Dsl Primer

Contents

1. Introduction

1.1 The Fundamental Problem of Communications 5

1.2 The Transmission Medium-Attenuation Constraints 9

1.3 The Transmission Medium- Interference Constraints 12

1.4 The Transmission Medium- Bandwidth Constraints 13

1.5 DSL Keeps Unshielded Twisted Pair (UTP) Copper Cable

Attractive as a Premises Transmission Medium 18

1.6 A Brief History of DSL 21

1.7 Program 22

2. xDSL Modems: Fundamentals and Flavors

2.1 The Simple DSL Transceiver 24

2.2 The Many Flavors of DSL 28

2.2.1 IDSL 28

2.2.2 The HDSL Family: HDSL, SDSL, MSDSL and HDSL2 28

2.2.3 The ADSL Family: ADSL, MDSL, RADSL and

Splitterless DSL 33

2.2.4 VDSL 36

3. The Role of DSLAMsers 37

4. Virtual DSL: The Role of the DSL Simulator 39

5. Standards 46

6. Digital Subscriber Line - DSL Glossary 48

Bibliography 95

Index of Illustrations

Figure 1-1 Source, User pair with information 5

Figure 1-2 Representations of information 6

Figure 1-3 Examples of sources and users generating/desiring “data” 6

Figure 1-4 Source, transmission medium, user 7

Figure 1-5 Disturbance travelling in transmission medium 7

Figure 1-6 The model which represents the fundamental problem of

Communications 8

Figure 1-7 Input data signal attenuating as it propagates down a

transmission medium 10

Figure 1-8 Regenerating and repeating an attenuated signal in order to

reach user 11

Figure 1-9 Example transfer function of a transmission medium 14

Figure 1-10 Binary data from source represented by impulse train put into

transmission medium by transmitter. Impulses are T seconds apart 15

Figure 1-11 Input signal is positive impulse. Resulting output signal shows

time dispersion 16

Figure 1-12 Cost trends of common transmission media 19

Figure 2-1 A typical DSL Transceiver block diagram 25

Figure 2-2 Transmitter of digital transmission system 26

Figure 2-3 Generic DSL Reference Model 27

Figure 2-4 T1 Components 29

Figure 2-5 The HDSL Architecture 30

Figure 2-6 Photo of Model 681/682 HDSL Modem 31

Figure 2-7 ADSL reference model 34

Figure 2-8 Conventional ADSL configuration with splitter 34

Figure 2-9 Photo of Model 684 MDSL Modem 35

Figure 2-10 The VDSL Architecture 37

Figure 3-1 DSL-based services reference diagram 39

Figure 4-1 Diagram of modem testing on local loop connection 41

Figure 4-2 Diagram of modem testing on coil of twisted pair cable 41

Figure 4-3 Diagram of modem testing on DSL Simulator 42

Figure 4-4 Photo of Model 454 - Local Loop Simulator 43

Figure 4-5 Photo of Model 455 - Local Loop Simulator 43

Figure 4-6 Photo of Model 457 - Automated Local Loop Simulator 44

Figure