Reduce Latency Fluctuations of Wireless Interactive Streaming with In-Flight Packet Management

Abstract

With interactive video streaming becoming increasingly popular, it also poses stringent requirements on the tail latency of network transport. However, achieving consistently low latency is challenging under the highly-variable wireless scenario. Existing transport mechanisms rely on network feedback (e.g., ACK) and can only react to network degradation after a time delay of RTT. When the network latency inflates abruptly, the first packets that experience the network degradation and the subsequent packets within that RTT suffer, resulting in a large portion of tail latency. To save these packets, this paper proposes Backl that actively accelerates the in-flight packets which face deadline missing risk, thus ensuring a robust latency performance against RTT inflations in the network. In specific, Backl monitors the in-flight video frames in fine granularity and duly duplicates video frames on multipath in a lightweight manner, to guarantee a consistently low latency against fluctuating wireless networks. Our evaluation shows that Backl could reduce tail latency by 40× with less than 4% redundant bandwidth overhead compared to the vanilla multipath in real-world traces. The real-world deployment of Backl in a large-scale cloud gaming service also demonstrates up to 17× fewer video stalls with a 2% bandwidth cost.

Jing Chen

Ph.D. of Computer Networking

My research interests include low-latency network transport, interactive video streaming and wireless networks.