Energy-Efficient Video Multicast in 4G Wireless Systems

Layer-based video coding, together with adaptive modulation and coding, is a promising technique for providing real-time video multicast services on heterogeneous mobile devices. With the rapid growth of data communications for emerging applications, reducing the energy consumption of mobile devices is a major challenge. This paper addresses the problem of resource allocation for video multicast in fourth-generation wireless systems, with the objective of minimizing the total energy consumption for data reception. First, we consider the problem when scalable video coding is applied. We prove that the problem is {\cal NP}-hard and propose a 2--approximation algorithm to solve it. Then, we investigate the problem under multiple description coding, and show that it is also {\cal NP}--hard and cannot be approximated in polynomial time with a ratio better than 2, unless {\cal P}={\cal NP}. To solve this case, we develop a pseudopolynomial time 2-approximation algorithm. The results of simulations conducted to compare the proposed algorithms with a brute-force optimal algorithm and a conventional approach are very encouraging.