Orthogonal Precoders For Integer-Forcing Multiple Input Multiple Output (MIMO) Channels based on Steepest Gradient-Based

In this talk, we will first briefly introduce integer-forcing linear receivers for MIMO Channels. We will then develop an orthogonal precoding scheme for integer-forcing (IF) linear receivers. 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 X-precoder in high-order QAM schemes, e.g., 64- and 256-QAM.