Towards Energy-Optimal and Reliable Data Collection via Collision-Free Scheduling in Wireless Sensor Networks

We consider the problem of supervision or periodic data collection for stationary wireless sensor networks and present a practical, energy-efficient, and reliable solution. Energy-efficiency is achieved by combining three design methods: (a) adopting network flow optimization techniques, the optimal scheme for balancing the communication load among all the nodes in the network is calculated. This gives the lower bound for the energy required for data collection process, (b) instead of using a fixed network topology (communication tree), a set of optimized trees is constructed and the communication tree varies over different data collection cycles. We show that this method achieves an average energy consumption rate very close to the optimal value, (c) the packet exchange procedure is designed based on collision-free schedules, to minimize the number of packets and the transmission and reception times for each node. Reliability of the process is guaranteed by including many retransmission opportunities in the schedules. The performance is evaluated through simulations.