ECast: An Enhanced Video Transmission Design for Wireless Multicast Systems Over Fading Channels

Conventional wireless video multicast schemes face a challenge due to their stair-shaped performance curves called "cliff effect" and the limited ability to accommodate multiple users with diverse channel conditions. Recently, a series of analog video coding approaches aiming to solve the problem have been proposed. In this paper, our goal is to enhance such schemes through a novel cross-layer design. A joint subcarrier matching and power-allocation scheme, which is proved to be optimal in terms of minimizing the mean square error, is proposed. The scheme can dynamically adapt to both channel conditions and video contents and, at the same time, maintain continuous quality scalability. Furthermore, the feedback overhead of the channel state information from multiple users is addressed, and a novel analog feedback method is proposed. The video qualities at various receivers are controllable through assigning different weights to different users. Therefore, this scheme is suitable for wireless video multicast systems. Simulation results validate the effectiveness of our proposal.