Performance of asynchronous data transfer methods of IEEE 802.11 MAC protocol

The desire to provide universal connectivity for mobile computers and communication devices is fueling a growing interest in wireless packet networks. To satisfy the needs of wireless data networking, Study Group 802.11 was formed under IEEE project 802 to recommend an international standard for WLANs. A key part of the standard is the MAC protocol needed to support asynchronous and time-bounded delivery of data frames. It has been proposed that unslotted CSMA/CA be the basis for the IEEE 802.11 WLAN MAC protocols. We conduct a performance evaluation of the asynchronous data transfer protocols that are a part of the proposed IEEE 802.11 standard, taking into account the decentralized nature of communication between stations, the possibility of "capture", and presence of "hidden" stations. We compute the system throughput and evaluate fairness properties of the proposed MAC protocols. Further, the impact of spatial characteristics on the performance of the system and that observed by individual stations is determined. A comprehensive comparison of the access methods provided by the 802.11 MAC protocol is done and observations are made as to when each should be employed.