This letter proposes a solution to the multicast subgroup formation problem that aims to maximize the aggregate data rate in Long Term Evolution (LTE) and beyond systems. We analytically demonstrate that, by reducing the solution search space and releasing some constraints, the problem can be solved in a closed form, and a very small number of operations are sufficient to find the optimal subgroup configuration, which is demonstrated to be always composed of one or two subgroups.

The relevance of the result is that the proposed technique can be easily implemented in practical LTE systems to avoid the heavy-processing burden of the exhaustive search or the suboptimality of solutions based on heuristics.