General Rank Multiuser Downlink Beamforming With Shaping Constraints Using Real-valued OSTBC
Abstract
In this paper we consider optimal multiuser downlink beamforming in the presence of a massive number of arbitrary quadratic shaping constraints. We combine beamforming with full-rate high dimensional real-valued orthogonal space time block coding (OSTBC) to increase the number of beamforming weight vectors and associated degrees of freedom in the beamformer design. The original multi-constraint beamforming problem is converted into a convex optimization problem using semidefinite relaxation (SDR) which can be solved efficiently. In contrast to conventional (rank-one) beamforming approaches in which an optimal beamforming solution can be obtained only when the SDR solution (after rank reduction) exhibits the rank-one property, in our approach optimality is guaranteed when a rank of eight is not exceeded. We show that our approach can incorporate up to 79 additional shaping constraints for which an optimal beamforming solution is guaranteed as compared to a maximum of two additional constraints that bound the conventional rank-one downlink beamforming designs. Simulation results demonstrate the flexibility of our proposed beamformer design.
Cite
@article{arxiv.1502.04488,
title = {General Rank Multiuser Downlink Beamforming With Shaping Constraints Using Real-valued OSTBC},
author = {Ka Lung Law and Xin Wen and Minh Thanh Vu and Marius Pesavento},
journal= {arXiv preprint arXiv:1502.04488},
year = {2015}
}