一种总发射功率最小化的协作MAC协议
Cooperative MAC protocol based on total transmission power minimization

针对能量受限的无线传感器网络，提出了一种能降低网络能耗的跨层协作MAC（Medium Access Control）协议。文中首先分析了直接传输和协作传输下的总发射功率，理论分析表明，在一定的误码率限制下，引入合适的中继节点能降低网络总的发射功率。在802.11DCF（Distributed Coordination Function）的基础上，通过监听邻居节点控制包，获得各信道的状态信息，并选出使总发射功率最小的最佳中继，同时扩展CTS（Clear To Send）、增加HTS（Helper ready To Send），完成自适应的协作传输。仿真表明，该MAC协议能有效降低网络能耗，延长网络寿命。
A cooperative medium access control (MAC) protocol based on total transmission power minimization is proposed to reduce the network energy consumption in energy limited wireless sensor networks. With theoretical analysis, appropriate relay nodes can reduce the total transmission power of the network and the bit error rate of the destination node constrained at a certain target level. Based on the 802.11 distributed coordination function (DCF), the channel state informations (CSIs) are estimated according to the strength of control frames and the best relay by minimizing the total transmission power of the network is selected. Furthermore, to design an adptive cooperative transmission scheme, the frame format of clear to send (CTS) is extended and a helper ready to send (HTS) frame is introduced. Simulation results show that the proposed MAC protocol can effectively reduce the energy consumption and extend the network lifetime