  We present a framework for studying the problem of media streaming in
technology and cost heterogeneous environments. We first address the problem of
efficient streaming in a technology-heterogeneous setting. We employ random
linear network coding to simplify the packet selection strategies and alleviate
issues such as duplicate packet reception. Then, we study the problem of media
streaming from multiple cost-heterogeneous access networks. Our objective is to
characterize analytically the trade-off between access cost and user
experience. We model the Quality of user Experience (QoE) as the probability of
interruption in playback as well as the initial waiting time. We design and
characterize various control policies, and formulate the optimal control
problem using a Markov Decision Process (MDP) with a probabilistic constraint.
We present a characterization of the optimal policy using the
Hamilton-Jacobi-Bellman (HJB) equation. For a fluid approximation model, we
provide an exact and explicit characterization of a threshold policy and prove
its optimality using the HJB equation.
  Our simulation results show that under properly designed control policy, the
existence of alternative access technology as a complement for a primary access
network can significantly improve the user experience without any bandwidth
over-provisioning.
