An Experimental Study of Latency for IEEE 802.11be Multi-link Operation

Will Multi-Link Operation (MLO) be able to improve the latency of Wi-Fi networks? MLO is one of the most disruptive MAC-layer techniques included in the IEEE 802.11be amendment. It allows a device to use multiple radios simultaneously and in a coordinated way, providing a new framework to improve the WLAN throughput and latency. In this paper, we investigate the potential latency benefits of MLO by using a large dataset containing 5 GHz spectrum occupancy measurements. Experimental results show that when the channels are symmetrically occupied, MLO can improve latency by one order of magnitude. In contrast, in asymmetrically occupied channels, MLO can sometimes be detrimental and increase latency. This is a result of packets being assigned to an interface before carrying out the backoff, which is more likely to be interrupted on the busier link. We overcome this issue by allowing multiple backoffs to run in parallel, assigning the packet to the particular interface where the backoff expires first, which also achieves lower latency overall.