Cognitive radio assisted quality compensation for scalable video multicast in cellular networks

• A novel cognitive radio assisted video quality compensation scheme is proposed.
• An easily-implemented spectrum access scheme is presented.
• An adaptive relay rates scheduling scheme is proposed.
• The performance of the proposed scheme attributed to several important factors is systematically evaluated.

Existing multicast schemes always employ the scalable video coding (SVC) to accommodate heterogeneous channel conditions. Although this method achieves a high spectral efficiency, it will lead to serious quality imbalance problem, i.e., the viewers who hold a better link conditions can obtain high video quality, but the viewers with bad reception conditions can only receive the video with poor quality. In this paper, we propose a novel Cognitive Radio Assisted Quality Compensation (CRAQC) scheme for enhancing the video quality of bad reception viewers. In CRAQC, the bad reception viewers can obtain from the good reception viewers the video content they cannot receive directly from the base station using cognitive relay links. One novel and promising design of the proposed scheme is that it considers a cooperative transmission style in relay process, in which viewers with the same relay content can simultaneously broadcast this content in the same channel, and therefore achieve the benefits of space diversity to the receiver. Through extensive simulations, we demonstrate that CRAQC is able to significantly improve the video performance of the bad reception viewers.