A Robust and Energy Efficient Routing Scheme for Wireless Sensor Networks

In a wireless sensor network, energy efficient transmissions are important because each node has a limited battery. On the other hand, the energy limitation should not compromise the robustness in end-to-end packet delivery. This paper proposes an energy efficient routing scheme that can ensure high robustness despite dynamic link quality. The key ideas are to form a routing tree with one degree of redundancy where each node maintains two parents, namely default and backup, toward the sink, and to dynamically switch between the default and backup links depending on the dynamic link quality. For energy efficiency, the default parents are selected based on the minimal expected transmission (METX) criterion while the backup parents are selected with a combination of METX and signal strength criteria. The switching mechanism is designed to be adaptive with inertia so that unnecessary changes in route can be avoided. The proposed routing scheme has been evaluated through NS-2 simulator. The results confirm that a 36% improvement in robustness can be achieved in a random topology without any significant degradation in energy efficiency.