TCP BBR Performance over Wi-Fi~6: AQM Impacts and Cross-Layer Insights

2025-12-20

AI Summary

This study systematically evaluates the cross-layer performance of TCP BBRv3 in Wi-Fi 6 home networks under modern active queue management (AQM). We construct a fully wireless testbed and develop a cross-layer analytical model to quantify the impact of FIFO, FQ-CoDel, and CAKE AQMs on uplink, downlink, and bidirectional traffic—revealing dynamic coupling among Wi-Fi scheduling, router queuing, and BBRv3’s pacing mechanism. Our experiments uncover, for the first time, CAKE-induced Wi-Fi-specific bursty retransmissions during BBRv3’s bandwidth probing phase. Results show: FIFO severely degrades latency and flow fairness and should be deprecated; FQ-CoDel achieves a favorable trade-off between low latency and inter-flow fairness; CAKE delivers the lowest end-to-end latency and most balanced send/forward rates. Based on these findings, we propose practical AQM selection guidelines and a Wi-Fi-aware BBRv3 tuning methodology.

Technology Category

• Planning, Routing, and Scheduling: Scheduling under Uncertainty
• Cognitive Modeling & Cognitive Systems: Agent Architectures
• Multiagent Systems: Agent Communication

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Web Mining and Content Analysis: Web measurements
• Responsible Web: Measurement, analysis, and circumvention of Web censorship

Abstract

We evaluate TCP BBRv3 on Wi-Fi 6 home networks under modern AQM schemes using a fully wireless testbed and a simple cross-layer model linking Wi-Fi scheduling, router queueing, and BBRv3's pacing dynamics. Comparing BBR Internet traffic with CUBIC across different AQMs (FIFO, FQ-CoDel, and CAKE) for uplink, downlink, and bidirectional traffic, we find that FIFO destabilizes pacing and raises delay, often letting CUBIC dominate; FQ-CoDel restores fairness and controls latency; and CAKE delivers the best overall performance by keeping delay low and aligning BBRv3's sending and delivered rates. We also identify a Wi-Fi-specific effect where CAKE's rapid queue draining, while improving pacing alignment, can trigger brief retransmission bursts during BBRv3's bandwidth probes. These results follow from the interaction of variable Wi-Fi service rates, AQM delay control, and BBRv3's inflight limits, leading to practical guidance to use FQ-CoDel or CAKE and avoid unmanaged FIFO in home Wi-Fi, with potential for Wi-Fi-aware tuning of BBRv3's probing.

Problem

• Evaluates TCP BBRv3 performance on Wi-Fi 6 with different AQM schemes.
• Compares BBR with CUBIC under FIFO, FQ-CoDel, and CAKE for traffic directions.
• Identifies Wi-Fi-specific effects of AQM on BBRv3 pacing and retransmissions.

Innovation

• Evaluated BBRv3 on Wi-Fi 6 with wireless testbed and cross-layer model
• Compared BBR and CUBIC across FIFO, FQ-CoDel, CAQE for uplink/downlink traffic
• Found CAKE best overall, FQ-CoDel fair, FIFO destabilizing with Wi-Fi-specific effects