Energy optimization in mobile TV broadcast networks

We consider energy optimization in mobile TV networks in which a base station broadcasts multiple TV channels to mobile receivers over a common wireless medium. In these systems, the base station broadcasts TV channels in bursts with bit rates much higher than the encoding rates of the video streams. Thus, mobile devices can receive a burst of traffic and then turn off their radio frequency circuits till the next burst in order to save energy. To achieve this energy saving, the base station must carefully construct the burst schedule for all TV channels. In this paper, we formulate the problem of determining the optimal burst schedules for broadcasting multiple TV channels. We show that this problem is NP-complete for channels with arbitrary bit rates. We then propose a practical simplification of the general problem, which allows TV channels to have different bit rates, but at power of two increments. Using this simplification, we propose and analyze an optimal burst scheduling algorithm. We implement our algorithm in a mobile TV testbed and we present empirical results to demonstrate its efficiency and optimality.