CWnd-Loan - A New Approach to Improve Live Video Performance in RTT-Spiking Networks

• Main Authors: Guo, Lingfeng, Liu, Yan, Yiu-Bun, Jack Lee, Wang, Fuyu, Ouyang, Changkui, Luo, Cheng, Yang, Wenzheng, Zhu, Shengtong, Tan, Kui
• Format: Conference Proceeding
• Language: English
• Subjects: 5G mobile communication; 6G mobile communication; congestion control; Fluctuations; IEEE 802.11ax Standard; live video; machine learning; QoE; QoS; RTT spikes; Streaming media; Transport protocols; Wireless networks
• ISSN: 2643-3303
• DOI: 10.1109/ICNP59255.2023.10355599

With the rapid advances in high-speed mobile networks such as 5G, Wi-Fi 6, and the upcoming 6G and Wi-Fi 7, streaming live video has become ubiquitous for mobile users. However, live video is susceptible to short-term network condition fluctuations which could lead to video stalls. Our investigations revealed that a substantial portion of such fluctuations were in fact caused by RTT spikes that were not congestion-related. These often confuse the transport protocol into dropping the transmission rate significantly, resulting in video stalls. This motivated us to develop a novel scheme called CWnd-loan to reduce the sender's CWnd-limited idle time during RTT spikes. We applied CWnd-loan to the QUIC protocol with BBR/CUBIC congestion control and strategically deployed it in a tier-1 live video service. The results show that CWnd-loan can effectively reduce sender CWnd-limited idle time by up to 18%, consequently reducing the duration and number of live video stalls by as much as 8.9% and 10.6%. Furthermore, CWnd-loan can also reduce the first-frame time and the playback failure rate by up to 3.2% and 2.7 % , respectively. CWnd-loan is designed to complement existing congestion control algorithms and thus could potentially be applied to current as well as future TCP/QUIC designs to tackle RTT spikes commonly found across mobile and wireless networks.