Multi-rate sequential data transmission

We investigate the data transmission problem in which a sequence of data is broadcast to a number of receivers via erasure channels with different erasure probabilities. Accordingly, the receivers wish to decode the data sequentially at different rates. We present a formulation of the problem and propose an optimal coding scheme. Our results can be employed in the streaming of a video clip by broadcasting, so that receivers with different bandwidths can play the video at different speeds. Specifically, receivers with sufficiently large bandwidth can play the video at normal speed, while others can play the video with pauses, or at a slower speed using time-scale modification. Our results completely characterize the fundamental tradeoff between the available bandwidth and the playback speed of the video.