An Energy Fairness Mechanism And Working Mode In MAC Layer Of Cooperative Wlan System

Wireless LAN MAC protocol research has an important significance on improving the performance of wireless network system. In this paper, focusing on system throughput, delay performance and energy consumption problem, mainly to complete the following tasks:First, the paper summarizes the character of wireless local area networks and discusses the correlative capability issues about IEEE 802.11 MAC protocol in aspect of throughput, access fairness and energy saving and so on, and concretely analyzes the random access MAC protocol CSMA/CA which works on DCF mode. A classical model of analyzing the work process of the protocol is introduced and we simulate it with certain conditions. Finally the paper explains the impact of station number and contention window on system performance.Second, an improved energy fairness mechanism for IEEE 802.11 wireless communication CoopMAC protocol is proposed. The paper introduces a popular cooperation MAC mechanism (CoopMAC), and analyses its performance characteristics. The existing protocol selects the best cooperative node (offer best time to transfer packets) form its cooperation table list to collaboratively send packets, although reduces the time of transferring packets and saves certain energy (the whole use of energy cuts down), because of the cooperation node selection mechanism, when the slowness of mobility considered, the use frequency of cooperation node will be obviously different, thus resulting the unfairness of energy consumption. The new mechanism can achieve a definite equilibrium about the use of cooperation node via to poll the node or choose by the status of node spare energy in cooperation list.In addition, two new PCF-based MAC collaborative working methods are given. Lot of collaboration applications of MAC mechanisms are concentrated in the DCF mode, the paper imports the cooperation mechanism to the mode of IEEE 802.11 PCF, and discusses the working (the order of frame transmission course). According to the simulation results, the cooperation PCF mechanism can get the performance improvement in system throughput and delay.At last, the paper gives a detailed description of the whole system simulation platform, including environment setting and simulation thought. And the paper summarizes the problems and methods in the process of MAC protocol simulation.