KR100982401B1 - Method for Building the Wireless Mesh Networke based on the Hexagonal Cluster - Google Patents

Abstract

The present invention relates to the design of a multi-channel multi-radio based wireless mesh network. To this end, the present invention facilitates the provision and load distribution of various wireless paths by using a regular hexagonal mesh cluster, Calculate the traffic and set the size of the mesh network. In addition, according to the number of connection hops between the gateway of the mesh cluster and the wireless mesh router and the radio channel usage accordingly, the antennas are differentially disposed to eliminate bottlenecks and minimize the construction cost. Such cost-optimized mesh clusters can be structured similarly to existing cellular networks to form an entire wireless mesh network, enabling the construction of a wireless mesh network with minimal deployment costs without radio interference areas.

Wireless mesh networks, clusters, antenna placement, deployment costs, optimization

Description

Method for Building the Wireless Mesh Networke based on the Hexagonal Cluster}

The present invention relates to an antenna arrangement capable of minimizing the structure and construction cost of a cluster for constituting an entire network in the design of a wireless mesh network (WMN), and more specifically, a gateway. The entire network is formed by arranging hexagonal clusters centered on the network, and the required amount of radio resources is calculated according to the distance (hop count) from the gateway. An antenna placement technique that can be used.

Recently, the wireless mesh network, which is receiving a lot of attention as the most suitable system structure for building the next-generation mobile environment, requires a high cost in infrastructure mode IEEE 802.11 WLAN to establish a wired network for connecting each access point (AP). This is a new type of network that solves the economic problems of (Wireless LAN) system. It is a subscriber network that can establish mobile internet environment in large area with low investment by connecting each AP by wireless link rather than wired.

In general, a wireless mesh network is composed of wireless mesh routers that can act as APs and routers. Some of the wireless mesh routers are directly connected to a wired network, and thus, a wireless mesh network and a core network or the Internet It acts as a gateway to connect. They are connected to each other via a wireless link like a mesh, creating a multi-hop environment similar to an ad hoc network. Through this structure, the wireless mesh network can greatly reduce the connection with the wired network, so that a wide area service can be performed at a lower construction cost than the infrastructure mode IEEE 802.11 WLAN system in which all APs are connected to the wired network.

Wireless channels used for connection of wireless mesh routers are classified into a multi-channel Single Radio-based and a multi-channel Multi-radio based wireless channel using a single antenna. In the case of a multi-channel multi-radio based wireless channel, by installing a plurality of antennas, the link capacity can be increased by using several channels simultaneously.

Due to the structure of the wireless mesh network that must pass through the gateway for the Internet connection, the traffic of the user connected to each wireless mesh router is transferred along the wireless link toward the gateway. In this process, traffic is concentrated as the number of wireless links decreases closer to the gateway. If the capacity of the gateway is smaller than the amount of traffic of the entire user generated in the wireless mesh routers, the gateway becomes a bottleneck. In order to solve this bottleneck problem, it is important to determine the size of the optimized cluster in consideration of the gateway capacity and the size of user traffic. In addition, since the traffic of all wireless mesh routers is delivered in multi-hops until reaching the gateway, the closer the mesh router is to the gateway, the more the traffic is concentrated. In this case, the bottleneck occurs in the wireless link between the wireless mesh routers, just as the bottleneck occurs in the wireless link between the gateway and the wireless mesh router. This bottleneck problem increases the number of delays and retransmissions and, consequently, acts as a decisive factor in reducing network efficiency.

In order to solve this problem, multi-channel multi-radio environment can reduce the bottleneck problem by increasing the capacity of the wireless link by operating a large number of antennas, but it is inevitable to increase the system construction cost by installing additional antennas. It may also lead to waste of resources and waste of construction costs by installing the antenna.

In constructing a wireless mesh network, existing methods employ a method of arranging wireless mesh routers randomly in a region to be constructed and installing a gateway that can be connected to an external network between them. However, such a method may cause a hearing loss due to random placement, and may cause waste of radio resources due to an irregular size of a cluster, which is a group of wireless mesh routers connecting to an external network through a specific gateway. In addition, when a cluster having a very small number of radio links with neighboring wireless mesh routers is formed, it is difficult to obtain a load balancing effect, and a problem in terms of robustness of a network may occur. In addition, as described above, a bottleneck problem may occur, and in the case of a multi-channel multi-radio environment, an additional antenna is installed to solve such a bottleneck, which incurs an additional cost in constructing the entire network. In this case, there is a problem in that a lot of construction costs are wasted if an additional antenna is installed indiscriminately.

In order to solve these problems, we will use a wireless mesh network with a regular cluster structure and provide a way to minimize the construction cost by adjusting the number of antennas to install antennas according to the amount of resources required by each wireless mesh router. .

The present invention consists of an antenna arrangement technique and a mesh cluster arrangement method for minimizing the construction cost without performance degradation due to the shape and bottleneck problem of the mesh cluster constituting the multi-channel multi-radio based wireless mesh network. First, the first step is to form and size a mesh cluster with a hexagonal regular structure, calculate the wireless channel requirements required by each wireless mesh router, and determine the number of antennas to be installed in the wireless mesh router differentially. A wireless mesh comprising a second step of determining and deploying the same to minimize deployment costs, and finally, a third step of constructing a multi-channel multi-radio based wireless mesh network by configuring the clusters thus constructed in a texture-free manner. Provide a network design method.

The present invention randomly arranges a wireless mesh router in an area where a wireless mesh network is to be constructed, and installs a gateway in a location where bottlenecks do not occur between them. Contrary to the method, first, the differential antenna arrangement eliminates the bottleneck problem and lays out a hexagonal mesh cluster with a regular structure that minimizes the construction cost, thereby eliminating the deafness area and providing a grid structure. By providing more wireless paths, it can facilitate load balancing and increase the robustness of the network, which enables effective load balancing. In addition, there is an advantage that the spatial reuse method of the frequency used in the existing cellular network can be used as it is by adjusting the transmission area of the antenna used for the user connection. At the same time, it is possible to build a wireless mesh network by minimizing the overall system construction cost.

Summary of the Invention In accordance with an aspect of the present invention, a regular hexagonal mesh cluster structure is used to facilitate load balancing and increase network robustness when constructing a multi-channel multi-radio based wireless mesh network. Accordingly, focusing on the different amount of radio resources required, the number of antennas installed in the wireless mesh router can be differentially disposed within a range where bottleneck problems do not occur, thereby minimizing system construction costs. By organizing the mesh clusters in this way, it is possible to construct the entire wireless mesh network with no deafness and minimal construction cost.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1A is a structural diagram of a hexagonal mesh cluster 100 used in the present invention, which includes a gateway 101, a wireless mesh router 102, a wireless link 103, and an omnidirectional antenna 104.

The configuration of the hexagonal mesh cluster is composed of one gateway 101 and wireless mesh routers 102 connected to the core network through the gateway 101, and each hop is configured in a hexagonal shape around the gateway 101. In this case, the wireless mesh router 102 of each hop is increased regularly by a multiple of 6 for each hop and is regularly arranged, and may be expressed by Equation 1 below.

In the above equation, i represents the distance from the gateway 101, that is, the number of hops and is expressed as an integer. In this case, the gateway 101 may be referred to as i = 0. R _i also means the number of wireless mesh routers 102 to be installed in hop i.

In addition, the antennas installed in each of the wireless mesh routers 102 are divided into two types for configuring an antenna used for an AP and a mesh network. An antenna used for an AP is used only for a user connection and a mesh network. The antenna used to construct the is used when exchanging traffic with neighboring wireless mesh routers 102. Basically, both types of antennas use omni-directional antennas. However, since there is only one wireless link 103 between the central gateway 101 and the mesh router located one hop away, a directional antenna is installed in each path in the gateway 101 as shown in FIG. 1B. Therefore, the channel capacity can be increased.

The size of the mesh cluster 100 is determined according to the size of the user traffic per wireless mesh router 102 and the expected user traffic size of the region where the mesh cluster 100 is to be installed, and may be expressed by the number of configuration hops. In order to eliminate the bottleneck problem in the gateway 101 described above, the sum of the total traffics of the wireless mesh routers 102 in the mesh cluster 100 to be configured is determined by the estimated user traffic size of the region where the mesh cluster 100 is to be installed. Should be exceeded, which is calculated according to equation (2).

W _U in the above equation represents the expected user traffic in the region where the mesh cluster 100 is to be installed, and the number of the wireless mesh router 102 located in each hop is represented by j. Accordingly, j is also an integer, and ij is a position coordinate of each wireless mesh router 102.

In this case, it is assumed that users are uniformly distributed in the mesh cluster 100, generate traffic of the same size, and access the wireless mesh router 102 of the nearest location. As a result, it can be said that the number of users connected to each wireless mesh router 102 is the same. In addition, it is assumed that all traffic generated by the user is transmitted to the external internet network through the gateway 101. Therefore, the traffic generated by the users connected to each wireless mesh router 102 is transmitted upward toward the gateway 101. Uplink traffic of users generated by each wireless mesh router 102 is represented by U _ij , which means the sum of traffic generated in a transmission area of an antenna for user access installed in the wireless mesh router 102 located in ij. do. On the other hand, the downlink transmission traffic means the traffic transmitted from the gateway 101 to the user connected to each wireless mesh router 102, which is assumed to occur at α times the uplink transmission traffic. That is, each wireless mesh router 102 generates uplink traffic of U _ij , receives downlink traffic of αU _ij , and transmits it to the user. Accordingly, the traffic of the mesh cluster 100 may be increased by U _ij through a routing path in the case of uplink transmission per wireless mesh router 102, and may be decreased by αU _{ij in} the case of downlink transmission traffic. Therefore, Equation 2 shows the range of the number of hops H that can be configured in the mesh cluster 100, and the smallest value of the number of hops that can be configured in order to minimize the deployment cost while eliminating the bottleneck that may occur in the gateway 101. It is necessary to configure the mesh cluster 100 using. This can be expressed as Equation 3.

The number of channels used in the wireless mesh router 102 is different depending on the type of the IEEE 802.11 standard technology, and because the spectrum does not overlap each other, the wireless channels without frequency interference can be used simultaneously.

FIG. 1B illustrates a configuration in which hexagonal mesh clusters are formed by installing a directional antenna in the gateway 101.

As such, when the directional antenna 105 is used in the gateway 101, since the directionality exists, the number of the wireless mesh routers 102 located in the first hop from the gateway 101, that is, when the omnidirectional antenna 104 is used, is used. 6 times of antenna can be installed. However, the antenna of the gateway 101 can be installed only in multiples of 6 for connection with the wireless path in all directions. The installation of the gateway 101 antenna is expressed using Equations 4 and 5 below.

In this case, β is a parameter for expressing a multiple of 6, μ is a parameter indicating whether the directional antenna is used, has a binary value of 0 or 1, and when 0 indicates the use of the omnidirectional antenna 104 and 1 day. This implies the use of the directional antenna 105. And A _max means the maximum number of antennas that can be installed in each wireless mesh router 102, W _max means the maximum capacity of the radio channel allocated per antenna. Therefore, the maximum number of antennas that can be installed in the gateway 101 may be expressed by βA _max , and the expected user traffic in the region where the mesh cluster 100 is to be installed should be smaller than the maximum capacity βA _max W _max of the antenna.

FIG. 2 is a diagram illustrating an example of differential antenna arrangement in the hexagonal mesh cluster 100, and represents the number of antennas in which numbers written in the wireless mesh router 102 are installed.

In order to place the antenna to minimize the construction cost within the range that does not cause bottlenecks in the wireless mesh routers 102 in the mesh cluster 100 configured through the above process, first, the user of the user transmitted through each wireless link It is necessary to know the movement path and size of up and down traffic.

The uplink traffic transmitted by the wireless mesh routers 102 located at hop i + 1 is relayed through the wireless mesh routers 102 of hop i. Accordingly, the hop meshes of the wireless mesh routers 102 transmit uplink again after receiving the traffic to be relayed. In this case, all traffic is transmitted to the gateway 101 through the shortest routing path, and the traffic received by the antennas of the wireless mesh routers 102 located at hop i through the antenna is assumed to be transmitted through the ideal load balancing at each wireless mesh router 102. Throughput T _Rx ⁱ can be expressed by Equation 6.

The received uplink traffic is then uplinked again with the traffic generated in hop i. Therefore, the throughput T _Tx ⁱ of uplink traffic to be transmitted through the antennas of the wireless mesh routers 102 located in the hop i may be represented by Equation (7).

The total size of the traffic, the wireless mesh router 102 in hop i are to be processed through a wireless channel is transmitted traffic throughput to be the upstream transmission to the traffic amount T _Rx ⁱ and hop i-1 received from the hop i + 1 T _It can be obtained by adding the sum of _Tx ⁱ and the throughput of downlink traffic which is α times thereof. At this time, since all traffic is transmitted through the ideal load balancing in each wireless mesh router 102 as assumed above, the size of the traffic that each wireless mesh router 102 located in hop i must process through the wireless channel is It can be the same as each other. Therefore, the amount of traffic processed through the antenna of each wireless mesh router 102, that is, the wireless channel usage T _A ⁱ is calculated as Equation (8).

Based on the wireless channel usage of each wireless mesh router 102 calculated as described above, it is possible to know the range of the number of antennas of the wireless mesh router 102 such that the bottleneck does not occur, which is expressed by Equation (9).

In this case, A _ij means the number of antennas to be installed in the wireless mesh router 102 located in ij.

Meanwhile, the gateway 101 may be referred to as T _Tx ⁱ = 0 because uplink traffic is transmitted through a wire and does not use a wireless link. Therefore, the range of the antenna that can be installed in the gateway 101 can be expressed through Equation 10 and Equation 11.

In this case, since only one gateway 101 exists in the center of the mesh cluster 100, ij = 01, and thus, a parameter representing the number of antennas to be installed is represented by A ₀₁ . In this case, when using the omni-directional antenna 104 (μ = 0) β = 1 can be installed up to A _max antennas. On the other hand, when the directional antenna 105 is used (μ = 1), β = 6, so that 6 times more antennas can be installed, and the number of antennas increases in the form of multiples of 6 as described above. do.

As can be seen from Equation 8, as the distance between the wireless mesh router 102 and the gateway 101 increases, that is, as the number of hops increases, the size of the wireless channel usage of the wireless mesh router 102 gradually decreases. In consideration of the characteristics of the wireless mesh network, it is possible to minimize the construction cost by differentially arranging the minimum antennas that can satisfy the wireless channel usage according to each hop within the ranges expressed in Equations 9 and 10. Do.

3 is a diagram illustrating an arrangement of hexagonal mesh clusters 100 for forming a wireless mesh network.

Through the above-described processes, a plurality of mesh clusters 100 are minimized to construct a whole wireless mesh network, and the wireless mesh routers 102 constituting each mesh cluster 100 are based on existing clusters. Like the wireless mesh network, the wireless mesh routers 102 in the adjacent mesh cluster 100 operate independently of each other without being directly connected through a wireless link. At this time, the arrangement of each mesh cluster 100 constitutes the entire wireless mesh network by treating each mesh cluster 100 like a cell in a similar manner as the base station arrangement used in the existing cellular network and arranging them in a textured manner.

1A shows the structure of a hexagonal mesh cluster.

1B is a diagram showing the structure of a hexagonal mesh cluster in which a directional antenna is installed in a gateway.

2 shows differential antenna placement in a hexagonal mesh cluster.

3 shows a layout of hexagonal mesh clusters for forming a wireless mesh network.

  <Description of the symbols for the main parts of the drawings>

100: mesh cluster

101: gateway

102: wireless mesh router

103: wireless link

104: omnidirectional antenna

105: directional antenna

Claims (7)

A first step of designing a hexagonal mesh cluster structure; A second step of determining and differentially arranging the number of antennas installed in the wireless mesh router in the mesh cluster; And And a third step of arranging the entire network by arranging several mesh clusters. Hexagon cluster-based wireless mesh network, characterized in that the size of the mesh cluster is determined in consideration of the size of the user's up and down traffic for each wireless mesh router within the range that can accommodate the expected user traffic in the region where the mesh cluster will be installed Way. The method of claim 1, Hexagon cluster-based wireless mesh network building method characterized in that the deployment of a hexagonal shape by increasing the number of wireless mesh routers installed every hop around the gateway to a multiple of six. The method according to claim 1 or 2, A method of building a hexagonal cluster-based wireless mesh network, comprising using an antenna of a gateway located in a mesh cluster to increase the capacity of a wireless link between a gateway and a wireless mesh router located one hop from the gateway. delete The method of claim 1, A method for constructing a hexagonal cluster-based wireless mesh network, comprising calculating user up / down traffic per wireless mesh router to determine the number of antennas of the wireless mesh router. The method of claim 1, A method for constructing a hexagonal cluster-based wireless mesh network, in which antennas are differentially arranged according to a distance from a gateway by installing a minimum number of antennas that satisfy a wireless channel usage of each wireless mesh router. delete

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