Channel Charting in Real-World Coordinates With Distributed MIMO
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Date
2025-09
Publication Type
Journal Article
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yes
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Abstract
Channel charting is an emerging self-supervised method that maps channel-state information (CSI) to a low-dimensional latent space (the channel chart) that represents pseudo-positions of user equipments (UEs). While channel charts preserve local geometry, i.e., nearby UEs are nearby in the channel chart (and vice versa), the pseudo-positions are in arbitrary coordinates and global geometry is typically not preserved. In order to embed channel charts in real-world coordinates, we first propose a bilateration loss for distributed multiple-input multiple-output (D-MIMO) wireless systems in which only the access point (AP) positions are known. The idea behind this loss is to compare the received power at pairs of APs to determine whether a UE should be placed closer to one AP or the other in the channel chart. We then propose a line-of-sight (LoS) bounding-box loss that places the UE in a predefined LoS area of each AP that is estimated to have a LoS path to the UE. We demonstrate the efficacy of combining both of these loss functions with neural-network-based channel charting using ray-tracing-based and measurement-based channel vectors. Our proposed approach outperforms several baselines and maintains the self-supervised nature of channel charting as it neither relies on geometrical propagation models nor on any ground-truth UE position information.
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published
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Journal / series
Volume
24 (9)
Pages / Article No.
7286 - 7300
Publisher
IEEE
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Edition / version
Methods
Software
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Date collected
Date created
Subject
Channel charting distributed multiple-input multiple-output (D-MIMO); Machine learning; Dimensionality reduction; Manifold learning; Neural network
Organisational unit
09695 - Studer, Christoph / Studer, Christoph
Notes
Funding
207314 - WiLoC: Wireless Localization with Channel State Information: Algorithms, Analysis, Defenses, and Deployment (SNF)
218704 - CHASER: Channel Charting as a Service (SNF)
218704 - CHASER: Channel Charting as a Service (SNF)