A Target Wake Time Based Power Conservation Scheme for Maximizing Throughput in IEEE 802.11ax WLANs
Qinghua Chen, Guoxi Liang, Zhengqiu Weng · 2019
IEEE 802.11ax, introducing Target Wake Time (TWT) mechanism, was proved as the next generation Wireless Local Area Network (WLAN) technology to improve QoS and QoE in dense scenarios. A novel broadcast TWT mechanism is proposed to save power by leveraging the new capability of uplink Orthogonal Frequency Division Multiple Access (OFDMA) based multiuser transmission. However, if the TWT is not properly scheduled, deteriorated throughput and high power consumption occur because of collisions. This paper investigates several key aspects, such as the number of simultaneously awake stations, the number of eligible random access resource units, and backoff stages, that have great impacts on the throughput and power efficiency. Based on the derived relationship, we further propose a TWT scheduling scheme (TSS) for negotiating Target Beacon Transmission Times (TBTTs) by making decisions on whether accepting the TWT request or not to maximize throughput. Besides, an algorithm on arranging stations to wake up in different beacon slots with appropriate offsets (i.e., first TBTTs) is presented. Simulation results demonstrate the effectiveness in terms of average throughput and power efficiency.