In this paper, we propose and study a new joint load balancing (LB) and power allocation (PA) scheme for a hybrid visible light communication (VLC) and radio frequency (RF) system consisting of one RF access point (AP) and multiple VLC APs. An iterative algorithm is proposed to distribute users on APs and distribute the powers of the APs on their users. In the PA subproblem, an optimization problem is formulated to allocate the power of each AP to the connected users for total achievable data rate maximization. In this subproblem, we propose a new efficient algorithm that finds optimal dual variables after formulating them in terms of each other. This new algorithm provides faster convergence and better performance than the traditional subgradient method. In addition, it does not depend on the step size or the initial values of the variables, which we look for, as the subgradient does. Then, we start with the user of the minimum data rate seeking another AP that offers a higher data rate for that user. Users with lower data rates continue reconnecting from one AP to another to balance the load only if this travel increases the summation of the achievable data rates and enhances the system fairness. Two approaches are proposed to have the joint PA and LB performed: a main approach that considers the exact interference information for all users, and a suboptimal approach that aims to decrease the complexity of the first approach by considering only the approximate interference information of users. The numerical results demonstrate that the proposed algorithms improve the system capacity and system fairness with fast convergence.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KAUST004
Acknowledgements: This work was funded by the Deanship of Scientific Research at the King Fahd University of Petroleum & Minerals (KFUPM) through grant number KAUST004. The work was also supported by the National Plan for Science, Technology, and Innovation (Maarifah)—King Abdulaziz City for Science and Technology—through the Science and Technology Unit at KFUPM—the Kingdom of Saudi Arabia, under grant number 15-ELE4157-04. The authors would also like to acknowledge the KFUPM-KAUST research initiative that resulted from this research work. This work is an extended version of our paper, which has been recently accepted and presented at the IEEE GLOBECOM Conference 2017 .