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Digital Radio-Relay Systems

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Digital Radio-Relay Systems - iii - TABLE OF CONTENTS Page CHAPTER 1 - INTRODUCTION........................................................................................ 1 1.1 INTENT OF HANDBOOK ..................................................................................... 1 1.2 EVOLUTION OF DIGITAL RADIO-RELAY SYSTEMS .................................... 2 1.3 DIGITAL RADIO-RELAY SYSTEMS AS PART OF DIGITAL TRANSMISSION NETWORKS............................................................................. 3 1.4 GENERAL OVERVIEW OF THE HANDBOOK .................................................. 5 1.5 OUTLINE OF THE HANDBOOK.......................................................................... 5 CHAPTER 2 - BASIC PRINCIPLES .................................................................................. 7 2.1 DIGITAL SIGNALS, SOURCE CODING, DIGITAL HIERARCHIES AND MULTIPLEXING .......................................................................................... 7 2.1.1 Digitization (A/D conversion) of analogue voice signals ........................... 7 2.1.2 Digitization of video signals........................................................................ 8 2.1.3 Non voice services, ISDN and data signals ................................................. 8 2.1.4 Multiplexing of 64 kbit/s channels .............................................................. 8 2.1.5 Higher order multiplexing, Plesiochronous Digital Hierarchy (PDH) ........ 8 2.1.6 Other multiplexers ....................................................................................... 11 2.1.7 Synchronous multiplexing, Synchronous Digital Hierarchy (SDH)............ 11 2.1.7.1 General principles.......................................................................... 11 2.1.7.2 Synchronous multiplexing scheme................................................ 12 2.1.7.3 Overhead functions........................................................................ 15 2.1.7.4 The Sub-STM-1 signal format ...................................................... 16 2.1.7.5 ATM transport in the SDH, SDH transport via PDH signals........ 18 2.1.8 Interconnection at baseband, physical interface characteristics .................. 19 2.1.9 Jitter and wander timing and synchronization............................................. 20 2.2 FUNDAMENTALS OF TERRESTRIAL DIGITAL RADIO-RELAY SYSTEMS ............................................................................................................... 20 2.2.1 Architecture of digital radio-relay systems.................................................. 22 2.2.1.1 Digital transmitter ......................................................................... 22 2.2.1.2 Digital receiver .............................................................................. 24 2.2.1.3 Radio transmitter and receiver ...................................................... 26 2.2.1.4 Channel combining and antenna considerations ........................... 28 2.2.1.5 Radio switching section ................................................................ 29 References to Chapters 1 and 2................................................................................................ 32 - iv - CHAPTER 3 - LINK DESIGN CONSIDERATIONS........................................................ 34 3.1 APPLICATIONS OF DIGITAL RADIO-RELAY SYSTEMS ............................... 34 3.1.1 General ....................................................................................................... 34 3.1.2 Available frequency bands .......................................................................... 35 3.1.3 Coexistence between analogue and digital radio systems ........................... 38 3.1.4 Digital channel capacity .............................................................................. 39 3.1.5 Digital networks .......................................................................................... 41 3.1.5.1 Long haul digital radio systems..................................................... 41 3.1.5.2 Short haul digital radio systems .................................................... 41 3.1.5.3 Digital radio access networks ........................................................ 42 3.1.6 Radio Local Area Networks (RLAN).......................................................... 42 3.1.6.1 General .......................................................................................... 42 3.1.6.2 Frequency bands ............................................................................ 43 3.1.6.3 Multiple access and modulation .................................................... 43 3.1.6.4 System configuration..................................................................... 44 3.1.6.5 Examples of RLANs ..................................................................... 45 3.2 PERFORMANCE AND AVAILABILITY OBJECTIVES..................................... 46 3.2.1 Hypothetical digital connection, path and section....................................... 46 3.2.2 Error performance parameters and objectives ............................................. 47 3.2.2.1 Error performance parameters and objectives based on ................ 47 ITU-T Recommendation G.821 .................................................... 47 3.2.2.2 Error performance parameters and objectives based on ITU-T Recommendation G.826 .................................................... 49 3.2.3 Availability performance parameters and objectives .................................. 54 3.2.4 Bringing-into-service and maintenance....................................................... 57 3.2.4.1 Relationship between performance limits and objectives ............. 58 3.2.4.2 Performance limits for bringing-into-service ................................ 59 3.3 UPGRADING FROM ANALOGUE TO DIGITAL RADIO SYSTEMS............... 60 3.3.1 Advantages of a new digital microwave system.......................................... 60 3.3.2 Existing analogue microwave system characteristics.................................. 62 3.3.3 Difficult digital microwave paths ................................................................ 62 3.3.4 Antenna feeder systems ............................................................................... 63 3.3.5 Digital microwave system overbuild ........................................................... 63 3.3.6 Analogue/digital RF coupling arrangements ............................................... 63 3.3.7 Analogue spur links..................................................................................... 64 3.3.8 Analogue-to-digital circuit cutover phases.................................................. 64 3.3.9 The circuit cutover....................................................................................... 64 3.4 RF CHANNEL ARRANGEMENTS....................................................................... 65 3.4.1 Introduction ................................................................................................. 65 3.4.2 Spectrum related parameters ....................................................................... 65 3.4.3 Type of channel arrangement ...................................................................... 66 3.4.4 Homogeneous pattern and channel subdivision .......................................... 69 3.4.5 Intra-system and inter-system interference criteria...................................... 70 - v - 3.5 BAND SHARING WITH OTHER SERVICES ...................................................... 73 3.5.1 Assessment of interference from other services .......................................... 73 3.5.1.1 General .......................................................................................... 73 ` 3.5.1.2 Degradation in performance and availability ................................ 73 3.5.1.3 Assessment of aggregate effects of interference from various sources ........................................................................................... 75 3.5.2 Basic parameters for sharing considerations ............................................... 77 3.5.2.1 Receiver side ................................................................................. 77 3.5.2.2 Transmitter side ............................................................................. 79 3.5.3 Status of studies on frequency sharing within Radiocommunication Study Group 9.............................................................................................. 82 References to Chapter 3............... ............................................................................................ 83 CHAPTER 4 - DESIGN PARAMETERS ........................................................................... 86 4.1 PROPAGATION RELATED ISSUES.................................................................... 86 4.1.1 Concept of free space loss ........................................................................... 86 4.1.2 Visibility...................................................................................................... 87 4.1.2.1 Refractive aspects .......................................................................... 87 4.1.2.2 Path profiles, clearance and obstructions ...................................... 91 4.1.2.3 Diffraction aspects......................................................................... 93 4.1.3 Surface reflection......................................................................................... 98 4.1.3.1 Introduction ..................................................................................
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