Steepest GradientBased Orthogonal Precoder For IntegerForcing MIMO
Abstract
In this paper, we develop an orthogonal precoding scheme for integerforcing (IF) linear receivers using the steepest gradient algorithm. Although this scheme can be viewed as a special case of the unitary precoded integerforcing (UPIF), it has two major advantages. First, the orthogonal precoding outperforms its unitary counterpart in terms of achievable rate, outage probability, and error rate. We verify this advantage via theoretical and numerical analyses. Second, it exhibits lower complexity as the dimension of orthogonal matrices is half that of unitary matrices in the realvalued domain. For finding ``good'' orthogonal precoder matrices, we propose an efficient algorithm based on the steepest gradient algorithm that exploits the geometrical properties of orthogonal matrices as a Lie group. The proposed algorithm has low complexity and can be easily applied to an arbitrary MIMO configuration. We also confirm numerically that the proposed orthogonal precoding outperforms UPIF type II in some scenarios and the Xprecoder in highorder QAM schemes, e.g., $64$ and $256$QAM.
 Publication:

arXiv eprints
 Pub Date:
 April 2019
 arXiv:
 arXiv:1904.09356
 Bibcode:
 2019arXiv190409356H
 Keywords:

 Computer Science  Information Theory;
 Mathematics  Optimization and Control