OFDMA random access has been proposed to support multi-user (MU) transmission in 802.11ax. In the OFDMA random access, the stations randomly select sub-channels to send their frames without coordination. As a result, the channel utilization is less than 37%. To this issue, a new OFDMA random access scheme is proposed to improve the channel utilization. The proposed scheme is theoretically analyzed, and simulated in several scenarios. The evaluation results demonstrate that th...