Reliable and energy-efficient routing protocol in dense wireless sensor networks

Delivering sensed data to the sink reliably in sensor networks calls for a scalable, energy-efficient, and error-resilient routing solution. In this paper, a reliable energy-efficient routing (REER) protocol is proposed to achieve the above goals for dense wireless sensor networks (WSNs). Based on the geographical information, REER’s design harnesses the advantage of high node density and relies on the collective efforts of multiple cooperative nodes to deliver data, without depending on any individual ones. We first select reference nodes (RN s) between source and sink. Then, multiple cooperative nodes (CN s) are selected for each RN. The reliability is attained by cooperative routing: each hop keeps multiple CN s among which any one may receive the broadcast data packet from the upstream hop to forward the data successfully. The distance between two adjacent RN s provides a control knob to trade off robustness, total energy cost and end-to-end data latency. The main difference between REER and the traditional geographical routing protocols are as following: (1) REER is stateless and does not need to store any neighbor information; (2) In unreliable communication environments, traditional routing protocols may fail to deliver data timely since link/node failures can be found out only after trying multiple transmissions. In REER, each data is only broadcast once at each hop. If there is at least one of the CN s is in good status, the data packet is delivered successfully; (3) In REER, the number of cooperative nodes are adaptively selected before data delivery, such that the number is minimized while achieving required reliability according to the link failure rate. The unselected nodes will enter sleeping mode to save energy during data dissemination. Extensive simulation experiments are carried out to show that REER achieves an efficient trade-off among reliability, energy consumption, and end-to-end delivery latency. We have evaluated the REER protocol through both analysis and extensive simulation.