Coverage-preserving routing protocols for randomly distributed wireless sensor networks

Sensing coverage is an important issue for sensor networks, since it is viewed as one of the critical measures of performance offered by a sensor network. The design of a routing protocol is generally independent of the sensing coverage issue. Since some nodes may become invalid after they have used up their own energy resource, the achievable sensing coverage will gradually degrade as time passes. Different routing protocols may motivate different distributions of energy dissipation among nodes, and thus induce different changes in the network topology after some nodes have died out. This implies that different routing protocols will lead to different sensing coverage when some nodes are no longer available. Considering the impact on the sensing coverage of a network, we have proposed coverage-preserving routing protocols which are modified from the LEACH and virtual grid routing protocols. These proposed protocols can substantially improve the performance of sensing coverage. According to the simulation results, the sensing coverage degradation of the coverage-preserving protocols is slower than that of the other baseline protocols. For the time duration maintaining the network coverage over 50%, a gain of 20% in overall sensing coverage can be obtained by using the coverage-preserving protocols.