In this letter, we propose a novel adaptive multi-user association strategy for non-orthogonal multiple access (NOMA) in visible light communication (VLC) systems, by which a number of user association (UA) schemes are obtained, in order to improve the multi-user system performance. Moreover, two new concepts called the redundant user and the multi-user association matrix are proposed to indicate UA status and data rates. The system throughput of the proposed strategy is evaluated and compared with the traditional NOMA without UA and NOMA-based pairwise coupling schemes, while the effect of the residual interference is also investigated.

This letter investigates the resource allocation optimization for indoor hybrid visible light communication (VLC)/radio frequency(RF) systems, where multiple Internet of Things (IoT) devices employ simultaneous lightwave information and power transfer (SLIPT) to work sustainably without any external power supply. IoT devices receive data and power themselves based on SLIPT via downlink while sending back data based on the harvested energy through the RF uplink. Given the sustainability-driven goal, an optimization problem to maximize the minimum data collection rate is formulated across all IoT devices within the given time period, resulting in a mixed integer nonlinear problem that is challenging to solve. To this end, an iterative algorithm of timeslot assignment and power allocation is proposed. Simulation results verify the superiority of the proposed scheme in data collection rate.

In this paper, we investigate joint subchannel assignment and power allocation for the energy efficiency (EE) optimization in an indoor visible light communication (VLC)-Internet of Things (IoT) system with simultaneous lightwave information and power transfer (SLIPT). A mixed-integer fractional nonlinear programming problem that is challenging to solve is formulated. To tackle this problem, the optimal transmission scheme is decomposed into subchannel assignment and power allocation. Firstly, a virtual cell formation and subchannel assignment (VCF-SA) scheme is proposed, which considers the location of IoT devices, quality of service requirements, and energy states. Secondly, a quadratic transformation-based power allocation (QTBPA) scheme is designed to transform the fractional nonlinear programming problem into a series of convex problems that can be solved iteratively. Simulation results illustrate the effectiveness of the proposed scheme in terms of system EE compared to the benchmarks. The impact of system parameters on the EE is also analyzed.

This letter presents three downlink transmission and user cooperation (UC) methods for visible light communication (VLC)/ radio frequency (RF) systems with non-orthogonal multiple access (NOMA), including NOMA-based VLC, simultaneous wireless information and power transfer-NOMA-based VLC/RF, and direct RF. Then, we propose an adaptive quality of service-oriented UC and link selection strategy, in order to improve the user experience. Besides, the cooperation transmission matrix is defined and the closed-form expression for the system throughput is derived. Simulation results show that the proposed strategy can significantly improve the system throughput regardless of residual interference in NOMA or VLC link blockage.

Non-orthogonal multiple access (NOMA) has been recognized as a promising technique to alleviate the bandwidth limitation in visible light communication (VLC) downlinks. Nevertheless, the corresponding power allocation problem is typically non-convex and computationally challenging under practical system constraints, which limits the effectiveness of conventional optimization approaches. To address this issue, this paper proposes an improved particle swarm optimization (IPSO)-based strategy that aims at maximizing the system sum rate and employs adaptive mechanisms including an adaptive dynamic inertia weight, cooperative evolutionary learning factors, and enhanced elite opposition-based learning (EEOBL) to strengthen both global search capability and convergence performance. Simulation results indicate that the proposed scheme significantly improves the overall system capacity across diverse interference scenarios, while achieving accelerated convergence and enhanced robustness.