Using Simulcast and Scalable Video Coding to Efficiently Control Channel Switching Delay in Mobile TV Broadcast Networks

摘要

Many mobile TV standards dictate using energy saving schemes to increase the viewing time on mobile devices, since mobile receivers are battery powered. 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. Broadcasting TV channels in bursts, however, increases channel switching delay. The switching delay is important, because long and variable switching delays are annoying to users and may turn them away from the mobile TV service. In this article, 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 analytically analyze the achieved energy saving. We also use scalable video coding to generalize the proposed schemes in order to support mobile devices with heterogeneous resources. We implement the proposed schemes in a mobile TV testbed to show their practicality and to validate our theoretical analysis. The experimental results show that the proposed schemes: (i) significantly increase the energy saving achieved on mobile devices: up to 95% saving is observed, and (ii) support both homogeneous and heterogeneous mobile devices.