PHY/MAC Enhancements and QoS Mechanisms for Very High Throughput WLANs: A Survey

Wireless local area networking has experienced tremendous growth in the last years with the proliferation of IEEE 802.11 devices in order to improve wireless technology. The first generation of high throughput networks known as IEEE 802.11n was developed in 2009 to reach 130 Mbps. Furthermore, to enhance the throughput, two new amendments for IEEE 802.11 are under developments which are IEEE 802.11ad and IEEE 802.11ac. The first one aims to reach 1Gbps with supporting multi-user access techniques. The second amendment aims to enable up to 7Gbp with the possibility of transmitting in the 60GHz band that provides the opportunity for much wider band channels. Another WLAN is already finalized called IEEE 802.11aa in the goal to provide a reliable multicast transport for video streaming. In this survey, we examine the different PHY and MAC enhancements introduced by all these WLAN specifications. Particularly, we focus on the characteristics of each amendment as well as the main MAC mechanisms that lead to improve the network performance. Based on the fact that all recent MAC mechanisms aim to increase QoS guarantee for real time multimedia applications, we have studied different schemes and mechanisms that provide QoS satisfaction for real time multimedia flows transport over WLANs. Namely, we investigate the scheduling mechanisms, the call admission control algorithms, and the anticipated MAC enhancement which are proposed for WLANs networks to support real time applications with QoS satisfaction.