In-relay Power Allocation for Multi-pair Full-duplex Massive-MIMO AF Relay Network

In this paper, a multi-pair two-way full-duplex relay network is investigated, in which multiple pairs of full-duplex single antenna users are served via a full-duplex amplify-forward multi-antenna relay. The relay uses zero-forcing beam-forming in both reception and transmission. Therefore, the inter-stream interference of users in reception and transmission is canceled out completely. An inter-stream power allocation algorithm is proposed for the relay node. The in-relay power allocation algorithm is obtained by solving an optimization problem using an iterative algorithm with Mean Square Error criterion under relay output power constraint. Then, assuming the number of user pairs larger than a computed threshold, a suboptimal closed-form solution for this problem is obtained. The performance of the proposed in-relay power allocation schemes is investigated using Monte-Carlo simulation and compared with the so-called the in-user and the jointly in-relay and users power allocation. The simulation results show a very small difference between the suboptimal and optimal algorithms and the superiority of in-relay algorithms over the in-user and jointly in-relay and users algorithms.