P V Sreekanth received his BE in electronics and communications engineering from Osmania University and his MTech, with specialisation in communications, from IIT Chennai. As an officer of the Indian Railway Service of Signal Engineers (IRSSE), he has 16 years of experience of working on various railway signalling and telecom projects. He has also served as a faculty member at IRISET (Indian Railway Institute of Signal Engineering and Telecommunications), Secunderabad. At present, he is General Manager (Operations & Maintenance), RailTel, Secunderabad. His published works include nine papers in national and international journals and two books: Digital Microwave Communications Systems (with selected topics on mobile communication) published by Universities Press, and Railway Signalling Installation and Quality Handbook, prepared for the exclusive use of the Indian Railways.

List of Abbreviations Preface Acknowledgements Prologue PART I: PDH SYSTEMS 1 The Three Theorems of IT and Their Outcome 1.1 Overview of Digital Transmission Systems 1.2 The Three Theorems of IT 1.3 Transmission Capacities of Various Media 1.4 The Role of Multiplexing 2 The Multiplexing Process and Its Evolution 2.1 Fundamentals of Digital Multiplexing Process 2.2 Characteristics of Various Traffics 2.3 Time Sharing in N Channel Multiplexing 2.4 How CCITT (ITU) Pioneered Evolution of Digital Multiplexing 2.5 Three Generations of Digital Multiplexing 3 PCM – The Entry Point 3.1 Basics of PCM Process 3.2 Exploring the PCM Process 3.3 Exploring E1 Frame Structure 3.4 Limitations of Normal Primary MUX 3.5 Add–Drop and Other Superior Features for Thin Routes 3.6 How Superior Features are Achieved 3.7 Functions of Vital Modules of Add–Drop Programmable MUX 4 PDH MUX-DEMUX Process 4.1 Multiplexing Methodology in PDH 4.2 ITU-T Recommendations Relevant to PDH Systems 4.3 Multiplexing E1s to Form E2 4.4 Demultiplexing E2 4.5 Multiplexing E2s to Form E3 4.6 Demultiplexing E3 4.7 Multiplexing E3s to Form E4 4.8 Demultiplexing E4 5 PDH Network Reliability Issues 5.1 Introduction 5.2 System Design Considerations in Tackling Noise 5.3 Tackling ISI 5.4 Jitter in PDH Networks 5.5 ITU-T Recommendations Regarding Control of Jitter and Wander 5.6 ITU-T Recommendations Regarding Jitter Measurement 5.7 Jitter Accumulation 5.8 Jitter Reduction Techniques PART II: SDH SYSTEMS 6 Evolution of SDH 6.1 What Led to the Evolution of SDH ? 6.2 Inadequacies of PDH 6.3 Guided Light Guides SDH Evolution 6.4 Bell and the Baby Bells Story 6.5 How SDH Was Lapped Up 6.6 STS-1 Frame of SONET 7 Multiplexing Process in SDH 7.1 Requirements of SDH Frame 7.2 Concept of Regenerator Section, Multiplexer Section and Path 7.3 Description of SDH Frames 7.4 Concept of Containers 7.5 Pointers 7.6 Mapping PDH Signals 7.7 Mapping ATM 7.8 Structure of STM-N Frame 7.9 Concept of Concatenation 7.10 Synchronisation in SDH Network 7.11 Alarm and Error Processing within an NE 8 SDH Network Elements and Network 8.1 Principles of SDH NE Design 8.2 Types of Optical Interfaces on SDH NE 8.3 Specifications for Optical Interfaces and Their Explanation 8.4 SDH Network Topology and Protection Mechanisms 8.5 Network Protection Objectives 8.6 Protection for IP Networks 8.7 Element Management and Network Management 8.8 ASON (Automatically Switched Optical Network) 9 Applications of SDH Network 9.1 Introduction 9.2 LAN to LAN Transport or Ethernet over SDH 9.3 MPLS over SDH Network 9.4 Internet Backbone Connectivity 9.5 VoIP on SDH Network 9.6 What is VoIP? 9.7 Evolution of NGN Switch 9.8 Signalling and Control Protocol for NGN Switch: ITU-T Rec.H.248/Megaco 9.9 SDH Support for NGN Switch Interconnection 10 Reliability Issues in SDH Networks 10.1 Introduction 10.2 Network Limits for Output Jitter and Wander at Any Hierarchical Interface 10.3 Network Limits for Jitter and Wander at Synchronisation Interfaces 10.4 Jitter and Wander Tolerance for Input Ports 10.5 Intrinsic Jitter 10.6 Jitter and Wander Transfer Function 10.7 Impairments and Interruptions Related to Jitter and BER 10.8 Design of Survivable and Resilient Multi-Ring SDH Networks PART III: OTH SYSTEMS 11 WDM Essentials 11.1 Introduction to WDM 11.2 Principle of WDM 11.3 WDM Varieties 11.4 ITU-T Grid for WDM 11.5 WDM Transmitters 11.6 Optical Amplifiers 11.7 WDM Receivers 11.8 Optical Switches 11.9 Wavelength Converters 11.10 Add–Drop Approaches in WDM 12 Essentials of OTH 12.1 Introduction 12.2 Overview of Transmission Process Using OTH across OTN 12.3 Network Entities and Transport Structures in OTH 12.4 Details of Framing and Overheads 12.5 Maintenance Signals 12.6 Scrambling 13 Mapping Client Signals in OTH 13.1 Mapping of Client Signals – The Scope 13.2 Mapping of STM Signals 13.3 Mapping of ATM Cell Stream into OPUk 13.4 Mapping of GFP Frames into OPUk 13.5 Mapping of Test Signal into OPUk 13.6 Mapping of Non-Specific Client Bit Stream into OPUk 13.7 Concatenation of OPUk 13.8 Mapping of Client Signals into OPUk-Xv 13.9 Mapping of ODUk Signals into ODTUGjk 14 Optical Transport Networks and Applications 14.1 Introduction 14.2 Architectural Features of OTN 14.3 Optical Line Terminal (OLT) 14.4 Optical Amplifier 14.5 OADM 14.6 Optical Cross-Connect (OXC) 14.7 Multi Protocol Lambda Switching (MPëS) 14.8 GMPLS over OTN 14.9 Fibre Access Network and OTN Support 14.10 OTN and NGN 15 Reliability and Survivability Issues 15.1 Introduction 15.2 Network Limits for the Maximum Output Jitter and Wander at an OTUk Interface 15.3 Jitter and Wander Tolerance of OTUk Interface 15.4 Intrinsic Jitter 15.5 Jitter Transfer Requirement of ODUk, OTUk 15.6 Effect of OTN on the Distribution of Synchronisation via STM-N Clients 15.7 Network Survivability through Optical Layer Protection 15.8 Dynamic Control and Management of Optical Network through ASON 15.9 Open Fibre Control Protocol for Optical Safety and Automatic Restart Appendix A Appendix B Appendix C Index