mmun. Engr. Journal, 3, January. Pine, R. (1971) Telecommunications power supplies - the next 24.16 Acknowledgement decade, British Post Office Elect. Eng. J. 64. April. Pine, R., Krimholtz, R., and Crawley, A. (1979) Anew British Post Thanks are expressed the Directors, Network, BT U.K., for per- Office standard power plant. In Proceedings of INTELEC, Washing- mission to use the information concerning its power systems. Also, acknowledgement is made of the work of those BT colleagues, past Roberts, G.K. (1989) Electrification, from science, technology, and present, and fellow engineers within the industry, who have and everyday life. 1870 1950 (Ed. C. Chant) Routledge and Open contributed to the high standing of the British telecommunication University 1989. power systems design. This page intentionally left blank Software systems in telecommunications R S Hurst BSc CEng Bell Northern Research Carolyn Story BSc (Hons) Bell Northern Research Contents Overview 25/3 25.2 Stages in the software lifecycle 25/3 25.3 Software design techniques 25/5 Lifecycle for each software design technique 25/7 Software simulation 25/11 Programming languages 25/12 25.7 Testing procedures 25/14 25.8 Software development environments 25/16 25.9 Software configuration management 25/17 25.10 Software cost estimating 25/18 25.11 Software quality and reliability 25/19 25.12 References 25/19 This page intentionally left blank Overview 25/3 25.1 Overview quirements jointly. There are also a small number of methods, for example CORE which aim to address the problem of requirements Frequently more than half of the design cost of a telecommunica- capture and analysis more rigorously. Tools such as Lotos enable the tions system lies in its software. This chapter offers an introduction user to capture protocol definition. to some of the software engineering techniques and technologies Often, during this stage, it is advisable to build a small model or which are applied. prototype of certain aspects of the system (for example the screens The tech