A Better Choice for Sensor Sleeping

Sensor sleeping is a widely-used and cost-effective technique to save energy in wireless sensor networks. Protocols at different stack levels can, either individually or simultaneously, make the sensor sleep so as to extend the application lifetime. To determine the best choice for sensor sleeping under different network conditions and application requirements, we investigate single layer and multi-layer sleeping schemes at the routing and MAC layers. Our results show that routing layer sleeping performs better when there is high network redundancy or high contention, while MAC layer sleeping performs better when there is low contention or in small networks. Moreover, multi-layer sleeping requires cross-layer coordination to outperform single layer sleeping under low contention. Therefore, our conclusions can not only guide the implementation of practical sensor networks, but they also provide hints to the design of cross-layer power management to dynamically choose the best sleeping scheme under different network and application scenarios.