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].

Technique		Weather condition	Attenuation level (dB/km)	Power level (dBm)	Data rate	Link distance (km)
SAC OCDMA-FSO	SDD	Heavy rain	8.68	0	2.5 Gbps	1.1
		Clear sky	3	0	2.5 Gbps	1.3
OFDM-FSO	OFDM-OSTB-FSO	Clear	0.155	0	2 Gbps	10
					5 Gbps	6
		Mild clear	0.441	0	2 Gbps	9
					5 Gbps	5
		Low haze	1.537	0	2 Gbps	5.4
					5 Gbps	3.4
		Mild haze	4.285	0	2 Gbps	3.2
					5 Gbps	2.2
		Heavy haze	10.115	0	2 Gbps	1.8
					5 Gbps	1.15
		Low fog	15.55	0	2 Gbps	1.35
					5 Gbps	1
		Mild fog	33.961	0	2 Gbps	0.720
					5 Gbps	0.540
		Heavy fog	84.904	0	2 Gbps	0.360
					5 Gbps	0.300
	OFDM-OSSB-FSO	Clear	0.155	0	2 Gbps	10.2
					5 Gbps	6.2
		Mild clear	0.441	0	2 Gbps	8
					5 Gbps	5.2
		Low haze	1.537	0	2 Gbps	5
					5 Gbps	3.6
		Mild haze	4.285	0	2 Gbps	2.8
					5 Gbps	2.5
		Heavy haze	10.115	0	2 Gbps	1.7
					5 Gbps	1.4
		Low fog	15.55	0	2 Gbps	1.26
					5 Gbps	1.2
		Mild fog	33.961	0	2 Gbps	0.740
					5 Gbps	0.590
		Heavy fog	84.904	0	2 Gbps	0.360
					5 Gbps	0.310
		Very clear	0.065	−10	2.5 Gbps	150
		Clear	0.233	10	2.5 Gbps	150
		Light haze	0.55	20	2.5 Gbps	150
		Heavy haze	2.37	40	155 Mbps	150
		Heavy haze	2.37	30	155 Mbps	55
WDM-FSO					622 Mbps	51.52
		Light rain	6.27	30	155 Mbps	22
					622 Mbps	20.8
		Medium rain	9.64	30	155 Mbps	14.7
					622 Mbps	13.9
		Heavy rain	19.28	30	155 Mbps	7.6
					622 Mbps	7.2