Serially DF relayed hybrid FSO/MMW links with Weibull fading, M-turbulence and pointing errors

The significance of the multiple advantages of the terrestrial FSO links decreases due to fact that their performance depends strongly on the atmospheric conditions. A commonly used way to counterbalance the effects of such phenomena is the employment of hybrid systems, which are using both the optical wireless technology and the millimeter waves as well. Although the use of hybrid technology increases the performance characteristics of the links, the effective link length cannot be extended. This can be done, by using the appropriate scheme with relay nodes. Thus, in this work, a wireless link which consists on multiple selection combining hybrid FSO/MMW subsystems serially connected through DF relays, is studied. In each subsystem, the optical beam of the terrestrial FSO link is assumed to propagate through M(alaga) modeled turbulence with spatial jitter while the MMW channel is assumed to follow Weibull fading statistics. For the whole hybrid FSO/MMW system under consideration, novel accurate performance expressions are derived and numerical results for realistic practical cases are derived. The novelty of this work is that it is the first time, to the best of our knowledge, that this configuration with the specific turbulence, spatial jitter and fading characteristics, is proposed and investigated simultaneously in both directions, i.e. in one hand to increase the performance characteristics of the optical link, using the hybrid technique, and on the other hand, to improve the effective link length, using the relay scheme.