KR20120113495A - Route reconfiguration method and apparatus in mobile wireless mesh networks - Google Patents

Abstract

The present invention is a path resetting method for providing end-to-end seamless service in a wireless mesh network composed of nodes having mobility. In the present invention, a path optimization procedure for operation or a path optimization procedure for restoration is performed in each node located on a path. It provides a method for starting the change procedure and determining when to start the change procedure using the path cost and the received signal strength. The path change method according to the present invention can continuously optimize the path for end-to-end transmission, and the path resetting before the intermediate link is completely disconnected by reflecting the received signal strength and the path cost to determine when the path resetting starts. Operation can be started to minimize service interruption due to mobility, and a route that provides better path costs can be used for a long time, thereby improving transmission performance even in a moving environment.

Description

Route Reconfiguration Method and Apparatus In Mobile Wireless Mesh Networks in Wireless Mesh Networks

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless mesh network, and more particularly, to a method for selecting a node for changing a path and determining a change point in a path changing method in a wireless mesh network.

 Mesh network refers to a network in which each node on the network exists as an independent router. Each node is connected to each other like a mesh so that if one connection is lost, it can communicate over the other.

A wireless communication network employing a mesh network is called a wireless mesh network (WMN). Wireless mesh networks use a multi-hop scheme. Multi-hop wireless networks must provide seamless end-to-end communication between wireless mobile terminals even without a separate backbone network supporting end-to-end communication between wireless mobile terminals.

An object of the present invention is to provide a method for changing a transmission path by determining a node to be changed and a change point in time to provide a seamless service in a wireless mesh network composed of nodes having mobility.

An object of the present invention is to provide a method for selecting a path to be changed in consideration of received signal strength and path cost for each candidate node of a wireless mesh network.

An object of the present invention is to provide a method for determining a change point of a transmission path in consideration of the quality of the transmission path for each node in a wireless mesh network.

The present invention relates to a path setting method of a current node in a wireless mesh network, and an embodiment of the present invention obtains signal strength with a communication node of a current path and a path cost of a communication path, and is a path movement target from a communication node. Obtaining a signal strength with candidate nodes and a path cost of a candidate path through the candidate nodes, calculating a necessary signal strength difference for changing a path to each candidate node based on the path costs, and a path to each candidate node A method for changing a path includes changing to a path through a corresponding node when a candidate node satisfying a required strength difference exists by using a required signal strength difference for changing a.

In this case, the current node may be a source node or an intermediate node on a data transmission path in the wireless mesh network, a communication node is a next hop node of a current transmission path, and a candidate node is a neighbor node of the current node. to be.

The route cost may have a smaller value as the quality of the route is better.

In addition, the required signal strength difference for each candidate node may have a smaller value as the cost of the path through the candidate node is smaller, and may be larger as the signal strength with the communication node is larger.

When there are a plurality of candidate nodes satisfying the required signal strength difference for each candidate node, a candidate node having the largest value obtained by subtracting the difference in the required signal strength from each signal node with each candidate node may be selected as a node to change the path. .

The present invention also relates to a method for selecting a mesh node of a terminal node operating by accessing a wireless mesh network, and an embodiment of the present invention relates to a signal strength with a communication mesh node currently performing communication and a cost of a path through the communication mesh node. Acquiring the signal strength with the candidate mesh nodes to be the path movement target from the mesh node and the path cost of the candidate path through the candidate mesh nodes, and for changing the path to each candidate node based on the path costs. Computing the necessary signal strength difference and using the necessary signal strength difference for changing the path to each candidate mesh node, and if there is a candidate mesh node that satisfies the required signal strength difference, the mesh node is selected as the corresponding mesh node. The mesh node selection method includes selecting a mesh node to change a path through.

In this case, the path cost through the communication mesh node and each candidate mesh node may be used as the path cost to the mesh gateway node.

The route cost may have a smaller value as the quality of the route is better.

In addition, the required signal strength difference for each candidate mesh node may be smaller as the cost of the path through the candidate mesh node is smaller, and may be larger as the signal strength with the communication node is larger.

When there are a plurality of candidate mesh nodes that satisfy the required signal strength difference for each candidate mesh node, the candidate mesh node having the largest value obtained by subtracting the difference in the required signal strength from the signal strength with each candidate mesh node may be selected.

The present invention also relates to a path change device for managing a path of an end-to-end connection in a wireless mesh network. An embodiment of the present invention provides a link quality measurement unit for measuring signal strength with a communication node and respective candidate nodes, and communication. Routing unit for measuring the path cost of the path through the node and each candidate node and determining the required signal strength for each candidate node, and if there is a candidate node that satisfies the required signal strength, the path is changed to the path through the node A route change device including a route change unit.

The higher the quality of the route, the smaller the route cost.

The difference in the required signal strength for each candidate node determined by the path changing unit may be smaller as the cost of the path through the candidate node becomes smaller.

The present invention also relates to a mesh node selection device for selecting a mesh node in a user terminal connected to a wireless mesh network, and an embodiment thereof provides a link quality for measuring signal strength with a communication mesh node and respective candidate mesh nodes. Determining the required signal strength for each candidate mesh node and the routing unit for measuring the path cost of the path through the measurement unit, the communication mesh node and each candidate mesh node, and if there is a candidate mesh node satisfying the required signal strength Mesh node selection device including a path management unit for connecting to the node.

In this case, the higher the quality of the route may have a smaller route cost.

In addition, the required signal strength difference for each candidate node determined by the path changing unit may be smaller as the cost of the path through the candidate node is smaller.

According to the present invention, a transmission path may be changed to provide a seamless service in a wireless mesh network.

According to the present invention, the transmission path may be changed in consideration of the received signal strength and the path cost of each node of the wireless mesh network.

According to the present invention, it is possible to determine a change point of the transmission path in consideration of the quality of the transmission path for each node in the wireless mesh network.

1 is a block diagram schematically illustrating an apparatus for changing a path of a system to which the present invention is applied.
2 schematically illustrates an example in which a connection is made in a wireless multi-hop node of a network to which the present invention is applied.
3 schematically illustrates path costs and signal strengths for communication nodes and candidate nodes in a network to which the present invention is applied.
4 schematically illustrates an example of received signal strength measured at a current node.
FIG. 5 is a diagram schematically illustrating a difference in reference signal strength and timing of a path change when a communication node and two candidate nodes exist.
6 is a flowchart schematically illustrating an example of a route changing method performed by a route changing apparatus according to the present invention.
7 is a flowchart schematically illustrating another example of a route changing method performed by a route changing apparatus according to the present invention.
8 is a diagram schematically illustrating performing a route change according to the present invention when the route cost is calculated using a hop count.
FIG. 9 is a diagram schematically illustrating selection of a mesh node to which a user terminal to access a wireless mesh network selects.

Several methods are used to change the path on the network.

First, in the wired network, RSVP, which is a routing and resource reservation method for providing end-to-end quality of service (QoS) when a path is changed, provides a rerouting method for recovering when a path problem occurs. . Since the rerouting method in the wired network is based on the information of the routing layer, it is started by an updated routing metric or link failure. However, this method cannot reflect the characteristics of the radio channel and the routing procedure can be started after the link is disconnected. Therefore, when applied to a wireless network, if the link is disconnected due to mobility, the service may be interrupted during the recovery time.

In addition, in a wireless network such as a wireless ad-hoc network and a wireless mesh network, an IP routing method is used for multi-hop transmission. The IP routing method determines the path using only the routing information in the upper layer. In this method, when a new neighbor node is discovered, the path is not immediately changed or changed according to the path cost through the node. If the new neighbor node has a better path cost, it attempts to communicate even if the link is of poor quality by changing the path immediately regardless of the signal strength of the new node. If the route being used is more expensive, the reroute operation is not performed until the active link is completely disconnected.

Meanwhile, in a cellular network, a terminal communicates with one base station and, when moving, performs a handoff procedure to a new base station. In the handoff procedure, only channel characteristics between the base station and the terminal are reflected, and routing metrics are not considered. In a wireless mesh network, the quality of a communication path is greatly influenced by a path for communication. When changing a node that performs communication by reflecting only channel characteristics, the quality of a changed path may be greatly degraded. Quality cannot be guaranteed.

Hereinafter, the contents of the present invention for changing the path in a wireless mesh network will be described with reference to the drawings.

1 is a block diagram schematically illustrating an apparatus for changing a path of a system to which the present invention is applied.

The path changing apparatus 100 includes a path changing unit 110, a routing unit 120, and a link quality measuring unit 130. The route change apparatus 100 may be located at each location capable of controlling route change in the wireless mesh network, and may be located, for example, in a routing device existing on each node.

The path changing unit 110 is connected to the routing unit 120 and the link quality measuring unit 130, and the routing unit 120 and the link quality measuring unit 130 are connected to the network.

The routing unit 120 calculates a path cost of a path to the destination node through each candidate node using routing information of the network. The routing unit 120 provides the calculated route cost to the route changing unit 110. In this case, the routing unit 120 may maintain a path cost to the destination node through routing using a distance vector routing algorithm (DVRA) or a link state routing algorithm (LSRA).

In the present invention, as the path cost, a hop count, an Expected Transmission Count (ETX), an Expected Transmission Time (ETT), and the like may be applied, and a higher path quality has a smaller path cost.

The link quality measuring unit 130 measures a link quality with a neighboring node by using a packet received from a communication node and each candidate node. The link quality may be represented by a received signal strength indicator (RSSI) from a neighbor node, and dBm may be used as a unit of signal strength.

The path changing unit 110 may determine a method of selecting a new communication node and a time point of changing the path to the new communication node by using information of the communication node in the current path and candidate nodes that can replace the node. The path changing unit 110 may determine whether or not to change the path to a new communication node based on the path cost calculated by the routing unit 120 and the link quality measured by the link quality measuring unit 130.

2 schematically illustrates an example in which a connection is made in a wireless multi-hop node of a network to which the present invention is applied. For convenience of description, a wireless multi-hop network will be described as an example of a network to which the present invention is applied.

Referring to FIG. 2, the currently set path is set as a path 220 connected from the source node (current node) 210 to the destination node 260 via the node n _r 230.

3 schematically illustrates path costs and signal strengths for communication nodes and candidate nodes in a network to which the present invention is applied. Also for convenience of explanation, a wireless multi-hop network will be described as an example of a network to which the present invention is applied.

In a wireless multi-hop network to which the present invention is applied, a node in which communication is made from a current node with respect to one unit connection (connection between two end nodes) is called a communication node n _r , and from the current node A node to which a connection can be made is called a candidate node n _i . Assume that there are N candidate nodes to which a connection can be made from the current node.

The path cost for the transfer from the source node to the destination node is expressed in m. Thus, it shows the path cost about shows the path cost about through the communication node to the destination node n _r transmitted by m _r, transmitted over the candidate node to the destination node n _i in m _i.

In addition, the signal strength for the unit connection is represented by S. Accordingly, the signal strength between the current node and the communication node S _r , and the signal strength between the current node and the candidate node S _i . Based on the symmetry of bidirectional communication, such as uplink and downlink symmetry, the signal strength between the current node and the communication node, between the current node and the candidate node is a packet transmitted from the communication node, a packet transmitted from the candidate node. It can be judged from

On the other hand, the signal strength between each node changes with time. The change in signal strength is due to various causes such as node mobility and channel change.

4 schematically illustrates an example of received signal strength measured at a current node. In FIG. 4, a change in signal strength S _r for a communication node n _r and a change in signal strength S ₂ for a candidate node n ₂ may be confirmed with time.

 Now, a path changing method in the network according to the present invention will be described in detail. For convenience of explanation, a wireless multi-hop network will be described as an example of a network to which the present invention is applied.

The path change method according to the present invention is determined using information of communication nodes and candidate nodes for each (unit) connection. Data is passed to the final receiving node via a path connected between the nodes. This final receiving node is called a destination node.

On the path to the destination node, data is passed from the current node to the next hop node (communication node).

In the present invention, the path changing unit of the path changing device operates on a multi-hop connection transmitted through each node.

The path changing unit may obtain a path metric for each candidate node through the routing unit, and the link quality for each candidate node may also be obtained through the link quality measuring unit. The path changing unit changes the path from the communication node to a node satisfying a predetermined criterion among candidate nodes based on the obtained path cost and link quality information. Candidate nodes, whose paths are changed to become new communication nodes, are referred to as replacement nodes by distinguishing them from existing communication nodes.

The method of changing the path will be described in more detail.

The path changing unit determines the reference signal strength difference h _i for each candidate node n _i . The reference signal strength difference h _i is a reference threshold between the received strength from the i-th candidate node and the received strength from the communication node, which is needed to change the path from the communication node to the i-th candidate node, and the i-th candidate node. The path cost for each of the and communication nodes is considered.

If the received signal strength from the i-th candidate node is h _i greater than the received signal strength from the communication node, the path changing unit selects the i-th candidate node as the alternate node and changes the transmission path from the communication node to the alternate node. .

That is, the received signals from the present invention, the path changing unit for the transmission path to the destination node, the candidate node (n _i) the route costs (m _i) and each of the candidate nodes (n _i) for the case through intensity ( In consideration of S _i ), a different reference signal strength difference h _i is determined for each candidate node. The path changing unit may determine whether to change the path and when to change the path according to the reference signal strength difference h _i for each candidate node n _i .

Therefore, according to the present invention, when the path is changed to the corresponding node as well as the reception strength from each node, the path change is determined in consideration of the cost of the entire transmission path, and thus adaptively takes into account the overall network situation. You can choose the path.

Referring to FIG. 4, it is possible to identify a time point t ₀ when the path is changed from the communication node n _r to the replacement node n ₂ . The path changing unit may determine the path change when the difference between the received signal strength from the n ₂ node and the reference signal strength from the communication node becomes h ₂ .

FIG. 5 is a diagram schematically illustrating a difference in reference signal strength and timing of a path change when a communication node n _r and two candidate nodes n ₁ and n ₂ exist. That is, FIG. 5 illustrates a case in which an additional candidate node n ₂ exists for the case of FIG. 4.

5 illustrates an example of received signal strengths S _r , S ₁ , and S ₂ for communication nodes and candidate nodes. Here, in consideration of the path cost for each node (n _r , n ₁ , n ₂ ), it is assumed that the reference signal strength difference h ₁ has a negative value, and the reference signal strength difference h ₂ has a positive value.

In consideration of the path cost, the path may be changed by selecting a candidate node whose strength of the received signal is not greater than the communication node as an alternate node. That is, the path can be changed in consideration of the overall situation of the network.

For example, as the h ₁ 5, if having a value of the reference signal strength difference is negative, change path when the received signal strength from the candidate node n ₁ h ₁ as greater than the received signal strength from the communication node n _r arose because, the received signal strength (S ₁₎ from the candidate node n ₁ greater than the required received signal strength (S _r) from the communication node n _r, it is possible to change the path.

 6 is a flowchart schematically illustrating an example of a route changing method performed by a route changing apparatus according to the present invention.

The path changing apparatus obtains information about the communication node n _r , for example, the received signal strength S _r and the path cost m _r at predetermined time intervals, and also receives the received signal strength S for each candidate node. _i ), information such as a route cost (m _i ) is obtained (S610). Here, it is assumed that the total number of candidate nodes is N.

The path changing apparatus determines the reference signal strength difference h _i for each candidate node (S620).

The reference signal strength difference h _i for each candidate node is, as described above, between the received strength from the i-th candidate node and the received strength from the communication node needed to change the path from the communication node to the i-th candidate node. As a reference difference, the path cost for each of the i th candidate node and the communication node is considered.

Therefore, the reference signal strength difference h _i may be determined in various ways in consideration of the path cost m _i for the corresponding candidate node n _i . Path by changing unit compares the difference in path cost (m _i) signal strength (S _r) from the reference signal intensity difference consideration (h _i) for i receiving strength (S _i) from the second candidate node and the communication node In addition, it decides whether to change the path considering the entire network.

As described above, the reference signal strength difference hi may be variously calculated, and as an example, a calculation equation such as Equation 1 may be considered.

Here, h is a reference threshold of the received signal strength necessary to change the path when selecting a path in consideration of the strength of the received signal without considering the path cost, and α is a predetermined threshold regarding the received signal strength. The first scaling factor.

(m _r -m _i ) represents the difference between the path cost of the current path through the communication node and the path cost of the path through the i th candidate node. (m _r -m _i ) has a positive value when the path through the i th candidate node is a better path, that is, when the path cost of the path through the i th candidate node is small.

Therefore, if the path cost of the path through the i th candidate node is smaller, the reference signal strength difference required for the path change is also smaller. In other words, the better the path quality, the smaller the difference in the reference signal strength can be.

In calculating the path cost, the reference signal strength difference h _i may have a negative value depending on which value among various values such as hop number, ETX, ETT, etc. is used. For example, in the case of FIG. 5, assume that there is a relationship of m ₁ <m _r <m ₂ between the path cost m _r , m ₁ , m ₂ of the paths through the communication node n _r and the two candidate nodes n ₁ and n ₂ . In this case, when calculating the reference signal strength difference h _i according to Equation ₁ , h ₁ may have a negative value as described above, and the received signal strength S ₁ from the candidate node n ₁ may be different. the communication node n _r even greater than the received signal strength (S _r) from a, it is possible to change the path.

The apparatus for changing a path starts to perform a procedure for determining whether to change a path from the first candidate node (i = 0) (S630). The node order from the first to the Nth may be arbitrarily set by the route changing device or may be predetermined. The apparatus for changing a path starts to perform a procedure for determining whether to change the path for the first (i = 0) candidate node, and in turn, performs a procedure for determining whether to change the path for the i-th candidate node. If a procedure for determining whether to change the path is performed for all candidate nodes (i = N), the procedure ends (S640).

The apparatus for rerouting determines the magnitude of the difference between the received signal strength S _i from the i th candidate node and the received signal strength S _r from the communication node and the reference signal strength difference h _i with respect to the i th candidate node. Compare (S650).

If the difference between the received signal strength S _i and the received signal strength S _r is greater than the reference signal strength difference h _i , the path changing apparatus may change the path to the transmission path through the candidate node n _i (S660). .

If the difference between the received signal strength _Si and the received signal strength S _r is not greater than the reference signal strength difference h _i , the redirection device moves the object of the rerouting procedure to the next candidate node (i ++). (S670).

7 is a flowchart schematically illustrating another example of a route changing method performed by a route changing apparatus according to the present invention.

In the case of FIG. 7, unlike the case of FIG. 6, after acquiring the reception strength and the path cost for the communication node, whether to change the path by acquiring the reception strength and the path cost for each candidate node and calculating the difference of the reference signal strength Decide

The path changing apparatus obtains the received signal strength S _r from the communication node and the path cost m _r of the path through the communication node (S710).

Subsequently, the apparatus for changing the path enters a procedure for changing the path for the first candidate node (i = 0) (S720). The node order from the first to the Nth may be arbitrarily set by the route changing device or may be predetermined. The apparatus for changing paths performs the following procedure for determining whether to change paths for the i-th candidate node in turn from the first (i = 0) candidate node, and for determining paths for all candidate nodes. If (i = N), the procedure ends (S730).

The apparatus for changing a path obtains the received signal strength (S _i ) from the i-th candidate node and the path cost (m _i ) of the path through the i-th candidate node with respect to the i-th candidate node (S740). The signal strength difference h _i is determined (S750).

The apparatus for rerouting determines the magnitude of the difference between the received signal strength S _i from the i th candidate node and the received signal strength S _r from the communication node and the reference signal strength difference h _i with respect to the i th candidate node. Compare (S760).

If the difference between the received signal strength S _i and the received signal strength S _r is greater than the reference signal strength difference h _i , the path changing apparatus may change the path to the transmission path through the candidate node n _i (S770). .

If the difference between the received signal strength _Si and the received signal strength S _r is not greater than the reference signal strength difference h _i , the redirection device moves the object of the rerouting procedure to the next candidate node (i ++). (S780).

8 is a diagram schematically illustrating performing a route change according to the present invention when the route cost is calculated using a hop count. In FIG. 8, for convenience of description, the intensity of the reference received signal is calculated using Equation 1, and it is assumed that the difference h of the received signal strength is 3 dB and the α value is 5.

Referring to FIG. 8, when using the hop number as the path cost, m _r of a transmission path from a current node (source node) 800 to a communication node n _r 820 to a destination node D 810 is communicated. The value is four.

In addition, the value of m ₁ for the transmission path leading to the destination node D 810 through the candidate node n ₁ 830 is 2, and the transmission path leading to the destination node D 810 through the candidate node n ₂ 840. It can be seen that the value of m ₂ for.

Equation 1 calculates h ₁ of -4.5 dB and h ₂ of 2.25 dB. Therefore, when the path change device determines the path change in the order of the candidate nodes n ₁ and n ₂ with respect to the source node 800, the signal change (S ₁ ) from the candidate node n ₁ and the communication node from the communication node. When a relationship of S ₁ > S _r −4.5 is established between the signal strengths S _r , the path is changed from the communication node n _r to the candidate node n ₁ .

As described above, the present invention can be applied to determining a path from one node to the next node of the wireless mesh network, and selects a mesh node to be accessed by a user of a terminal who wants to access the network through the wireless mesh network. The same applies to

In addition, the present invention can be equally applied to selecting a mesh node to be newly connected to reset the path even when the user terminal (node) is moving.

FIG. 9 is a diagram schematically illustrating selection of a mesh node to which a user terminal to access a wireless mesh network selects. In this case, the user terminal may be a terminal for newly accessing the wireless mesh network, or may be a terminal for changing the connection to a new mesh node for resetting a path while moving.

In this case, the user node (terminal node 900) becomes the source node, the gateway node 970 becomes the destination node, and the above-described contents of the present invention can be equally applied.

For example, a user (user node) who wants to connect to a mesh network for the first time may set any candidate node as a communication node and apply the contents of the present invention as described above. In addition, a moving user (user node) may set a node currently in communication as a communication node and apply the contents of the present invention as described above.

In detail, the path changing unit of the user node 900 may obtain information of the current communication node 910 and the candidate nodes 920, 930, and 940 through the routing unit and the link quality measuring unit of the user node 900. The path changing unit of the user node 900 determines the reference signal strength difference h _i necessary to change the connection for each candidate node based on the path cost to the gateway 950 through each node and the received signal from each node. The connection node can be changed based on this.

By applying the present invention as described above, in order to maintain a good path between the gateway node 950, the user node 900 can change the mesh node to be connected, and the mesh node that provides a good path quality; The communication can be performed longer.

As described above, according to the present invention, the reference signal strength for changing the communication node in consideration of the received signal strength from the candidate node and the path cost of the path through the candidate node in the process of changing the transmission path for multi-hop transmission You can decide the car. As a result, the smaller the path cost for the path to be changed than the path cost for the current path, the smaller the difference in the required signal strength is required, so that the path change can be performed faster, and conversely, the path for the path other than the current path. As the cost is greater than the path cost for the path currently being used, the required reference signal strength difference increases, allowing the current path to be kept longer and then performing a path change.

Each node of the wireless mesh network may perform a path change operation on a transmission path in use, and may use a path having a good quality by performing a path change in consideration of the path quality. Therefore, it is possible to provide a seamless service. In addition, by determining the path change time based on the quality of the path, it is possible to maintain a good path for a long time to improve the multi-hop transmission performance.

On the other hand, it has been described that the present invention is applied to the wireless multi-hop network so far, but for convenience of description, the present invention is not limited thereto, and may be applied to various networks within the scope of the technical idea of the present invention.

In the present invention, the description "includes" a specific configuration does not exclude a configuration other than the configuration, it means that additional configuration may be included in the scope of the technical spirit of the present invention or the present invention.

In the above-described exemplary system, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . It will also be understood by those skilled in the art that the steps shown in the flowchart are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (19)

In the routing method of the current node in the wireless mesh network,
Acquire the signal strength with the communication node of the current path and the path cost of the communication path, obtain the signal strength with the candidate nodes to be the path movement target from the communication node and the path cost of the candidate path through the candidate nodes. Doing;
Calculating a necessary signal strength difference for changing a path to each candidate node based on the path costs; And
And changing to a path through the corresponding node when there is a candidate node that satisfies the required strength difference by using a required signal strength difference for changing a path to each candidate node. The method of claim 1,
The route cost has a smaller value as the quality of the route becomes better. The method of claim 1,
And the current node is a source node in an end-to-end connection. The method of claim 1,
And the current node is an intermediate node of an end-to-end connection. The method of claim 1,
The difference in the required signal strength for each candidate node is smaller as the cost of the path through the candidate node is smaller. 6. The method of claim 5,
The required signal strength difference for each candidate node is a path change method characterized in that the greater the signal strength with the communication node. The method of claim 1,
If there are a plurality of candidate nodes that satisfy the required signal strength differences for each candidate node, selecting a candidate node having the largest value minus the difference in the required signal strengths from each of the candidate nodes as the node to change the path. Characterized in the path change method. In selecting a mesh node of a terminal node operating by connecting to a wireless mesh network,
Obtain the signal strength with the communication mesh node currently performing communication and the cost of the path through the communication mesh node, the signal strength with the candidate mesh nodes to be the path movement from the mesh node and the candidate mesh nodes Obtaining a path cost of the candidate path through;
Calculating a necessary signal strength difference for changing a path to each candidate node based on the path costs; And
And selecting a corresponding mesh node when a candidate mesh node satisfying the required signal strength difference exists by using a required signal strength difference for changing a path to each candidate mesh node. 9. The method of claim 8,
A method for selecting a mesh node, characterized by using a path cost through a communication mesh node and each candidate mesh node as a path cost to a mesh gateway node. The method of claim 8,
The path cost has a smaller value as the path quality is better. The method of claim 8,
The difference in the required signal strength for each candidate mesh node is smaller as the cost of the path through the candidate mesh node is smaller. The method of claim 8,
The required signal strength difference for each candidate mesh node increases as the signal strength with the communication node increases. The method of claim 8,
When there are a plurality of candidate mesh nodes that satisfy the required signal strength difference for each candidate mesh node, the candidate mesh node having the largest value minus the difference in the required signal strength is selected from the signal strength with each candidate mesh node. How to select mesh nodes. In the path change device for managing the path of the end-to-end connection in the wireless mesh network,
A link quality measuring unit measuring signal strength with a communication node and respective candidate nodes;
A routing unit for measuring a path cost of a path through the communication node and each candidate node; And
And a path changing unit for determining the required signal strength for each candidate node and changing to a path through the corresponding node when a candidate node satisfying the required signal strength exists. The method of claim 14,
And the routing unit has a smaller path cost as the path quality is better. The method of claim 14,
The difference in the required signal strength for each candidate node determined by the path changing unit is smaller as the cost of the path through the candidate node is smaller. In the mesh node selection apparatus for selecting a mesh node in a user terminal connected to a wireless mesh network,
A link quality measuring unit measuring signal strength between the communication mesh node and each candidate mesh node;
A routing unit for measuring a path cost of a path through the communication mesh node and each candidate mesh node; And
And a path management unit for determining the required signal strength for each candidate mesh node and connecting to the corresponding mesh node when a candidate mesh node satisfying the required signal strength exists. 18. The method of claim 17,
And the routing unit has a smaller path cost as the path quality is better. 18. The method of claim 17,
The difference in the required signal strength for each candidate node determined by the path changing unit is smaller as the cost of the path through the candidate node is smaller.

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