OCC: Physical-Layer Assisted Congestion Control for Real-Time Communications

2026-04-24

AI Summary

This work addresses the challenge of simultaneously achieving low latency and high bandwidth utilization in real-time communication (RTC) systems under high-demand conditions, where conventional trial-and-error-based congestion control struggles to accurately and promptly estimate available bandwidth. To overcome this limitation, the study introduces physical-layer information into RTC congestion control for the first time, proposing three key strategies: frame-aware bandwidth measurement, application constraint-aware estimation, and encoder-friendly rate control. These mechanisms enable rapid adaptation to dynamic wireless environments. Real-world over-the-air experiments on an open-source cellular testbed demonstrate that the proposed approach reduces tail network latency by 13%–68% and increases video frame bitrate by 1.2–3.5×, effectively mitigating RTC-specific challenges such as traffic bursts, application constraints, and encoder lag.

Technology Category

• Multiagent Systems: Agent Communication
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Machine Learning: Online Learning & Bandits

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Security and Privacy: Large-scale security measurements
• Responsible Web: Measurement, analysis, and circumvention of Web censorship

Abstract

Real-time communications (RTC) is a core technology for emerging applications in 6G, such as cloud gaming, teleoperation, and extended reality (XR), which require consistently low latency and high bitrates. Existing RTC solutions fundamentally struggle to maintain low latency while supporting high bitrates due to their reliance on trial-and-error-based mechanisms. These mechanisms fail to probe the available bandwidth (ABW) promptly and accurately, leading to a trade-off between latency reliability and bandwidth utilization. The tension becomes extremely more critical as the cellular bandwidth and application's demand fluctuate with a larger range in cellular networks nowadays. To address this trade-off, we propose OCC, a novel approach that utilizes physical-layer information to explicitly obtain the ABW in real time, enabling rapid adaptation to dynamic wireless network conditions. However, the unique characteristics of RTC, including traffic bursts, application (APP) limits, and encoder lag, make the physical-layer informed control non-trivial. OCC effectively addresses these issues through three innovative strategies: frame-aware bandwidth measurement, APP-limit-aware bandwidth estimation, and encoder-friendly rate control. Extensive over-the-air experiments on an open-source cellular testbed demonstrate that OCC significantly enhances the performance of mobile RTC, reducing tail network latency by $13\%$ to $68\%$ and improving video frame bitrate by $1.2\times$ to $3.5\times$.

Problem

• real-time communications
• congestion control
• available bandwidth
• low latency
• cellular networks

Innovation

• physical-layer information
• real-time communications
• congestion control
• available bandwidth estimation
• cellular networks