**8. Important questions related to this chapter for self-evaluation:**


short distance links. In this chapter, we briefly introduced the concepts of FSO technology, mathematical approach of this technique. Practical part, we take the climate effects for deployment of FSO in Yemeni territorial as a case study. We have studied in detail the total attenuation influencing FSO systems. The total attenuation in this case study depends on two parameters: scattering and geometric losses. This work was concentrated on two different designs as demonstrated in Table 6. These results showed that when the link range, divergence angle, and transmitter aperture were increasing, the geometric loss increased too. But, we found that geometric loss decreased with the increasing of the receiver aperture diameter. Total attenuation also increased with increasing of the distance link, low visibility, and with decreasing of the wavelength. It was also shown that the effect of rainfall on the FSO system performance was so small that we can neglect it. In general, FSO performance was bad in Taiz at the low visibility compared to Sana'a and Aden. However, in the average visibility, the FSO

We concentrate on the scintillation effects on the performance of FSO links. The analysis was carried out for the variance, SNR, and BER in the environment of Yemen. Scintillation for the Yemeni environment is wavelength and distance dependent. The wavelength of 1550 nm turned out to be interesting since it is less sensitive to atmospheric turbulence and harmless to the human eye. The results indicate that the performance of the FSO system is good during the worst conditions in Yemen. To improve the transmission efficiency of FSO systems, the wavelength of 1550 nm must be used and the distance between transmitter and receiver must be reduced. To achieve a BER of 10–9 during air turbulence, the distance between transmitter and receiver should be 2600 m. Thus, the FSO system may be applied in Yemeni territorial

**8. Important questions related to this chapter for self-evaluation:**

performance was effective in three cities.

208 Contemporary Issues in Wireless Communications

efficiently even in case of the presence of air turbulence.

**2.** What is the maximum speed can FSO products offer? **3.** What are the operating wavelengths of FSO systems?

**7.** What is the recommended distance of the FSO link? **8.** What is the different between FSO and fiber-optics?

**11.** Can FSO systems operate through windows glass?

**6.** What are the advantages and disadvantages of FSO technology?

**1.** What is free-space optical communication?

**4.** What are the FSO technology applications? **5.** Do you need a license to operate FSO system?

**9.** Is FSO safe for eyes and human body?

**12.** Is the sunlight influence on FSO link?

**10.** Is FSO transmission secure?

	- **a.** Graphical represent of the eye looking at a tower.
	- **b.** calculate the size of retinal image of the tower (*h*) that's reflected primarily in the area of the fovea.

**answer***: h=2.83 mm*

