Date Added: Dec 2009
Real-time communication is important for Wireless Sensor Networks (WSNs) to accomplish collaborative event sensing tasks with specific timing constraints. In this paper, a Service-Differentiated Real-time Communication Scheme (SDRCS) is proposed to provide soft real-time guarantees for event-based converge-cast traffic in WSNs. SDRCS features a cross-layer packet forwarding design to integrate the real-time routing functionality with a novel polling-contention-period-based prioritized medium access control scheme. Based on this design, SDRCS performs distributed packet traversal speed estimation for traffic classification and admission control. SDRCS also performs receiver-contention-based prioritized forwarding so that the routing decision is locally optimized for packet traversal speed maximization. The proposed SDRCS design requires minimum hardware support at the sensor nodes, where no localization, transmission power adaptation or multiple channel transmission support is required.