A channel reservation based cooperative multi-channel MAC protocol for the next generation WLAN

Recently, explosive growth of bandwidth demands has motivated many technological revolutions in the Wireless Local Area Networks (WLANs) such as the IEEE 802.11ax task group, which is established to enhance the throughput performance for the Next Generation WLANs (NGW) under high dense deployment scenarios. However, on the one hand, it is known that the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) has become a generally accepted access mechanism in the WLANs, which is shown to bring about serious collisions when the stations (STAs) are relatively crowded. In this case, the channel access efficiency is definitively decreased and thus some frequency channel resources are eventually wasted. On the other hand, due to the inherent fading effect of wireless channel, network throughput of the NGW (i.e., 802.11ax) is further degraded by the existence of Low-Rate-Links (LRLs), where the available data transmission rate is relatively low. To resolve the above two technical issues, a distributed multi-channel MAC protocol, called CRC-MMAC, is proposed for the NGW. In the proposed CRC-MMAC, the concept of reserved-cooperative-link (RCL) is proposed and initiated under multi-channel environment, to fully exploit the potential of both channel reservation and cooperative relay. Accordingly, collisions in the network are effectively decreased using channel reservation as well as the data transmission rate of LRLs is significantly improved with cooperative relay. Furthermore, an analysis of the upper bound of saturation throughput gain is derived, which is validated by extensive simulations. Compared with the ‘Baseline’ scheme, i.e., the existing Dynamic Channel Assignment (DCA) protocol [1] using TXOP (Transmission Opportunity), the experiments results show that the saturation throughput of CRC-MMAC exceeds about 140%, and the average packet delay is decreased by nearly 60%.