An Energy-Efficient Channel Access With Target Wake Time Scheduling for Overlapping 802.11ax Basic Service Sets

Higher requirements in wireless Internet access have led to a dense deployment of Wi-Fi networks, which results in severe collisions and deteriorated throughput. In this article, we propose a grouping-based medium access control protocol with target wake time (TWT) scheduling for IEEE 802.11ax overlapping basic service sets (OBSSs), i.e., GTSO. It aims to improve the reutilization of the resource units (RUs) by increasing the number of parallel transmissions with sleep/wake-up period scheduling which is adaptive to the traffic loads. First, we divide the stations into different groups by mapping the OBSS architecture into an undirected graph. Based on the graph, we use the Welch Powell algorithm to find the minimum number of colors in the graph coloring problem to make as many parallel transmissions as possible. Finally, an optimization problem is proposed to realize a contention-free channel access with simultaneously active stations no more than the number of RUs under the constraint of packet delay through TWT scheduling. Simulation results show that the GTSO performs better than existing schemes in terms of throughput and energy efficiency in dense scenarios.