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Department of Computer Science and Technology



Course pages 2023–24

Principles of Communications

Principal lecturer: Prof Jon Crowcroft
Taken by: Part II CST
Term: Michaelmas
Hours: 16
Format: In-person lectures
Suggested hours of supervisions: 4
Prerequisites: Computer Networking. This course may be useful for the Part III course on Network Architectures. Useful related courses: Computer Systems Modelling, Information Theory, Digital Signal Processing
Exam: Paper 8 Question 10; Paper 9 Question 10
Past exam questions, Moodle, timetable


This course aims to provide a detailed understanding of the underlying principles for how communications systems operate. Practical examples (from wired and wireless communications, the Internet, and other communications systems) are used to illustrate the principles.


  • Introduction. Course overview. Abstraction, layering. Review of structure of real networks, links, end systems and switching systems. [1 lecture]
  • Routing. Central versus Distributed Routing Policy Routing. Multicast Routing Circuit Routing [6 lectures]
  • Flow control and resource optimisation. 1[Control theory] is a branch of engineering familiar to people building dynamic machines. It can be applied to network traffic. Stemming the flood, at source, sink, or in between? Optimisation as a model of networkand user. TCP in the wild. [3 lectures]
  • Packet Scheduling. Design choices for scheduling and queue management algorithms for packet forwarding, and fairness. [2 lectures]
  • The big picture for managing traffic. Economics and policy are relevant to networks in many ways. Optimisation and game theory are both relevant topics discussed here. [2 lectures]
  • System Structures and Summary. Abstraction, layering. The structure of real networks, links, end systems and switching. [2 lectures]

1 Control theory was not taught and will not be the subject of any exam question.


At the end of the course students should be able to explain the underlying design and behaviour of protocols and networks, including capacity, topology, control and use. Several specific mathematical approaches are covered (control theory, optimisation).

Recommended reading

* Keshav, S. (2012). Mathematical Foundations of Computer Networking. Addison Wesley. ISBN 9780321792105
Background reading:
Keshav, S. (1997). An engineering approach to computer networking. Addison-Wesley (1st ed.). ISBN 0201634422
Stevens, W.R. (1994). TCP/IP illustrated, vol. 1: the protocols. Addison-Wesley (1st ed.). ISBN 0201633469