Bounding switching delay in mobile TV broadcast networks

Since mobile devices are battery powered, several mobile TV standards dictate using energy saving schemes to increase the viewing time on mobile devices. The most common scheme for saving energy is to make the base station broadcast the video data of a TV channel in bursts with a bit rate much higher than the encoding rate of the video stream, which enables mobile devices to turn off their radio frequency circuits when not receiving bursts. While broadcasting bursts saves energy, it increases the channel switching delay. The switching delay is an important performance metric, because long and variable switching delays are annoying to users and may turn them away from the mobile TV service. In this paper, we first analyze the burst broadcasting scheme currently used in many deployed mobile TV networks, and we show that it is not efficient in terms of controlling the channel switching delay. We then propose new schemes to guarantee that a given maximum switching delay is not exceeded and that the energy consumption of mobile devices is minimized. We prove the correctness of the proposed schemes and derive closed-form equations for the achieved energy saving. We also implement the proposed schemes in a mobile TV testbed to show their practicability and to validate our theoretical analysis.