Dynamic Link Selection and Power Allocation With Reliability Guarantees for Hybrid FSO/RF Systems

In this paper, we study transmission strategies for hybrid free space optical (FSO)/radio frequency (RF) systems by jointly considering link selection, power allocation, and reliability guarantees. Specifically, under an explicit long-term average reliability requirement, the transmitter in the hybrid FSO/RF system makes decisions about which links should be selected and how much power should be allocated to the corresponding active link. The problem of minimizing the power consumption cost while guaranteeing packet success-probability requirements and peak and average power constraints is considered and formulated as a stochastic problem. Using the Lyapunov optimization techniques, we solve this problem and derive closed-form power allocation solutions for different link selection modes. Furthermore, we design a dynamic link selection and power allocation algorithm that can arbitrarily push the consumed power approach to the optimum at the expense of a tradeoff over reliability queue occupancy. Simulation results verify the theoretical analysis and validate the performance superiority of our proposed scheme.