Free space optical communication systems operate like traditional Free Space Optical systems. FSO technology is based on the connectivity between FSO-based optical wireless units; each consists of an optical transceiver with a transmitter and a receiver to provide full-duplex capability (bi-directional). There is a fiber at the receiver side which turns the electrical signal to the optical signal in this end. A laser driver amplifies this electrical signal and provides enough current to drive the laser diode. Controlled light from the laser is directed to the receiver which focused their beam onto a silicon Avalanche photo Diode (APD). APD convert the optical signal to an electrical signal. After reshaping and some noise filtering the electrical signal is converted back to the Optical signal. The maximum amount of data that can transport is at a speed of 2.5 Gbps. The limitation of the bandwidth does not let these signals to be well operated.