An OFDMA-based New MAC Mechanism for IEEE 802.11ax

Two types of MAC mechanisms namely, random access and reservation can be employed for OFDMA-based wireless LANs. As OFDMA-based wireless networks promise to support heterogeneous applications, researchers assume that applications with and without traffic specifications will coexist. Thus, both reservation-based and random access schemes are required for an OFDMA-based WLAN. Eventually, OFDMA-based wireless LAN will deploy hybrid MAC mechanisms inheriting traits from random access and reservation. In this paper we propose a new MAC protocol which employs one kind of hybrid mechanism that will provide high throughput of data as well as maintains improved fair access policy to the medium among the stations. The protocol works in two steps, where in step 1 sub-channels are approximately evenly distributed to the stations and in step 2 stations within in a sub-channel will contend for medium randomly if the total number of stations of the system are larger than the number of sub-channels. The details of the protocol is illustrated in the paper and we evaluate the performance of the proposed OFDMA-based multi-channel hybrid protocol through comprehensive computer simulations. Simulation results validate that the performance of our designed protocol far better than the conventional CSMA/CA protocol.