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Central Office Concepts
High Level OverviewIntroduction to Telephony Basics
Created by:Eddie Phillips
Revision date: 6/2002
Verizon Course # YYJ8166
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C.O. Concepts - Table of Contents
Slide Topic__________
Purpose 7 Purpose of High Level Overview
Introduction 9 Telephone Services10 POTS – Plain Old Telephone Service11 Special Circuits – Generic Types21 Special Circuit Overview23 Sound versus Frequency25 Analog lines, Digital trunks26 Converting an Analog signal to Digital27 Filtering, Sampling & PAM29 PAM – Pulse Amplitude Modulation30 Quantizing Error31 PCM32 Voice to PAM to PCM
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Table of Contents (Continued)Slide Topic_____________
Data Rate Overview & low bit-rate circuits33 Why Digital?34 Effect of Noise36 Digital Signal Rate 0 – DS037 Data Rates - DS0, DS1, DS339 Time Division Multiplexing – TDM43 DS1 - Digital Signal Rate 147 Uni- and Bi-polar signals51 B8ZS - Binary 8-bit Zero Substitution53 DS3 Multiplexer 55 DS-30 format58 Lines versus Trunks59 Signaling63 Robbed-bit Signaling68 Extended Superframe – ESF 70 ISDN BRI 73 ISDN PRI76 Central Office Layout77 Main Distribution Frame79 MDF - Pair protection
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Table of Contents (Continued)Slide Topic_____ ______
89 DSX-1 cross-connect96 D4 channel bank100 Dual Ringing Generators102 Special Circuits108 ISDN channel bank112 Digital Cross-connect System - DCS115 DCS 1/0 - DS1 input/DS0 cross-connect122 DCS Functional types 126 Hi-cap circuit127 DS1 versus T1129 Line Termination Shelf130 T1 Repeater Housing133 Repeater Housing Symbol134 T1 Repeatered Span Line 137 HDSL143 Fractional T1 (DS1)147 DSX-3 Cross-connect153 M13 Asynchronous Multiplexer148 Fiber Systems - Asynchronous159 Fiber Optic Systems – interoffice components
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Table of Contents (Continued)Slide Topic_____________
166 SONET Fiber Optic Systems169 SONET Hierarchy & Rates173 SONET Rings - UPSR174 SONET Rings - BLSR176 Fiber Cable Termination - LGX189 Tracing an FX circuit through an office190 Wave Division Multiplexing193 Dense WDM196 Wideband DCS199 Broadband DCS201 Microwave Radio208 Digital Loop Carrier (DLC’s)218 MDF in DLC’s – Equipment protection
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Table of Contents (Continued)Slide Topic_______________________
220 ADSL231 Timing 242 Power Diagram249 Main Power Board feeding Trans. Dist. Power Board253 Batteries256 Generator257 AC Transfer Switch258 Grounding - protection from lightning, etc
The pictures on this page are of antique operator cordboards.
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Central Office Concepts
Purpose: To provide an high level overview
of the signal formats, circuits andequipment types that are foundin a typical telephone office.
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Central Office ConceptsOverview - Part One
• Telephone Services - POTS Vs. Special Circuits• Analog to Digital Conversion• Data Rates - DS0, DS1, DS3• Main Distribution Frame• DSX-1, DSX-3 Jacks• D4 Channel Bank• ISDN Banks• DCS 1/0 - Digital Access Cross-connect System
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Telephone Services
POTS
CLASS
PBX
Centrex
Operator
Call Center
ACDAutomatic Call Distribution
ISP IXCCLEC
DS1Hi-caps
Special Circuits
ADSL
Telephone Office
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POTSPlain Old Telephone Service
Voice Signal
Telephone Office2 wires, 1 pair
Maximum distance from telephone office – 18,000 feet.Under 12,000 feet is preferred.
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Special CircuitsEverything Else but POTS
Central Office
To distant office
To Internet
To customer’s network
To ISDN line circuit
Digital Circuits
Alarm & control circuits
Analog Phone
Personal Computer
DS1 Hi-cap to Network
ISDN phone
Computer circuits
Utility company circuit
Overview of Generic Types
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POTS & Special Circuits
Phone line
Phone line
Trunk
TransmissionEquipment
Network
Digital Switch
Telephone Office
POTS
Special CircuitsAnalog Phone
Personal ComputerDS1 Hi-cap to Network
ISDN phone
Computer circuitsUtility company circuit
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Digital Switch – Nortel DMS-100
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Digital Switch- Automatic
ElectricGTD-5
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TransmissionEquipment
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TransmissionEquipment
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MainDistribution
Frame- terminates
copper outsideplant cables &
equipment cables
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Copper outside plant cables
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Copper cable splice closuresin vault
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Fiber Optic cable& jumper
termination
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Special Circuits Overview3 Broad Categories
• Voice-grade circuits– Foreign exchange - draws dial tone from a ‘foreign
office’• Analog Data circuits - non-digital
– ex. Circuits for real-time measurements;– pump starting, water levels, door open/close etc.
• Digital Data circuits• digital circuits, ISDN, hi-caps, etc.
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Introduction Summary
What a telephone office does:
• POTS – normal 7 or 10 digit dialing forcalls we make everyday.
• Special Circuits – unique circuits requestedby the customer to meet a specific customerrequirements.
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Sound versus Frequency
Sound Waves- unit of measure is
Hertz or cycles per secondHuman ear - 20 -10,000 Hertz (and higher)
Frequency - Electrical representation of sound
Analog Signal - electrical signal analogous to real sound
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How voice circuits go through the networkPOTS, Special Circuits
Voice or Analog signal
Voice or Analog signal
Digital signal- analog signal
converted to a binary code - 1’s and 0’s.
NetworkTelephone Office
Telephone Office
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Analog lines, Digital trunks
Line
Line
Line
Analog Signal
1 0 1 1 0 1 0 1
1 0 1 1 0 1 0 1
Digital Trunk
Telephone Office
Telephone Office
Telephone Office
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Converting an Analog Signal to aDigital Signal
‘1’ - presence of a pulse‘0’ - absence of a pulse
Analog Signal Digital Signal
Binary 8-bit word or ‘byte’
Binary digit or ‘bit’ 1 0 1 1 0 1 0 1
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Filtering, Sampling & PAM - PulseAmplitude Modulation
125 microseconds
Low-pass Filter Output
Original Voice Frequency Signal
8000 times per second (Hertz) sampling
20 Hz to 10,000+ Hz
20 Hz - 4000 Hz
Measuring signal levels in real-time
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Voice signal voltage ‘sampled’ at125 microseconds intervals.
- 8000 times per second
125 microseconds between measurements
T0 T1 T2 T3 T4 T5 T6 T7 T8 T9 Time
Voltage
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PAM - Pulse Amplitude ModulationVoltage level compared to Quantization level
T0 T1 T2 T3 T4 T5 T6 T7 T8 T9 Time
QuantizationLevel
7 - 111
6 - 110
5 - 101
4 - 100
3 - 011
2 - 010
1 - 001
0 - 000
Decimal - Binary
3-bit binary code
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Quantizing Error – small distortionof signalQuantization
Level
T0 T1 T2 Time
7 - 111
6 - 110
5 - 101
4 - 100
3 - 011
2 - 010
1 - 001
0 - 000
Quantizing Error
Decimal - Binary
3-bit binary code
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PCMPulse Code Modulation
10000001 110000010 2
10000011 310000100 410000101 5
10000110 6
11111111 128
00000001 -100000010 -200000011 -300000110 -4
00000101 -5
00000110 -6
01111111 -128
time
Maximumdistortion
Quantization error
PAM pulse
8-bit Binary Code
00000000 0
Each voltage level has a pre-assigned code
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Voice EncodingVoice to PAM to PCM - 8-bit word
DS0 = 64,000 bits per second
Each PAM valueconverted to8-bit word PCM encoder
125 microseconds
1 0 1 1 0 1 0 1 1 0 1 0 1 1 0 1
8-bits 8-bits
8000 samples/sec X 8 bits/sample= 64,000 bits/sec digital stream per voice channel
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Why Digital?Analog Transmission Noise Problems
Analog Signal
Signal Plus Noise
After Transmission AttenuationPlus Increased Noise
Amplified Signal Plus Noise
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Effect of NoiseAnalog versus Digital
+ =
+ =
Signal Noise Received Signal
Signal Noise ReceivedSignal
PCM + NoiseEncoded (PCM)
Analog-only signal plus noise:
Digital Signal plus noise:
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Summary• Analog lines, digital trunks• Voice frequency:
– Filtered– Sampled – PAM – Pulse Amplitude Modulation– Quantized – PCM – Pulse Code Modulation
8-BIT word – 8,000 times per second• PCM – 64,000 bits/second = 1 DS0
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Digital Signal rate 0 - DS08-bit format - 64 kbs
DS0 = 8000 8-bit words per second = 64,000 bits/second = 64 kbs
1 0 1 1 0 1 0 1
1 2 3 4 5 6 7 8
Fundamental digital signal in telecommunicationsBuilding block of most of all other signals
125 microsecond interval per 8-bit word
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Data Rates & Formats
• DS1 - 24 DS0's = 24 x 64,000 = 1.544 Mbit/sec
• DS3 - 28 DS1's = 28 x 1.544 Mbs + overhead = 44.736 Mbit/sec
- 672 DS0’s = 24 DS0’s x 28 DS1’s
• DS0 - 64,000 bits/sec (64 kbs) channel - digitized voice or data
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Information is on leading edgeof pulse
1 0 1 1 0 1 0 1
1 2 3 4 5 6 7 8
Width of each pulse is ‘squeezed’ to occupy less time so other circuits can be added in the same time frame.
Information is on the ‘leading edge’ of the pulse.
8-bit word represents a 125-microsecond sampling interval
8-bit word can occupy less time than 125 microseconds
1 0 1 1 0 1 0 1
1 2 3 4 5 6 7 8
Same 8-bit word, but occupying less time.
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Time Division Multiplexing - TDM
1
2
3
24
DS0 - 64 kbs
DS1 - 1.544 Mbs
Low-speed side High-speed side
Bi-directional multiplexer.Only one direction is shown.
TDM
The pulse widths of bits in the 24 channels are ‘squeezed’ to put all 24 channels on one high-speed channel.
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Time Division MultiplexingTDM - 24 DS0’s into a DS1
TDM
DS0 12345
21222324
1 0 1 0 1 0 1 0
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
1 0 1 0 1 0 1 0DS0
Only one direction shown
124
Framing bit
Channel
TDM - Interleaved together in time.One frame = 24 channels X 8 bits/chan. + 1 framing bit=193 bits/frame Rate = 193 bits/frame X 8000 frames/sec
= 1,544,000 bits/sec = 1.544 Mbs
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Voice to Digital to TDM
TimeDivision
Multiplexer
Analog to
Digital Converter
1
2
3
24
24 channels ‘multiplexed’ together in time.
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A/D-Mux - TDM – Demux-D/A
TimeDivision
Multiplexer Analog
to Digital
Converter
1
2
3
24
TimeDivision
De-multiplexer Digital
to Analog
Converter
1
2
3
24
24 channels ‘multiplexed’ together in time.
Only one direction is shown.
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DS-1 Digital Signal rate 124 channels TDM + Framing bit
1 DS1 frame is:24 DS0 channels (64 kbs) plus one framing bit= 24 channels X 8 bits/channel + 1 framing bit= 193 bits/frame.
Rate per second: 193 bits/frame X 8000 frames/sec
= 1,544,000 bits/sec -OR- 1.544 Mbs.Framing Bit indicates the beginning of the frame.
12324DS0’s
Framing bit
193 bits/frameDS1 Frame
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Bits in a DS1 are Bi-polarEvery other ‘1’ bit is reversed in polarity
0 1 1 0 1 0 1 1 01101011 0 1 1 0 1 0 1 1
DS1 bit stream
DS0 DS0 DS0
Max bit rate = 1.544 Mbs Max frequency = 772 kHz
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One 24-channel frameA DS1 has a signal going in both directions,
a Transmit signal and a Receive signal
1 24
1 8 1 8
Framing Bit
(24x8) +1 = 193 bits/frame
One 8-bit channel One 8-bit channel
125 microseconds
8-bit channel
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One DS1 frame
1 24
24 8-bit words = 192 bits
Framing bit(1 bit only)
1 2 3 4 5 6 7 87-bit word
8-bit word
24 8-bit words +1framing bit = 193 bits
Least Significant Bit
125 microseconds
TX - TransmitRX - Receive
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Uni-polar & Bi-polar SignalsSignals look different, but binary codes are the same
1 0 1 1 0
1 0 1 1 0
Uni-polar signal
Bi-polar signal
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Line Frequency of Uni-polar andBi-polar signals
1 0 1 1 0
1 0 1 1 0
A
B
‘B’ has half the frequency of ‘A’
6 times crossing reference line
3 times crossing reference line
Uni-polar signal
Bi-polar signal
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Bi-polar signals cut the effectivefrequency in half
1 0 1 1 0
1 0 1 1 0
A
B
A
6 times crossing reference line
3 times crossing reference line
Uni-polar signal
Bi-polar signal
‘Bipolar’ has half the frequency of ‘Uni-polar’
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Bi-polar SignalsDoubles digital signal distance on copper wire
Cutting the frequency in half, doubles the distance the signal can travel
Uni-polar signal
Bi-polar signal
2 times Distance
Distance
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The Zero Problem B8ZS - Binary 8-bit Zero Substitution
0 0 0 0 0 0 0 08 zero’s
Flat line
0 0 0 1 1 0 1 1
Solution:Substitute with B8ZS line encoding
Bi-polar violation (by design)
8 zero’s line code
One 8-bit word with all ‘0’s
Rule: Every 8-bit word MUST have at least one ‘1-bit’
A code is substituted when all zero’s appear.
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Summary• DS0 – one digitized voice channel• TDM – combines 24 voice channels into a DS1
– Mux – multiplexes DS0’s together in time into a DS1– DeMux – de-multiplexes DS0’s from a DS1 into individual
channels.• Binary digits in a digital bit stream are bi-polar• Bi-polar signals have lower frequency & can travel
further on copper wire.• B8ZS – substitutes a special code for eight zero’s.
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DS3 MultiplexerTDM - 28 DS1’s to 1 DS3
12345678910
262728
DS1 - 1.544 Mbs
DS3 - 44.736 MbsDS3
Multiplexer
28 DS1’sLow-speed side
High-speed side
Multiplex : 28 DS1s to 1 DS3
De-multiplex : 1 DS3 to 28 DS1s
The pulse widths of the bits in the 28 DS1’s are ‘squeezed’ to put all 28 channels on one high-speed DS3 channel.
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DS3 Frame Format
5 4 3 2 128 27 26
DS3 rate = 44.736 Mbit/sec
DS1DS1 DS1DS1DS1DS1DS1DS1 Header
24 DS0 channels for each DS1
• 672 DS0 channels = (28 DS1’s X 24 DS0’s/DS1)• Bi-directional - TX and RX
• 28 DS1 channels plus DS3 framing
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DS-30
• Like a DS1, but with 32 channels instead of 24 channels;no framing bit used.
• 30 channels voice, 2 channels control• European standard• Sometimes used by switch vendors inside digital switches
12332DS0’s
193 bits/frame
DS-30 Frame
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ComparisonDS0, DS1, DS3
DS1
24 DS0’s
DS328 DS1’s
DS0
Digital voice
DS-30
32 DS0’s
Bit rate
64 kbs
1.544 Mbs
2.048 Mbs
44.736 Mbs
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Central Office• Switching
– Lines, Trunks• Transmission
– connection between offices– special circuits– most anything else
• Switching & Transmission are blendingtogether
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1 Trunk = one 2-path digital voice circuit = 1 DS0Transmit & Receive on two separate facility paths
Lines versus Trunks
- access from customer to the network
Line
Trunk - connection from office-to-office
1 Line = one 1-path voice circuitTransmit & Receive on 1 cable pair - analog or digital connection
Line
Telephone Office
Telephone Office
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Signaling
Signaling is the process by which two or more telephone offices communicate between each other to setup and take down a telephone call.
LineLine
Telephone Office
Telephone Office
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In-band Signaling from Telephoneoffice to Telephone office
LineLine
Telephone Office
Telephone Office
A B
A informs B of incoming call.B checks line for on-hook or off-hook condition.B informs A of status of line.B applies ringing to the line. When phone answers, voice path is created between A & B. If off-hook, a busy tone is sent from B to A.When a phone is again on-hook, path is dropped.
Trunk
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SignalingCalling-office to Called-office
LineLine
Robbed-bit Signaling is used to transfer signaling information from calling-office to called-office.Ex. when calling-phone goes off hook; sending dialed digits.
Digital Trunk - DS0
Telephone Office
Telephone Office
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SignalingCalled-office back to Calling-office
LineLine
Robbed-bit Signaling is used to transfer signaling information back from called-office to calling-office.Ex. When called-phone answers, or hangs up.
Digital Trunk - DS0
Telephone Office
Telephone Office
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Robbed-Bit Signaling in DS1
1 6 12 18 24
A frameEvery 6th frame is robbed of the least significant bit in all channels
1 24
1 8 1 8
1 24
1 81 8
Dot isrobbed-bit
channel
193 bit frame 193 bit frame
Channels Channels
Bit is used for signaling, not voice.
DS1 – 24 frames shown
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Robbed-bit Signaling56 kbs - Computer to Computer
LineLine
Robbed-bit Signaling limits the maximum digital bit rate to 56 kbs (DS0=64 kbs).
Digital Trunk - DS0
Telephone Office
Telephone Office
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SS7 Signaling - Signaling System 7Out-of-band signaling
HostOfficeSSP
SS7 Signaling uses a separate data paths to send call setup information from the calling office to the called office. STP
HostOfficeSSP
SCP
Voice path - Trunk
database
This Town That Town
Big CityReally Big City
Line Line
SSP - Signal Service Point - local officeSTP - Signal Transfer Point - one per regional areaSCP - Signal Control Point - database for customer info
data paths
SS7 is implemented nationally & regionally and is required for advanced features such as caller id, etc.
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Summary
• Lines – many one-path circuits• Trunks – fewer two-path circuits• Signaling is used for telephone offices to
communicate so a telephone call can be set up andtaken down.
• Robbed-bit signaling is an in-band signal systemthat uses the least significant bit in a DS0 trunk tosend signaling between offices.
• SS7 is an out-of-band signaling system withadvanced features.
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DS1 Superframe
Superframe = 12 frames grouped together
1 6 12
One frame - 193 bits
1 24
1 8 1 8
193 bit frameFraming bitat beginningof frame beforefirst 8-bit word
DS1 Superframe – 12 frames
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DS1 Extended SuperframeESF
1 6 12 18 24
One frame (193 bits)
- Framing bits of 24 frames = virtual 8000 bits/second channel – just like a DS0.‘Framing Channel’ used to send call setup informationwithout ‘Robbing bits’ from the bit stream.
This allows the entire 64 kbs bandwidth in each DS0 voice channel to send voice information.
Also, the Framing Channel sends error checking codes & information about the status of the facility.
Extended Superframe = 24 frames grouped together
Framing bits – 1st bit in each frameDS1 ESF = 24 frames
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ISDN - Integrated SubscriberDigital Network
• all digital connection from telco to phone• higher quality voice circuits• high speed data lines
Digital Line
1 cable pairTelephone Office
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ISDNBRI - Basic Rate Interface
2 digital voice channelsISDN line cardin line bay orchannel bank
NT1Local 2-wire loop
Network Termination 1
2B + D = 160 kbs
Customer PremiseTelephone office and local loop
Demarcation
1 Bearer channel64 kbs
1 Bearer channel64 kbs
Digital 1-path circuit
BRI
Entire 64 kbs channel used for voice.
ISDN phone
ISDN phone
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ISDNBRI - Basic Rate Interface
One 128 kbs channelISDN line cardin line bay orchannel bank
NT1Local 2-wire loop
Network Termination 1
2B + D = 160 kbs
Customer PremiseTelephone office and local loop
demarcation
Digital 1-path circuit
BRI
2 Bearer channels 128 kbs
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ISDN BRIBRI - Basic Rate Interface – all digital circuit
2 B
D
160 kbs channel
Overhead
64 kbs
64 kbs16 kbs
16 kbs
BRI = 2 x 64kb + 16kb + 16kb = 160kb/sec
2B + D - 2 Bearer channels (2 DS0’S) - 64kb each (voice or data) 1 Data channel - 16kb plus 1 overhead channel for signaling - 16 kb
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ISDN PRI - Primary Rate Interface• DS1 format, but channels are - 23B + D = 24 channels• 23 Bearer channels – 23 DS0’s
- 64 kbs each (voice or data)• 1 data channel - 64kbit – 1 DS0
1 24
FramingBit
125 microseconds8-bit, 64 kbs channels
B B B B B B B B B B B B B B B B B B B B B B B B D
PRI = 23B + D
1.544 Mbs DS1 rate
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ISDN BRI LineInternet connection
PRI, a DS1, uses each entire 64 kbs DS0 channel for information.Signaling information is sent via the Data channel & ESF.Allows for clear channel data transfer – ALL 8 bits in each DS0.No Robbed-bit signaling is used.
PRI TrunkingInternet ServiceProvider (ISP)
Telephone Office
Telephone Office
2B + DPRI – DS1PRI – DS1
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Summary• ISDN BRI – Basic Rate Interface
– 2B+D - 2 ‘Bearer’ channels, 1 Data channel– Full 64,000 bits/sec – no robbed bits– Higher quality, all digital phone lines– Used also for data connections.
• ISDN PRI – 23B+D– DS1 with 23 full 64kbs rate channels– Used by Internet Service providers for higher speed
connections and ISDN connections.
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Central Office Layout
MDF
ISDN
M13 Mux Fiber Optic System
Dig
ital s
witc
h
DSX-1DSX-1DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
Span powered DS1 (T1)
DCS1/0
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MainDistributionFrame – C.O.- 2 sided frame
Vertical side - cable protectorsHorizontal side - line blocks
Horizontal side
Verticalside
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Main DistributionFrame -Vertical side - pair protectionProtectors- termination of cable pairs- may also have blocks
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Main Distribution Frame in atypical central office
• Pair Protection– Protectors
• terminate the outside plant pair• provide lightning protection on the pair
– Blocks• terminate the lines from the equipment• wired out to a cross connect cabinet
Copper pairsin outside plant cable
Protector
Line equip. jumper Equipment cabling
Terminal block LineEquipment
Bay
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Vertical side – Cosmic frame
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Main Distribution Frame cable pairprotector (connector)
- 100-pair termination of cable pairs- lightning protection; sends lightning surge to the c.o. ground field
Protector module (solid state)
82
Main Frame Cable pairprotector- jumpers to line circuits of telephone switch.
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Main Frame Horizontal side
Blocks- termination of line circuits
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Blocks onMain Distribution Frame
85
Blocks – Cosmic frame
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‘Tipping’ cablesfrom frame
to vault
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Vault – Splice Closures - connects ‘tipping’ cable to
outside plant cable
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Summary• Main Distribution Frame terminates all
voice grade connections in a telephoneoffice.– Outside Plant cables– Line cables– Special circuits
• Pair protection – each cable pair isgrounded if a lightning surge occurs.
89
Central Office Functional Layout
MDF
ISDN
M13 Mux Fiber Optic System
DCS1/0
Dig
ital s
witc
h
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
DSX-1DSX-1DSX-1
OutsidePlant cables
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DSX-1 Cross-connectConnecting DS1 circuits
between equipment
jacks
30-pair high-frequency cabling from equipment
jacks
DSX-1 module DSX-1 module
DS1 DS1Bantam patch cord (dual)
5-wire jumper(flipped over)
LEDMON
INOUT
LEDMON
INOUT
Terminates DS1’sfrom equipment
Light
30-pair high-frequencycabling from equipment
Terminates DS1’sfrom equipment
91
DSX-1 BaysTerminations for DS1’s
Cross-connects to other DS1’s
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DSX-1 Bays
93
DSX-1 Bays5-wire jumpers
94
DSX-1 jumpers – what NOT to do
95
Central Office Layout
MDF
ISDN
DSX-1DSX-1
M13 Mux Fiber Optic System
Dig
ital s
witc
h
DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
DCS1/0
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D4 Channel BankA/D, D/A conversion + TDM
• Aggregates many lowspeed circuits into onehigh speed circuit fortransport
• 24 low speed circuits- converted to 64kbit/sec – DS0
• 1 DS1 high speed side- 1.544 Mbit/sec
24 Voice channels
1 DS1 D4
channelbank
1
24
24 VoiceFrequency
circuits24 DS0’s 1 DS1
A/D, D/A TDM
Low-speedside
High-speedside
97
D4 channel bank
Alcatel (Charles Ind.)- dual di-group - two - 24 channels- common cards in the middle of eachdi-group (digital group)
12 channels
12 channels
Common cardsfor one di-group
98
D4 bank to D4 bank
DS1 D4
channelbank
D4channel
bank
24 Voice channels
Office ‘A’ Office ‘B’
1
24
24 Voice channels
1
24
99
Nortel D4- dual di-group- two - 24 channels- common cards on right side of shelf
100
Dual Ringing Generators
101
Summary
• DSX-1 jacks – terminating DS1 cables,providing cross-connections between DS1circuits.
• D4 Bank – Combines 24 incoming voicechannels into 1 DS1 output.24 Low-speed VF – A/D, D/A – TDM –High-speed DS1.
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Special Circuits
– FX - Foreign exchange historically most popular special circuit used for extending dial tone from another office
Voice Grade:
Foreign Dial tone office– Washington, DC
ChannelBanks
Local office – Austin, TX
DS1 DS1Network
Line
103
Special Circuits
E & M - Ear & Mouth - used for trunk circuits in electromechanical offices.
Voice Grade:
Analogtrunks
DS1
Analogtrunks
ChannelBanks
104
Special Circuits
- ETO - Equalized Transmission Onlyused mainly for sending analog data
• on/off condition• real-time measurements, etc.• utility company circuits
Analog Data:
Data centerChannelBanks
DS1
105
Special Circuits
- Data rates 64 kbs or less (1 DS0 or less)• 2.4 kbs, 4.8 kbs, 9.6 kbs, 19.2 kbs, 56 kbs, 64 kbs
Digital Data:
- Fractional T1 - data rate multiples of 64 kbs• 128 - 384 kbs (2-6 DS0’s)
- operates at a DS1 rate, but with only the DS0’s used turned on.
Typically used with Frame Relay circuits.
ChannelBanks
DS1Digital data Digital data
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Special CircuitsISDN - Integrated Services Digital Network
– digital connection from telco to phone– 3 DS0's per low speed circuit – 3 slots used.
• ISDN card occupies one slot in channel bank, but the 2nd & 3rd slots are unusable for anything else.• 2 ‘Slot-Blocker’ cards are used to prevent other
cards from being placed in the 2nd & 3rd slots.– 8 ISDN channels MAX per D4 bank or
di-group.
1 2 3 4 5 6 7 8 9 10 11 12
DS1
Slots in channel bank
3 DS0’s used
Channel bankChannel bank
ISDNcircuit
ISDNcircuit
107
Central Office Layout
MDF
ISDN
M13 Mux Fiber Optic System
Dig
ital s
witc
h
DSX-1DSX-1DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
DCS1/0
108
ISDN Channel Bank
DS1 ISDN
channelbank
Office ‘A’ Office ‘B’
ISDNchannel
bank
• Only 8 physical slots, not 24 channels• 3 DS0’s per physical slot
• Can interface another ISDN bank, D4 or DACS
1 82 3 4 5 6 7 1 82 3 4 5 6 7
109
Adtran BR1/10 ISDN dual-channel banks- two di-groups (digital groups) per shelf.
110
Summary• Special Circuits:
– Foreign Exchange – dial tone from a different c.o.– E & M – Ear & Mouth – analog trunks– ETO – Equalized Transmission Only – analog data.– Digital Data – data rates from 2.4 kbs to 64 kbs.– ISDN in channel bank uses 3 slots.
• ISDN Banks have 8 channels per di-group.
111
Central Office Layout
MDF
ISDN
DSX-1DSX-1
M13 Mux Fiber Optic System
Dig
ital s
witc
h
DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
DCS1/0
112
DCS–Digital Cross-connect System
• Partial elimination of channel banks• Device to access the DS0’s in a DS1 bit stream, while
keeping the circuits all digital• No analog to digital conversion necessary.• Facilitates a cost-effective management of
special circuits in an office.• Higher quality circuits DS1
DS1
DS1
DACS
DS1
DS1
DS1
113
DCSDigital Cross-connect System
DS1
DS1
DS1
DACSDS1
DS1
DS0 cross-connects
DS1
24 DS0’s each DS1
114
Why have a DCS?Before DCS: Back-to-Back D4’s
D4Channel
Bank
D4Channel
Bank
D4Channel
Bank
D4Channel
Bank
D4Channel
Bank
D4Channel
Bank
DS1
DS1
DS1
DS1
DS1
DS1
VF circuits VF circuits
Jumpers
Main Distribution Frame
115
DCS - 1/0DS1 input / DS0 cross-connectBack-to-Back D4 elimination
D4Channel Bank
.
.
.
.
DS1
DS1
DS1
DS1
DACS1/0
DS1
DS1
DS1
DS0 cross connects in 1/0 DACSD4 bank forlocal circuits.
DS0 cross-connects
in matrix
Port cards
Permanently connected ‘virtual’
cross-connectedDS0 circuits.
116
DS0 cross-connects
in matrix
28 DS1’s
Unit Shelves
28 DS1’s
Unit Shelves
Matrix
28 DS1’s 28 DS1’s
28 DS1’s
28 DS1’s
28 DS1’s
Digital Cross-connect SystemUnit shelves & Matrix
DS1 input / DS0 cross-connectInter-shelf bus
117
Dual, on-line matrices and dual data paths for full circuit protection Fully distributed A and B power feeds Dual power supply architecture Single DS1 per port card Distributed processing
Matrix Shelf
Admin Shelf
Filler Panel
Fuse Panel
DS1 Unit Shelf
DS1 Unit Shelf
DS1 Unit Shelf
DS1 Unit Shelf
Fuse Panel
DS1 Unit Shelf
DS1 Unit Shelf
DS1 Unit Shelf
DS1 Unit Shelf
Unit Bay Expansions to 5,376 DS1s
Admin and/or Matrix Bay
DS1 Unit Bay DS1 Unit Bay
Fuse PanelFuse PanelFuse Panel
Disk Drive
DSC - ALCATELDEXCS Bay layout
118
Alcatel DS1 Unit Bay
112 ports per bay
28 ports per unit shelf
28 ports per unit shelf
28 ports per unit shelf
28 ports per unit shelf
1 DS1 per port card
119
AlcatelDEXCS 1/0Bay lineup
Unit bays
Admin bay
Matrix bay
120
Alcatel DEXCS Unit Shelf28 DS1 Ports per shelf
Unit cards ( 28 1-DS1 cards )
Power Supplycard
Controllercards
Power Supplycard
121
Alcatel NarrowbandDEXCS sizes - matrix Size
• CS1S - 84 DS1's - small
• CS1 - 336 DS1's - medium
• CS1L - 1544 DS1's - large
• CS1VL - 5376 DS1's - very large
Matrix Shelf
Admin Shelf
Filler Panel
Fuse Panel
Disk Drive
122
Digital Cross-connect SystemsFunctional types – Generic terms
• Narrowband - 1 / 0– DS1 input, DS0 cross-connect
• Wideband - 3 / 1 – DS3 & DS1 input, DS1 cross-connect
• Broadband - 3 / 3 / fiber– DS3 & fiber optic input, DS3 cross-connect
123
Summary• 1/0 DCS – DS1 input, DS0 cross-connect• DCS accesses all DS0’s in a DS1 bit stream,
while keeping the circuits digital; no A/Dconversion
• reduces the need for back-to-back channelbanks for ‘through’ circuits.
• Saves on equipment quantity and cost,keeps quality of signal high.
• Easier to add, delete, & manage circuits.
124
Central Office ConceptsOverview Part Two
• T1 Span lines, HDSL• M13 Multiplexer• Introduction to Fiber Systems• Fiber Cable Termination – LGX• Broadband DCS• Digital Loop Carrier• ADSL• Timing - BITS Clock• Power - AC/DC, Batteries, Generator• Grounding - protection from lightning, etc.
125
Central Office Layout
MDF
ISDN
DSX-1DSX-1
M13 Mux Fiber Optic System
DCS
Dig
ital s
witc
h
DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
126
Hi-CapHigh Capacity Line – DS1 to Customer
1 2 3 24DS0’s
Framing bit 193 bits/frame
DS1 Frame
Telephone Office DS1
• Various services can be carried on a hi-cap circuit: PBX trunks (voice), Frame Relay, ATM, ISDN PRI, video, etc.• Hi-caps can connect directly to local telco network or pass through to another carrier.
Business or Industry
127
DS1 versus T1
0 Volts
+ 5 Volts
- 5 Volts
0 Volts
+130 Volts
Max bit rate = 1.544 MbsMax frequency = 772 kHz
DC power component added
+135 Volts
+125 Volts
DS1 - low voltage levels, typically 5-12 volts.Limitation of 400 ft in an office.
T1 - has added DC power componentused to power line repeaters.
128
Central Office Layout
MDF
ISDN
DSX-1DSX-1
M13 Mux Fiber Optic System
DCS1/0
Dig
ital s
witc
h
DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
129
Line Termination Shelf(span shelf)
Wired toDSX-1 jacks Wired to block
On MDF to access cable pairs
DSX1
Two 12-pair
Shielded Cables
Two 12-pair
Shielded Cables
12-slot shelf
To cable pairs
C.O. repeater cards
130
T1 Repeater Housing
To next repeater housingFrom previous repeater housing
12 - Position25 - Position50 - Position
Housings
Aerial or Buried Cable
Local Cable or Toll Cable (T-Screen)
Telephone pole
131
Span line repeater housingregeneration of signal
Pulse degenerates into: Repeater makes a new pulse:
Line repeater card
To next repeater housingFrom previous repeater housing
132
New Pulse Generation symbols
One pairin and out
Repeater makes a newpulse in each direction
Side 1
Side 2
133
Repeater HousingSymbol
Side 1
Side 2
134
T1 Repeatered Span LineCentral Office ‘A’
Line Termination ShelfCentral Office ‘B’
Line Termination Shelf
Repeater Housings
C.O. repeater
Line Repeater,
12, 25, 50 slots
Outside plantcopper cable
135
Line termination shelf
Line termination shelf
T1 Repeaters
T1 Span Line - SchematicSpacing Between
Housings- 3000-5000 feet
DS1 in
DS1 out
DS1 out
DS1 in
DC power componentadded to signal to powerrepeater housings - see slide ‘DS1 vs. T1’
T1 signal (DC powered DS1)
C.O.Repeater
Office A Office B
Typically, no new T1 span lines are placed, except in rural areas.
136
Central Office Layout
MDF
ISDN
DSX-1DSX-1
M13 Mux Fiber Optic System
Dig
ital s
witc
h
DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
DCS1/0
137
HDSL
High-bit-rate Digital Subscriber Line
Delivers DS1’s to remotes, DS1’s forcustomer high-caps WITHOUT a repeaterup to 12,000 feet.
Central OfficeHDSL
Remote / Customer Premise
HDSL
No repeater housings
Up to 12,000 feet
138
HDSL
00
01
10
11
• 2B1Q - 2 binary, 1 Quaternary• Two Binary digits per pulse• 4 Pulse levels• cuts line frequency in half from T1 HDSL=384 kHz; T1=772 kHz
Distances up to 12,000without a repeater.
139
HDSL shelf & wiring
12-pair high-frequency cabling to DSX-1 jacks
12-pair high-frequency cabling to main
distribution frame
C N T R L
H T U R
H T U R
H T U R
H T U R
H T U R
H T U R
H T U R
H T U R
H T U R
H T U R
H T U R
H T U R
H T U R
H D S L
140
HDSL shelf
Wired toDSX-1 jacks
Wired to block on MDF to access cable pairs
DSX1
Two 12-pair
Shielded Cables
Two 12-pair
Shielded Cables
13-slot shelfTo
cable pairs
HTU-C cards
HDSL controller card
MDF Block
141
HDSLHTU-C & HTU-R
HTU-C HTU-R2-wire circuit 12 DS0’s
2-wire circuit 12 DS0’s
DS1DS1
Central Office Customer Premise
Up to 12,000 feet
HTU-C - HDSL Terminating Unit - Central OfficeHTU-R - HDSL Terminating Unit - Remote
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
142
HDSL Repeaterdoubles the distance
HTU-C
2-wire circuit 12 DS0’s
2-wire circuit 12 DS0’sDS1
2-wire circuit 12 DS0’s
2-wire circuit 12 DS0’s
HDSL Repeater HTU-R
12,000 feet 12,000 feet
DS1
Central OfficeCustomerPremise
Two HDSL repeaters may be used to go 36,000 feet
143
Fractional T1 (Fractional DS1)• DS1 rate, but with only a portion of the 24 DS0’s carrying
traffic - can be delivered via a T1 span line or HDSL• customer wanting MORE than ONE 64Kbps channel• typically 2-6 DS0's - rate - 128kbps to 384kpbs• Can be provisioned on one pair
Framing bit(1 bit only)
24 8-bit words +1framing bit = 193 bits
124
12345678
6
6 DS0’s shown
144
Fractional T1 over HDSL
D4 bank
HTU-C HTU-R
2-wire circuit, 2-6 DS0’s, 12 max
Central OfficeCustomer Premise
Up to 12,000 feet
Only one pair requiredDS1
4-wirecircuit
Fractional DS1 (6-DS0) 2-wire circuit
MDF
LC
24
Customer’sEquipment
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0
DS0 DS0 DS0 DS0 DS0 DS0
DS0 DS0 DS0 DS0 DS0 DS0
24Fractional T1 with 6 DS0’s carrying traffic
1
1
6 DS0’s in D4 bank
High-speedside
Low-speed side
1 6 12
1612
145
Summary
• Hi-cap – DS1 to customer• T1 span line – transports DS1’s on copper
cable facilities from one office to another;uses T1 repeater housings 3000-5000 feetapart.
• HDSL – transports DS1’s on copper cablefacilities up to 12,000 feet without arepeater housing.
146
Central Office Layout
MDF
ISDN
DSX-1DSX-1
M13 Mux Fiber Optic System
Dig
ital s
witc
h
DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
DCS1/0
147
DSX-3 Cross-Connect- connecting DS3 circuits
between equipment
cross-connect cables(backside of modules)
jacks
coaxial cablingfrom fiber
optic terminal
jacks
DSX-3 module DSX-3 module
coaxial cablingFrom M13 mux
DS3 DS3Patchcords
INOUTI-XO-X
INOUTI-XO-X
MONMON
Light
Cables flipped over
FrontFrontRearRear
148
DSX-3 Bay – front
149
DSX-3 Lineup
150
DSX-3 Bay-Rear View- equipment termination- cross-connect cables
151
Coaxial Terminations
152
Central Office Layout
MDF
ISDN
DSX-1DSX-1
M13 Mux Fiber Optic System
Dig
ital s
witc
h
DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
DCS1/0
153
M13 Asynchronous Multiplexer
• 28 DS1's multiplexup to 1 DS3
• typically use NortelDMT-300 mux orTelco SystemsRC-28D
1
28
DS1
DS3 M13
Multiplexer
to DSX-3 jacks
to DSX-1 jacks
.
.
.
.
.
.
154
Nortel DMT-300 M13 multiplexer4 drawers per shelf
coaxial cablesfor DS3terminations
30-pairHigh-frequencyCabling for28 DS1 terminations
Multiplexer (mux) drawer
empty slot
155
Telco 828 M13 multiplexer
156
NEC RC-28D M13 Multiplexer
157
Central Office Layout
MDF
ISDN
DSX-1DSX-1
M13 Mux Fiber Optic System
Dig
ital s
witc
h
DSX-1
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
OSP fiber cable
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
DCS1/0
158
Fiber System - AsyncFundamental structure
DS3
DS3
Fiber Optic Terminal
working
protection
TxRx
TxRx
.
.
.
.
DSX3
159
Fiber optic system -interoffice components
Fiber Optic Terminal
FOT
DS3’s
Office A
Fiber Optic Terminal
FOT
DS3’s
Office B
LGX
LGX
Outside plantfiber cable
Fiber opticsplice closure
Inside plant‘mic’ cable
DSX3
DSX3
Fiber terminationpanel
Point-to-Point configuration
160
Basic Fiber Optic TerminalSimplified block diagram
DS3 #1
DS3 #2
DS3 #3
working
protection
Low-speed side, orEquipment side
High-speed side, orFacility side
To DSX-3 panels To outside plant fiber facilities
DE
MUX
XCVR
MUX
XCVR
45 Mb/s
135 Mb/s
Light – 1300 nmwavelengthTx or In
Rx or Out
DS3
DS3
DS3
3-DS3 Fiber Optic Terminal
161
FD-565 Fiber Optic Terminal
Controllercard
Transmit card Receive card
Working sideOptics cards
(Tx, Rx,Mux, Demux)
Protection sideOptics cards
Power supplies
DS3 interface cards
Fiber jumper slack storage
Coaxial termination
162
Multiplexing Hierarchy & wiring
Fiber Optic Terminal
FOT
DS3M13mux
DS1 #1
DS1 #28
D4Channel
bank
DS0 channel 1
DS0 channel 24
Fibers to next office
Coaxialcable
30-pair24-gaugeshielded
cable
25-pair24-gauge
voice frequency
cable
64 Kbs1.544 Mbs 45.736 Mbs
163
Test EquipmentDS1, DS3, SONET T-Berd
Acterna Products - formerly TTC
164
Mux, DSX-3, & F.O.T.connections
DS3
.
.
.DS3
FiberOptic
Terminal
working
protection
TxRx
TxRx
DS3
DSX-3PANEL
DSX-3PANEL
M13MUX
To fiber termination panel
DS1
coaxialcable coaxial
cable
High-frequency
cabling
coaxial cross-connect
cords
165
Summary• DSX-3 jacks - terminating DS3 cables,
providing cross-connections between DS3circuits. Connects to M13 muxes & FOT’s.
• M13 Multiplexer – TDM device combining28 DS1’s into one DS3.
• Fiber Optic Terminal – TDM devicecombining lower speed DS3 (and DS1)circuits together into a high speed circuit.This high speed circuit is converted into lightpulses and connected to a fiber cable.
166
SONETSynchronous Optical NETwork
• SONET is a standard for synchronous data transmissionon fiber optic equipment.
• STS-1 Synchronous Transport Signal rate 1.- fundamental bit rate within SONET hierarchy.
• SONET rate = 51.840 Mbs. When transmitted via light,called Optical Carrier rate 1, or OC-1.
• STS-1 typically is a DS3 signal within a SONET frame.
5 4 3 2 128 27 26
DS1 DS1SONET Frame
DS3
HeaderDS1DS1DS1DS1DS1DS1DS1DS1
167
SONET FrameSynchronous Transport Signal Rate - 1
Optical Carrier - Rate 1
Frame Rate=9 Rows X 90 Columns X 8 bits/sec X 8000 frames/sec = 51.84 Mbs Payload = 50.112 Mbs, Transport Overhead = 1.728 Mbs
87 Columns
90 Columns
9 Rows
Payload
Transport Overhead
8-bit word
8-bit word
STS-1 – electrical, OC-1 - optical
168
SONETFiber Optic
System
SONETAdvantages:• Mix and match fiber vendors on same span.• Since the SONET bit streams are byte-
interleaved and timed from a common,stable clock source, the individual lower-rate bit streams can be accessed without de-multiplexing the entire bit stream.
DS3
.
.
.
SONETFiber Optic
SystemDS3
.
.
.
.
Vendor “A” Vendor “B”
.
.
.
.
.
.
.
.
.
.
.
.
169
SONET Hierarchy & Rates# DS3's SONET OPTICAL Rate Capacity - DS1's
1 STS-1 OC-1 51.84 Mbs 28 DS1's3 STS-3 OC-3 155 Mbs 84 DS1's12 STS-12 OC-12 622 Mbs 336 DS1's48 STS-48 OC-48 2488 Mbs - 2.4 Gbs 1344 DS1's
192 STS-192 OC-192 9953 Mbs - 9.9 Gbs 5376 DS1's
SONETFiber Optic
SystemDS3
.
.
.
.
.
.
.
170
Lucent DDM-2000OC-3 shelfTransceiver cards
Processorcards
DS1 Interfacecards – Group A28 DS1’s
Group B - emptyGroup C - empty
Drop down door
Timing Cards
171
SONET Fiber Optic SystemSynchronous Optical NETwork – OC12
Fan shelf
Transceiver cards
OperationalController
OPCTiming
cards
Processorcard
DS3 or DS1Interface cards
172
Fujitsu FLM-150 Fiber Shelf
173
12 STS-1’s maximum available around the ring.
SONET RingsUPSR - Uni-directional Path Switched Ring
B
12 STS-1’s
OC-12 UPSR RingNumber of available STS-1’s = rated capacity of system (N)
DS3’s DS3’s
DS3’s
Example:A-B - Ch.1 workingB-C-A - Ch.1 protection
X – where DS3 interfaces the ring.
CONTROL
POWER
POWER
OC -
12XCVR
OC -
12XCVR
PROT .
MAPPER
SW I TCHER
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
T I
M I N GBC
ONTROL
POWER
POWER
OC -
12XCVR
OC -
12XCVR
PROT .
MAPPER
SW I TCHER
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
T I
M I N GA
CONTROL
POWER
POWER
OC -
12XCVR
OC -
12XCVR
PROT .
MAPPER
SW I TCHER
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
T I
M I N GC
174
SONET RingsBLSR –Bi-directional Line Switched Ring
Number of available STS-1’s = N/2 * number of nodes
Each segment is has ½ working STS-1’s and ½ protection STS-1’s
A B
C
½ STS-1’s working &½ STS-1’s protection
½ STS-1’s working,½ STS-1’s protection
½ STS-1’s working,½ STS-1’s protection
CONTROL
POWER
POWER
OC -
12XCVR
OC -
12XCVR
PROT .
MAPPER
SW I TCHER
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
T I
M I N GBC
ONTROL
POWER
POWER
OC -
12XCVR
OC -
12XCVR
PROT .
MAPPER
SW I TCHER
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
T I
M I N GA
CONTROL
POWER
POWER
OC -
12XCVR
OC -
12XCVR
PROT .
MAPPER
SW I TCHER
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
MAPPER 14 DS-1'S
T I
M I N GC
DS3’s DS3’s
DS3’s
6 STS-1’s available in each segment.
OC-12 BLSR Ring
175
Summary
• SONET – standard format for fiber opticequipment.
• Accesses bits in the bit stream withoutde-multiplexing the entire bit stream.
• Allows concatenation of signals togetherfor higher speeds.
• Equipment must be synchronized or timedtogether.
176
Fiber Cable TerminationOSP cable - closure - fiber panel
Outside Plant fiber cable
Inside Plant fiber cable(mic cable)
Fiber closure fiber
connector panel
177
LGXLight Guide Cross-Connect
6-pack
Fiber connectors
Fiber optic connectorBulkhead connector
- mates to fiber optic connector
Pigtail (or jumper)
178
Fiber optic connectors
Fiber optic connector
Bulkhead connector in termination shelf
Mated together in fiber termination shelf
Fiber opticjumper
Fiber opticpigtail
equipment sidefacility side
179
Fiber Optical connectors
ST SC FC BiconicMost commonlyused in telephony
Used in videoapplications
Older type,not beingplaced innew systems
180
Fiber Termination Bays- Lucent
LGX – Light Guide Cross-connect
also called,
OSX- Optical Signal Cross-connect
Facility-side bay &| equipment-side bay
181
Fiber Termination Bay- ADC
Fiber termination panel – jumpers slide out to side
182
Fiber termination shelves
Fiber jumpers
Fiber pigtail (72 in bundle)
Fiber terminationshelf
Connectors (72 per shelf)
Designationstrip
183
OCEF Optical Cable
Entrance Facility
MIC cable from LGX bay
184
Fiber Jumper Inter-connect
FiberOptic
Terminal
Fiber Jumper- connects to front of LGX panel
MIC cable- terminateson back ofLGX panel
Fiber closure LGX panel
Outside Plant Fiber
185
Fiber Jumper ConnectionsInter-connect
FiberOptic
Terminal
Fiber closureLGX panel– top view
EquipmentJumpers (4)
MIC cable12-, 24-, 72-fiber, etc.
Fiber opticconnectors
186
Fiber Jumper cross-connect
FiberOptic
Terminal
Fiber X-CJumper
- terminateson front
mic cable- terminateson back ofLGX panel
Fiber closure
LGX panelfacility side
Fiber equipmentJumper
- terminateson rear
LGX panelequipment side
187
Fiber Jumper ConnectionsCross-connect
FiberOptic
Terminal
Fiber closure
LGX panelfacility-side
LGX panelequipment-side
Cross-connect Jumpers (4)
EquipmentJumpers (4)
MIC cable12-, 24-, 72-fiber, etc.
ST connectors
188
Summary• LGX – fiber cable & jumper termination;
allows for fiber cable management.• MIC cable is fire retardant• ST & SC connectors are the most
commonly used in telephony.• Inter-connect & cross-connect are both
used.
189
Tracing an FX circuit through an officeSummary of circuits, signals & equipment
DS1 D4
channelbank
DSX3
DSX3
DS3 M13
MultiplexerDS1
FX circuit
MDF
DSX-1
work prot
Fiber Optic Terminal
DS3
DSX-1
DSX-1
DS1 DS1
DACS
matrixDS0
DSX-1
LGX
LGX
Outside Plantfiber cable
Fiber jumpers
Over network to ‘foreign exchange’
for dial tone
190
Wave Division MultiplexingWDM
Fiber Optic Terminal #2Rx
Fiber Optic Terminal #1Rx
Fiber Optic
Terminal #2
Tx
Fiber Optic Terminal #1
Tx WDMDevice
WDMDevice
Office A Office B
WDM is used to place multiple wavelengths of light on a single fiber.
+
191
Wave Division MultiplexingWavelengths of Light
Fiber optic lasers traditionally operated at 1310 nm, 1550 nm.Dense Wave Division Multiplexing uses finer increments
of wavelengths – 0.1 nanometers.DWDM uses wavelengths such as 1557.1, 1557.2, 1557.3,1557.4, and higher.
Wave length(s)
Nanometers – nm
Lambda - λ
192
Basic Wave Division Multiplexing
Fiber Optic
Terminal #2
Tx
Rx
Fiber Optic
Terminal #1
Tx
Rx
Fiber Optic
Terminal #2
Tx
Rx
Fiber Optic
Terminal #1
Tx
Rx
WDMDevice
WDMDevice
WDM - passive devices,no power required
Fiber optic cable Between telephone
offices
1310 nm 1310 nm
1550 nm1550 nm
Not shown are the fiber termination panels, etc.
Office A Office B
Requires ONLY four fibers, NOT eight fibers.
Both 1310 nm and 1550 nm light signals are on same fiber in one direction.
Only the Working side is displayed.
λ−1 λ−1
λ−2 λ−2
193
DWDM – Four wave length systemRequires only four fibers, not sixteen fibers.
Only the Working side is displayed.
F.O.T.#1 1557.1 Tx
F.O.T.#2 1557.2 Tx
F.O.T.#3 1557.3 Tx
F.O.T.#4 1557.4 Tx
F.O.T.#1 1557.1 Rx
F.O.T.#2 1557.2 Rx
F.O.T.#3 1557.3 Rx
F.O.T.#4 1557.4 Rx F.O.T.#4 1557.4Tx
F.O.T.#3 1557.3Tx
F.O.T.#2 1557.2Tx
F.O.T.#1 1557.1Tx
F.O.T.#4 1557.4Rx
F.O.T.#3 1557.3Rx
F.O.T.#2 1557.2Rx
F.O.T.#1 1557.1Rx
4-inputWDMDevice
4-inputWDMDevice
Transmitter and receivers must be matched properly.
Office A Office B
194
DWDM – 8 wavelength system
1557.1
1557.2
1557.3
1557.4
1557.5
1557.6
1557.7
1557.8
1557.1
1557.2
1557.3
1557.4
1557.5
1557.6
1557.7
1557.8
8-input WDM device
F.O.T.Transmitters
8-input WDM device
F.O.T.Receivers
Only one direction of the working sides shown.Requires only four fibers, not thirty-two fibers.
Office A Office B
195
Summary
• Wave Division Multiplexing is used to addanother fiber optic system to the same set offibers, but with optic cards with differentwavelengths.
• DWDM adds many fiber systems to thesame set of fibers, with optic cards only0.1 nm apart in wavelength.
196
Wideband DCSDS3, SONET fiber input, DS1 cross-connect
DS3
DS3
DS3
DS3
DCS3/1
DS3
DS3
DS1 cross connects in 3/1 DCS
DS1 cross-connects
in matrix
Port cards
SONET Fiber optic interface
OC-1, OC-3, OC-12
Verizon approvedTellabs Titan 5500
-‘Grooming’ DS1 circuits from one port to another.- Reduces back-to-back equipment.
197
Tellabs Titan 5500SONET 3/1 DCS
198
Titan 5500 unit shelfDS3 input
199
SONET Fiber optic interface
OC-1, OC-3, OC-12
SONET Broadband DCSDS3, SONET fiber input, DS3 cross-connect
DS3
DCS3/3
DS3
DS3
DS3 cross connects in 3/3 DCS
DS3 cross-connects
in matrix
Port cards
‘Grooming’ DS3 circuitsfrom one port to another.
200
Summary• Wideband DACS – DS3/fiber input, DS1 cross-
connect; management of DS1 circuits.• Reduces the need for M13 multiplexers,
DSX-1 jack panels, etc.• Broadband DACS – DS3/fiber input,
DS3 cross-connect; management of DS3circuits.• Reduces the need for fiber optic terminals;
allows direct interface of fiber optics.• Reduces the need for DSX-3 jack panels.
201
Microwave RadioPoint-to-Point Radio Transmission
202
Microwave RadioPoint-to-Point - DS1 & DS3 circuits
Telephone Office
Telephone Office
2 – 11 GigaHertz Microwave carrier
frequencies
Waveguide
Parabolic Dish Antenna
Tower structure
203
Microwave Radio Waveguide
DS3
DS3
MicrowaveRadio
Terminal
DSX-3Panel
coaxialcable
Waveguide
Parabolic Dish Antenna
3-DS3 maximum per radio Tower structure
204
Microwave Radio Equipment
Radio/Antenna Interface - Rigid Waveguide
Telephone OfficeWave guide
Ports
Tower structureMW RadioEquipment
DS1 or DS3Inputs
205
Microwave RadioFrequencies & Distances
• 2 GHz – now used for PCS.Existing systems - grandfathered
• 6 GHz – 11 to 30 miles• 11 GHz – 3 to 15 miles• 18 GHz – 0 to 5 miles• 38 GHz – across the street Typically, transmit power is only
one Watt.Microwave dishes are from 2 – 15 feet in diameter. The larger the dish, the higher the gain, hence greater distanceis achieved.
206
Microwave Radio
Telephone Office Telephone
Office
Passive Reflector
Reflectors are used to bounce microwave beam over or
around an obstruction.
207
Summary
• Microwave Radio – used to transport telephony signals in lieu of fiber cable; over mountains, bodies of water, etc.
• Both DS1 and DS3 circuits are transported
208
Digital Loop CarrierExisting copper plant
600-pair ‘Feeder’ cable
450 homes
100-pair feeder cable
500-pair feeder cable
75 homesDistribution cables
Distribution cablesTelephone
Office
209
Digital Loop CarrierDLC added in growing subdivision
600-pair ‘Feeder’ cable
450 homes
100-pair feeder cable
500-pair feeder cable
75 homes
300 new homes
DLC
Distribution cables
Distribution cablesTelephone
Office
210
Digital Loop CarrierDLC distribution cable
& span cable added
600-pair ‘Feeder’ cable
450 homes
100-pair feeder cable
500-pair feeder cable
75 homes
300 new homes
DLCExisting
distribution cable
New T1 ( or HDSL) span cable
New DLCdistribution cable
Distribution cables
Distribution cablesTelephone
Office
211
Digital Loop CarrierDLC is cutover; old feeder cable is
free to be reused
600-pair ‘Feeder’ cable
450 homes
100-pair feeder cable
500-pair feeder cable
75 homes
300 new homes
DLC
New T1 ( or HDSL) span cable
New DLCdistribution cable
Existing 100-pair feeder cablecan be reused for other customers
Distribution cables
Distribution cables
New distribution cablesfor another subdivision
Telephone Office
212
NGDLCNext Generation Digital Loop
Carrier
DLC cabinetCross-connect
cabinet
Concrete pad
• POTS• Special Circuits - ISDN, FX, etc.• Hi-caps• ADSL
Fiber or copper DS1’s to central office
To provide telephone services to areas where it would be economically unfeasible to place copper cable.
AFC AccessMax (formerly UMC-1000A), Alcatel Litespan,Zhone (formerly Nortel) AccessNode,Lucent SLC-96, SLC-5, SLC-2000Marconi DISC*S (Reltec), and others.
213
Digital Loop Carrier cabinet site672 lines maximum
Outside plant cable
Cross connect cabinet
Digital LoopCarrier cabinet
AC Powercabinet
Generator
214
Walk-in Cabinet672 to 2688+ lines
215
Walk-inCabinet
Digital Loop Carrier equipment (lines) directly cabled to protectors. ProtectorsCabled to external cross-connect cabinet – no blocks, no jumpers required in DLC cabinet.
DLC bays Protectors
216
DLCDigital Loop Carrier
Universal arrangement
Line bayMDF
Central Office DLC
Fiber optics or copper DS1’s
672 lines
240 lines
672 linesDLC cabinet
COT - Central Office Terminal
Cross-connectcabinetJumpers
Central office / remote
217
DLCDigital Loop Carrier
Direct interface into switch
DS1 port bay Central Office DLC
Fiber opticsno lines
672 linesDLC cabinet
Cross-connectcabinet
4-6 DS1 connections
Host central office
Copper span linesLine termination shelf
4-6 DS1 connections
DS1interfaces
672 linesDLC cabinet
218
Main Distribution Frame inDLC’s & walk-in cabinets
• Equipment Protection– Protectors
• terminate the lines from the equipment• provide lightning protection on the equipment
– Blocks– terminate the outside plant pair– also used in walk-in cabinets
Cable pair
Protector
Line equip. jumper Equipment cabling
Terminal blockDLCline
equipment
219
Digital Loop Carrier DLC is telephone line
equipment placed inan area where it ismore cost effectivethan placing copperfacilities to the area.
Inter-cabinetcabling
Fiber cableto central office
Cross-Connect cabinet
DLC
protectors
Fibertermination
panel
terminals
jumpers
800-pairEquipment
Side
1600-pairField side
Ground rodsfor ground field
OutsidePlant
distributioncable
220
ADSLAsymmetrical Digital Subscriber
Line
ADSL
Telephone Office
One cable pair
Basic phone circuitAnd
Digital Subscriber Line for High Speed Internet ServiceOn
221
Asymmetrical DigitalSubscriber Line
ADSL
Frequency
4kHz 140 KHz 1.1 MHz
ADSLUpstreambandwidth
ADSLDownstreambandwidth
POTS
Signal level
20 kHz
High speed internet withphone both working at same time.
Signal versus Frequency
Cable Pair Spectrum
222
Basic phone circuit – before ADSL
LC
LineBlock Protector
Main DistributionFrame
Cable PairLine cabling
LC-line card
Jumper
RegularNID
Telephone OfficePOTSLine Bay
223
Basic phone circuit - with ADSL
SplitterNID
LineBlock
POTSLine Bay Protector
Main DistributionFrame
Cable PairLine cabling
ADSLSplitter Block
ATU-R
Jumpers
DS1 to Frame Relay
switch Ethernet connection
Fujitsu SpeedportADSL
ATU|
C
Telephone Office
LC
xLC=xDSL line card
224
Fujitsu ADSL shelf
Jumper to line circuit, andjumper to cable pair
48 circuits per shelf.16 circuits per splitter block.3 splitter blocks required per shelf.
MDF-mountedsplitter block -passive electronics
Newer installations use rack-mounted splitter
225
ADSL Service Offerings• Bronze CIR=10 kbs
256 kbs downstream / 64 kbs upstream• Silver CIR= 32 kbs
384 kbs downstream / 384 kbs upstream• Gold CIR = 64 kbs
768 kbs downstream / 768 kbs upstream• Platinum CIR = 192 kbs
1.5 Mbs downstream / 768 kbs upstream• Platinum Plus - Multi-User CIR=384 kbs
1.5 Mbs downstream / 768 kbs upstreamCIR = Committed Information Rate
226
frequency
4kHz 140 KHz 1.1 MHz
Upstream Downstream
POTS
Signal level
20 kHz
‘Weak’ frequency in cablepair
ADSL “carriers” or “channels227 maximum carriers
3 kHz spacingbetween carriers
‘Carriers’ used by ADSLto send high-speed digital bit stream
0 kHz
QAM – Quadrature Amplitude Modulation.2-8 bits per carrier.
Bit rate64 Kbs-768 Kbs
Bit rate256 Kbs-1.5 Mbs
227
ADSL Components atCustomer Premise
RJ48 ADSL Data
RJ11 Voice
6 Line Protector
Network Interface Card
Power Supply
Homerun RJ48 if Customer has second line.
CAT 5 Patch Cable betweenRJ48 and Modem
CAT 5 Patch Cable betweenModem and NIC card in PC
RADSL Modem
Test Boardin C.O.
228
G.LiteUniversal ADSL
Universal ADSL or G.Lite• Lower bit-rate & lower frequency ADSL service
– 1.5 Mbs downstream / 384 kbs upstream
• Splitter-less NID• Works through special
line card in existingline bay.
G.LiteRegularNID
Cable pair
4kHz140 KHz
1.1 MHz
POTS
20 kHz0 kHz
Upstream Downstream
550 KHz
Microfilter
229
G.Lite
G.LiteUniversal ADSL
xLC
RegularNID
LineBlock Protector
Main DistributionFrame
Cable PairLine cabling
xLC=xDSL line card
2-wirejumper
D-BIC- Splitter-less, lower bit-rate ADSL- 1.5 Mbs downstream- 384 kbs upstream- Standard protocol - works with any vendor’s ADSL equipment- Small modification to line bay
DS1 to Frame Relay
switch
Modificationto Line bay;
D-BICData-Bus
Interface Card
POTSLine Bay
Microfilter
1-pair
230
Summary
• ADSL – POTS & high speed data oversame cable pair.
• Keeps Internet traffic off of the PublicSwitched Telephone Network (PSTN).
• G.Lite – lower speed & splitter-less versionof ADSL.
231
TIMING - What is it?• Everybody is marching to the same 'beat'
• BITS - Building Integrated Timing Supply– Stable timing source for digital networks
• allows equipment to synchronize or'sync up’ to one reliable timing source sodigital circuits are timed together.
232
TIMING - Why is it?• Required for prevention of Binary Digit Slips• a slip is loss of a block of bits due to
frequency shift, phase shift, etc. betweennetworks.
• causes outages, loss of data, audible clickingon line, facsimile distortions
Original Signal
Bit Slip
233
• Purely analog circuits DO NOT requiretiming.
Timing required for:• D4 channel banks – only for digital circuits• SONET fiber systems• DACS• Digital switch
TIMING - For what equipment?
234
TIMING - How?
• BITS Clock Building Integrated Timing Supply Clock
– accurate & stable clock oscillator– obtains timing from the GPS - Global
Positioning System• GPS distributes a timing reference to
non-GPS sites
235
GPS & BITS Clock
GPS receiveron roof
Coaxial or fiber cable fromroof to timing shelf
power cableto roof mountedreceiver
gathers timing referencesfrom multiple satellites
Stratum 2Clock
GPS satellites
236
GPSAntenna
237
3 clock levels of timing - Stratum Levels
Stratum 2 Stratum 2
GPS
Stratum 3 Stratum 3 Stratum 3
TelephoneOffice
TelephoneOffice
Telephone Office
Telephone Office
Telephone Office
Stratum 1 Stratum 1
GPS
238
TIMING - Stratum levels• Stratum 1 Clock - directly from GPS receiver
– typically put at host offices with Stratum 2– stability – infinite – continuously connected to GPS
• Stratum 2 Clock - stability - 28 days w/out externalinput
• Stratum 3 Clock - stability - 5 days w/out externalinput– typically put at main wire centers other than hosts
• Stratum 4 Clock - stability - less than 24 hours– typically for clocks put on fiber optic cards
239
BITS Clock/Timing Distribution Shelf& GPS Antenna control shelf
240
BITS
“TOTA” output.DS1 outputs
to digital switch, 1/0 DACS, 3/1 DACS,
Broadband DACS,SONET fiber optic
terminals, etc.
Stratum 2Clock
Timing Outputs
“TOCA” outputor ‘composite clock’.
DS0 outputsto channel banks,
ISDN banks, DLC’s.
Coaxial cable or fiber cablefrom roof to timing shelf
GPS Antenna
TOCA Output
TOTAOutput
Power cable toroof mountedreceiver
241
Summary
• Timing – keeping all digital circuits andequipment synchronized together to prevent lossof information.
• GPS – Global Positioning System – an accuratetiming source sent from satellites to a roofmounted receiver.\
• BITS – Building Integrated Timing Supply –supplies accurate timing signals for all equipmentin a telephone office.
242
Power
RectifiersAC to DC Batteries
Power Board
- -- +
+shunt
-48V -48VTo
C.O.equipment
+
Common bus for (+) & ( -)
-48VAC
AC
DC DC
c.o. ground bus
Fuses
meters
Output power:large office - 600-10,000+ Amps @ -48 VDCsmall office - 100-600 Amps @ -48 VDC
Input power:- 120/240 Volts-AC - 208 or 440 Volts-AC 3-phase
243
Main Power Board
4 main fuses (600 Amp) - for feeding secondary power boards
Distribution:32 ‘A’ fuses (30 Amp)32 ‘B’ fuses (30 Amp) - for feeding fuse panels in equipment bays.
244
POWERMain Power Board
• measures voltage & current used by office– Shunt - measures current - ammeter
• provides main fuses to powersecondary distribution boards
• may provide distribution fuses fortransmission racks (remote)
• provides a 'battery return' bus forbattery grounds
Shunt
Voltage Current
Fuses
245
Shunt – used to measure office current
Shunt - Measures current by measuring voltage. - provides protection for power plant - plates heat up & fall out or burn up Measured Current = Voltage drop across shunt Resistance plates - known, accurate
individual plates
246
POWERSecondary Power Distribution
BoardsSwitching – PDC
- Power Distribution Center– located in switching lineup
Transmission - BDFB - Battery Distribution Fuse Board– located in transmission equipment area
Voltage Current
247
Nortel SwitchingPDC
Power Distribution Centerfor digital switch
248
POWERTransmission Distribution Power
Board• provides secondary power distribution
to transmission racks• may be fuses or breakers• A & B sides - 2 Shunts, 2 voltmeters,
2 ammeters• powers A & B battery & ground to
fuse panels with 2 power inputs• distribution fuses typically 10 to 30 Amp
• requires two 600-Amp fuses from MainPower Board for diversity protection
A-side
B-side
Voltage Current
shunt shunt
Fuses or breakers
249
Main Power Board feedingTransmission Power Board
Main Power Board
Transmission Power Board
‘A’ side
‘B’ side
BDFB
shunt
Voltage Current
To TransmissionRacks to Powerfuse panels.
30-70 Amp fuses / breakers600 Amp fuses
Voltage Current
shunt shunt
-48V
250
Power DistributionDual power feeds with ground
BDFB
-48V
‘A’ side
‘B’ sideEquipment
Rack
BDFBGround Bar
Battery plant Ground Bar
TelephoneEquipment
Fuse panel
Main Power Board
Ground leadsGround
cable
shunt
Voltage CurrentVoltage Current
Shunt Shunt Shunt
251
TransmissionDistributionPower Board
Meter Panel for A & B sides30 Amp breakers
A side Distribution
B side Distribution
Power cablesFeeding powerBoard, and Powering otherEquipment.
252
Remote buildingPower Boardwith Rectifiers
Two Rectifiers,100-Amp each- Load not toexceed 100
Amps (Maximum load
+1 rectifier)
Meter panel
Main Distribution panelSecondary Distribution panel
Shunt panel
Secondary Distribution panel
253
Batteries
RectifierAC to DC
Batteries Power Board Main or Distribution
- -- +
+-48V -48V
ToC.O.
equipment
+
Common bus for (+) & ( -)
-48VAC
AC
DC DC
3-hour backup with Generator8-hour backup without Generator
C.O. ground bus
Shunt
Voltage Current
254
Batteries24 Cells-48 Volts nominal-52 Volts Charge
voltageWet Cell -
lead calcium 20 -25 year life
255
Batteries- Sealed ‘Dry’ cells- Valve Regulated- GNB “Absolyte” has Absorbent glass mat.- 20 year life
256
Backup Generator• provides electrical power to run the office in event of A/C
power failure - typically 7.5 kW to 60 kW units
• larger sizes for main central offices – 250kW to 750kW+
• runs on propane (older installations) or diesel fuel (newerinstallations.
Shown is a365 kW dieselGenerator.
257
AC Transfer SwitchCommercial AC Power
Backup Generator
AC Load
Automatic Transfer Switch
To: rectifiers air conditioning lights
Normal
Emergency
258
GroundingKeep People & Equipment Safe from Lightning
4 Grounding Elements:– Producers– Absorbers– Isolated Ground Zone - IGZ– Non-Isolated Ground Zone - Non-IGZ
259
Grounding
Producers – anythingthat allows lightninggets into a telephoneoffice.– sheath of cables
entering office– firing point of protector
modules– radio towers
Outside plantCopper cable
MDF protectors
Grounding pointsconnected to ground bar
260
Grounding
Absorbers – anythingthat absorbs alightning surge.– ground field around
office - 5 ohm grounddesired
– building structure /metal water pipes
Telephone Office
Ground field/ring – 8-foot deep ground rods buried 8-feet apart
261
Grounding
• •
• •
• •
• •
Producer Absorber Non-IGZ IGZ
Master Ground Bar – MGB
262
Master Ground Bar - MGB
Producers Absorbers Non-IGZ IGZ
P.A.N.I. bar
263
GroundingIGZ
IGZ - Isolated Ground Zone– All cards in equipment bays are isolated from
the bay ironwork.Digital switch has a separate IGZ bus bar -
Ground Window Bar - GWB– GWB connects to IGZ zone on MGB
• •
• •
Ground Window Bar - GWB
MGBTo IGZ(digital switch)
264
GroundingNon-IGZ
Non-Isolated Ground ZoneTransmission equipment:
– May not have the cardsisolated from the shelves
– May not have the shelvesisolated from the bays
– i.e. the cards & shelves maybe grounded to the ironworkwhich violates the IGZ concept
TransmissionEquipment
Fuse panel
TransmissionEquipment
Rack
Cardsshelf
265
OSP fiber cable
MDF
ISDN
M13 Mux Fiber Optic System
Dig
ital s
witc
h
LGX
D4 ChannelBank
HDSL
DS1 line termination shelf
DSX-3DSX-3
DS1
DS1
DS1
DS1
DS1
DS1
DS1
HDSL DS1
Span powered DS1 (T1)
VF signal
2B + DBRI
DS3
DS3
fiberjumpers
coaxialcable
coaxialcable
OutsidePlant cables
DSX-1DSX-1DSX-1
DCS1/0
Central Office Layout