Acknowledgements

I would like to thank my supervisors, Mark Searle of UCL and Ian Wright of Fujitsu Europe Telecom R & D Centre, for their help and advice. I am particularly grateful to Wajahat Jalisi of the Industrial Systems Group at Imperial College and Steven Fung of Foresight Interactive Services for use of their computing facilities. I am also very much indebted to Dominico De Seta of Fondazione Ugo Bordoni, Italy for his advice and comments on my work.