Scalable transcoding for video transmission over space-time OFDM systems
A new scheme combining a scalable transcoder with space time block codes (STBC) for an orthogonal frequency division multiplexing (OFDM) system is proposed for robust video transmission in dispersive fading channels. The target application for such a scalable transcoder is to provide successful access to the pre-encoded high quality video from mobile wireless terminals. In the scalable transcoder, besides outputting the fine granular scalability (FGS) bitstream, both size of video frames and the bit rate are reduced. And an array processing algorithm of layer interference suppression is used at the receiver which makes the system structure provide different levels of protection to different layers. Furthermore, by considering the important level of scalable bitstream, the different bitstreams can be given different level protection by the system structure and channel coding. With the proposed system, the concurrent large diversity gain characteristic of STBC and alleviating the frequency-selective fading effect of OFDM can be achieved. The simulation results suggest that the proposed schemes integrating scalable transcoding can provide a basic quality of video transmission and outperform the convention single layer transcoding transmitted under the random and bursty error channel conditions.