Efficient Routing Protocols for Multi-radio Wireless Mesh Networks: Architectures, Protocols, and Algorithms

The unique characteristics of multi-radio wireless mesh networks, such as shared nature of wireless channels, use of multiple radio interfaces, stationary mesh routers, and user-to-gateway traffic pattern, make them different from wired-networks and other wireless networks. In particular, the effects of an unbalanced load can cause rapid gateway overloading, center overloading, or channel overloading. Since most traffic in a WMN is destined towards gateways, traffic concentration at gateway nodes creates a load imbalance at certain gateways, which in turn results in gateway overloading. The issue of center overloading refers to the nodes located near the geographical center of the network becoming overloaded in comparison to other nodes in the network. Finally, channel overloading in a multi-radio wireless mesh network refers to certain channels becoming overloaded compared to other channels. Thus, load balancing is necessary to avoid hot spots and to increase network utilization, as bad routes can exist for a long time in a static network and result in congestion and inefficient use of network resources.