 100-1 knows the current load state of the node 200-1, and if the load is low, the node 200-1 having a good link quality is the parent until the load increases.

(B-3) Effects of the Second Embodiment According to the second embodiment, in addition to the effects of the first embodiment, the load on the parent candidate having a higher link quality than the current parent is reduced more than before. Even in such a case, it is possible to increase the opportunity to change the connection destination to the parent candidate.

DESCRIPTION OF SYMBOLS 1 ... Wireless communication system 10, 100, 100A, 200, 200A ... Wireless communication apparatus, 100, 100A ... Wireless communication apparatus, 101 ... Wireless communication part, 102 ... Packet transmission / reception part, 103 ... Parent node management part, 104, 104A ... parent candidate table management unit, 105 ... storage unit, 106 ... timer management unit, 150 ... antenna, 200, 200A ... wireless communication device, 201 ... wireless communication unit, 202 ... packet transmission / reception unit, 203 ... cumulative transfer amount management unit, 204 ... Timer management unit, 250 ... antenna D1 ... coefficient determination table, D2 ... parent candidate table L ... transfer allowable amount, S ... cumulative transfer amount, T1, T2 ... timer.

However, even if the bias is eliminated based on the number of child nodes as in the technique described in Patent Document 1, the bias of the power consumption of each node is not necessarily suppressed. This is because the actual problem is the packet transmission frequency and data amount of the child node. If the packet transmission frequency and the amount of data are constant, the technique described in Patent Document 1 has a certain effect. For example, when the number of child nodes of node A is 5 and the number of child nodes of node B is 10, In some cases, the amount of data relayed by node A in one minute is 50 and node B is 20. In this case, a busy state towards the node A, the child node of the node B changes the parent node A, it will be worse busy more nodes A, thus conducive to bias power There is a fear.

According to a first aspect of the present invention, in the wireless relay device that relays a packet received from the first wireless communication device to the second wireless communication device, (1) itself and the first wireless communication device or the second wireless communication device. A first wireless communication unit that transmits and receives packets to and from a communication device; and (2) a packet cumulative value that is a cumulative value of packets received from all wireless communication devices that are relayed to itself within a predetermined period. A cumulative packet amount management unit that holds and determines whether the packet cumulative value obtained by adding the packet newly received from the first wireless communication device exceeds a first threshold; (3) the cumulative When the packet amount management unit determines that the packet accumulated value exceeds the first threshold, the packet accumulated value exceeds the first threshold using the first wireless communication unit. and indicates that the first The notification packet radio communication apparatus includes a packet accumulated excess information is information for changing the destination of the packet from the wireless relay apparatus, and a said packet transceiver which performs control to transmit to the first wireless communication device It is characterized by that.

According to a second aspect of the present invention, in a wireless communication device that can be wirelessly connected to a plurality of wireless relay devices, (1) a second wireless communication unit that transmits and receives packets between itself and each of the wireless relay devices; ) A priority information storage unit that stores priority information that defines the priority order of each wireless relay device that is wirelessly connected to itself; and (3) one wireless relay device from among the wireless relay devices based on the priority information. And (4) the communication amount information indicating that the communication amount of the connection destination wireless relay device has exceeded a predetermined threshold from the connection destination wireless relay device. A priority information management unit that updates the priority information in consideration of the newly received traffic information of the connection destination .

The packet transmission / reception unit 202 performs processing related to packet transmission / reception. The packet transceiver unit 202 has a function of analyzing a packet radio communication unit 2 01 is received (ability to analyze whether packet or not incorporated into a self-device). The packet transmitting / receiving unit 202 notifies the cumulative transfer amount management unit 203 of the data amount of the packet obtained by analyzing the packet. Further, the packet transmitting / receiving unit 202 creates a packet including the cumulative transfer amount S notified from the cumulative transfer amount management unit 203.

In FIG. 1, the wireless communication device 100 includes a wireless communication unit 101, a packet transmission / reception unit 102 , a parent node management unit 103, a parent candidate table management unit 104, a storage unit 105, and an antenna 150. In FIG. 1, only the part related to the control of the communication path (selection of the parent node), which is a characteristic part of the present embodiment, is illustrated, and the other configuration is omitted.

Claims (8)

In the wireless relay device that relays the packet received from the first wireless communication device to the second wireless communication device,
A first wireless communication unit that transmits and receives packets between itself and the first wireless communication device or the second wireless communication device;
The packet accumulated value that is the accumulated value of the packets received from all the wireless communication devices having the relay destination as the relay destination within a predetermined period is held, and the packet newly received from the first wireless communication device is added. A cumulative packet amount management unit that determines whether the packet cumulative value exceeds a first threshold;
When the accumulated packet amount management unit determines that the accumulated packet value exceeds the first threshold value, the accumulated packet value is set to the first threshold value using the first wireless communication unit. And a packet transmission / reception unit for controlling transmission of a notification packet including packet accumulation excess information, which is information indicating that the packet exceeds the first wireless communication device, to the first wireless communication device.   The wireless relay device according to claim 1, wherein the notification packet is a response signal indicating that the packet has been normally received from the first wireless communication device.   The radio relay apparatus according to claim 1, wherein the packet accumulation excess information is the packet accumulation value. In a wireless communication device that can be wirelessly connected to a plurality of wireless relay devices,
A second wireless communication unit that transmits and receives packets between itself and each of the wireless relay devices;
A priority information storage unit that stores priority information that defines a priority order of each of the wireless relay devices wirelessly connected to itself;
A connection destination management unit that selects one wireless relay device from among the wireless relay devices as a connection destination based on the priority information;
Based on at least the link quality information indicating the link quality between itself and each of the wireless relay devices at a predetermined timing, and the traffic information regarding the traffic volume within a predetermined period of each of the wireless relay devices. And a priority information management unit for updating the wireless communication device.   The wireless communication apparatus according to claim 4, wherein an initial value is set for the communication amount information. The predetermined timing is a timing at which the communication amount information is received from the wireless relay device selected as a connection destination by the connection destination management unit,
The wireless communication apparatus according to claim 4 or 5, wherein the priority information management unit re-updates the priority information based on the received traffic information.   The wireless communication apparatus according to claim 4, wherein the priority information management unit re-updates the priority information after periodically returning the communication amount information to an initial value. In a wireless communication system having a plurality of wireless relay devices and a plurality of wireless communication devices,
A wireless relay device according to any one of claims 1 to 3 is applied as the wireless relay device, and a wireless communication device according to any one of claims 4 to 7 is applied as the wireless communication device. Communications system.

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