Channel modeling and capacity optimization for optical RIS aided NOMA in indoor multiuser visible light communication...

Area of Science:

• Optical Communications
• Wireless Networks
• Signal Processing

Background:

• Visible Light Communication (VLC) faces challenges in 5G/6G networks, including demands for higher spectral efficiency (SE), data rates, and quality of service (QoS).
• Existing systems require optimization for indoor environments, green Internet of Things (IoT), and users with mobility.
• The integration of advanced technologies like reconfigurable intelligent surfaces (RIS) and novel modulation schemes is crucial for future optical wireless networks.

Purpose of the Study:

• To propose and evaluate a novel visible light communication (VLC) system that addresses the evolving demands of 5G and 6G networks.
• To enhance spectral efficiency, data rates, and physical layer security (PLS) in VLC systems.
• To investigate the performance of optical reconfigurable intelligent surfaces (ORIS)-aided multiple-input multiple-output (MIMO) integrated with non-orthogonal multiple access (NOMA) and DFT-s-OTFS modulation.

Main Methods:

• Development of a VLC channel model for ORIS-aided NOMA-OTFS systems incorporating MIMO technologies.
• Formulation and solution of a capacity maximization problem considering transceiver parameters, RIS reflections, transmit power, and delay-Doppler (DD) channels using a relaxation algorithm.
• Integration of discrete Fourier transform spread orthogonal time-frequency space (DFT-s-OTFS) modulation to support DD channels and minimize Peak-to-Average Power Ratio (PAPR).

Main Results:

• The proposed ORIS-aided DFT-s-OTFS-based NOMA-MIMO VLC system demonstrates superior performance compared to ORIS-assisted OFDM.
• Significant improvements were observed in bit error rate (BER), channel capacity, spectral efficiency (SE), and security rates.
• The system effectively enhances spatial diversity, optimizes bandwidth, and improves power allocation in VLC-IoT environments.

Conclusions:

• The developed ORIS-aided DFT-s-OTFS-based NOMA-MIMO VLC system offers a promising solution for future high-performance optical wireless communication.
• The findings provide valuable insights for advancing optical RIS-assisted MIMO-VLC technologies, particularly for 5G and 6G applications.
• The proposed framework effectively addresses key challenges in VLC, paving the way for more efficient and secure optical communication systems.