JP2014236413A - Radio communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which: in a conventional multi-hop network, a receiving node determines the congestion state of a radio link by use of the number of multi-hop communication path changing times described in a packet transmitted by a transmitting node; but the receiving node cannot correctly determine the congestion state of a packet if the packet does not reach the receiving node correctly.SOLUTION: A transmitting node transmits a message describing peripheral information to a receiving node, and the receiving node grasps the peripheral information on the transmitting node. If a packet does not reach the receiving node, the receiving node calculates a congestion determination value by use of the peripheral information on the transmitting node and determines whether congestion has occurred or not.

Description

  The present invention relates to a wireless communication device in a multi-hop network.

In wireless communication, a multi-hop network is known in which not only wireless nodes communicate directly but also communication between nodes over a wider range through other nodes. Among them, in a tree-type multi-hop network, a system is configured by a sink node that terminates data and a node that transmits data to the sink node. In such a system, the traffic of the radio link changes due to an increase in the number of nodes and a change in the number of transmissions of the nodes. When the wireless link traffic exceeds an allowable value, congestion occurs and data delay or loss occurs in the communication path. Therefore, it is necessary for the sink node to analyze the traffic of the radio link and perform control so that the congestion state does not occur as much as possible.

As a technique for detecting congestion of a wireless link, the conventional technique described in Patent Document 1 describes the number of communication path changes during multi-hop transmission in a packet transmitted from a node. The sink node reads the number of changes in the multi-hop communication path from the received packet, and determines the congestion state of the radio link using the read number of changes.

International Publication No. 2012/101763

In the prior art, the congestion state of a node is determined using the number of changes of the multi-hop communication path described in the packet arriving at the sink node. However, when the congestion state of the radio link is severe, there are many cases where packets do not reach the sink node, and there is a problem that the congestion state cannot be correctly determined using the arrived packets.

  The present invention has been made in view of the above, and it is an object of the present invention to correctly determine the congestion state of a target wireless node even when packets often do not reach the sink node.

  In order to achieve the above object, a communication apparatus according to the present invention includes a receiving unit that receives a message transmitted from a wireless node via a wireless multi-hop network, and reception of a message that confirms a living state from the wireless node. A first management unit that stores a state; a second management unit that stores peripheral information of the wireless node acquired from the received message; and the first management unit and the second management unit. And a determination unit that determines whether or not the wireless link of the wireless node is in a congested state using the received information.

  The communication apparatus according to the present invention determines whether or not a radio link congestion state has occurred using peripheral information of the target radio node even if the radio link is congested and a message does not reach in many cases. It becomes possible to judge.

The figure which shows the structure of the radio | wireless multihop network which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the node which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the sink node which concerns on Embodiment 1 of this invention. The flowchart which performs judgment of a congestion state in Embodiment 1 of this invention.

Embodiment 1 FIG.
Through all the following embodiments, a wireless communication apparatus that transmits and receives packets in a wireless multi-hop network is referred to as a node, and a path that communicates between nodes is referred to as a communication path. Also, the number of communication paths from the transmission node to the reception node is called the hop number.

FIG. 1 shows the configuration of a wireless multi-hop network according to Embodiment 1 of the present invention. In the figure, the wireless multi-hop network includes a sink node 100 and nodes 201 to 215, and data transmission from the nodes 201 to 215 to the sink node 100 is performed via the wireless multi-hop network. Hereinafter, in each figure, the same code | symbol shows the same or an equivalent part.

The nodes 201 to 215 existing under the sink node 100 transmit a hello message to the sink node 100 at a constant cycle. Here, the hello message is a message periodically transmitted by the nodes 201 to 215 to confirm the survival state.

A signal from a node that does not reach the sink node 100 directly is transmitted to the sink node 100 by relaying the signal from another node in the wireless multi-hop network. Note that the route construction method and control method for performing multi-hop wireless communication may be any method known so far. Although the number of nodes is 15 in FIG. 1, the number of nodes in the wireless multi-hop network may be any value.

The sink node 100 detects whether a hello message has been received from each of the nodes 201-215. In addition, the sink node 100 holds the reception state of the hello message from each of the nodes 201 to 215 and the route message transmitted from each of the nodes 201 to 215, and detects the congestion state of the communication route of each of the nodes 201 to 215. Hereinafter, the details of this control will be described.

FIG. 2 is a block diagram showing the configuration of the node 201. Here, one node 201 is taken up and described, but the same configuration can be applied to all the nodes 201 to 215. The node 201 includes a hello message creation unit 2001, a route message creation unit 2002, and a signal transmission unit 2003. In FIG. 2, only the characteristic configuration of the first embodiment of the present invention is described, and the description of other general configurations is omitted.

The hello message creation unit 2001 of the node 201 creates a hello message at a constant cycle and passes the created hello message to the signal transmission unit 2003. Also, the route message creation unit 2002 creates a route message indicating the change when the communication route for performing multi-hop communication to the sink node 100, the number of adjacent nodes, the number of hops, or the number of child nodes is changed. To the signal transmission unit 2003. Here, the “communication path” has the ID (Identifier) of the node that relays the signal as information, and the “number of adjacent nodes” is not limited to the communication path, but is the number of other nodes in the range in which a wireless signal from the node can be detected. , “The number of hops” is the number of multi-hop communication paths from the node to the sink node 100, and “the number of child nodes” is the number of nodes that directly transmit data to the node. Specifically, the adjacent nodes of the node 204 are nodes within a range 220 in which a signal from the node 204 can be detected, and are the node 201, the node 202, the node 203, the node 205, the node 206, the node 207, and the node 208. . Child nodes of the node 204 are a node 205 and a node 206.

The signal transmission unit 2003 transmits the message received from the hello message creation unit 2001 and the route message creation unit 2002 to the sink node 100.

FIG. 3 is a block diagram showing the configuration of the sink node 100 according to Embodiment 1 of the present invention. The sink node 100 according to Embodiment 1 of the present invention includes a signal reception unit 3001, a hello message management unit 3002, a node information management unit 3003, and a congestion judgment unit 3004. FIG. 3 shows a characteristic configuration of the first embodiment of the present invention, and a description of other general configurations is omitted.

The signal receiving unit 3001 of the sink node 100 receives a message such as a hello message or a route message transmitted from the nodes 201 to 215 via the wireless multi-hop network. The signal receiving unit 3001 passes the message to a suitable processing unit according to the type of the received message. Specifically, if the received message is a hello message, the signal reception unit 3001 passes the message to the hello message management unit 3002, and if the received message is a route message, the signal reception unit 3001 sends the message to the node information management unit 3003. give.

The hello message management unit 3002 manages the reception status of the hello message of each node 201-215. Specifically, the node number and information indicating whether or not a hello message is received from the node having the node number are managed. Information indicating whether or not a hello message has been received is reset when the congestion determination unit 3004 determines that the congestion state is present.

The node information management unit 3003 manages route messages transmitted by the nodes 201 to 215 as peripheral information. The peripheral information managed by the node information management unit 3003 includes a communication path from each of the nodes 201 to 215 to the sink node 100, the number of adjacent nodes, the number of hops, and the number of child nodes. The peripheral information managed by the node information management unit 3003 may be any one of a communication path, the number of adjacent nodes, the number of hops, and the number of child nodes, or any combination of two or more.

The congestion determination unit 3004 is activated at a constant cycle, and determines the congestion state of the nodes 201 to 215 based on information from the hello message management unit 3002 and the node information management unit 3003.

FIG. 4 is a flowchart for the sink node 100 to determine the congestion state. The operation for the sink node 100 to determine the congestion state is performed at a constant cycle. The fixed period may be set using a timer, for example.

In determining the congestion state, the congestion determination unit 3004 refers to the hello message management unit 3002 and selects a node that has not yet reached the hello message. Further, a route message related to the acquired node is acquired from the node information management unit 3003. The route message acquired from the node information management unit 3003 is the number of adjacent nodes, the number of hops, and the child node ID of the node that has not yet reached the hello message (step S400). Also, the congestion determination unit 3004 acquires the hello message arrival rate of the child node having the ID from the hello message management unit 3002 based on the ID of the child node acquired in step S400.

The number of adjacent nodes, the number of hops, and the hello message arrival rate of the child nodes that have not yet reached the hello message acquired in step S400 have different units. Therefore, the congestion judgment unit 3004 converts the parameter into a value hierarchized into a plurality of stages so that it can be handled as the same unit (step S401). Hierarchization of parameter values may be performed by conversion that replaces a value within a predetermined range with another value. Further, the value to be converted may be changed according to the scale of the network to be used.

The congestion determination unit 3004 calculates a congestion determination value for determining the congestion state using the hierarchized value (step S402). The calculation formula for calculating the congestion judgment value is as follows.
Congestion judgment value = (number of adjacent nodes x W1)
+ (Hello message arrival rate of child node x W2)
+ (Number of hops x W3) (1)
Here, the values hierarchized in step S401 are used for “the number of adjacent nodes”, “the hello message arrival rate of child nodes”, and “the number of hops”. W1, W2, and W3 in the congestion determination value are parameters for weighting parameters to be used.

The congestion judgment unit 3004 sets the weights W1, W2, and W3 according to the degree of influence of the “neighboring node number”, “child node hello message arrival rate”, and “hop number” on the congestion state. In this embodiment, weighting is set in the priority order of “number of adjacent nodes”, “hello message arrival rate of child nodes”, and “hop count”.

Based on the congestion determination value calculated in step S402, the congestion state is determined on the communication path of the node that has not yet reached the hello message. Here, if the congestion judgment value is above a preset threshold, it is judged that the communication path is congested, and if the congestion judgment value is below the preset threshold, wireless communication is determined. It is determined that the wireless link is in a poor connection state due to the influence of the wireless environment, not the link congestion state (step S403). As described above, the congestion determination unit 3004 uses the information stored in the hello message management unit 3002 and the node information management unit 3003 to determine whether the communication path of the node to which the hello message has not reached is in a congestion state. To do.

When step S403 ends, the process returns to step S400, and the determination of the congestion state of the nodes is repeated until there is no node that has not yet reached the hello message (step S404).

In step S403, it is determined whether there is a problem in the congestion state where the wireless link is congested or the connection state of the wireless link based on the relationship between the value of the congestion determination value and the threshold value. The reason for this will be described below.

First, when the number of adjacent nodes is large, in addition to the target node, many adjacent nodes transmit data to any one of the nodes at the respective timings within the range in which the wireless signal can be detected. . In order to avoid radio signal collision, the target node must wait without transmitting data while other adjacent nodes transmit data, and the time that the target node can transmit data is adjacent. Decreases as the number of nodes increases. As a result, as the number of adjacent nodes increases, there is a high possibility that data transmission of the target node will be delayed, and there is a high possibility that a congestion state will occur.

In addition, when the child node has a high hello message arrival rate, it is presumed that the wireless connection environment is good and the wireless connection environment of the target node is also good. Therefore, it is considered that there is a high possibility that the traffic is congested.

In addition, when the number of hops is large, it takes a long time to transmit data from the target node to the sink node 100. In addition, data may be discarded due to congestion at each hop of the communication path, and there is a high possibility that a hello message will be delayed or not reached. Therefore, the number of hops is also a parameter that affects the determination of the congestion state.

Therefore, depending on the size of the congestion judgment value combining the parameters “number of adjacent nodes”, “child node hello message arrival rate”, and “number of hops”, whether the radio link traffic is congested or the radio link It is possible to determine whether there is a problem in the wireless environment. As a result, it is possible to determine whether the hello message has not yet arrived due to congestion in the wireless multi-hop network or due to a communication path state problem.

In this way, the sink node 100 receives messages such as route messages and hello messages transmitted from the nodes 201 to 215 that are radio nodes via the radio multi-hop network by the signal reception unit 3001, and the hello message management unit 3002. Stores the reception status of the messages from the nodes 201 to 215, the node information management unit 3003 stores the peripheral information of the wireless node acquired from the received message, and the congestion determination unit 3004 includes the hello message management unit 3002 and the node information management Using the information stored in the unit 3003, it is determined whether or not the radio links of the radio nodes 201 to 215 are in a congestion state. In addition, when the hello message management unit 3002 does not reach a message from a node, the congestion determination unit 3004 determines whether the wireless link of the node is in a congested state or there is a problem with the wireless connection environment.
Such control makes it possible to determine the congestion state of the wireless links of the nodes 201 to 215 even when the message has not arrived from the nodes 201 to 215.

Embodiment 2.
In the first embodiment, the congestion determination value is calculated using the number of adjacent nodes, whereas in the second embodiment of the present invention, the congestion determination value is calculated using the number of child nodes as shown in the following equation. .
Congestion judgment value = (number of child nodes x W1)
+ (Hello message arrival rate of child node x W2)
+ (Number of hops x W3) (2)
When the number of child nodes is large, the traffic increases, so that there is a high possibility that congestion will occur. Therefore, in this embodiment, the congestion determination value is calculated using the number of child nodes.

By using the number of child nodes instead of the number of adjacent nodes, information on the number of adjacent nodes included in the route message notified by each of the nodes 201 to 215 can be reduced. This operation can be performed by the congestion determination unit 3004 acquiring information on the number of child nodes from the node information management unit 3003 in step S400 and calculating a congestion determination value in step S402.

Also, instead of the hello message arrival rate of the child node, as shown in the following equation, the number of consecutive non-delivery of hello messages calculated from time series information on whether or not a hello message has been received is used to calculate the congestion judgment value. You may use.

Congestion judgment value = (number of adjacent nodes x W1)
+ (Number of consecutive non-delivery of Hello messages x W2)
+ (Number of hops x W3) (3)
By using the number of consecutive non-delivery of hello messages based on time-series information indicating whether or not a hello message has been received, it is possible to determine the congestion state in consideration of the time characteristics of the hello message reception state.

Further, the congestion state may be determined using a parameter of the following equation obtained by combining the parameters of Equation (2) and Equation (3).
Congestion judgment value = (number of child nodes x W1)
+ (Number of consecutive non-delivery of Hello messages x W2)
+ (Number of hops x W3) (4)

In Embodiments 1 and 2, the hello message management unit 3002 and the node information management unit 3003 may be referred to as a first management unit and a second management unit, respectively. A node may be called a wireless node. Further, although the operation of the tree-type wireless multi-hop network has been described, other than a tree-type network configuration may be used. The signal reception unit 3001 may be referred to as a reception unit, and the congestion determination unit 3004 may be referred to as a determination unit.

100: sink node, 201-215: node, 220: range in which a signal from the node 204 can be detected, 2001: hello message creation unit, 2002: route message creation unit, 2003: signal transmission unit, 3001: signal reception unit, 3002 : Hello message management unit, 3003: Node information management unit, 3004: Congestion judgment unit

Claims (4)

A receiver for receiving a message transmitted from a wireless node via a wireless multi-hop network;
A first management unit for storing information indicating a reception state of a message for confirming a survival state from the wireless node;
A second management unit that stores peripheral information including the number of hops from the wireless node acquired from the received message;
Using the information stored in the first management unit and the second management unit, a determination unit that determines whether or not the radio link of the radio node is in a congestion state;
A wireless communication apparatus comprising:   When the first management unit has not reached the message for confirming the survival state from the wireless node, the determination unit determines whether the wireless link of the wireless node is in a congested state or there is a problem in the wireless connection environment. The wireless communication apparatus according to claim 1, wherein it is determined whether or not there is.   The second management unit stores the number of child nodes of the wireless node, the number of wireless nodes adjacent to the wireless node, or the number of hops of a message received from the wireless node as peripheral information of the wireless node. The wireless communication device according to claim 1, wherein the wireless communication device is a wireless communication device. A receiving step of receiving a message transmitted from a wireless node via a wireless multi-hop network;
A first management step of storing information indicating a reception state of a message for confirming a survival state from the wireless node;
A second management step of storing peripheral information of the wireless node obtained from the received message;
Using the information stored in the first management step and the second management step to determine whether or not the radio link of the radio node is in a congested state;
A wireless communication method comprising:

Images