$L^{2}$: Lazy Forwarding in Low-Duty-Cycle Wireless Sensor Network

In order to simultaneously achieve good energy efficiency and high packet delivery performance, a multihop forwarding scheme should generally involve three design elements: media access mechanism, link estimation scheme, and routing strategy. Disregarding the low-duty-cycle nature of media access often leads to overestimation of link quality. Neglecting the bursty loss characteristic of wireless links inevitably consumes much more energy than necessary and underutilizes wireless channels. The routing strategy, if not well tailored to the above two 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 by employing multivariate Bernoulli link model. Further incorporated with synchronized rendezvous, L2 enables sensor nodes to work in a lazy mode, keep their radios off most of the time, and realize highly reliable forwarding by scheduling very limited packet transmissions. We implement L2 on a real sensor network testbed. The results demonstrate that L2 outperforms state-of-the-art approaches in terms of energy efficiency and network yield.