Towards intelligent and adaptive optical wireless communications and sensing for 6G

Iqbal, Rashid (2026) Towards intelligent and adaptive optical wireless communications and sensing for 6G. PhD thesis, University of Glasgow.

Abstract

Future sixth generation (6G) networks are expected to support high-speed communication together with secure, adaptive, and environment-aware operation. Meeting these requirements motivates the use of complementary wireless technologies that can provide additional bandwidth while supporting precise spatial control. Optical wireless communication (OWC) is promising in this context because it offers large unlicensed bandwidth, spatial confinement, immunity to radio-frequency electromagnetic interference, and the potential to support communication, localisation, and sensing. Within the broader OWC family, visible light communication (VLC) is particularly attractive for indoor environments because visible light can be used for both illumination and wireless transmission. However, the performance of indoor optical wireless systems remains strongly dependent on blockage, user orientation, receiver field-of-view (FoV), transmitter-receiver geometry, and the presence of eavesdroppers.
These limitations motivate the development of optical wireless systems that can actively control propagation and obtain information about their surrounding environment. Accordingly, this thesis investigates intelligent and adaptive OWC and sensing techniques for future indoor 6G networks. The research focuses on improving security, spatial adaptability, and environmental awareness through optical reconfigurable intelligent surfaces (ORISs), light-emitting reconfigurable intelligent surfaces (LeRISs), and adaptive beam-management techniques.
First, to address the security limitations of conventional indoor VLC, ORIS-assisted VLC is investigated for physical layer security (PLS). The proposed approach exploits ORIS-induced propagation delays to control the reflected optical paths and improve the secrecy of the legitimate link. For the single-eavesdropper worst-case geometry, the proposed ORIS allocation improves the secrecy capacity by 253.7% at an optical transmit power of 3 W compared with the line-of-sight (LoS)-only case. When the analysis is extended to multiple eavesdroppers, the proposed proximal policy optimisation (PPO)- based allocation achieves secrecy-capacity improvements of up to 235% compared with allocating all ORIS elements to the legitimate receiver.
Building on this ability to control reflected optical paths, the second part of the thesis focuses on where the reflected beams are directed. A geometry-aware non-uniform codebook is therefore developed for ORIS-assisted VLC to improve spatial coverage and support multi-user resource allocation. When combined with sparrow search algorithm (SSA)-based power allocation, the proposed LoS+ORIS framework increases the sum rate from approximately 4.4 bps/Hz to 9.6 bps/Hz over the considered ORISsize range while maintaining improved multi-user fairness.
While adaptive beam control improves communication performance, further adaptability requires knowledge of the user location and surrounding obstacles. The third part of the thesis therefore extends the reconfigurable surface from communication control to environmental awareness through a vertical-cavity surface-emitting laser (VCSEL)-based LeRIS architecture. Narrow VCSEL beams are used for user localisation and obstacle mapping, and the resulting spatial information is then used to support blockage-aware millimetre wave (mmWave) communication. For the considered simulation settings, the proposed VCSEL-based architecture achieves millimetre-level localisation accuracy, compared with centimetre-level accuracy for a light-emitting diode (LED)-based LeRIS benchmark, while the localisation and mapping information enables adaptive route selection and improved blockage resilience.
Overall, the three contributions follow a common progression from securing the optical link, to controlling the spatial distribution of reflected beams, and finally to using optical sensing to make the communication environment aware of users and obstacles. The results demonstrate that programmable optical surfaces, optical sensing, and adaptive beam management can jointly improve the security, adaptability, and environmental awareness of indoor wireless systems, contributing towards intelligent OWC and sensing for future 6G networks.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Abumarshoud, Dr. Hanaa, Zoha, Dr. Ahmed and Imran, Professor Muhammad
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-86329
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 10 Nov 2026 15:40
• Last Modified: 10 Nov 2026 15:43
• Thesis DOI: 10.5525/gla.thesis.86329
• URI: https://theses.gla.ac.uk/id/eprint/86329

Related URLs

• Article DOI
• Article DOI
• Pre-print
• Pre-print
• Conference proceeding
• Conference proceeding