Utility optimization of grouping-based uplink OFDMA random access for the next generation WLANs

In this paper, a grouping-based uplink orthogonal frequency division multiple access (OFDMA) random access method is studied which can improve users’ satisfaction in the next generation wireless local area networks (WLANs). The next generation WLANs standard, IEEE 802.11ax introduces a random access mechanism, uplink OFDMA random access (UORA), to allow users to access channel randomly. Although UORA has the advantages of low signaling overhead, no need to report uplink transmission requirements, it does not have any characteristics to improve users’ satisfaction. Because the AP can’t allocate resources to users adopting UORA, some users’ quality of experience (QoE) will decline greatly. In this paper, a grouping-based UORA (G-UORA) method is proposed. The AP determines the number of groups, and then clusters users to different groups according to their utility. Then, the AP assigns resources to these groups to maximize the total utility of all users. We present a theoretical utility prediction model of G-UORA and propose the corresponding resource allocation algorithm based on utility. According to simulation results, the algorithm achieves better users’ satisfaction and fairness than the traditional UORA mechanism in IEEE 802.11ax and the user utility gain is 1.6 times. Therefore, the proposed method has greater practical significance.