Channel Charting: an Euclidean Distance Matrix Completion Perspective

Agostini, Patrick; Utkovski, Zoran; Stańczak, Sławomir

doi:10.1109/icassp40776.2020.9053639

Cited by 20 publications

(16 citation statements)

References 16 publications

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“…The conversion of subcarrier CSI into the delay domain to extract relative time-of-flight information has been used in [21], [47]- [49]. The use of cross-correlation in the spatial domain and 1dimensional autocorrelation in the delay domain has been used in [27], [28] and [20], [29], [50], respectively. Such methods improve resilience to small-scale fading and common hardware impairments, including time synchronization errors as well as residual carrier frequency and sampling rate offsets.…”

Section: B Contributionsmentioning

confidence: 99%

CSI-Based Multi-Antenna and Multi-Point Indoor Positioning Using Probability Fusion

Gönültaş

Lei

Langerman

et al. 2022

IEEE Trans. Wireless Commun.

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Channel state information (CSI)-based fingerprinting via neural networks (NNs) is a promising approach to enable accurate indoor and outdoor positioning of user equipments (UEs), even under challenging propagation conditions. In this paper, we propose a positioning pipeline for wireless LAN MIMO-OFDM systems which uses uplink CSI measurements obtained from one or more unsynchronized access points (APs). For each AP receiver, novel features are first extracted from the CSI that are robust to system impairments arising in real-world transceivers. These features are the inputs to a NN that extracts a probability map indicating the likelihood of a UE being at a given grid point. The NN output is then fused across multiple APs to provide a final position estimate. We provide experimental results with realworld indoor measurements under line-of-sight (LoS) and non-LoS propagation conditions for an 80 MHz bandwidth IEEE 802.11ac system using a two-antenna transmit UE and two AP receivers each with four antennas. Our approach is shown to achieve centimeter-level median distance error, an order of magnitude improvement over a conventional baseline.

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Section: B Contributionsmentioning

confidence: 99%

CSI-Based Multi-Antenna and Multi-Point Indoor Positioning Using Probability Fusion

Gönültaş

Lei

Langerman

et al. 2022

IEEE Trans. Wireless Commun.

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“…[40]- [42]. Here, two DR techniques are briefly presented: 1) principal component analysis (PCA) and 2) Isomap, which will be the DR technique used in our numerical experiments.…”

Section: Several Dimensionality Reduction (Dr) Techniques Have Been U...mentioning

confidence: 99%

Pilot Reuse for mMTC with Spatially Correlated MIMO Channels: A Channel Charting Approach

Ribeiro¹,

Leinonen²,

Al-Tous³

et al. 2022

Preprint

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Massive multiple-input multiple-output (mMIMO) technology is a way to increase the spectral efficiency of machine-type communications (MTC). To exploit the benefits from large antenna arrays, accurate channel estimation through pilot signals is needed. Massive MTC systems cannot avoid pilot reuse due to the enormous numbers of connected devices. We propose a pilot reuse algorithm based on channel charting (CC) to mitigate pilot contamination in a multi-sector single-cell massive MTC system having spatially correlated channels. We show that after creating an interference map via CC, a simple strategy to allocate the pilot sequences can be implemented. The simulation results show that the CC-based pilot reuse strategy improves channel estimation accuracy, which subsequently improves the symbol detection performance and increases the spectral efficiency compared to other existing schemes.Moreover, the performance of the CC pilot assignment method approaches that of exhaustive search pilot assignment for small network setups. I. INTRODUCTIONMassive machine-type communications (mMTC) is a class of services introduced in 5G systems to provide access to enormous numbers of devices. These devices create, exchange, and

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“…where f n ∈ R C is the point in the C-dimensional CC corresponding to d n , where typically C = 2 or C = 3. Several unsupervised DR techniques have been proposed to map the extracted features into a lower dimension embedding [12], [22]- [24]. We propose the use of Laplacian Eigenmaps (LE) as a DR technique as it aims to preserve the local structure of the high-dimensional embedding by minimizing Algorithm 1: Nearest neighbor pilot assignment Input : 1) The set of UEs N = {1, .…”

Section: B Cc-aided Pilot Assignmentmentioning

confidence: 99%

Exploiting Spatial Correlation for Pilot Reuse in Single-Cell mMTC

Ribeiro

Leinonen

Al-Tous

et al. 2021

2021 IEEE 32nd Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

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As a key enabler for massive machine-type communications (mMTC), spatial multiplexing relies on massive multiple-input multiple-output (mMIMO) technology to serve the massive number of user equipments (UEs). To exploit spatial multiplexing, accurate channel estimation through pilot signals is needed. In mMTC systems, it is impractical to allocate a unique orthogonal pilot sequence to each UE as it would require too long pilot sequences, degrading the spectral efficiency. This work addresses the design of channel features from correlated fading channels to assist the pilot assignment in multi-sector mMTC systems under pilot reuse of orthogonal sequences. In order to reduce pilot collisions and to enable pilot reuse, we propose to extract features from the channel covariance matrices that reflect the level of orthogonality between the UEs channels. Two features are investigated: covariance matrix distance (CMD) feature and CMD-aided channel charting (CC) feature. In terms of symbol error rate and achievable rate, the CC-based feature shows superior performance than the CMD-based feature and baseline pilot assignment algorithms.

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Channel Charting: an Euclidean Distance Matrix Completion Perspective

Cited by 20 publications

References 16 publications

CSI-Based Multi-Antenna and Multi-Point Indoor Positioning Using Probability Fusion

CSI-Based Multi-Antenna and Multi-Point Indoor Positioning Using Probability Fusion

Pilot Reuse for mMTC with Spatially Correlated MIMO Channels: A Channel Charting Approach

Exploiting Spatial Correlation for Pilot Reuse in Single-Cell mMTC

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