Coverage is one of the most important issues in Wireless Sensor Networks (WSNs). However, full coverage only can be achieved when surplus mobile sensors contribute a coverage area larger than the hole size. When there is no surplus mobile sensor to cover a big hole, previous studies have utilized mobile sensors by moving the hole from one location to another, therefore achieving temporal full-coverage, where each location on the monitoring region has been ever covered by mobile sensors during a fixed time interval. However, with only some mobile sensors participating in the hole-movement task, this results in an energy-imbalance WSN. This paper considers a mobile WSN that contains a big hole where there exists no redundant mobile sensor to heal the hole. Three distributed algorithms, called Basic, Forward-Only, and Any-Direction movement mechanisms, are proposed to achieve the purpose of temporal full-coverage in a way that the total energy consumption is minimized or that the energy consumption of all mobile sensors that participate in the hole-movement task are balanced. Simulation results reveal that the proposed hole-movement mechanisms enhance the coverage of WSNs and balance the energy consumption of mobile sensor nodes.
Wireless Communications and Mobile Computing 12(5), pp.445–462