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arXiv · 2607.23767

Fake It No More: Evaluating L4S with SCReAM on Video Traffic

Nawel Alioua·Ryan Zanone·Cheng Xi·Elizabeth Belding
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Abstract

The growing interest in Low Latency, Low Loss, and Scalable Throughput (L4S) reflects the need for lower latency in interactive multimedia applications. In this paper, we use an open-source DualPI2 implementation over the Mahimahi emulator to evaluate the impact of L4S on SCReAM congestion controlled video traffic. To do so, we augment the SCReAM BW tool with a video codec, enabling the generation of video traffic in addition to its original synthetic RTP mode. We evaluate both network-level and Quality of Experience (QoE) metrics on a mobile network trace, under random packet loss, and with different motion-complexity levels. In our baseline scenario, L4S reduces the median per-run $95^{th}$ percentile queue delay by 35%, at the cost of a 42% drop in sender throughput. Under 1% packet loss, L4S yields more pronounced QoE gains compared to the lossless scenario, despite narrower network-level benefits. Across video content complexities, L4S also maintains more stable QoE than Classic. These results underscore the importance of evaluating QoE alongside network-level metrics when assessing the effect of L4S on end-user application performance.

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Nawel Alioua, Ryan Zanone, Cheng Xi, Elizabeth Belding. 2026-07-26. Fake It No More: Evaluating L4S with SCReAM on Video Traffic. https://arxiv.org/abs/2607.23767

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