Optical fiber plays a significant part in the revolution of communication technologies as one of the most influential access technologies. Passive Optical Network (PON) is a point to multipoint (P2MP) network where an optical line terminal (OLT) at the service provider distributes services to many customers per shared fiber line. Gigabit passive optical network (GPON) is one of the Time Division Multiplexing (TDM) PON. This Thesis evaluated the comparison between three different PONs which are CO-OFDM, WDM CO-OFDM, and GPON without OFDM. By taking different values of transmitted power, fiber cable length, and operating wavelengths with multiple scenarios. The system was analyzed depending on values of Bit Error Rate, Q factor, Optical Received power, Electrical Received power, and eye diagram from simulation results when using OptiSystem software. We also evaluated the model of the system, design algorithms, and performance analysis of the network by calculating the power budget and rise time budget analysis of the network. After analyzing and comparing three different GPONs we get an achievement which is that GPON without OFDM is the best one to apply University of Hargeisa. The University consists of 14 different blocks which have different distances. For each block, we used Free Space Optics (FSO) to transmit data from the transmitter and receiver. In the thesis, we used three different weather conditions according to the FSO which are Clear, Haze, and Rainy. The parameters we used in the thesis are bitrate 10Gbps, transmitted power 0-16dB, and receiver sensitivity which is -35dBm. Finally, we simulated the 14 different blocks with three different weather conditions and we achieved in the results and discussion that the FSO Network in the University of Hargeisa has suitable to deploy and implement in the University. Keywords: Bit error rate, Eye Diagram, Optical Line Terminal, Optical Network Unit, Passive Optical Network, Q factor.