W HEN I began lecturing a course on the performance of communication systems in
the electrical engineering department of the University of Twente in the fall of
1990, I had difficulty in finding a suitable textbook for this course. Many books were too
much mathematically oriented, others used only a very limited set of evaluation techniques,
e.g.,only the MlGll q ueue. I therefore decided to use a collection of book chapters, recent
survey articles and some research papers, thereby focusing on the performance evaluation
of network access mechanisms. During the semester, however, I began to realise that using
material from different sources is not the most adequate. To overcome this inadequacy, I
started to develop my own course material in the years that followed.