Cross-Layer Optimized MAC to Support Multihop QoS Routing for Wireless Sensor Networks

This paper presents an efficient hybrid medium-access control (HMAC) protocol with an embedded cross-layer optimization solution to provide routing-layer coarse-grained end-to-end quality-of-service (QoS) support for latency-sensitive traffic flows. A novel channel-reservation technique is proposed to significantly reduce the end-to-end delay for delay-sensitive traffic flows by allowing packets to go through multiple hops within a single medium-access control (MAC) frame and by also giving them higher priority channel access to reduce possible queuing delay. Our proposed protocol (HMAC) combines energy-efficient features of the existing contention-based and time-division multiple-access (TDMA)-based MAC protocols and adopts a short frame structure to expedite packet delivery. Simulation results in ns-2 show that HMAC achieves significant performance improvements in energy consumption, latency, and throughput over existing MAC protocols.