Enhancing 802.11 carrier sense for high throughput and QoS in dense user settings

Abstract

The distributed coordination function (DCF) for 802.11 medium access control (MAC) leads to poor spatial spectral reuse and results in low user throughput in dense user settings. In this paper, we consider simple modifications to the carrier sense mechanism that substantially improve the bits/sec/Hz/area, without increasing transceiver complexity. For 802.11g and 802.11ac, we augment the CTS with channel gain information and modify the virtual and physical carrier sense for the duration of NAV in the CTS. In addition, we consider a roughly synchronized network with alternate control and data transmission phases. During the control phase, a carrier sense multiple access with collision avoidance (CSMA-CA) MAC is used to exchange a few RTS-CTS messages in a local network neighborhood to determine the transmission scheme in the ensuing data phase. Our methods enable the application of signal to interference and noise (SINR) based scheduling algorithms to WiFi networks resulting in tremendous increase in throughput and QoS/fairness.