Energy efficient resource allocation for the software-defined VLC and RF small cells

Visible light communication (VLC) is considered as a promising candidate to improve the performance of indoor communication as the complement of wireless radio frequency (RF) communications due to the scarcity of RF resources. Combining VLC with software-defined small cell networks will substantially improve the user data rates in indoor environments. In this paper, we introduce the software defined philosophy into orthogonal frequency division multiple access (OFDMA) based heterogeneous twinned VLC and RF small-cell systems. The pivotal issues of energy efficient subchannel and power allocation are investigated in the context of software-defined VLC and RF small-cell networks. We formulate the energy efficient resource allocation problem as a non-convex optimization problem, and then transform it into a convex one using Dinkelbach's method. Additionally, distributed subchannel and power allocation algorithms for both VLC and RF are proposed for solving the problem based on the powerful alternative direction method of multipliers (ADMM). Simulation results verify the effectiveness of resource allocation algorithms conceived for heterogeneous software-defined twinned VLC and RF small-cell networks in terms of its good convergence and overall performance.