Cross-Layer Optimization for OFDMA-Based Wireless Mesh Backhaul Networks

We consider the background of a mesh network consisting of fixed base station routers connected by wireless links. Some of the mesh routers have connections to the wired network, and therefore can function as gateways. The network has multi-hop capability where the traffic entering the mesh backhaul through the gateway routers can be carried over multiple wireless links towards the destination mesh routers. The objective in this work is to study the capacity of such networks. More specifically, assuming the use of an OFDMA air-interface for the mesh backhaul network, we formulate a cross-layer optimization problem that involves power control, channel allocation, link scheduling and routing. Our results indicate that, when the radio resources are optimized carefully, OFDM transmissions may provide tone-diversity advantages in the form of efficient bandwidth utilization by choosing better channels for transmissions and scheduling, or in the form of improved routing performance by providing more path options to route the traffic. Using our framework, we quantify the throughput of a mesh backhaul in realistic cellular environments.