Review Article

Free Space Optics: Current Applications and Future Challenges

Table 2

Comparison table of various techniques based on system parameters on wavelength of 1550 nm [4, 5, 11, 21].

TechniqueWeather conditionAttenuation level (dB/km)Power level (dBm)Data rateLink distance (km)

SAC OCDMA-FSOSDDHeavy rain8.6802.5 Gbps1.1
Clear sky302.5 Gbps1.3

OFDM-FSOOFDM-OSTB-FSOClear0.15502 Gbps10
5 Gbps6
Mild clear0.44102 Gbps9
5 Gbps5
Low haze1.53702 Gbps5.4
5 Gbps3.4
Mild haze4.28502 Gbps3.2
5 Gbps2.2
Heavy haze10.11502 Gbps1.8
5 Gbps1.15
Low fog15.5502 Gbps1.35
5 Gbps1
Mild fog33.96102 Gbps0.720
5 Gbps0.540
Heavy fog84.90402 Gbps0.360
5 Gbps0.300
OFDM-OSSB-FSOClear0.15502 Gbps10.2
5 Gbps6.2
Mild clear0.44102 Gbps8
5 Gbps5.2
Low haze1.53702 Gbps5
5 Gbps3.6
Mild haze4.28502 Gbps2.8
5 Gbps2.5
Heavy haze10.11502 Gbps1.7
5 Gbps1.4
Low fog15.5502 Gbps1.26
5 Gbps1.2
Mild fog33.96102 Gbps0.740
5 Gbps0.590
Heavy fog84.90402 Gbps0.360
5 Gbps0.310

Very clear0.065−102.5 Gbps150
Clear0.233102.5 Gbps150
Light haze0.55202.5 Gbps150
Heavy haze2.3740155 Mbps150
Heavy haze2.3730155 Mbps55
WDM-FSO622 Mbps51.52
Light rain6.2730155 Mbps22
622 Mbps20.8
Medium rain9.6430155 Mbps14.7
622 Mbps13.9
Heavy rain19.2830155 Mbps7.6
622 Mbps7.2