Distributed Realcast A Mobile Video Broadcast Scheme Based On Real Value

The development of mobile communication technologies and the popularization of electronic smart devices makes it is possible for people to access to video services from Internet anytime and anywhere. Since the video data traffic is growing rapidly, mobile video broadcasting service which provides video services to multiple users with a single data stream is considered to be one of the most promising applications. However in the mobile video broadcast scenario, user’s channel-state is different from each other. The traditional digital design which has to pick up a signal modulation scheme and bit rate to transmit video data could not provide users the video quality that matching their channel status.The mobile video broadcasting technology based on real value uses a series of linear transforms to encode the video frame and retains the linear relationship between the video signal and video pixels. As a result the channel noise in received signal is proportional to the distortion in reconstructed video. It provides channel adaptive video quality naturally. In this paper we will discuss about the distributed representation scheme for video frame in real value and the optimized transmission scheme for the video signals.For the problem of representing video frame in real value, this paper designs a distributed video coding scheme, the coset difference method. It combines the features of coset coding and frame difference method. The motion estimation and frame difference method remove the redundancy between successive video frames. And the coset coding could be used to avoid error propagation. The coset difference method efficiently removes the inter-frame redundancy and retains the linear relationship between the received video quality and channel noise. It achieves graceful channel adaptive video qualityTo optimize the transmission of video signal in real value, this paper proposed a series of schemes to fully utilize the channel resources and improve the transmission efficiency when the video is encoded by the proposed coset difference method. The traditional motion compensated interpolation method can be replaced by an extrapolation method to avoid the transmission of motion vector and improve the transmission efficiency. Meanwhile in the narrow band or wide band scenarios, the video can be adjusted to match the channel bandwidth by discarding high-frequency components or retransmitting low-frequency components. In addition, the64K-QAM modulation can be introduced into the distributed Realcast to make full use of the OFDM symbol space and enhance the anti-noise properties.By designing the distributed representation scheme for video frame in real value and the optimized transmission schemes, this paper proposed distributed Realcast, an efficient mobile video broadcast scheme in real value. Distributed Realcast enables users to receive the channel adaptive video quality and outperforms Softcast in resisting the channel noise and adaptation to the channel bandwidth.