On the optimality of group network codes

It is well-known that linear network codes are sufficient to achieve maximal network throughput (or bandwidth utilization efficiency) in the single-session multicast scenario. However, it is not known whether they are still optimal in maximizing network throughput in the multiple-session scenario (either single-source or multiple-source ones). In this paper, we prove that a more general class of network codes - group network codes - are sufficient to achieve the maximal throughput in the single-source multiple-session multicast scenario