DLR is Germany's national research center for aeronautics and space. Its extensive research and development work in aeronautics, space, transportation and energy is integrated into national and international cooperative ventures.The Institute of Communications and Navigation develops and investigates new systems and methods for radio transmission and positioning. These are widely used in broadcasting multimedia contents as well as for internet connection of satellites, airplanes and remote areas. In the field of high rate data communications between satellite and ground the Institute works on optical free-space transmission methods.In satellite navigation the Institute puts emphasis on safety-critical applications, which require a reliable positioning and timing information, and on positioning in urban canyons and indoors.