Formal Methods for Telecommunication System
Requirements: A Survey of Standardized Languages
Mark A. Ardis
Naperville, IL 60566-7013
Modern telecommunications systems are so complicated that informal languages are no
longer sufficient for expressing their requirements. A brief introduction to the nature of require-
ments for telecommunication systems is given in this paper. The three standardized formal lan-
guages for telecommunications, Estelle, LOTOS, and SDL, are described and compared. Each
language is evaluated, and a comparison of all three is offered. Throughout the paper a common
example is used.
(Appeared in Annals of Software Engineering 3 (1997) 157-187.)
Telecommunication systems are becoming more and more complex. It is no longer possible to
give a reasonably complete and consistent set of requirements in natural language. We need lan-
guages that allow us to check our specifications for errors with automated tools.