Optimal Resource Allocation in Multicast Device-to-Device Communications Underlaying LTE Networks

In this paper, we present a framework for resource allocations for multicast device-to-device (D2D) communications underlaying the uplink of a Long-Term Evolution (LTE) network. The objective is to maximize the sum throughput of active cellular users (CUs) and feasible D2D multicast groups in a cell, while meeting a certain signal-to-interference-plus-noise ratio (SINR) constraint for both the CUs and the D2D groups. We formulate the general problem of power and channel allocation as a mixed integer nonlinear programming (MINLP) problem, where one D2D group can reuse the channels of multiple CUs and where the channel of each CU can be reused by multiple D2D groups. Distinct from existing approaches in the literature, our formulation and solution methods provide an effective and flexible means to utilize radio resources in cellular networks and share them with multicast groups without causing harmful interference to each other. The MINLP problem is transformed so that it can be solved optimally by a variant of the generalized Bender decomposition method with provable convergence. A greedy algorithm and a low-complexity heuristic solution are then devised. The performance of all schemes is evaluated through extensive simulations. Numerical results demonstrate that the proposed greedy algorithm can achieve close-to-optimal performance and that the heuristic algorithm provides good performance, even though it is inferior than that of the greedy, with much lower complexity.