# Asymptotics of Nonlinear LSE Precoders with Applications to Transmit Antenna Selection

## TL;DR

This paper analyzes the large-system behavior of nonlinear LSE precoders with applications to transmit antenna selection, using the replica method to derive performance properties and compare different penalty functions.

## Contribution

It introduces a general analytical framework for LSE precoders with arbitrary penalties, including RSB analysis, and explores antenna selection constraints.

## Key findings

- LSE precoders with $\
- Performance predictions differ between RS and RSB, especially with antenna constraints.
- $\

## Abstract

This paper studies the large-system performance of Least Square Error (LSE) precoders which~minimize~the~input-output distortion over an arbitrary support subject to a general penalty function. The asymptotics are determined via the replica method in a general form which encloses the Replica Symmetric (RS) and Replica Symmetry Breaking (RSB) ans\"atze. As a result, the "marginal decoupling property" of LSE precoders for $b$-steps of RSB is derived. The generality of the studied setup enables us to address special cases in which the number of active transmit antennas are constrained. Our numerical investigations depict that the computationally efficient forms of LSE precoders based on "$\ell_1$-norm" minimization perform close to the cases with "zero-norm" penalty function which have a considerable improvements compared to the random antenna selection. For the case with BPSK signals and restricted number of active antennas, the results show that RS fails to predict the performance while the RSB ansatz is consistent with theoretical bounds.