Optical IRS-Aided Simultaneous Lightwave Information and Power Transfer for NOMA-Based VLC Systems: An Energy Consumption Perspective

The growth of indoor terminals has put higher demands on wireless communications, which not only need to support high-rate communications, but are also required to provide power for energy-limited terminals. However, conventional wireless communication systems face challenges in meeting these demands due to the spectrum congestion and electromagnetic interference. Recently, visible light communication (VLC) has been emerged as a promising technology, which can take advantage of its ability to operate within the unlicensed spectra. Therefore, in this paper, VLC benefits from the facilitation of optical intelligent reflecting surface (OIRS) and non-orthogonal multiple access (NOMA) to support energy-constrained devices through simultaneous lightwave information and power transfer (SLIPT), which is well suited for future VLC systems. Moreover, an optimization framework is proposed for NOMA-based VLC systems with OIRS for SLIPT, and then the problem is formulated to minimize the total energy consumption with several key constraints. To solve this non-convex problem, we decompose it into four sub-problems, including the OIRS configuration, NOMA coefficient assignment, transmit power allocation, and direct current bias arrangement, which are solved iteratively by the block coordinate descent algorithm through relaxed iterative optimization, minorization-maximization algorithm, and successive convex approximation. Simulation results validate the convergence and effectiveness of the proposed algorithm, demonstrating the influence of OIRS unit number and other key factors on the system performance. These findings highlight the potential of OIRS to enhance the power transfer capabilities of future optical communications.