Revising Quorum Systems for Energy Conservation in Sensor Networks

Quorum systems are well-known techniques designed to enhance the performance of distributed systems, such as to reduce the access cost per operation, to balance the load, and to improve the system scalability. All of these properties make quorum systems particularly attractive for large- scale sensor applications involving coordinated tasks, such as rescue applications. In this paper we analyze quorum techniques in the specific context of sensor networks and energy conservation, and show why quorum systems designed for wired networks and their metrics fail to address the challenges introduced by sensor networks. We then redefine quorum metrics such as access cost, load balance, and capacity in a way that takes into account the limitations and the characteristics of sensor networks, and discuss some energy-efficient design strategies. In addition, we propose a family of energy-efficient quorum systems and a particular construction, called Regional quorum system (RQ), which reduces the quorum access cost. Finally, we propose a data diffusion protocol built on top of the RQ system, which improves energy consumption by reducing message transmissions and collisions, and increases the available bandwidth. We apply our diffusion protocol to analyze the RQ system using our novel metrics.