Supporting Adaptive Sampling in Wireless Sensor Networks

Adaptive sampling is proposed to improve the power efficiency of wireless sensor networks in that the sampling rate of a sensor node can change in response to the changes in the environment. To transmit the sampled data promptly, the nodes with different and dynamically changing sampling rates have to transmit at different and changing rates correspondingly, which in turn causes severe packet loss and power consumption. To address this problem, we propose a routing-layer scheduling scheme, SPAS, to support adaptive sampling. In SPAS, each node keeps a record of packets to be forwarded and wakes up at scheduled times to transmit and to receive. Furthermore, each node can dynamically optimize its route to the sink based on the transmission rates of its neighboring nodes. Our simulation results show that SPAS achieves both high power efficiency and a low packet loss rate in adaptive sampling.