Sleep Scheduling and Gradient Query in Sensor Networks for Target Monitoring

Duty cycling is an important method for energy constrained sensor networks to prolong its lifetime. Current researches on duty cycling are often based on such assumption that all the sensory coverage should be maintained while some nodes are sleeping. For the applications of target monitoring, however, it is not necessary anymore to keep the whole sensory coverage of the sensor networks. It only needs to make sure that such kinds of nodes are active which can perceive the activities of the monitored targets. This observation brings new challenges to the design of duty cycling for the sensor networks. This paper proposes the novel duty cycling design for the sensor networks of target monitoring, which includes two algorithms of the sleep scheduling algorithm and the gradient query algorithm based on sleep periods. Under the proposed design, most of the sensor nodes can be in sleep, while still keep the functions of target monitoring and target query in the sensor networks. The performance of our design has been evaluated through both theoretical analysis and simulations, which prove the functionality of the proposed design on the reduction of energy consumption.