A Local Information Exchange Based Coverage-Preserving Protocol For Wireless Sensor Networks

Coverage preserving solutions have been reported and are basically based upon node scheduling and quality coverage. Node scheduling based solutions presents at least three challenging problems: 1) resolving conflicts when determining what nodes should be turned-off to save energy; 2) finding optimal wakeup strategies that avoid waking up more nodes than necessary; and 3) keeping connectivity and coverage of the network while optimizing the number of nodes. This paper presents a novel distributed solution that extends the coverage calculation method proposed by Tian and Georganas, referred here as C-PNSS scheme. The solution is based on local information exchange without the uncertainty of self-schedule algorithms. Our Optimal Coverage-Preserving Scheme (OCoPS) comprises a new Decision algorithm, devised to resolve the off-duty conflict problem for different network densities, and an energy aware Wakeup scheme that solves problems, such as coverage holes, that exist in current schemes. We discuss the implementation of OCoPS with the new Decision algorithm as an extension of LEACH. A set of simulation experiments was performed to evaluate OCoPS performance when compared to the C-PNSS scheme. Our results indicate that our solution outperforms C-PNSS by over 20% on network lifetime and by over 25% on network lifetime when the coverage rate is higher than 80%. The experimental results also show that our coverage scheme based on our extended coverage calculation method effectively limits the on-duty node number when compared the original C-PNSS scheme.