A Novel Cooperative Layered Video Multicast Scheme

Multicast is a spectrum-efficient way to support emerging multimedia services over wireless network, where a group of users receive messages over a common wireless channel. Cooperative transmission is a promising technology to improve multicast performance by exploring the cooperative diversity. Different from conventional cooperative multicast schemes, we take the heterogeneity of the multicast group users into consideration and propose a novel two-stage cooperative scheme to accommodate different users with different video quality flexibly. Video streams are coded into base and enhancement layers using scalable video coding technology. The users that successfully decode base layer in stage 1 can receive enhancement layer from BS in stage 2, while the users with bad channel conditions only decode base layer with the help of fixed relays during two stages. The simulation results show that compared to previous multicast schemes, the proposed one can help the users with good channel quality achieve a better spectral efficiency performance while guarantee all users can receive basic video services. We also analyze the the impact of power allocation in stage 2 on the spectral efficiency of both layers.