Adaptive Uplink OFDMA Random Access Grouping Scheme for Ultra-Dense Networks in IEEE 802.11ax

IEEE 802.11ax, which is the next-generation WLAN standard, aims at providing highly efficient communication in ultra-dense networks. However, due to the high quantity of stations (STAs) in dense deployment scenarios, the potential high collision rate significantly degrades the network efficiency of WLAN. In this paper, we propose an adaptive grouping scheme to overcome this challenge in IEEE 802.11ax using Uplink OFD-MA Random Access (UORA). In order to achieve the optimal utilization efficiency of resource units (RUs), we first analyze the relationship between group size and RU efficiency. Based on this result, an adaptive STA grouping algorithm is proposed to cope with the performance fluctuation of 802.11ax due to remainder stations after grouping. The analysis and simulation results demonstrate that our adaptive grouping algorithm dramatically improves the performance of both the system and each STA in the ultra-dense network.