[Project Name] Post-Mortem

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SDH/SONET
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The Digital Revolution
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Analog Signal Transmission
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Digital Signal Transmission
The Solution

• Convert all signals to digital
• Employ time division multiplexing (TDM)

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11 000 000 000!
How to convert speech to a sequence of ones and
zeros
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Pulse Amplitude Modulation - PAM
a Amplitude t Time
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Pulse Code Modulation - PCM
Designated to Carry Digitized Voice (Based on 4
kHz Channels in ATTs FDM Hierarchy)
Step 1
Sample analog signal at 8 kHz
Results Pulse Amplification Modulation
Step 2
Digitize PAM samples to 13 (or 14) bits and
compress to 8-bits using A-law or m-law tables
Results Pulse Code Modulation
Transmission Requirement 8,000 samples/second
8-bits 64 kbps 1 octet/125 msec
FDM Frequency Division Multiplexing
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Pulse Code Modulation - PCM (Cont.)
Transmit Side
Receive Side
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CODEC Quantizing - USA
The Formula
The North American standard for assigning and
decoding a signals amplitude is m-law 255. This
law defines how many quantizing levels are used
and how they are arranged
m 255 (compression parameter)
Character Signal Binary Code
Curve of m-Law Compander
This is the bit pattern transmitted for
positive input values. The left-most bit is a 0
for negative input values
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CODEC Quantizing - Europe
The European standard is the A-law and its
formula is
A½c½ 1 1n (A)
1 ½nA½c½ 1 1n (A)
F (c) sgn (c)
F (c) sgn (c)
when
and
when
Character Signal Binary Code
Curve of A-Law Compander
For positive input values. The left-most bit is
a 0 for negative input values. Even bits
(beginning with 1 at the left) are inverted
before transmission
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Network Evolution
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Time Division Multiplexing
For Analog Signals
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Time Division Multiplexing
For Digital Signals
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T1 Frame Structure
Extended Superframe Frame Format
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PDH The Plesiochronous Digital Hierarchy
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Plesiochronous Drop Insert
Add/Drop operation requires complete demultiplex
NG to locate A channels bits
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The Add/Drop Operation
New Technologies

• Very tight synchronization
• Use pointers to locate channels

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Frame Format
64 kbps - - - - - - 64 kbps
130 or 31
31 . . . . . . . . . . . . . . . .
. . 0
PCM 30
Voice withCAS SignalingApplications
30 64 kbps 1.920 Mbps Signaling (Timeslot
16) 0.064 Mbps Framing (Timeslot 0) 0.064
Mbps Total, E1 2.048 Mbps
Data ApplicationsorCCS Signaling
31 64 kbps 1.984 Mbps Framing (Timeslot
0) 0.064 Mbps Total, E1 2.048 Mbps
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E1 - The European Digital Revolution
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What is E1?
A high speed digital communications link that
enables the transmission of voice, data, and
video signals at a rate of 2.048 Mbps

• Initially designed for transmission of 30
  telephone channels
• Basis for design PCM voice digitizing using 64
  kbps for each channel
• The E1 frame consists of 32 8-bit channels
  (timeslots) 32 8 256 bits/frame
• E1 frames are transmitted at the rate of 8,000
  frames/s 256 8,000 2,048 kbps
  or 2,048 Mbps

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What is E1? (Cont.)

• Serial synchronous bit stream at 2.048 Mbps
• Specifications defined in CCITT recommendations
• G.704/G.732 Frame definition (for framing
  over E1 and T1)
• G.703 Interface physical specs (pulse mask,
  etc.)
• G.823 Jitter requirements
• Interface (G.703) - two alternatives
• 4-wire, balanced120W, pulse 3.00 volts nominal
• 4-wire, unbalanced, 2 coaxial connectors75W,
  pulse 2.37 volts nominal

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HDB3 Coding
Alternate Mark Inversion
HDB3 (High Density Bipolar of Order 3)
0000 gt 000V or
B00VSo that violations alternate polarity
HDB3Code
HDB3Decode
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Frame Format for E1
1 Frame 256 bits (125 ms)
Bit Rate 2.048 kbps
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E1/T1 Error Conditions
Principal T1/E1 Alarms
Red Alarm (FAS Loss)
Produced by a receiver to indicate that it has
lost frame alignment
Yellow Alarm (RAI)
Returned to a transmitting terminal to report a
loss of frame alignment at the receiving terminal
Normally, a T1/E1 terminal will use the
receivers red alarm to request that a yellow
alarm be transmitted
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E1/T1 Error Conditions (Cont.)
Blue Alarm (AIS)
A continuous ones pattern without
framing,indicates an upstream failure
Loss here
Blue (AIS)
Red (LOF)
T3/E3 MUX
T1/E1 MUX
Yellow (RAI)
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Principal Error Conditions
Loss of Carrier
Receive data was 0 for 31 consecutive bits
Bipolar Violation
A failure to meet the AMI T1 line code
F Bit Error
Framing bit is in error
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T1 - The American Digital Revolution
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T1 Frame Format
ATT - 1957
DS 1
CH 24 . . . . . . . . . . . . . .
. . . . . . . . 1
8 bit PCM Codes 24 Channels 1 Framing Bit
193 bits (Overhead)
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D4 Channel Bank
DS 1 1.544 Mbps
193 bit, 125 ms

• Voice sent as 8-bit codes
• Signaling by having the 8th bit (every 8th frame)
  indicate loop open or loop closed
• Framing based on placing a 12-bit pattern in the
  framing bit (193rd bit)

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T1 Frame Structure
Extended Superframe Format
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Line Code - Bipolar, 50 RTZ

• To guarantee 0 DC element on the line, bipolar is
  used
• To eliminate high frequency components that can
  interfere with other transmissions, digital
  services utilize 50 duty cycle, known as

Alternate Mark Inversion (AMI) (Mark Logic 1)
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Bipolar Violations
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T1 Standard
ANSI T1.403 - 1989

• Line Rate 1.544 MHz
• Cable Length 6.000 ft max.
• Pulse Amplitude 2.7 to 3.3 V
• Maximum Successive Zeros 15
• Receive Attenuation 15 to 22.5 dB
• Line Build Out 0.0, 7.5, 15 dB

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T1 Summary

• Serial Synchronous Bits Stream at 1.544 Mbps
• Timeslot 8 bits
• 24 Timeslots 8 24 192 bits
• Frame 24 T.S. 1 Framing Bit 192 1 193
  bits
• Sampling Rate 8.000 samples/sec
• T1 Bit Stream 8.000 Frames (192 bits/frame 1
  bit/frame) 1.536 Mbps 0.008 Mbps (framing)
  1.544 Mbps
• Line Code AMI (50 Duty Cycle) or B8ZS (for clear
  channel)
• Synchronization From Line
• Interface 4-wire, Balanced, 100 W, RJ-45
  Connector (or dB-15)

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SDH/SONET
Synchronous Digital Hierarchy Synchronous Optical
Network

• Developed as a result of PDH inability to cater
  for new digital data transmission requirements
• Evolved as a joint world-wide standardization
  effort (ITU-TANSI)
• Few differences still exist between European
  (ETSI) SDH and North-American (ANSI) SONET
• Had to accommodate older PDH systems that are
  still operating

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The Hierarchical Network
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The Transmission Equipment Hierarchy
PDH
SDH
Core, Backbone 565 Mbps Fiber 2.5 Gbps OLS
Trunk, Long 140 Mbps Fiber 2.5 Gbps
ADMDistance 140 Mbps Radio 155M Radio 34/14
Mbps Multiplex 4/4 DXC Regional, Urban, 140 Mbps
Fiber 2.5 Gbps OLS Metropolitan 34 Mbps Fiber 2.5
Gbps ADM 34 Mbps Radio 622M OLS 34/140
Multiplex 622M ADM 2/34 Mbps Multiplex 155M
Radio 4/3/1 DXC Local Junction, 8 Mbps
Fiber 622M OLS Access 4 ? 2M Radio 622M ADM 2M
Radio 155M ADM 2/8 Multiplex Access Flex
Mux Primary Multiplexer Channel Bank Access
Multiplexer
?4
Equivalent Capacity
?4
?4
2M
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SDH/SONET Bit Rates
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The SDH Add/Drop Operation
New Technologies

• Very tight synchronization (very few slips)
• Uses pointers to locate channels

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The STS-1 Frame (52 Mbps)
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The STM-1 Frame (155 Mbps)
Frame Period 125 ms
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VC-4/AU-4 Mapping to STM-1 Frame

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STM-1 Structure
VC-4 Payload
SOH
Seat on the Carriage Tugs
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Populating the Seats in the Carriage
TUG2 Seats
One LargePassenger ? VC2
Three SmallerPassengers ? 3 VC12
Four Even SmallerPassengers ? 4 VC11
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STM-N Frame Structure
270 N Columns (bytes)
9 N
261 N
9 rows
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STM-Nc - Concatenated Frame Structure
270 N Columns (bytes)
10 N
260 N
9 rows
Payload Overhead. N 1 Columns. One Column -
Real Payload Overhead. Others - Fixed Stuff
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Multiplexing of N AUGs into STM-N
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STM-1 SOH
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Ring In Interoffice Application
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Network Management
New Technologies

• Embedded overhead channels (EOC) for management
  messages
• Uses standard communications protocols

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SDH Standards

• G.651 Multimode Fiber Specification
• G.652 Single Mode Fiber Specification
• G.700 Framework of the G.700, 800, 900 Rec.
• G.701 Vocabulary of Terms
• G.702 Digital Hierarchy Bit Rates
• G.703 Physical/Electrical Characteristics
  Interfaces
• G.704 Synchronous Frame Structures Primary
  Secondary Levels
• G.705 Characteristics - Terminate Digital Links
  on a Digital Exchange
• G.707 Network Node Interface for SDH Incl.
  Multiplexing Structure
• G.774.04 SDH Management for SNC Protection for
  the NE
• G.780 Vocabulary of Terms for SDH Networks and
  Equipment
• G.781 Structure Rec. for Multiplexing Equipment
  for the SDH

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SDH Standards (Cont.)

• G.783 Characteristics of SDH Equipment Functional
  Blocks
• G.784 SDH Management
• G.803 Architectures of Transport Networks Based
  on SDH
• G.825 Control of Jitter Wander in Digital Nets
  based on SDH
• G.826 Error Performance Parameters and Objectives
• G.831 Management Capabilities of Transport Nets
  based on SDH
• G.832 SDH Elements on PDH Networks Frames and
  Multiplexing
• G.841 SDH Protection Rings and Other
  Architectures
• G.957 Physical Parameters for SDH Optical
  Interface
• G.958 Provides overall Requirements for Optical
  Interfaces
• ITU-R Architectures Functional Aspects of Radio
  Relay for SDH
• O.SDH Equipment to Assess Error Performance on
  SDH Interface

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ANSI Standards
Phase I

• T1.105
• Byte interleaved multiplexing format
• Line rates for STS - 1, 3, 9, 12, 18, 24, 36 and
  48
• Mappings for DS0, DS1, DS2, DS3
• Monitoring mechanisms for section, line and path
  structures
• 192 kbps and 576 kbps DCC
• T1.106 - This is an associated standard that
  establishes the optical parameters for the SONET
  standards. Single mode fiber is defined as the
  standard optical transmission medium
• T1.107 - Digital hierarchy format specification

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ANSI Standards (Cont.)
Phase II

• T1.105R1
• SONET format clarification and enhancements
• Timing and synchronization enhancements
• Automatic protection switching (APS)
• Seven-layer protocol stack for DCC and embedded
  operations channels
• Mapping of DS4 (139 Mbps) signal into STS-3c
• T1.117 - Optical parameters for short-haul (2 km)
  multimode fiber cable
• T1.102-199X - Electrical specifications for STS-1
  and STS-3 signals

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ANSI Standards (Cont.)
Phase III

• T1.105.01-1994 - Protection for two four fiber
  bidirectional line switched SONET rings
• T1.105.05-1994 - Tandem connection overhead layer
  for SONET
• T1.105.03-1994 - Jitter for SONET and SONET-PDH
• T1.119-1994 - Management of SONET NE, OSI
  compliant interface
• T1.204 - OAMP lower layer protocols for TMN
  interfaces
• T1.208 - OAMP upper layer protocols for TMN
  interfaces
• T1.214 - OAMP network model for interfaces
  between OS NE
• T1.215 - OAMP fault management messages for OS
  NE
• T1.229 - OAMP performance management messages
  for OS NE
• T1.231 - Layer 1 in-service transmission
  performance monitoring