Multicast multigroup beamforming for per-antenna power constrained large-scale arrays

Abstract

Abstract-Large in the number of transmit elements, multiantenna arrays with per-element limitations are in the focus of the present work. In this context, physical layer multigroup multicasting under per-antenna power constrains, is investigated herein. To address this complex optimization problem lowcomplexity alternatives to semi-definite relaxation are proposed. The goal is to optimize the per-antenna power constrained transmitter in a maximum fairness sense, which is formulated as a non-convex quadratically constrained quadratic problem. Therefore, the recently developed tool of feasible point pursuit and successive convex approximation is extended to account for practical per-antenna power constraints. Interestingly, the novel iterative method exhibits not only superior performance in terms of approaching the relaxed upper bound but also a significant complexity reduction, as the dimensions of the optimization variables increase. Consequently, multicast multigroup beamforming for large-scale array transmitters with per-antenna dedicated amplifiers is rendered computationally efficient and accurate. A preliminary performance evaluation in large-scale systems for which the semi-definite relaxation constantly yields non rank-1 solutions is presented.

A Minorization-Maximization Method for Optimizing Sum Rate in the Downlink of Non-Orthogonal Multiple Access Systems

“…Recently, in the context of weighted sum rate maximization and physical layer multicasting, similar ideas were used by Hanif et al and Tran et al in [19], [20], respectively. In addition, Christopoulos et al [21] have studied a successive convex approximation scheme, which is similar in spirit to the MMA approach, for multicast multigroup beamforming with applications to large scale antenna arrays.…”

Reducing the Computational Complexity of Multicasting in Large-Scale Antenna Systems

“…In [26], the SCA technique has been applied to reduce the computational complexity of beamforming design in singlegroup multicasting for large-scale antenna arrays. However, the SCA method is not suitable for multigroup multicasting communications as it requires an initial feasible point, which is hard to compute in these scenarios [11]. To handle this issue, a feasible point pursuit SCA (FPP-SCA) algorithm is proposed in [27] and applied to multigroup multicasting in [11].…”

Multigroup Multicast Precoding in Massive MIMO

“…In this section, we introduce the MMF power control problem and derive the optimal uplink training power and downlink transmit power policies in closed form. Assuming perfect CSI, the existing works in the literature [5], [6], [14]- [18], [20] consider the instantaneous SINR as the metric of interest and just account for the available power at the BS, while ignoring CSI acquisition and its associated overhead.…”

“…Particularly, [13] presents a successive convex approximation technique for single-group single-cell multicasting of large-scale antenna arrays which reduces the computational complexity to O(N 3.5 ). The system set-up of [13] has been extended to a multi-group singlecell multicasting in [14]. Therein a feasible point pursuit based algorithm with a complexity of O((GN) 3.5 ) is presented.…”