Research On The High Energy-Efficient Cooperative MAC Protocol For Wireless Local Area Networks

IEEE802.11 wireless local area network (WLAN) medium access control (MAC) protocol plays a vital role for wireless network performance. In this paper, focuses on system energy consumption, energy-saving mechanisms and other issues, mainly to complete the following tasks:First of all, based on the analysis of IEEE 802.11 wireless LAN standard, researches IEEE 802.11 wireless LAN MAC protocol in DCF distributed mechanism, especially details of the DCF Distributed Coordination mechanism including CSMA/CA carrier sense mechanism, RTS/CTS four times handshake mechanism and the binary exponential back off algorithm. Analyzes the energy efficiency of IEEE 802.11DCF and studies the PAMAS and PSM which are two kinds of energy-saving mechanism.Next, the article introduces the concept of cooperative communication,, proposed an improved MAC protocol based on the problems of existing cooperative MAC protocols. This paper focuses on the rDCF cooperative MAC protocol, studies show that there exists an obvious flaw for rDCF:the process of recording cooperative table requires each node of the table listening the entire network, and access to the course of the entire network topology will have a huge overhead; the overuse of the best relay leads its energy to reduce, or even withdraw from collaboration, thus reducing the overall throughput of the system. This cooperative design of the new forms for the energy and transmission rate for a compromise deal to avoid a large number of high-speed node, the node caused by the use of energy overdraft introduction of the "credit value" to ensure the fairness of transmission opportunities.Finally, drawing on Dual Busy Tone Multiple Access (DBTMA) to use in the busy tone, busy tone function is proposed based on the cooperative relay MAC Protocol (BCRMAC). The protocol focuses on the method of optimal relay selection, introduces the busy tone, the length of which can be changed. Whenever the source wants to send data, relay starts cooperation by sending busy tone. The length of busy tone is connected with relay's capability of forwarding, source judges length of busy tones and determines the optimal relay accurately.The selected optimal relay is used to forward data from source to destination.Relays are not limited to hear each other in this method, which means the scope of the relay selection can be expanded.This method is simple and workable. Simulation results show that, BCRMAC agreement almost no energy consumption increases with the nodes, much better than rDCF protocol, reducing the energy consumption, is a high energy efficiency cooperative MAC protocol.