Digital Satellite Communication Techniques: A review

A panoramic view on the study and design of digital satellite communication links is the focus of this paper. The theoretical foundations of our universe of discourse are probability, statistics, electromagnetic field propagation, communications theory, and information theory. And although it is true that considerations on fundamental limits, bounds, criteria, algorithms, complexity and implementation details are not dissimilar from those used for terrestrial digital communications, it is also undeniable that there are certain peculiarities of satellite links that make it essential to have specific tools and approaches. Two keywords help to describe in a nutshell our design objectives: efficiency, which should be intended both in terms of spectrum efficiency and in terms of power efficiency, and flexibility, which is an unavoidable necessity for designing physical layers which not only can adapt dynamically to time varying channel conditions, but that can also be used in generic and somewhat unspecified systems. In other words, for a given bandwidth the information rate must be maximized in conjunction to the minimization of the signal-to-noise ratio (SNR) required to achieve the specified quality of service, in harmony with the experienced channel conditions. In this tutorial paper we revisit all the essential elements that allow the engineer to tackle the design of a digital satellite communication link, including: a characterization of the propagation channel, a review of the state-of-the-art in coding and modulation techniques, an overview over the ancillary but fundamental blocks for parameter estimation, synchronization, distortion countermeasure, diversity, and fade mitigation. The paper also includes a discussion on trends in multiuser communications and software radio. A good list of bibliographic references will serve the reader as a guide to further exploration.