Wi-Fi Multi-Link Operation: An Experimental Study of Latency and Throughput

TL;DR

This study evaluates the real-world performance of Wi-Fi multi-link operation (MLO) in terms of latency and throughput, demonstrating its advantages in dense environments and identifying conditions where it may be detrimental.

Contribution

It provides an experimental analysis of MLO's performance in real-world scenarios, highlighting its benefits and limitations based on link occupancy patterns.

Findings

MLO achieves higher throughput than single-link operation in crowded scenarios.

MLO can reduce latency by an order of magnitude when links have similar occupancy.

Asymmetric link occupancy can cause MLO to increase latency, due to suboptimal packet mapping.

Abstract

In this article, we investigate the real-world capability of the multi-link operation (MLO) framework -- one of the key MAC-layer features included in the IEEE 802.11be amendment -- by using a large dataset containing 5 GHz spectrum occupancy measurements on multiple channels. Our results show that when both available links are often busy, as is the case in ultra-dense and crowded scenarios, MLO attains the highest throughput gains over single-link operation (SLO) since it is able to leverage multiple intermittent transmission opportunities. As for latency, if the two links exhibit statistically the same level of occupancy, MLO can outperform SLO by one order of magnitude. In contrast, in asymmetrically occupied links, MLO can sometimes be detrimental and even increase latency. We study this somewhat unexpected phenomenon, and find its origins to be packets suboptimally mapped to either link before carrying out the backoff, with the latter likely to be interrupted on the busier link. We cross validate our study with real-time traffic generated by a cloud gaming application and quantify MLO's benefits for latency-sensitive applications.