Improving QoS mechanisms for IEEE 802.11ax with overlapping basic service sets

With the growing quantity of wireless devices, the demands for wireless transmission are increasing exponentially. More and more WiFi access points (APs) have been built in the environment to serve these stations (STAs). As the density of devices increases, two or more basic service sets (BSSs) are too close to hear each other, which leads to overlapping BSS (OBSS) problems. When the OBSS problem occurs, the STAs in the OBSS area are interfered with by the AP signals from the overlapping BSSs, which causes the data transmission delay, and the quality of service of the user cannot be guaranteed. In this paper, we designed a scheme with a controller which maintains the Overlapping Area Record (OAR) of each BSS. By utilizing the OAR, we proposed a mechanism that reduces the transmission power of the interfering APs and extends the transmission opportunity limits of the low-QoS stations (LQ-STAs). Moreover, we give priority to the LQ-STAs in the multi-user multiple-input multiple-output transmission to deal with the OBSS problem. Through simulations, when the data arrival rate is 128 kbits/s, our method reduces the average downlink transmission delay of interfered high-efficiency STAs and legacy STAs by 21.4% and 25% compared to the base case scenario. When the data arrival rate is 512 kbits/s, our method outperforms the base case scenario up to 99%, which greatly ameliorates the OBSS problem in IEEE 802.11ax.