CSVC system uses the nonuniform quantizer based on Differential Pulse-Code Modulation (DPCM), DPCM-NQ for short, which first computes the residual of measurement value between adjacent subblocks to reduce coding redundancy and then quantifies the residual.
The decoder framework of CSVC system is shown in Figure 4.
To ensure high-quality recovery of key frames, CSVC system uses multihypothesis smoothing Landweber iterative algorithm used in  to solve model (4).
The features of CSVC system constructed according to the above codec process are as follows: (1) compared to DISCOVER, CSVC system eliminates virtual channel and feedback channel, and thus the difficulty of engineering is reduced; (2) since there is no correlation between the CS measurement and image content, the code rate is determined only by the measurement rate, which makes it easier for CSVC system to control the code rate; (3) each measurement value contains all the image information; therefore, it is easy to implement scalable coding; (4) the data security can be enhanced by the random generation of the measurement matrix.
The performances of H.264, DISCOVER, and CSVC are evaluated, respectively, using four standard video sequences named Foreman, Bus, Mobile, and Football in CIF format.
Figure 5 shows the rate-distortion curves for H.264, DISCOVER, and CSVC encoders under different test video sequences.
In this paper, we propose a new scheme of adaptive CSVC for wireless video transmission by partial CSI in MIMO-OFDM systems.
To the best of our knowledge, an adaptive CSVC scheme that uses the limited feedback of partial CSI to enhance the quality of video streaming through MIMO-OFDM systems has not been studied yet.
* We exploit and analyze the potential of partial CSI over closed-loop precoding MIMO-OFDM for video transmission using CSVC. The adaptive characteristic of the CSVC encoder is based on the medium grain scalability (MGS), the coarse grain scalability (CGS) and the spatial scalability by using the same matrix from the partial CSI precoding MIMO-OFDM.
The performance of the adaptive CSVC scheme with partial CSI is better than non-adaptive CSVC system (without CSI); more precisely, the results in the MGS mode have a gain of 2.7-3.1 dB for Y-PSNR and 0.5-1.5 dB improvement in signal-to-noise ratio (SNR) at BER of [10.sup.-3].
Section 2 presents a description of the system including CSVC, MIMO-OFDM systems using partial CSI feedback.
In this section, we introduce how to produce SVC and CSVC from JSVM test model of H.264/AVC standards, some concepts of partial CSI in MIMO-OFDM systems, and then describe system model of the proposed framework scheme on adaptive CSVC.