The central topic of this article is the past, present and future evolution of the technical aspects of the GSM system and its derivatives such as DCS 1800 and DCS 1900, as viewed from the European standardization bodies. An important part of the article outlines the current evolution, trying to identify the major trends that are likely to show where the future lies. While the past can be reported rather objectively, this is not the case for the present or the future. In a number of places, working assumptions are presented which are not fully stabilized; they may or may not represent the solution finally adopted by the engineers. This article is thus somewhat dated; to be precise, it reflects the state of the work as of summer 1995. Similarly, the stress on this evolving trend reflects the authors choice, as independent consultants, and does not necessarily reflect the ideas of other involved parties, nor even the general feeling in the GSM community.
