Research Of MAC Access Technology In IEEE802.11ax

With the rapid development of the Internet and mobile Internet, WLAN quickly get the extensive application with the advantage of high throughput and low cost. As the technical basis of WLAN, the standard of IEEE802.11 series has evolved to IEEE802.11ac, which single link throughput can be closed to 7Gbit/s theoretically. However, with the rapid growth of the number of intelligent terminals and wireless devices, more and more users have to share the same AP. So the efficiency of access sharp decline, leading the service quality of WLAN and user-experience worse. Nowadays, low efficiency of the MAC access mechanism has become the key restriction. So it is of great significance that researching the access technology adapted to the next generation WLAN.The paper introduced CSMA/CA mechanism based on DCF firstly in standard and analyzed the bottlenecks in dense scenes by simulation. The paper proposes a new access scheme, Selection-Access based access category and SNR, which reduce collision probability and guarantee user’s QoS. As for collision increase caused by competition window reset in crowded scenes, we analyze the existing window optimization scheme and the SD scheme, and then this paper puts forward an improved access scheme, Dynamic Adjustment of Window Coefficient, which changes the speed of competition window down according to the congestion of the network. The scheme is proved that the access performance is better than that of CSMA/CA access mechanism and the SD scheme. When the scene of network congestion rapidly fall or the scene is idle, the traditional way of backoff counter gradually reducing one is difficult to make full use of idle channel. This paper proposes a quick access scheme based on decreased step adjustment, which effectively improve the access efficiency and reduce the access delay. Finally, according to the variety of scenarios in IEEE802.11ax, combined with improved access scheme proposed in this paper, we provided an idea of access mode dynamic switching. The users select appropriate access scheme according to the indication of AP based on the congestion of the network. By simulation, it is verified that the idea has a lower collision probability and higher throughput performance.