Energy-efficient routing under delay constraint in duty-cycle wireless sensor networks

In this paper, we investigate the problem of energy-efficient routing design from a sensor node to a sink node under a given delay constraint. The network topologies in duty-cycle wireless sensor networks (WSNs) are changed from one time-slot to another due to each sensor node's active/dormant schedule. A series of network topologies over a period of time are modelled as a virtual time-expanded graph. Then, the problem of routing design on the time-expanded graph is defined, whose aim is to find a space-time path from a sensor node to the sink node with the minimum energy consumption under a delay constraint. Next, an energy-efficient routing algorithm in time-expanded graph (ERTG) is proposed to find the optimal space-time path. Simulation results validate the effectiveness of the proposed algorithm in energy savings.