Demonstration of an FSO/RF hybridcommunication system on aeronautical and space applications

The generated amount of data on high flying platforms like aircrafts, satellites and Unmanned Aerial Vehicles (UAV) increases continuously, due to the technical improvement of modern sensor systems. The resulting demands for higher data rates on airborne and space platforms motivates the development of Laser Communication terminals for aircrafts and satellites in the last years. DLRs Institute of Communications and Navigation has a successful track record in developing Free Space Optical (FSO) terminals for flying platforms like stratospheric balloons, aircrafts and small satellites to transfer data from moving platforms down to earth in real-time. Beside the advantages of FSO such as high data rates and a secure transfer channel against Radio Frequency (RF) interferences, a direct line of sight is mandatory for a successful link. Traditional RF-Communication is more robust and less effected by atmospheric disturbances or weather conditions. Thus, new system concepts have been developed to benefit from the provided high data rates of the FSO and the reliability of RF-Communication technologies. As part of this trend, DLR has developed and demonstrated a Hybrid FSO/RF-communication system capable of overcoming the spurious effects of the atmosphere. This paper gives an overview about DLRs current studies and developments with the goal to combine the advantages of FSO and RF-Communication. It discusses possible implementation concepts on different platforms and presents experimental results of the implemented FSO/RF hybrid communication system operating for airborne, optical downlinks at 1Gbps