A QoS-Guaranteed Cooperative MAC Protocol for Wireless Networks

To meet the quality-of-service (QoS) of different traffic, a QoS-guaranteed cooperative medium access control (QC-MAC) protocol is proposed for wireless networks to distinguish the priorities of different traffic. By using a busy tone transmission scheme, each sender competes to access the channel, and the sender with the highest priority traffic can succeed to get the right to transmit its data packet. According to the cooperative gain achieved by each relay, the optimal relay can win the contention to forward data packets for the successful sender. A piggyback reservation mechanism is also adopted to allow the successful sender, optimal relay or recipient with the highest priority traffic to use the channel for piggyback transmissions without reservation and packet collisions, which effectively decreases the reservation overhead, improves the channel utilization and guarantees the QoS. Simulation results show that the proposed protocol can achieve higher throughput, lower average packet delay than those of the 802.11e enhanced distributed channel access (EDCA) and differentiated cooperative MAC (DC-MAC) protocols.