SSIM-based cross-layer optimized video streaming over LTE downlink

Many research efforts have been done to guarantee the quality of service for video streaming over LTE. Among them, cross-layer optimized video delivery is one of the most commonly adopted approaches. However, most existing schemes of cross-layer optimized video delivery adopt PSNR as the optimization target, but do not well consider human vision characteristics. In this paper, we adopt a new metric - Structural Similarity (SSIM) in video quality evaluation and develop a SSIM-based cross-layer optimization scheme with the suppression of propagated error for video delivery over LTE downlink. The modulation and coding scheme at the physical layer of LTE downlink is selected by jointly considering the characteristics of video packets and time-varying channel states. Correspondingly, the quantization parameter of video codec at the application layer is adjusted to make the bit rate of the video stream adapt to the varying throughput of the physical link. Moreover, the error-resilient rate-distortion optimization is adopted in the proposed cross-layer optimization to suppress the effect of error propagation on the video quality degradation. Experimental results show that the proposed cross-layer optimization scheme can maintain more structural information than the conventional schemes in the received video, which correspondingly improves the video quality perceived by the end user.