Multiplexing Video on Broadcast Channels via Convex Programs

We propose a joint power- and rate-control scheme to broadcast a multiplicity of video sequences over a broadcast channel. The formulation is intended to be general in scope, without assumptions about specific coding or modulation schemes. However, we assume the broadcast channel undergoes quasi-static fading, with channel state information available at the transmitters and receivers. With a weighted sum of distortion terms as a metric, the scheme computes a jointly-optimal source-rate and transmit-power allocation under a power constraint. Besides minimizing distortion, the algorithm must also ensure that delay and buffer constraints are satisfied. Although the problem is not convex when formulated directly, it can be reformulated in convex form as a geometric program. We present numerical results via variable bit-rate (VBR) rate-control of H.264-coded video, optimized jointly with power-control of simple idealized broadcast transmitters.