Video Streaming with Kairos: An MPC-Based ABR with Streaming-Aware Throughput Prediction

Abstract: In this paper, we present Kairos, a model predictive control (MPC)-based adaptive bitrate (ABR) scheme that integrates streaming-aware throughput predictions to enhance video streaming quality. Kairos features an attention-based throughput predictor with buffer-aware uncertainty control, improving prediction accuracy and adaptability to network conditions. Specifically, we introduce a multi-time attention network to handle the irregularly sampled sequences in streaming data, creating uniformly spaced latent representations. Additionally, we design a separate prediction network that estimates future throughput at multiple percentiles and incorporates a buffer-aware uncertainty adjustment module. This module dynamically selects the appropriate throughput percentile based on the buffer size, enhancing robustness to varying network conditions. Lastly, to mitigate QoE smoothness penalties caused by predictors focused solely on accuracy, we introduce a smoothness regularizer. By embedding streaming-aware characteristics, such as sampling irregularity, buffer occupancy, and smoothness, into the throughput predictor design, Kairos significantly improves bitrate decision-making within the MPC framework. Extensive trace-driven and real-world experiments demonstrate that Kairos outperforms state-of-the-art ABR schemes, achieving an average QoE improvement of 1.52% to 7.28% under various network conditions.