Route-aware MAC protocols for Sensor Networks

Fundamental tradeoffs between energy consumption and sustainable quality of services such as throughput and response time are critical in sensor networks because of limited and often irreplaceable battery power. This paper presents a novel energy saving approach, namely route-awareness. This approach provides a wide spectrum of design alternatives even under an extremely low energy budget. Route-awareness is a form of cross-layer optimization techniques that allows sensor nodes to save energy by “sleeping” opportunistically when they are not part of a routing path. This can drastically save energy in large scale sensor network applications that monitor and track infrequently occurring events. Routeawareness meshes well with existing MAC schemes including both contention and schedule based MAC (TDMA) ones to form a class of route-aware sensor MAC protocols. We explore tradeoffs between energy consumption and performance such as throughput and delay which are enabled by route-awareness for sensor networks employing directed diffusion. We found that MAC protocols employing routeawareness provide a far richer set of design choices, especially over a low energy budget, than when they are used alone. In particular, the simulation results show that routeaware TDMA provides better energy-delay tradeoffs than route-aware contention-based MAC schemes.