Wireless Mesh Network: Introduction
Wireless Mesh Network (WMN) is a promising wireless technology for several emerging and commercially interesting applications, e.g., broadband home networking, community and neighborhood networks, coordinated network management, intelligent transportation systems. It is gaining significant attention as a possible way for Internet service providers (ISPs) and other end users to establish robust and reliable wireless broadband service access at a reasonable cost. figure 1 contains an example of wireless mesh network.
figure 1 example wireless mesh network
Wireless Mesh Networks (WMN) is believed to be a highly promising technology and will play an increasingly important role in future generation wireless mobile networks. WMN is characterized by dynamic self-organization, self-configuration and self-healing to enable quick deployment, easy maintenance, low cost, high scalability and reliable services, as well as enhancing network capacity, connectivity and resilience. Wireless mesh network (WMN) is a radical network form of the ever evolving wireless networks that marks the divergence from the traditional centralized wireless systems such as cellular networks and wireless local area networks (LANs).
Wireless Mesh Network: Definition
A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. It is also a form of wireless ad hoc network. Wireless mesh networks often consist of mesh clients, mesh routers and gateways. The mesh clients are often laptops, cell phones and other wireless devices while the mesh routers forward traffic to and from the gateways which may, but need not, connect to the Internet. The coverage area of the radio nodes working as a single network is sometimes called a mesh cloud. Access to this mesh cloud is dependent on the radio nodes working in harmony with each other to create a radio network. A mesh network is reliable and offers redundancy. When one node can no longer operate, the rest of the nodes can still communicate with each other, directly or through one or more intermediate nodes. Wireless mesh networks can self form and self heal. Wireless mesh networks can be implemented with various wireless technology including 802.11, 802.15, 802.16, cellular technologies or combinations of more than one type. Nodes automatically establish an ad hoc network and maintain the connectivity due to that network provide dynamically self-organization and self-healing and self configuration and selects the optimal path back to the “wired” network. WMNs consist of mesh routers and mesh clients. Mesh routers provide network access for both mesh and conventional clients. Mesh routers form the mesh backbone and provides the minimum mobility. It provides the same coverage as conventional routers do but with the lower transmission power. Usually it has multiple wireless interfaces but has similar hardware.
Benefits and Characteristic of WMN
Some of the benefits and characteristics of wireless mesh networks are highlighted as follows.
Increased Reliability: In WMNs, the wireless mesh routers provide redundant paths between the sender and the receiver of the wireless connection. This eliminates single point failures and potential bottleneck links, resulting in significantly increased communications reliability. Network robustness against potential problems, e.g., node failures, and path failures due to RF interferences or obstacles, can also be ensured by the existence of multiple possible alternative routes. Therefore, by utilizing WMN technology, the network can operate reliably over an extended period of time, even in the presence of a network element failure or network congestion.
Low Installation Costs: Recently, the main effort to provide wireless connection to the end-users is through the deployment of 802.11 based Wi-Fi Access Points (APs). To assure almost full coverage in a metro scale area, it is required to deploy a large number of access points because of the limited transmission range of the APs. The drawback of this solution is highly expensive infrastructure costs, since an expensive cabled connection to the wired Internet backbone is necessary for each AP. On the other hand, constructing a wireless mesh network decreases the infrastructure costs, since the mesh network requires only a few points of connection to the wired network. Hence, WMNs can enable rapid implementation and possible modifications of the network at a reasonable cost, which is extremely important in today’s competitive market place.
Large Coverage Area: Currently, the data rates of wireless local area networks (WLANs) have been increased, e.g., 54 Mbps for 802.11a and 802.11g, by utilizing spectrally efficient modulation schemes. Although the data rates of WLANs are increasing, for a specific transmission power, the coverage and connectivity of WLANs decreases as the end-user becomes further from the access point. On the other hand, multi-hop and multichannel communications among mesh routers and long transmission range of WiMAX towers deployed in WMNs can enable long distance communication without any significant performance degradation.
Automatic Network Connectivity: Wireless mesh networks are dynamically self-organized and self-configured. In other words, the mesh clients and routers automatically establish and maintain network connectivity, which enables seamless multi-hop interconnection service. For example, when new nodes are added into the network, these nodes utilize their meshing functionalities to automatically discover all possible routers and determine the optimal paths to the wired Internet. Furthermore, the existing mesh routers reorganize the network considering the newly available routes and hence, the network can be easily expanded.
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