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2011-10-08, 05:53 PM
Digital Microwave Communication Principles
Contents
1 Microwave Communication Overview.................................................................................... 7
1.1 Basic Concepts of Digital Microwave .......................................................................... 7
1.2 Microwave Development Course................................................................................. 8
1.2.1 Microwave Evolution in the World........................................................................ 8
1.2.2 Microwave Evolution in China.............................................................................. 9
1.3 Characteristics of Digital Radio Communication System .......................................... 10
1.4 Challenges and Opportunities for Digital Microwave Communication ...................... 11
1.4.1 Optical Fiber Communication—Biggest Challenge for Digital Microwave Communication ................................................................................................................. 11
1.4.2 Opportunities for Digital Microwave Communication ......................................... 12
1.5 Microwave Frequency Band Choice and RF Channel Arrangements....................... 14
1.6 Digital Microwave Communication System Model .................................................... 16
1.6.1 Modulation Method of Digital Microwave ........................................................... 16
1.6.2 Channel Utilization of Each Modulation ............................................................. 18
1.7 Digital Microwave Frame Structure ........................................................................... 19
1.8 Conclusion ................................................................................................................. 21
2 Introduction to Digital Microwave Equipment ..................................................................... 21
2.1 Digital Microwave Equipment Classification .............................................................. 21
2.2 Microwave antenna and feeder ................................................................................. 23
2.2.1 Microwave antenna............................................................................................ 23
2.2.2 Classification of Microwave Antennas ............................................................... 25
2.2.3 Feeder System................................................................................................... 26
2.2.4 Branching System.............................................................................................. 27
2.3 Outdoor unit (ODU).................................................................................................... 27
2.3.1 Constituents of Digital Microwave Transmitter and Major Performance Indexes28
2.3.2 Constituents and Major Indexes of Receiver ..................................................... 30
2.4 Indoor Unit ................................................................................................................. 33
2.5 Installation and Adjustment of Split Microwave System............................................ 33
2.6 Conclusion ................................................................................................................. 36
3 Microwave System Networking and Application................................................................. 36
3.1 Microwave System Typical Networking Modes and Station Types........................... 36
3.1.1 Typical Networking Modes................................................................................. 36
3.1.2 Microwave Station Types................................................................................... 37
3.2 Relay Station ............................................................................................................. 38
3.2.1 Passive Relay Station ........................................................................................ 38
3.2.2 Active Relay Station ........................................................................................... 42
3.3 Digital Microwave Application.................................................................................... 44
3.4 Conclusion ................................................................................................................. 45
4 Microwave Propagation Theory ............................................................................................ 45
4.1 Electric Wave Propagation in Free Space................................................................. 45
4.1.1 Free Space......................................................................................................... 45
4.1.2 Propagation Loss of Electric Waves in Free Space........................................... 46
4.2 Influence of Ground Reflection on the Electric Wave Propagation ........................... 46
4.2.1 Concept of Fresnel Zone ................................................................................... 47
4.2.2 Influence of Ground Reflection on Receiving Level........................................... 48
4.3 Influence of Troposphere on Electric Wave .............................................................. 54
4.3.1 Ray Bend in Atmosphere ................................................................................... 55
4.3.2 Concept of Equivalent Earth Radius.................................................................. 56
4.3.3 Refraction can be classified into three categories based on the K value .......... 56
4.3.4 The Meaning of K Value in Engineering Design ................................................ 57
4.4 Fading caused by Several Atmospheric and Earth Effects ....................................... 58
4.4.1 Fading Types ..................................................................................................... 58
4.4.2 Influence of Troposphere on Electric Wave Propagation .................................. 59
4.4.3 Fading Rules (microwave frequency bands lower than 10 GHz) ...................... 61
4.5 Frequency Selective Fading...................................................................................... 62
4.5.1 Multi-path Propagation of Electric Waves.......................................................... 62
4.5.2 Influence of Frequency Selective Fading on Transmission Quality of Microwave Communication Systems .................................................................................................. 63
4.6 Statistic Feature of Fading......................................................................................... 64
4.6.1 Microwave Fading Model—Rayleigh Distribution Function ............................... 64
4.6.2 Engineering Calculation of Rayleigh Fading Probability .................................... 65
4.7 Conclusion ................................................................................................................. 66
5 Anti-Fading Technology in Digital Microwave Equipment ................................................. 67
5.1 Overview.................................................................................................................... 67
5.1.1 Purposes of Taking Anti-Fading Measures........................................................ 67
5.1.2 Classification of Anti-Fading Measures ............................................................. 68
5.1.3 Evaluation on Anti-Fading Measures................................................................. 69
5.2 Adaptive Equalization ................................................................................................ 70
5.2.1 AFE .................................................................................................................... 70
5.2.2 ATE .................................................................................................................... 72
5.3 Cross-Polarization Interference Counteracter (XPIC) ............................................... 73
5.4 Automatic Transmit Power Control (ATPC)............................................................... 74
5.5 Diversity Reception.................................................................................................... 76
5.5.1 Classification of Diversity Reception.................................................................. 76
5.5.2 Description of Space Diversity ........................................................................... 78
5.5.3 Compound Mode of Diversity Signals................................................................ 80
5.6 Microwave Equipment Protection Mode.................................................................... 81
5.6.1 HSM ................................................................................................................... 81
5.6.2 HSB.................................................................................................................... 82
5.6.3 Classification of Digital Microwave Equipment Protection Modes ..................... 83
5.7 Interference and Main Methods against Interference................................................ 84
5.7.1 Interference Source ........................................................................................... 84
5.7.2 Basic Methods of Communication System against Interference ....................... 85
5.8 Conclusion ................................................................................................................. 86
Contents
1 Microwave Communication Overview.................................................................................... 7
1.1 Basic Concepts of Digital Microwave .......................................................................... 7
1.2 Microwave Development Course................................................................................. 8
1.2.1 Microwave Evolution in the World........................................................................ 8
1.2.2 Microwave Evolution in China.............................................................................. 9
1.3 Characteristics of Digital Radio Communication System .......................................... 10
1.4 Challenges and Opportunities for Digital Microwave Communication ...................... 11
1.4.1 Optical Fiber Communication—Biggest Challenge for Digital Microwave Communication ................................................................................................................. 11
1.4.2 Opportunities for Digital Microwave Communication ......................................... 12
1.5 Microwave Frequency Band Choice and RF Channel Arrangements....................... 14
1.6 Digital Microwave Communication System Model .................................................... 16
1.6.1 Modulation Method of Digital Microwave ........................................................... 16
1.6.2 Channel Utilization of Each Modulation ............................................................. 18
1.7 Digital Microwave Frame Structure ........................................................................... 19
1.8 Conclusion ................................................................................................................. 21
2 Introduction to Digital Microwave Equipment ..................................................................... 21
2.1 Digital Microwave Equipment Classification .............................................................. 21
2.2 Microwave antenna and feeder ................................................................................. 23
2.2.1 Microwave antenna............................................................................................ 23
2.2.2 Classification of Microwave Antennas ............................................................... 25
2.2.3 Feeder System................................................................................................... 26
2.2.4 Branching System.............................................................................................. 27
2.3 Outdoor unit (ODU).................................................................................................... 27
2.3.1 Constituents of Digital Microwave Transmitter and Major Performance Indexes28
2.3.2 Constituents and Major Indexes of Receiver ..................................................... 30
2.4 Indoor Unit ................................................................................................................. 33
2.5 Installation and Adjustment of Split Microwave System............................................ 33
2.6 Conclusion ................................................................................................................. 36
3 Microwave System Networking and Application................................................................. 36
3.1 Microwave System Typical Networking Modes and Station Types........................... 36
3.1.1 Typical Networking Modes................................................................................. 36
3.1.2 Microwave Station Types................................................................................... 37
3.2 Relay Station ............................................................................................................. 38
3.2.1 Passive Relay Station ........................................................................................ 38
3.2.2 Active Relay Station ........................................................................................... 42
3.3 Digital Microwave Application.................................................................................... 44
3.4 Conclusion ................................................................................................................. 45
4 Microwave Propagation Theory ............................................................................................ 45
4.1 Electric Wave Propagation in Free Space................................................................. 45
4.1.1 Free Space......................................................................................................... 45
4.1.2 Propagation Loss of Electric Waves in Free Space........................................... 46
4.2 Influence of Ground Reflection on the Electric Wave Propagation ........................... 46
4.2.1 Concept of Fresnel Zone ................................................................................... 47
4.2.2 Influence of Ground Reflection on Receiving Level........................................... 48
4.3 Influence of Troposphere on Electric Wave .............................................................. 54
4.3.1 Ray Bend in Atmosphere ................................................................................... 55
4.3.2 Concept of Equivalent Earth Radius.................................................................. 56
4.3.3 Refraction can be classified into three categories based on the K value .......... 56
4.3.4 The Meaning of K Value in Engineering Design ................................................ 57
4.4 Fading caused by Several Atmospheric and Earth Effects ....................................... 58
4.4.1 Fading Types ..................................................................................................... 58
4.4.2 Influence of Troposphere on Electric Wave Propagation .................................. 59
4.4.3 Fading Rules (microwave frequency bands lower than 10 GHz) ...................... 61
4.5 Frequency Selective Fading...................................................................................... 62
4.5.1 Multi-path Propagation of Electric Waves.......................................................... 62
4.5.2 Influence of Frequency Selective Fading on Transmission Quality of Microwave Communication Systems .................................................................................................. 63
4.6 Statistic Feature of Fading......................................................................................... 64
4.6.1 Microwave Fading Model—Rayleigh Distribution Function ............................... 64
4.6.2 Engineering Calculation of Rayleigh Fading Probability .................................... 65
4.7 Conclusion ................................................................................................................. 66
5 Anti-Fading Technology in Digital Microwave Equipment ................................................. 67
5.1 Overview.................................................................................................................... 67
5.1.1 Purposes of Taking Anti-Fading Measures........................................................ 67
5.1.2 Classification of Anti-Fading Measures ............................................................. 68
5.1.3 Evaluation on Anti-Fading Measures................................................................. 69
5.2 Adaptive Equalization ................................................................................................ 70
5.2.1 AFE .................................................................................................................... 70
5.2.2 ATE .................................................................................................................... 72
5.3 Cross-Polarization Interference Counteracter (XPIC) ............................................... 73
5.4 Automatic Transmit Power Control (ATPC)............................................................... 74
5.5 Diversity Reception.................................................................................................... 76
5.5.1 Classification of Diversity Reception.................................................................. 76
5.5.2 Description of Space Diversity ........................................................................... 78
5.5.3 Compound Mode of Diversity Signals................................................................ 80
5.6 Microwave Equipment Protection Mode.................................................................... 81
5.6.1 HSM ................................................................................................................... 81
5.6.2 HSB.................................................................................................................... 82
5.6.3 Classification of Digital Microwave Equipment Protection Modes ..................... 83
5.7 Interference and Main Methods against Interference................................................ 84
5.7.1 Interference Source ........................................................................................... 84
5.7.2 Basic Methods of Communication System against Interference ....................... 85
5.8 Conclusion ................................................................................................................. 86