Selection Transmit Diversity for FSO Links Over Strong Atmospheric Turbulence Channels

Rate-Adaptive Free-Space Optical Links Over Atmospheric Turbulence and Misalignment Fading Channels

“…Additionally, as previously reported by the authors [25,26], a relevant improvement in performance must be noted as a consequence of the pulse shape used, providing an increment in the average SNR of 10 log 10 ξ decibels. This superiority has been previously reported by the authors in terms of closed-form expressions corresponding to the average BER performance in several FSO scenarios [19,24,26], as well as from the point of view of information theory [22].…”

“…The advantage of using pulses with high PAOPR has also been corroborated in FSO links over atmospheric turbulence channels by closed-form expressions corresponding to the average BER performance [19,24,26], suggesting its application to the turbulent FSO scenario. A similar expression to (2) for the optical intensity corresponding to this adaptive technique only based on variable silence periods can be written as…”

“…We consider OOK formats with any pulse shape and reduced duty cycle, allowing the increase of the PAOPR parameter [19,26]. In spite of the atmosphere can cause pulse distortion and broadening during propagation at extremely high signalling rates and, especially, at high levels of turbulence strength when increasing either C 2 n or the path length L, or both, pulse shape distortion is assumed to be negligible for the typical FSO scenario here analyzed [15,49].…”

“…In [20,24,26], selection transmit diversity is proposed for FSO links over strong turbulence channels, where the transmit diversity technique based on the selection of the optical path with a greater value of irradiance has shown to be able to extract full diversity as well as providing better performance compared to general FSO space-time codes (STCs) designs, such as conventional orthogonal space-time block codes (OSTBCs) and repetition codes (RCs). The combined effect of atmospheric and misalignment fading is analyzed in the case of single-input/single-output (SISO) FSO channels in [5].…”

“…In [23], a new and simple rate-adaptive transmission scheme for FSO communication systems with intensity modulation and direct detection over atmospheric turbulence channels is analyzed. This scheme is based on the joint use of repetition coding and variable silence periods, exploiting the potential time-diversity order (TDO) available in the turbulent channel as well as allowing the increase of the peak-to-average optical power ratio (PAOPR), which has shown to be a favorable characteristic in IM/DD FSO links [19,24,26].…”