We are currently observing a discussion about the usefulnessof space research and the amount of spin-off we obtain fromspace programs. One area which is widely overlooked isdigital communications, although it is quite clear that theapplication of space research which has directly affectedmost people is certainly space communication via satellite.Direct broadcasting satellites, international telephonecallsvia geostationary satellites and the growing mobileservices by satellites serve more and more users.This book provides an overview of the state-of-the-art incommunications systems in space . Leading experts fromarount the world the contributions in this book describeadvanced features of their fields and give an outlook at thenext steps in such communications systems. Special emphasisis on digital modulation and codingwhere progress intechnology allows the implementation of sophisticatedmethods reaching almost the limits of theory. The papersinclude survey articles as well as advanced research topics.