To improve the efficiency of node cooperation and multiple access performance in multihop wireless networks, a rapid cooperation-differentiated medium access control (MAC) protocol is proposed. In the protocol, the helper selection process is divided into a priority differentiation phase and contention resolution phase for helpers with the same priority. A higher priority helper can choose an earlier minislot in the priority differentiation phase to send a busy tone. As a result, the protocol promptly selects all the highest priority helpers. The contention resolution phase for the same priority helpers can use any existing collision resolution scheme, such as the k-round elimination contention scheme. Helpers sending a busy tone first can proceed to the next round, while others, sensing the busy tone, subsequently withdraw from contention. Therefore, a unique optimal helper is selected from the highest priority helpers with high probability. A packet piggyback mechanism is also adopted, which allows a high data rate helper with its own data packets, to transmit these to their recipient without reservation. This significantly decreases the reservation overhead and effectively improves cooperation efficiency and channel utilization. Simulation results show that the maximum throughput of the proposed protocol is 39.6% and 9.6% higher than those of the cooperative MAC-aggregation (CoopMACA) and instantaneous relay-based cooperative MAC protocols, respectively, in a wireless local area network environment, and 40.8% and 31.9% higher, respectively, in an ad hoc network environment.

Fast reservation list-to-send (FRLS) medium access control (MAC) protocol is proposed to apply to wireless networks with long propagation delay. In the protocol, a central control node (CCN) is applied to allocate the channel resources of two channels, and all the nodes transmit packets over the two channels without collision. Packet train transmission mechanism ensures that a number of packets are transmitted continuously with small guard interval and just a one-way propagation delay. Once a node successfully reserves the channel resources for a communication session, it can transmit the whole message without the need of any other reservations, which gain high utilization of the channels. Moreover, CCN can provide uniform time benchmark to make the network working in an asynchronous fashion. Simulation results show that FRLS protocol outperforms centralized scheduling-based MAC (CSMAC) protocol in terms of throughput, average packet access delay and average packet dropping rate, and effectively resolves low channel utilization problem due to long propagation delay.