A coverage hole detection method and improvement scheme in WSNs

In wireless sensor networks (WSNs), coverage is a key factor of affection the lifetime of networks. In this paper, we study the coverage problem for network which is comprised of mobile sensor nodes with sensing radius r and communication radius R = 2r. For a possible movable redundant sensor, we present a coverage hole detection method (CHDM) by mathematic analysis, and then give a node mobility scheme which is engaged to improve the system coverage by moving the redundant node to an appropriate location to cover the detected hole. With the assumption that every sensor can be aware of its geography location, the redundant sensor determinates its mobility state and target location by the distribution of its neighbor nodes. Because each node determines its behaviors independently, the scheme can be implemented in a distributed manner. Simulation results show our scheme can improve the coverage obviously.