Pointing error evaluation in FSO link

Pointing error results from misalignment between transmitter and receiver or turbulence. In long FSO links range pointing error and attenuation can results in increased BER and link failure. A small change in pointing error can cause high power losses. To overcome this problem system techniques like auto tracking, narrow and high power transmitted beams, highly sensitive receivers, monitoring of weather conditions should be adopted. In this paper maximum pointing error is calculated for proposed FSO link to achieve BER less than 10^-9. Link is optimized for weak and normal turbulent channel with attenuation ranging between 4dB/km and 56dB/km.