Wireless Optical Communications Through the Turbulent Atmosphere: A Review

Quality Metrics and Reliability Analysis of Laser Communication System

“…All these effects result in both average received power loss and instantaneously received power fluctuation, called fading, at the receiver aperture. This leads to increased system bit error rate (BER), decreased channel capacity and reliability of the overall system 6,10,11,16 . These effects interrupt the high data rate of laser communication link from achieving the availability of five nines 6,8,10 i.e., 99.999 per cent.…”

“…This leads to increased system bit error rate (BER), decreased channel capacity and reliability of the overall system 6,10,11,16 . These effects interrupt the high data rate of laser communication link from achieving the availability of five nines 6,8,10 i.e., 99.999 per cent. One approach to address these problems is increasing the optical power level launched into the air when the propagation loss becomes high.…”

“…This is primarily because of factors such as the unpredictability of the FSOC channel effects at the optical frequencies as well as difficulties associated with stabilising the transmitting and receiving platforms against wind and other disturbing agents which affect the quality of beam alignment, power fluctuations (intensity noise) and wavefront aberration (phase noise) 8,[12][13][14] . Optical beam propagation through the turbulent atmospheric channel severely suffers from the atmospheric attenuation (A att ), angular deflection and phase distortion in horizontal (terrestrial) propagation rather than the vertical 6,8,14,15 . Attenuation here is described as photons being extinguished.…”

“…One approach to address these problems is increasing the optical power level launched into the air when the propagation loss becomes high. However, the use of high-power optical fiber amplifiers (OFAs) as boosters will increase the cost steeply 6,8 . Another approach for reducing the optical power fading is using slightly diverged beam and receiving it via larger size aperture telescope 4,6,8 .…”

“…However, the use of high-power optical fiber amplifiers (OFAs) as boosters will increase the cost steeply 6,8 . Another approach for reducing the optical power fading is using slightly diverged beam and receiving it via larger size aperture telescope 4,6,8 . however, a diverged beam usually causes significant loss of average received power and large aperture telescope generally collects more background optical noise as well.…”