Summary 
This module considers the performance of computer
networks from a statistical aspect, using queuing theory. It
is shown that the performance of a computer network depends
heavily on the traffic flow in the network, and different
models of traffic and queues are used. These include
singleserver queues, multiple server queues, and the
concept of blocking is discussed. Although the analysis is
entirely statistical, all the relevant background is
provided in the lectures, such that the course is entirely
selfcontained. Problem sheets are provided in order to
assist the students with the course material. Students should be aware that there are limited places available on this course. 
Session 
Spring 2021/22 
Credits 
15 
Assessment 
Formal examination (2 hours) 
Lecturer(s) 
Dr Joab Winkler 
Resources 

Aims 
 To introduce a statistical analysis of computer
networks
 To show how queuing theory can be used to analyse
computer networks
 To show the applications of queuing theory to other
areas of science and engineering

Objectives 
By the end of the unit the candidate should be able to:
 Analyse queuing networks and their application to
computer networks
 Show how to design a computer network so that the
queues are within specified bounds
 Appreciate the importance of queuing theory to other
areas of engineering

Content 
 Review material:
 Networking Introduction.
 Random processes and probability theory.
 The Poisson distribution
 A simple network queue:
 M/M/1 queue
 Birth death processes
 Little's formula
 Richer queueing models:
 M/M/M/1.
 Queues in which the arrival and service rates are functions of the state system
 Queues with blocking
 Erlang delay.
 Erlang loss system.
 Erlang B and C curves.
 M/G/1.
 Overview of Simulation:
 Sampling theory.
 Obtaining samples from Markov chains.

Essential skills 
The course requires basic probability theory and knowledge of arithmetic and geometric progressions. This knowledge is basic and it is covered in all undergraduate engineering and physics degrees. 
Teaching Method 
The teaching method is by lectures with numerous example
and problem sheets so that the students have a good
theoretical and practical understanding of the subject.
 30 Hours of formal lectures, which includes problem classes.

Feedback 
Problem sheets are are set and discussed in class and this
provides an opportunity for feedback. 
Recommended Reading 
Highly Recommended
 Data Networks (Second Edition) by Dimitri Bertsekas
and Robert Gallager
Recommended
 Computer Networks by Andrew S. Tanenbaum
