Very Small Aperture Terminal (VSAT) Systems for Digital Satellite Communication: An Overview

Abstract

This paper presents an overview of digital satellite communication systems based on low-cost, very small aperture terminals (VSATs) located directly at subscribers' premises. Over the last few years, such VSAT systems have become feasible because of a combination of recent advances in satellite and earth station technology. These include the deployment of higher power satellites, the use of Ku-band (14/12 GHz) frequencies, the availability of lowcast earth station antennas and microwave electronics, along with the development of cost-effective implementations for modulation, spectrum spreading, forward error control (FEC) and protocol processing. Digital communication services which potentially achieve reasonable combinations of VSAT cost and satellite usage are identified for consideration. Specific applications considered are: one-way data distribution, point-to-point data, two-way interactive-data packet networking, digital voice (including telephony and packet voice messaging), and satellite ISDN. Approaches to providing each of these services using VSAT technologies are outlined, and the key component elements of these systems are discussed. System design issues related to the selection of components & parameters with the objective of achieving an appropriate balance between capacity, performance and equipment cost, are briefly examined and illustrated with specific numerical examples.

Indexing terms:

• Very small aparture terminal (VAST)
• Digital sattelite communication