Power-controlled wireless links for media streaming applications

We investigate a power-controlled transmission scheme for streaming media traffic over wireless links. The server (source) transmits encoded media packets to a client (user) over a fluctuating wireless channel. The client stores received packets into a fixed-size buffer and plays them out at a constant rate. Due to random channel interference, the source needs to adapt its transmission power and rate according to the channel conditions to guarantee a certain level of received media quality of service (QoS). The latter is primarily measured by the distortion due to packets missing their playtime deadlines at the receiver. The goal is to find an efficient power/rate control policy to minimize the average power (energy) consumption for a required quality level of media reception. We formulate a simple, yet powerful, model for media streaming over wireless links, allowing identification and characterization of optimal power/rate control policies, using dynamic programming methodologies. Furthermore, having observed the structural properties of optimal policies, we propose two practical heuristic algorithms for power and rate control. The proposed algorithms are extensively simulated and significant performance improvements are observed when compared to standard benchmarks.