The modeling and simulation of intersatellite laser communication systems

Free Space Optical (FSO) Communication Systems are alternatives to Radio Frequency (RF) communication systems due to the high data rate, high bandwidth capacity, smaller size, and weight, less power consumption, high security, resistance to interference etc. There are many manufactured satellites orbiting around the earth and RF technique, which is a conventional communication method for satellite systems, is used in order for them to communicate with each other. It is possible to send several Gbps data to thousands kilometers distances with laser communication. This is done by means of adopting optical wireless communication technology into space technology; hence, intersatellite optical wireless communication is developed. In this thesis, detailed literature survey about free space optical communication system has been done. The importance of laser systems for free-space communication has been discussed and the status of laser techniques for intersatellite communication has been examined. The functions of the each basic component such as laser source, photodetector, modulation type, telescope used in a typical system have been examined. The intersatellite link has been modeled and simulated by means of Optiwave Software for the various link configurations and the system performance (BER/Q-Factor) has also been analyzed in terms of each basic parameter such as transmitted power, wavelength, data rate, range and telescope diameter in order to achieve minimum BER. APD type and PIN type photodetector comparison has been performed. Moreover, Erbium Doped Fiber Amplifier (EDFA) has been used for the intersatellite link to recognize its effect on the link quality. It has been shown that communication performance of the system can be improved by choosing the most appropriate component in terms of communication requirements. Key Words: Intersatellite Laser Communication, Free Space Optical Communication, Optical Wireless Channel, Bit Error Rate, Q Factor.