DRA-OFDMA: Double Random Access Based QoS Oriented OFDMA MAC Protocol for the Next Generation WLAN

With the increasing diversity of wireless services and explosive growth of traffic, Wireless Local Area Network (WLAN) has become the main carrier of wireless traffics. Therefore, how to ensure the quality of service (QoS) requirements of high priority traffics is one of the momentous targets of the next generation WLAN. The Orthogonal Frequency Division Multiple Access (OFDMA) has been introduced into the next generation WLAN as the key technology and has become an important feature. However, less attention is played to the QoS-guaranteed and fairness-guaranteed in the existing OFDMA-based Media Access Control (MAC) protocols. This article proposes a double random access QoS oriented OFDMA MAC protocol for the next generation WLAN, named DRA-OFDMA. What different from the existing work is that the idea of two phases for parallel OFDMA random access is introduced in the protocol. The traffic priorities are not distinguished in the first phase of the random access, thus fairness of traffic is ensured at some extent. Users, which are failed to be accessed in the first phase, with high priority are allowed to be accessed in the second phase on the remaining available sub-channels, thus the QoS for the high priority traffic is well guaranteed. The DRA-OFDMA MAC protocol proposed in this paper has good compatibility advantage. It can completely reuse available frame defined by 802.11ax standard. In addition, the Markov chain based theoretical analysis model for the proposed protocol is formulated and the corresponding network performance is also analyzed in our paper. Finally, the correctness of theoretical analysis model and performance analysis are verified by simulation. Simultaneously, the simulation results show that the throughput of DRA-OFDMA with high priority traffic is enhanced 22.05% and 89.6% than that of RA-OFDMA and OMAX respectively, and the fairness of low priority traffic is also well guaranteed.