Multi working sets alternate covering scheme for continuous partial coverage in WSNs

Coverage of wireless sensor networks is a fundamental problem which has been studied for more than two decades. In duty cycle based wireless sensor networks, the nodes are sleep/wake periodic working, and the sleeping of nodes selected to achieve coverage results in a lack of network coverage, which make the coverage of the research difficult to apply in practice. In this paper, a Multi Working Sets Alternate Covering (MWSAC) scheme is proposed to achieve continuous partial coverage of the network. Firstly, a distributed algorithm is proposed to construct the maximum number of working sets, each working set is required to satisfy the partial coverage requirement of the application. Then, the sleeping time of the working nodes is scheduled, which makes the nodes belonging to the same working set wake up synchronously and nodes between multiple working sets wake up asynchronously. Thus, at any time, as long as the nodes of one working set are in waking state, the nodes of other working sets are adjusted to sleeping state to save energy. Due to multiple working sets are alternately covered under MWSAC, the workload and wake-up time of each working node is greatly reduced, which makes the energy consumption more balanced and the network lifetime longer. Both the theoretical analysis and the experimental results show that, compared with the previous continuous coverage scheme, MWSAC scheme has obvious advantages in terms of coverage, network lifetime and node utilization.