Flexible Broadcasting of Scalable Video Streams to Heterogeneous Mobile Devices

We study the scalable video broadcasting problem in mobile TV broadcast networks, where each TV channel is encoded into a scalable video stream with multiple layers, and several TV channels are concurrently broadcast over a shared air medium to many mobile devices with heterogeneous resources. Our goal is to encapsulate and broadcast video streams encoded in scalable manner to enable heterogeneous mobile devices to render the most appropriate video substreams while achieving high energy saving and low channel switching delay. The appropriate streams depend on the device capability and the target energy consumption level. We propose two new broadcast schemes, which are flexible in the sense that they allow diverse bit rates among layers of the same stream. Such flexibility enables videos to be optimally encoded in terms of coding efficiency, and allows the coded video streams to be better matched with the capability of mobile devices. We analyze the performance of the proposed broadcast schemes. In addition, we have implemented the proposed schemes in a real mobile TV testbed to show their practicality and efficiency. Our extensive experiments confirm that the proposed schemes enable energy saving differentiation: between 75 and 95 percent were observed. Moreover, one of the schemes achieves low channel switching delays: 200 msec is possible with typical system parameters.