Computer‐aided evaluation of propagation impairment restoration techniques

Abstract

With the increasing need for efficient exploitation of the 14/11 and 14/12 GHz frequency bands, the satellite link designer is faced with the problem of designing communication links in an environment where propagation impairment can be severe. In order to provide a communication service which will meet the desired quality and availability objectives, the designer may choose to employ any of the numerous propagation impairment restoration techniques which have been implemented or proposed in the literature. To determine the optimum technique for a given purpose requires a detailed technical and economic comparison of the candidate restoration schemes with specific reference to the defined service objectives. This paper details a computer program, IMPRES, which has been designed to provide a consistent and reproducible basis for evaluating impairment restoration techniques. The program draws on a knowledge-base containing a profile of each restoration scheme which includes information such as the cost of implementation, the impact on the network operators and users, and the technological and economic risk associated with each scheme. The software design is such that this knowledge-base may be easily updated and extended to accommodate advances in technology and changing costs, thus ensuring that the unified approach to the restoration technique selection problem provided by IMPRES remains valid in the rapidly changing satellite communication environment. KEY WORDS Propagation Fade countermeasures* This paper is based on work performed under the sponsorship of the International Telecommunications Satellite Organization (INTELSAT). Any views expressed are not necessarily those of INTELSAT. Computer-aided designOf the variety of restoration techniques which have been proposed for reducing or eliminating propagation impairments, no single technique can be identified as optimum over a wide range of communication network conditions. The attractiveness of each technique, and thus the selection of the optimum technique, will depend on the application and will be influenced by many technique specific factors, such as the restoration performance, the cost and difficulty of technique implementation for existing earth-station operators, and the technical maturity of the technique, and by network-dependent factors such as the impact of the technique on network operations, and the number and geographical spread of earth-stations in the network. In order to provide solutions to satisfy a variety of communication requirements, it is therefore necessary to perform individual analyses of candidate restoration techniques for each specific requirement. Clearly, in view of the repetitive nature of such analyses, a computer-based solution to the restoration technique comparison problem is desirable, not only to increase the efficiency of the link design process but also to provide a consistent framework for restoration technique comparison.This paper reports on the development of a computer program for the automated comparison of propa...