Access-Network Association Policies for Media Streaming in Heterogeneous Environments

TL;DR

This paper analyzes the trade-offs between cost and user experience in media streaming over heterogeneous wireless networks, proposing optimal control policies modeled as Markov decision processes.

Contribution

It introduces a novel analytical framework for designing and verifying optimal access-network selection policies considering cost and QoE trade-offs.

Findings

Optimal control policies with threshold structures

Analytical characterization of cost-QoE trade-offs

Verification of policy optimality using HJB equations

Abstract

We study the design of media streaming applications in the presence of multiple heterogeneous wireless access methods with different throughputs and costs. Our objective is to analytically characterize the trade-off between the usage cost and the Quality of user Experience (QoE), which is represented by the probability of interruption in media playback and the initial waiting time. We model each access network as a server that provides packets to the user according to a Poisson process with a certain rate and cost. Blocks are coded using random linear codes to alleviate the duplicate packet reception problem. Users must take decisions on how many packets to buffer before playout, and which networks to access during playout. We design, analyze and compare several control policies with a threshold structure. We formulate the problem of finding the optimal control policy as an MDP with a probabilistic constraint. We present the HJB equation for this problem by expanding the state space, and exploit it as a verification method for optimality of the proposed control law.