Geographic Transmission with Optimized Relaying (GATOR) for the Uplink in Mesh Networks

We consider communication in the uplink of a wireless mesh or sensor network. A group of mobile radios or sensors (“nodes”) have information to transmit to one or more access points (APs). When the channels from the nodes to the APs suffer from fading, direct transmissions to the APs may have a high failure probability, and packets may need to be relayed through other nodes. In conventional routing, the relay is preselected, and hence fading may cause a high failure probability at the router. Geographic approaches can improve performance through opportunistic reception, in which a relay is selected from those nodes that receive the packet correctly and move it toward the AP. Existing geographic transmission schemes use an ad hoc design for the protocol that selects the relay node. In this paper, we propose Geographic Transmission with Optimized Relaying (GATOR), which provides a mathematical design for relay selection in a time-slotted geographic communication scheme. For path-loss exponent two, the relay selection scheme simplifies to depend on circular regions around the destination. Simulation results show that GATOR provides better performance than direct transmission, routing, and other geographic transmission schemes, especially when the signal-to-noise ratios are low and APs are sparse.