Adaptive Sleep-Time Management Model for WSNs

The energy consumption of a wireless sensor network affects its lifetime which in turn affects the scope and usefulness of the network. Most existing or proposed MAC protocols enable nodes to specify a duty cycle, so that they can sleep much of the time to save energy. However, only very few models exist to determine the appropriate time and duration of a sleep phase. Existing approaches rely on pre-calculated sleep durations or are difficult to implement on real platforms. We propose a runtime and adaptive model to estimate the sleep time and duration of wireless sensor nodes. Our model takes the statistics of incoming and outgoing packets at a relay node which is then supplied to a general queueing model. The model is lightweight and can be fitted into any existing MAC protocol. We have implemented our model for TelosB platform and TinyOS environment. We integrated our model with two existing protocols (TinyOS LPL MAC and XMAC) and compared the performance of these protocols with and without our model. The performance evaluation results show that the energy consumption of a relay node reduced by 11.4 - 64.8%. The overall throughput of the network increased by up to 24%. Moreover, our model readily responded to changes in packet traffic rate while at the same time increasing the packet transmission reliability by 64.5 - 67.4% for different traffic scenarios.