Joint rate and power allocation for cooperative layered video multicast systems

In this paper, we investigate the joint rate and power allocation problem in cooperative layered video multicast system which incorporates 2-hop user cooperation and layered video coding in multicast system. Layered video coding encodes the video data into base layer (BL) and enhancement layer (EL). At hop-1, the base station broadcasts BL and EL respectively. Then users who correctly decode BL and EL serve as relays at hop-2 to forward BL and EL to other users respectively. Receivers at hop-2 combine data received in both hops through maximal ratio combining (MRC) to improve the signal-to-noise ratio (SNR). Under this architecture, two joint rate and power allocation schemes are proposed aiming at maximizing the date rate of the enhancement layer while guaranteeing the minimum data rate requirement of the base layer. These two schemes are based on two channel state information (CSI) scenarios at the base station: full feedback CSI at the base station and no feedback CSI at the base station. Simulation results show that the cooperative layered video multicast system significantly outperforms conventional direct multicast system and the proposed joint rate and power allocation schemes show attractive properties.