Regularized Approximate Message Passing for Overloaded Discrete Linear Inversion

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Hauptverfasser: Shrestha, Shreesal, Rexhepi, Getuar, Ranasinghe, Kuranage Roche Rayan, Rou, Hyeon Seok, de Abreu, Giuseppe Thadeu Freitas
Format: Preprint
Veröffentlicht: 2026
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author Shrestha, Shreesal
Rexhepi, Getuar
Ranasinghe, Kuranage Roche Rayan
Rou, Hyeon Seok
de Abreu, Giuseppe Thadeu Freitas
author_facet Shrestha, Shreesal
Rexhepi, Getuar
Ranasinghe, Kuranage Roche Rayan
Rou, Hyeon Seok
de Abreu, Giuseppe Thadeu Freitas
contents We propose regularized approximate message passing (RAMP), a low-complexity algorithm for discrete signal detection in overloaded multiple-input multiple-output (MIMO) systems where the number of transmit antennas exceeds the number of receive antennas. While the state-of-the-art (SotA) iterative discrete least squares (IDLS) framework achieves near-optimal discrete-aware performance, its iterative matrix inversions impose a prohibitive $\mathcal{O}(M^3)$ complexity. RAMP resolves this by deriving an adaptive, state-dependent scalar denoiser that enforces arbitrary discrete constellation constraints within the approximate message passing (AMP) framework, reducing per-iteration complexity to $\mathcal{O}(NM)$. A robust variant is further proposed by incorporating an $\ell_2$-norm penalty, analogous to a linear minimum mean squared error (LMMSE) estimator, to enhance noise resilience. Simulation results under uncorrelated Rayleigh fading demonstrate that both proposed algorithms closely track their exact IDLS counterparts while avoiding the catastrophic failure of standard AMP in the overloaded regime, achieving steep bit error rate (BER) waterfall curves at a fraction of the computational cost.
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id arxiv_https___arxiv_org_abs_2604_03717
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Regularized Approximate Message Passing for Overloaded Discrete Linear Inversion
Shrestha, Shreesal
Rexhepi, Getuar
Ranasinghe, Kuranage Roche Rayan
Rou, Hyeon Seok
de Abreu, Giuseppe Thadeu Freitas
Signal Processing
We propose regularized approximate message passing (RAMP), a low-complexity algorithm for discrete signal detection in overloaded multiple-input multiple-output (MIMO) systems where the number of transmit antennas exceeds the number of receive antennas. While the state-of-the-art (SotA) iterative discrete least squares (IDLS) framework achieves near-optimal discrete-aware performance, its iterative matrix inversions impose a prohibitive $\mathcal{O}(M^3)$ complexity. RAMP resolves this by deriving an adaptive, state-dependent scalar denoiser that enforces arbitrary discrete constellation constraints within the approximate message passing (AMP) framework, reducing per-iteration complexity to $\mathcal{O}(NM)$. A robust variant is further proposed by incorporating an $\ell_2$-norm penalty, analogous to a linear minimum mean squared error (LMMSE) estimator, to enhance noise resilience. Simulation results under uncorrelated Rayleigh fading demonstrate that both proposed algorithms closely track their exact IDLS counterparts while avoiding the catastrophic failure of standard AMP in the overloaded regime, achieving steep bit error rate (BER) waterfall curves at a fraction of the computational cost.
title Regularized Approximate Message Passing for Overloaded Discrete Linear Inversion
topic Signal Processing
url https://arxiv.org/abs/2604.03717