An OFDMA-based joint reservation and cooperation MAC protocol for the next generation WLAN

The rapidly increasing use of mobile devices and the explosive growth of wireless traffic demands continuously drive the development of wireless networks. IEEE 802.11ax, as the emerging standard for the next generation wireless local area network (WLAN), aims to improve the network throughput in the densely deployed wireless networks. In the dense networks, the increased collisions for the large number of nodes and the inevitable transmission failures for aggregate interference and channel fading severely degrade the network throughput, posing an intractable challenge that urgently requires resolution. Channel reservation scheme that reduces the access collisions, and cooperative relay scheme that enhances the transmission reliability have consequently drawn considerable attention in recent years. Joint channel reservation and cooperation has been proved as a promising way to improve the network throughput in our recent study, but how to design a high-performance medium access control (MAC) protocol combined with reservation and cooperation for the next generation WLAN still remains an open issue. In this paper, we propose an orthogonal frequency-division multiple access (OFDMA) based joint reservation and cooperation MAC (OJRC-MAC) protocol for the next generation WLAN. The OJRC-MAC adopts the channel reservation scheme to reduce the access collisions, and enables the cooperative relay scheme to enhance the transmission reliability simultaneously. A resource unit based Markov model is introduced to analyze the network throughput, and the impacting factors on the throughput can be clarified by the derived closed-from expression. Simulation results validate the analytical results, and show that OJRC-MAC outperforms the basic uplink OFDMA-based random access (UORA), only reservation-enabled MAC (RES-MAC), and only cooperation-enabled MAC (COOP-MAC).