Optimizing channel access for bandwidth versus latency in 802.11ac WLANs

It has been a major criticism to 802.11ac that there are no well-defined channel selection rules when the devices are contending for the secondary 20MHz channel. This leads to inefficient selections. We define efficiency in two distinct ways, latency optimization and bandwidth optimization. We propose a simple greedy strategy of channel assignment for latency optimization, i.e., start assigning stations (STAs) to the highest frequency band they can support and move down from there if that channel is unavailable. For bandwidth optimization, we propose two heuristic based rules for the Medium Access Control (MAC) protocol. A capability based contention window and a bottom up approach towards channel assignment, i.e., start channel contention for the lowest frequency band that a STA can support and jump up to a higher band if contention is high. Detailed simulation studies show that our strategies indeed lead to better latency and bandwidth optimizations.