Network coding based SVC multicast over broadband wireless networks

Video multicast over wireless networks has its own challenges when facing the heterogeneity of networks and end-user capabilities, along with packet losses. Scalable video coding using different modulation and coding schemes (MCSs) applied to different video layers can provide different video qualities to different users according to their channel conditions. A layered hybrid NC/ARQ scheme is proposed in this paper to handle packet losses together with a structure network coding (SNC) technique to encode the SVC stream. It is important to choose an appropriate MCS for each layer, decide how many SNC packets in one layer should be transmitted, and determine the resources allocated to multiple video sessions to apply scalable video coding to wireless multicast streaming. We prove that such a resource allocation problem is NP-hard and propose an optimal algorithm with a pseudo-polynomial run time under a reasonable assumption. We also discuss the phenomenon of unexpected packet losses caused degradation of the layered hybrid NC/ARQ schemes in a high packet loss ratio environment, and propose a solution for overcoming such a problem. Our algorithm can attain the optimal transmission configuration for maximizing the expected utility for all receivers. The results from simulations revealed that our algorithm offers significant improvements to the video quality over an optimal algorithm without needing feedback from the receivers and an algorithm using a layered hybrid FEC/ARQ scheme, and it has the outstanding ability to combat unexpected packet losses.