Grouping-Based Hybrid Channel Access Mechanism for Ultra-Dense IEEE 802.11 ax Networks

IEEE 802.11ax offers Uplink OFDMA Random Access (UORA) to support simultaneous multiuser operation. In dense WLANs scenario, as the stations (STAs) access the RUs (Resource Units) on a random basis, the risk that either STAs collide on the same RU, or some idle RUs are not utilized. In this paper, we present a Grouping-based hybrid channel access (HCA Grouping) mechanism, in which STAs during contention process use hybrid channel access mechanism, that consist of OFDMA based backoff and MC-CSMA-CA (Multichannel-CSMA-CA) to increase RUs utilization efficiency and throughput performance. The results justify that our proposed grouping mechanism achieves improved RUs efficiency by reducing idle RUs probability and also increase in throughput compared with conventionl UORA and adaptive grouping schemes.