Abstract
We study the problem of broadcasting multiple variable bit rate scalable video streams from a base station to a large number of mobile receivers. Our objective is to maximize bandwidth utilization, energy saving and perceived quality of the transmitted videos. In practice, the aggregate bitrate of the video streams can be greater than the available bandwidth and then the receivers may experience playout glitches. We propose an algorithm to take advantage of opportunities provided by scalable video coding to improve performance when the bandwidth is limited. To achieve this, we provide a model for prioritizing video packets coded in medium grain scalability and a decision mechanism to drop quality layers of video frames when the bandwidth is limited. The result is increased bandwidth utilization and quality of the transmitted videos. Our experiments, performed on a real mobile TV testbed, show that our algorithm significantly out-performs current methods in terms of bandwidth utilization and also achieves near optimal energy saving and quality of the transmitted video streams.