Analysis Of The Function P(X)-detection Carrier Sense Multiple Access/Acknowledge Protocol For Wireless Local Area Network

With the development of deeper and broader exploration of information, IEEE 802.11 wireless local area network (WLAN) with its unique advantages such as reliable performance, high flexibility etc. develops rapidly. Now it is widely used in people's work and life. But compared with the wired LAN, WLAN's Channel is open, link is unstable, and its bandwidth resources are limited, in terms of performance and quality of service there is a big gap. The major function of WLAN's MAC layer is to provide a fair, reliable and effective scheduling mechanism to allocate radio channel resources. MAC protocol's performance is directly connected to the wireless channel's utilization and the network's performance.Considering the widespread use of WLAN equipment is based on IEEE 802.11 protocol, the main object of the paper's study is IEEE 802.11 MAC protocol. In IEEE 802.11 MAC protocol, DCF is the basic way of data transmission control. No matter what topology of the network, all sites must be competed to obtain the qualifications of the channel access. DCF's core technology is based on CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) random access protocol. Therefore, the analysis and improvement of CSMA/CA protocol's performance have great significance to practical application.This paper researches IEEE 802.11 WLAN technology, random multiple access protocol and a large number of other relevant literature. It summarizes the standard of IEEE 802.11 series, WLAN's network topologies, WLAN's logical structure and the analysis method of WLAN's MAC protocol. The paper evaluates a lot of typical random access protocols, and then introduces the CSMA/CA protocol's working principle in detail. On the basis, to improve the channel resources utilization rate, from the perspective of the existing standard in the IEEE 802.11 CSMA/CA basic access mode, this paper proposed to a new protocol:the function p(x)-detection Carrier Sense Multiple Access/acknowledge protocol (FPDCSMA/ACK).The FPDCSMA/ACK protocol proposed two improvements which are based on the slotted probability-based detection multi-access protocol. First, it uses a detection probability function with more flexibility instead of a fixed detection probability in the original protocol, and then it uses the function method to select the optimal detection probability. What's more, on the basis of the original protocol, the FPDCSMA/ACK protocol increases the ACK signal, it simply and easily improves the reliability of the system. Through the theoretical analysis of the average period method, the paper analyzes the normalized system model and IEEE 802.11 system model, and then obtains the performance of the system's important indicators such as the throughput. Meanwhile, according to the protocol's working principle, in the MATLAB platform, we select different p(x) function curves to make simulation experiments and numerical analysis, and then compare the theoretical analysis and simulation results. The results show that the detection probability curves should be set which based on different requirements of the network environments, the theoretical analysis is valid. The function p(x)-detection Carrier Sense Multiple Access/Collision Avoidance protocol can make effective distribution of LAN channel resources, improve the system's transmission quality, to further expand the FPDCSMA/ACK protocol for wireless local area network provides the basis for the application.This paper's ideas and methods is also Applied to the study of other wireless network protocols.