# Towards Channel Charting Enhancement with Non-Reconfigurable Intelligent Surfaces

arXiv: https://arxiv.org/abs/2511.00919 · HTML: https://mlsanity.com/paper/2511.00919/

## Key facts

- No citing papers in the map yet (data through 14 Oct 2026).
- Builds on 20 of its 37 references that are in the map.
- First posted on arXiv 2 Nov 2025.

## Builds on (most cited first, 20 of 20)

- [Sionna RT: Differentiable Ray Tracing for Radio Propagation Modeling](https://mlsanity.com/paper/2303.11103/) (2023)
- [Intelligent Reflecting Surface Enhanced Wireless Network via Joint Active and Passive Beamforming](https://mlsanity.com/paper/1810.03961/) (2018)
- [Channel Charting: Locating Users within the Radio Environment using Channel State Information](https://mlsanity.com/paper/1807.05247/) (2018)
- [Improving Channel Charting with Representation-Constrained Autoencoders](https://mlsanity.com/paper/1908.02878/) (2019)
- [Wireless Channel Charting: Theory, Practice, and Applications](https://mlsanity.com/paper/2304.08095/) (2023)
- [Channel Charting in Real-World Coordinates with Distributed MIMO](https://mlsanity.com/paper/2406.13722/) (2024)
- [A Review of Indoor Millimeter Wave Device-based Localization and Device-free Sensing Technologies and Applications](https://mlsanity.com/paper/2112.05593/) (2021)
- [Semi-Supervised Learning for Channel Charting-Aided IoT Localization in Millimeter Wave Networks](https://mlsanity.com/paper/2108.08241/) (2021)
- [An RSSI-based Wireless Sensor Node Localisation using Trilateration and Multilateration Methods for Outdoor Environment](https://mlsanity.com/paper/1912.07801/) (2019)
- [Semi-supervised t-SNE for Millimeter-wave Wireless Localization](https://mlsanity.com/paper/2111.13573/) (2021)
- [Channel Charting for Streaming CSI Data](https://mlsanity.com/paper/2312.04514/) (2023)
- [The Impact of Mobile Blockers on Millimeter Wave Cellular Systems](https://mlsanity.com/paper/1807.04388/) (2018)
- [Wireless Communications with Programmable Metasurface: New Paradigms, Opportunities, and Challenges on Transceiver Design](https://mlsanity.com/paper/1907.01956/) (2019)
- [Conformal Metasurfaces: a Novel Solution for Vehicular Communications](https://mlsanity.com/paper/2201.08820/) (2022)
- [Wave-Controlled Metasurface-Based Reconfigurable Intelligent Surfaces](https://mlsanity.com/paper/2202.03273/) (2022)
- [Generalized Analysis and Unified Design of EM Skins](https://mlsanity.com/paper/2207.08419/) (2022)
- [Network-Controlled Repeaters vs. Reconfigurable Intelligent Surfaces for 6G mmW Coverage Extension](https://mlsanity.com/paper/2211.08033/) (2022)
- [Wireless Communications with Space-Time Modulated Metasurfaces](https://mlsanity.com/paper/2302.08310/) (2023)
- [Optimizing Curved EM Skins for Opportunistic Relaying in Vehicular Networks](https://mlsanity.com/paper/2405.09730/) (2024)
- [Channel Charting in Smart Radio Environments](https://mlsanity.com/paper/2508.07305/) (2025)

## Abstract (arXiv)

We investigate how fully-passive electromagnetic skins (EMSs) can be engineered to enhance channel charting (CC) in dense urban environments. We employ two complementary state-of-the-art CC techniques, semi-supervised t-distributed stochastic neighbor embedding (t-SNE) and a semi-supervised Autoencoder (AE), to verify the consistency of results across nonparametric and parametric mappings. We show that the accuracy of CC hinges on a balance between signal-to-noise ratio (SNR) and spatial dissimilarity: EMS codebooks that only maximize gain, as in conventional Reconfigurable Intelligent Surface (RIS) optimization, suppress location fingerprints and degrade CC, while randomized phases increase diversity but reduce SNR. To address this trade-off, we design static EMS phase profiles via a quantile-driven criterion that targets worst-case users and improves both trustworthiness and continuity. In a 3D ray-traced city at 30 GHz, the proposed EMS reduces the 90th-percentile localization error from > 50 m to < 25 m for both t-SNE and AE-based CC, and decreases severe trajectory dropouts by over 4x under 15% supervision. The improvements hold consistently across the evaluated configurations, establishing static, pre-configured EMS as a practical enabler of CC without reconfiguration overheads.