Throughput maximization in hybrid FSO/RF communication systems

In this paper, we analyze the problem of power allocation with the objective of maximizing the throughput for hybrid free-space optical/radio-frequency (FSO/RF) communication systems. Such systems consist of a free space optical link as well as an RF link. We consider both soft switching (SS) and hard switching (HS) schemes. In the former, at any time slot only one of the links is active while in the latter, both links simultaneously transmit data and the available power is divided between the two links. It is shown that for a given visibility, the obtained spectral efficiency is always greater than that of HS. The superiority of the SS scheme over the HS scheme is so significant such that the SS scheme outperforms the HS scheme for a visibility as bad as fives times lower than that of the HS case.