OSC-MAC: Duty cycle scheduling and cooperation in multi-hop wireless sensor networks

An On-demand Scheduling Cooperative MAC protocol (OSC-MAC) is proposed to address the energy hole problem in multi-hop wireless sensor networks (WSNs). By combining an on-demand strategy and sensor cooperation intended to extend range, OSC-MAC tackles the spatio-temporal challenges for performing cooperative transmission (CT) in multi-hop WSN: cooperating nodes are neither on the same duty cycle nor are they in the same collision domain. We use orthogonal and pipelined duty-cycle scheduling, in part to reduce traffic contention, and devise a reservation-based wake-up scheme to bring cooperating nodes into temporary synchrony to support CT range extension. Compared with existing MAC protocols, our NS-2 simulations with REACT show that while we explicitly account for the overhead of CT and practical failures of control packets in dense traffic, OSC-MAC still gives almost 80% increase in network lifetime.