2002/08/01 by Xiaoming Zhu, J.M. Kahn, Joseph M. Kahn · 1,610 citations
Engineering · Mathematics · Physics and Astronomy · #Adaptive optics and wavefront sensing #Advanced optical system design #Antenna diversity #Channel state information #Computer science #Decoding methods #Diversity scheme #Electronic engineering #Engineering #Fading #Fading distribution #Free-space optical communication #Mathematics #Optical Wireless Communication Technologies #Optical communication #Rayleigh fading #Spatial correlation #Statistics #Telecommunications #Wireless
paper · doi:10.1109/tcomm.2002.800829
published in IEEE Transactions on Communications 50(8), 1293-1300 (IEEE Communications Society)
openalex publication_date 2002/08/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received light signal, impairing link performance. We describe several communication techniques to mitigate turbulence-induced intensity fluctuations, i.e., signal fading. These techniques are applicable in the regime in which the receiver aperture is smaller than the correlation length of fading and the observation interval is shorter than the correlation time of fading. We assume that the receiver has no knowledge of the instantaneous fading state. When the receiver knows only the marginal statistics of the fading, a symbol-by-symbol ML detector can be used to improve detection performance. If the receiver has knowledge of the joint temporal statistics of the fading, maximum-likelihood sequence detection (MLSD) can be employed, yielding a further performance improvement, but at the cost of very high complexity. Spatial diversity reception with multiple receivers can also be used to overcome turbulence-induced fading. We describe the use of ML detection in spatial diversity reception to reduce the diversity gain penalty caused by correlation between the fading at different receivers.