Research On Efficient MAC Layer Access Mechanism In WLAN

In recent years,WLANs have developed rapidly,and our daily lives are increasingly inseparable from wireless networks.At the same time,with the proliferation of wireless access devices,the number of users in WLANs has grown exponentially.However,the existing IEEE 802.11 MAC layer access protocol is not designed for dense user scenarios,and its drawbacks are increasingly apparent as the number of wireless users increases.In order to improve the efficiency and system throughput of WLAN in dense user scenario,the MAC layer access mechanism of current WLAN needs to be optimized.This paper focuses on the study of MAC layer access protocols in IEEE 802.11 WLANs.It aims to improve the MAC efficiency and system throughput of WLANs in dense scenarios,and provide higher quality services for wireless users.First of all,this paper conducts an in-depth study on the MAC layer access scheme adopted in the current WLANs.The key factors affecting the current MAC layer access efficiency in dense user scenarios are analyzed.After that,a greedy strategy based contention window heuristic adjustment mechanism is proposed.In the proposed mechanism,the initial contention window is dynamically adjusted to the optimal according to the current collision probability.The simulation results show that the proposed contention window heuristic adj ustment scheme can significantly improve the network throughput.Then,the OFDM A technology to be adopted in the next-generation WLAN standard IEEE 802.11ax and OFDMA based MAC access mechanism are studied deeply.And an efficient group-based multi-user MAC layer access mechanism supporting OFMDA is proposed.In this mechanism,the stations that have data to.transmit first contend for channel resources in time-frequency two domains by RTS frame.Then,a grouping and RU joint allocation algorithm is proposed to group stations with successful contention and allocate RUs to them in each group.The simulation results verify the efficiency of the proposed multi-user MAC layer access mechanism.