An Investigation of Random Access Window Slot Adjustment Techniques in IEEE ۸۰۲.۱۱ah Protocol

The Restricted Access Window (RAW) component of IEEE ۸۰۲.۱۱ah is deployed to drastically reduce channel contention in dense and heterogeneous sensor network environment. It divides sensor nodes or stations into groups and slots, allowing channel access only to one RAW slot at a time. Several algorithms and channel access optimization techniques have been proposed to optimize the RAW parameters, to ensure a contention free network or at least, minimally reduce it .These techniques often rely on previous traffic demands, collision rates and send/receive matrices to accurately predict the future of stations in an IoT environment by systematically adjusting its operations to reduce contention among the stations and the Access Point(AP), and ensuring a flexible transmission even in a dense network environment. This paper critically investigated and analyzed some of these RAW size adjustment schemes and also compared their performances through simulation results of the following metrics - throughput, data transmission, network delay, successful transmission probability and registration. Identifying their deficiencies and performance indices are the concerns so as to proffer better solutions and reduce any slot contention overhead in the network.