MESH, RELAY, AND INTERWORKING NETWORKS
Despite advances in wireless technologies that allow improvement in data rates and transmission reliability, it is challenging for cellular base stations (BSs) to provide adequate coverage in cluttered urban areas where signal obstructions caused by tall structures are common. Mesh and relay networks serve to bridge that gap in coverage with wireless routers deployed at street level. These mesh routers allow end-user devices to access the network by forwarding data traffic wirelessly. Unlike BSs, the mesh or relay routers can be deployed in strategic locations (e.g., in places experiencing high traffic volume) to minimize power consumption. This in turn benefits battery-powered user handsets and enables energy-efficient network deployment. This chapter focuses on the 802.11s, 802.16j, and 802.11u mesh, relay, and interworking amendments.
Simple methods of extending wireless coverage include the use of a signal repeater or a single-hop packet relay. Femtocells employ such relays that forward incoming traffic from the BS to the handset, whereas 802.11 range extenders employ signal repeaters. Unlike these methods, a mesh network comprises a concatenation of wireless hotspots that may require packet routing. Each hotspot constitutes a hop, and may serve a number of stations within a home, a classroom, an office, a street café or even a restaurant. These hops form a wireless backhaul network, which ultimately connects ...