ally left blank Acknowledgements The production of this reference book would have been im- Hiltek possible without the good will, help and co-operation of the tele- Hutchinson Microtel communications industry, the users of telecommunication IBA Engineering Division equipment and members of the academic profession. Bare acknow- ISICAD ledgements are very inadequate but the editor wishes to thank the Multitone Electronics following firms and organisations which SO readily made available information and illustrations and permitted members of their Newbridge Networks specialist staffs to write contributions: Northern Telecom Omincom Inc AT&T EasyLink Services Queen Mary and Westfield College Alcatel Bell Telephone Radio Communications Agency Anderson Consulting Reichle De Massari Aston University Rockwell International Bell Northern Research Rohde & Schwarz British Aerospace Rutherford Appleton Laboratory Cellnet South Midlands Communications Commission of the European Communities Sprint International Dowty Communications TeleSciences Transmission Systems ELMAC Services Telindus Ericsson Trend Communications Gandalf Digital Communications University of Cambridge GN Netcom University of Essex Hewlett-Packard Vodafone List of Contributors Malcolm Appleby, MA J E Flood, OBE DSc FInstP CEng FIEE Cellnet Aston University Steve Berrisford Harold C Folts, BSEE MSSM Northern Telecom Omnicom Inc Paul W Bizzell J R Fox, MA (Cantab) MSc PhD MIEE CEng MSCTE AT&T EasyLink Services BT Laboratories Richard A Boulter, BSc (Hons) CEng FIEE Jim Giacobazzi TeleSciences Transmission Systems PA Bradley, BSc MSc CEng MIEE R J Gibbens, MA, Dip Math Stat, PhD Rutherford Appleton Laboratory University of Cambridge D G Bryan, DFH CEng FIEE Terry Goble Telecommunications Consultant Northern Telecom Europe J H Causebrook, BSC PhD CEng MIEE R V Goodman, CEng MIEE Vodafone Ltd Broadcasting and Telecommunications Engineering Consultant Luc Ceuppens, Ind Ing David Green Telindus Ltd Rohde & Schwarz G J Cook, BSc (Eng) CEng MIEE Takis Hadjifotiou BT