POLO: Phase-Only Localization in Uplink Distributed MIMO Systems

Fuente: arXiv
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Autores principales: Dey, Sauradeep, Keskin, Musa Furkan, Tagliaferri, Dario, Seco-Granados, Gonzalo, Valkama, Mikko, Wymeersch, Henk
Formato: Preprint
Publicado: 2025
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author Dey, Sauradeep
Keskin, Musa Furkan
Tagliaferri, Dario
Seco-Granados, Gonzalo
Valkama, Mikko
Wymeersch, Henk
author_facet Dey, Sauradeep
Keskin, Musa Furkan
Tagliaferri, Dario
Seco-Granados, Gonzalo
Valkama, Mikko
Wymeersch, Henk
contents We propose a low-complexity localization framework for uplink distributed MIMO (D-MIMO) systems, targeting the challenge of minimizing the highly spiky maximum-likelihood (ML) cost function that arises in sparsely deployed phasecoherent access points (APs) with narrowband transmission. In such systems, ML-based localization typically relies on dense grid search, incurring prohibitive computational complexity. To address this, we introduce phase-only localization (POLO), an approach that leverages differential carrier-phase measurements from selected APs to generate a compact set of candidate user positions. The ML cost function is then evaluated only at these candidates, reducing complexity significantly. A key challenge is to devise an AP selection mechanism that reduces the number of candidate points while maintaining reliable coverage. We propose two variants: POLO-I, which selects three APs to provide closed-form candidate positions with low computational cost, and POLO-II, which selects four APs using an alternative strategy that enhances coverage at marginally higher runtime. Comprehensive analytical and simulation results show that POLO achieves a favorable coverage-complexity trade-off, reducing cost by orders of magnitude relative to exhaustive grid search with only marginal loss in coverage. By characterizing this tradeoff under diverse AP configurations, we also provide practical guidelines for selecting between POLO-I and POLO-II depending on latency and coverage requirements.
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id arxiv_https___arxiv_org_abs_2512_10879
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle POLO: Phase-Only Localization in Uplink Distributed MIMO Systems
Dey, Sauradeep
Keskin, Musa Furkan
Tagliaferri, Dario
Seco-Granados, Gonzalo
Valkama, Mikko
Wymeersch, Henk
Signal Processing
We propose a low-complexity localization framework for uplink distributed MIMO (D-MIMO) systems, targeting the challenge of minimizing the highly spiky maximum-likelihood (ML) cost function that arises in sparsely deployed phasecoherent access points (APs) with narrowband transmission. In such systems, ML-based localization typically relies on dense grid search, incurring prohibitive computational complexity. To address this, we introduce phase-only localization (POLO), an approach that leverages differential carrier-phase measurements from selected APs to generate a compact set of candidate user positions. The ML cost function is then evaluated only at these candidates, reducing complexity significantly. A key challenge is to devise an AP selection mechanism that reduces the number of candidate points while maintaining reliable coverage. We propose two variants: POLO-I, which selects three APs to provide closed-form candidate positions with low computational cost, and POLO-II, which selects four APs using an alternative strategy that enhances coverage at marginally higher runtime. Comprehensive analytical and simulation results show that POLO achieves a favorable coverage-complexity trade-off, reducing cost by orders of magnitude relative to exhaustive grid search with only marginal loss in coverage. By characterizing this tradeoff under diverse AP configurations, we also provide practical guidelines for selecting between POLO-I and POLO-II depending on latency and coverage requirements.
title POLO: Phase-Only Localization in Uplink Distributed MIMO Systems
topic Signal Processing
url https://arxiv.org/abs/2512.10879