Shi, Fangzhan;
(2025)
Localization and Sensing using Wi-Fi Multi-link Round-Trip Channel State Information.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
This study introduces a Wi-Fi Multi-link Round-Trip Channel State Information (ML-RTCSI) protocol and corresponding processing algorithms tailored for wireless localization and sensing with low-specification Wi-Fi devices. Unlike systems that depend on antenna arrays and wide bandwidths, this protocol does not require Multiple-In-Multiple-Out (MIMO) and operates within a modest 20 MHz bandwidth, making it particularly suitable for cost-effective IoT chips. As there is neither an antenna array for angle-of-arrival estimation nor a wide bandwidth for accurate time-of-arrival/round-trip time estimation, the key innovation associated with the proposed solution is to estimate Doppler frequency shifts from the Wi-Fi communication signals between multiple links for localization and tracking. The carrier frequency offset is canceled by the round-trip Wi-Fi communications for Doppler frequency estimation, and the multi-link structure enables the proposed system to utilize multiple Wi-Fi communication devices. The proposed protocol has two modes: one for device-based localization (e.g., pinpointing a mobile device) and another for device-free target sensing (e.g., tracking a moving human). They share a similar workflow, and the only difference lies in the topologies. The localization and sensing processing back-ends also share a similar structure and are based on particle filters with different observation models. A real-world prototype for both localization and sensing has been designed and built using Raspberry Pi CM4 units, and evaluation shows both approaches can reach decimeter-level accuracy. In addition, the localization and tracking algorithms can efficiently run on the Raspberry Pi units in real time with 20\% CPU usage and a 2.5W power supply. In summary, the proposed solution can enable accurate localization and sensing capability on resource-limited Wi-Fi devices and could potentially be integrated with future standards for joint communication and sensing.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Localization and Sensing using Wi-Fi Multi-link Round-Trip Channel State Information |
| Language: | English |
| Additional information: | Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Security and Crime Science |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10204443 |
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