A distributed multi-channel MAC protocol with parallel cooperation for the next generation WLAN

As one of the significant driving forces of the future broadband heterogeneous networks (5G), the Next Generation WLAN (NGW) has been initiated following the 802.11 HEW (High-Efficiency WLAN) study group with a focus on improving spectrum efficiency and area throughput. However, Low-Rate-Links (LRLs) severely degrade the overall wireless network performance, particularly under the dense environments in the NGW. To improve the data rate of wireless links, cooperation communication is proposed to divide a low-rate-link into multiple successive wireless links with much higher data rate over the same frequency channel, which is denoted as 'Serial-Coop'/'SC' strategy. However, the existing 'Serial-Coop' strategy suffers from the disadvantage of large cumulative delay because the packets are relayed within two successive timeslots. In this paper, a distributed Multi-channel MAC protocol with Parallel Cooperation is proposed for the NGW, called PC-MMAC, to initiate concurrent cooperation communications over multiple frequency channels in a distributed fashion. Then, an approximate analysis on the upper bound of saturation throughput gain is derived. Further, an enhanced mechanism is proposed to strengthen the robustness of PC-MMAC, by dynamically adjusting the cooperation strategy based on the number of available data channels. Extensive simulation results show that the saturation throughput of PC-MMAC outperforms 'Serial-Coop' strategy and 'Non-Coop' scheme¹ by 25% and 33% respectively.