Reconfiguration Modeling of Reconfigurable Hybrid FSO/RF Links

The purpose of devising a hybrid FSO/RF (Free Space Optics/Radio Frequency) system is to allow for reconfiguration, which enables an increased availability and reliability grade of the communication system. In the event of loss of an active FSO link, path reconfiguration ensures utilization of the FSO path queued next in priority. Thus, communication can be maintained in the optical domain with increased efficiency for a longer period. However, for all its benefits, path reconfiguration may inadvertently cause increased system delay and lower throughput, as well as packet loss. Given these advantages and disadvantages, path reconfiguration studies for hybrid systems are of great importance. A mathematical investigation and statistical consideration of path reconfiguration probability is the focus of this theoretical paper. A closed-form expression of the reconfiguration probability will be derived. The first-order Markov chain will provide a mathematically tractable model for atmosphere turbulence fading channels, as it uses only the received SNR of the FSO symbol immediately preceding the current one. Results show that increasing the intensity of turbulence-induced lognormal fading for FSO link will not necessarily increase the reconfiguration probability.