BF-assisted joint relay selection and power control for cooperative multicast in MmWave networks

We present optimization algorithm for relay (RLY) selection and, source (SRC) and RLY power allocations in a cooperative multicast millimeter-wave (mmWave) system with non-line-of-sight (non-LoS) sensing. We show that there is a significant benefit to the system outage performance by allocating powers for the SRC and the RLYs selected from the candidates availing of line-of-sight (LoS) paths. Specifically, we consider the joint optimization of RLY selection, and, SRC and RLY power allocations to minimize the largest outage probability among all the common-multicast group (co-MGroup) users. The joint optimization problem is non-convex and the complexity of finding the optimal solution is extremely high. Using the dual-step iterative optimization (DIO) algorithm, the joint problem is decomposed into a non-convex RLY selection, and, a convex SRC and RLY power allocation problem. By exploiting the search method and the Lagrange multipliers algorithm, we present efficient algorithms that yield the optimal solutions for both RLY selection (non-convex) and, SRC and RLY power allocation problems. The simulation results indicate significant improvements both on outage probability and power consumption performances over the traditional two-stage multicasting.