Rendezvous cost-aware opportunistic routing in heterogeneous duty-cycled wireless sensor networks

This paper analyzes the packet transmission cost in asynchronous heterogeneous duty-cycled wireless sensor network systems (WSNs). We discover limitations of conventional opportunistic routing protocols when they are applied to asynchronous heterogeneous duty-cycled WSNs. The key reason is that the conventional opportunistic routing protocols overlook the rendezvous cost in calculating the packet transmission cost. To solve the above issue, we introduce a novel routing metric, expected transmission cost (ETC), which is designed with the rendezvous cost-aware. The proposed metric, ETC, appropriately captures the packet transmitting cost in heterogeneous duty-cycled WSN environments by incorporating the estimation for both expected communication as well as rendezvous cost. We then design an efficient ETC-based opportunistic routing protocol (EoR) which selects the best forwarding candidates with the least packet transmission cost to reduce the actual energy consumption of sensors in packet transmission. We conduct comprehensive testbed experiments and simulations with Telosb motes for the performance evaluation of EoR in comparison with the state-of-the-art routing protocols. Obtained experimental results indicate that EoR achieves significant improvements in terms of packet latency, delivery ratio, and energy efficiency, in comparison with the state-of-the-art protocols.