Hard switching in hybrid FSO/RF link: Investigating data rate and link availability

This paper investigates the performance dependence of a hybrid free space optical (FSO)/radio frequency (RF) communication system on the data rate, link distance and link availability. In existing hybrid FSO/RF systems with hard switching, an algorithm is used to switch between FSO and RF and vice versa based on the feedback of the channel state information. In particular, two methods based on time hysteresis (TH) and power hysteresis (PH) are widely used in hard switching protocols. Although switching parameters including the time and power thresholds have been studied, the effect of link parameters has not been investigated in the literature. In this paper, we analyse the performance of a hybrid FSO/RF system under realistic channel conditions for both TH and PH switching schemes. By means of analysis and simulation, we show that increasing the data rate of individual FSO or RF link does not necessarily result in higher data rate and improved link availability in a hybrid FSO/RF system