Data-Aided Regularization of Direct-Estimate Combiner in Distributed MIMO Systems

Fuente: arXiv
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Hauptverfasser: Gouda, Bikshapathi, Atzeni, Italo, Tölli, Antti
Format: Preprint
Veröffentlicht: 2025
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author Gouda, Bikshapathi
Atzeni, Italo
Tölli, Antti
author_facet Gouda, Bikshapathi
Atzeni, Italo
Tölli, Antti
contents This paper explores the data-aided regularization of the direct-estimate combiner in the uplink of a distributed multiple-input multiple-output system. The network-wide combiner can be computed directly from the pilot signal received at each access point, eliminating the need for explicit channel estimation. However, the sample covariance matrix of the received pilot signal that is used in its computation may significantly deviate from the actual covariance matrix when the number of pilot symbols is limited. To address this, we apply a regularization to the sample covariance matrix using a shrinkage coefficient based on the received data signal. Initially, the shrinkage coefficient is determined by minimizing the difference between the sample covariance matrices obtained from the received pilot and data signals. Given the limitations of this approach in interference-limited scenarios, the shrinkage coefficient is iteratively optimized using the sample mean squared error of the hard-decision symbols, which is more closely related to the actual system's performance, e.g., the symbol error rate (SER). Numerical results demonstrate that the proposed regularization of the direct-estimate combiner significantly enhances the SER, particularly when the number of pilot symbols is limited.
format Preprint
id arxiv_https___arxiv_org_abs_2501_12092
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Data-Aided Regularization of Direct-Estimate Combiner in Distributed MIMO Systems
Gouda, Bikshapathi
Atzeni, Italo
Tölli, Antti
Signal Processing
Information Theory
This paper explores the data-aided regularization of the direct-estimate combiner in the uplink of a distributed multiple-input multiple-output system. The network-wide combiner can be computed directly from the pilot signal received at each access point, eliminating the need for explicit channel estimation. However, the sample covariance matrix of the received pilot signal that is used in its computation may significantly deviate from the actual covariance matrix when the number of pilot symbols is limited. To address this, we apply a regularization to the sample covariance matrix using a shrinkage coefficient based on the received data signal. Initially, the shrinkage coefficient is determined by minimizing the difference between the sample covariance matrices obtained from the received pilot and data signals. Given the limitations of this approach in interference-limited scenarios, the shrinkage coefficient is iteratively optimized using the sample mean squared error of the hard-decision symbols, which is more closely related to the actual system's performance, e.g., the symbol error rate (SER). Numerical results demonstrate that the proposed regularization of the direct-estimate combiner significantly enhances the SER, particularly when the number of pilot symbols is limited.
title Data-Aided Regularization of Direct-Estimate Combiner in Distributed MIMO Systems
topic Signal Processing
Information Theory
url https://arxiv.org/abs/2501.12092