L2: Lazy forwarding in low duty cycle wireless sensor networks

Energy-constrained wireless sensor networks are duty-cycled, relaying on multi-hop forwarding to collect data packets. A forwarding scheme generally involves three design elements: media access, link estimation, and routing strategy. Most existing studies, however, focus only on a subset of those three. Disregarding the low duty cycle nature of media access often leads to overestimate of link quality. Neglecting the characteristic of bursty loss over wireless links inevitably consumes much more energy than necessary and underutilizes wireless channels. The routing strategy, if not well tailored to the above factors, results in poor packet delivery performance. In this paper, we propose L², a practical design of data forwarding in low duty cycle wireless sensor networks. L² addresses link burstiness using multivariate Bernoulli link model. Further incorporated with synchronized rendezvous, L² enables sensor nodes to work in a lazy mode, keep their radios off as long as they can, and allocates the precious energy for only a limited number of promising transmissions. We implement L² on real sensor network testbeds. The results show that L² outperforms state-of-the-art approaches in terms of energy efficiency and network yield.