Optimizing Quality of Experience of Dynamic Video Streaming over Fading Wireless Networks

TL;DR

This paper formulates an optimal control strategy for dynamic video streaming over fading wireless networks, balancing quality, outages, and power constraints using a decomposed CMDP approach with threshold policies.

Contribution

It introduces a novel CMDP model for multi-client video streaming, demonstrating that optimal policies depend only on buffer levels and decompose into single-client MDPs.

Findings

Optimal policies have a threshold structure based on buffer levels.

The multi-client problem decomposes into independent single-client MDPs.

The approach effectively balances quality, outages, and power constraints.

Abstract

We address the problem of video streaming packets from an Access Point (AP) to multiple clients over a shared wireless channel with fading. In such systems, each client maintains a buffer of packets from which to play the video, and an outage occurs in the streaming whenever the buffer is empty. Clients can switch to a lower-quality of video packet, or request packet transmission at a higher energy level in order to minimize the number of outages plus the number of outage periods and the number of low quality video packets streamed, while there is an average power constraint on the AP. We pose the problem of choosing the video quality and transmission power as a Constrained Markov Decision Process (CMDP). We show that the problem involving $N$ clients decomposes into $N$ MDPs, each involving only a single client, and furthermore that the optimal policy has a threshold structure, in which the decision to choose the video-quality and power-level of transmission depends solely on the buffer-level.