Post on 06-Nov-2015
description
CETTM MTNL
1TRANSMISSION OVERVIEW
TRANSMISSION OVERVIEW
MODULE ID: TGENOVT001
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Introduction to Transmission NetworksTransmission Media PCM & Higher Order MultiplexingTransmission SystemsSDH Concepts WDM BasicsMPLS BasicsMLLN
Topics
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Signal: Physical magnitude specific for each medium, change with respect to timeTransmission medium: consists of links that connect nodesNodes : Network elements that receive/retransmit further until reaching final usersInformation : Consists message exchanged between final users ,coded as signalsAnalog signal: can take an unlimited number Of values within a given rangeDigital signal: Take limited number of values.
Key Terms
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Message signal
Transmitter Medium Receiver Out put
signal
Transmission System Architecture
The telecommunications network transmits a variety of information, in two basic forms, analog or digital from one place to another
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Advantages of digital communication
Improved signal to Noise RatioCompatibility of different media,trafficNo additional interference as noiseEconomyNovel facilities and sevicesApplicability in extremely difficult transmission pathsSimpler equipment (no need of filters)Easy repeatability of design.
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Digital Transmission Systems
Higher Order Multiplex
Higher Order Multiplex
TERMINAL
TERMINAL
CCITT Interface
CCITT Interface
Media
Line (Coax cable)
Optical fiber
Satellite
Digital Radio
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Problems of legacy media
Bandwidth and capacity limitationsAttenuation, cross talk, noise ,distortionElectromagnetic interferenceWire separation limits to achieve distortionless condition in /wire, ug cablesRequirement of filters,line and office repeaters , ccps,(repeater spans 1.5 km in case ug cable pairs, 4.5 km for cxl cablesFading , reflection, absorption ,line of sight problems in case of microwaveHigh initial cost of Satelite, royalty for RF
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Microwave System Configuration
Base BandTx Unit
SupervisoryChannels
Modulator UpConverterBRANCHING
UnitDownConverterDemodulator
Tx1
Tx2
Rx2
Rx1
FromMUX
Base BandRx Unit
ToMUX
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Classification of O F CableBased on material usedGlass Fiber & Plastic clad Silica
Based on Size or ModeMulti mode - Large core dia..50/62.5/85/100
umSingle mode - Small core dia (8/9/10 um)
Based on Refractive IndexStep Index - Uniform R.I for the coreGraded Index - Non uniform R.I for the core
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Frequency division multiplexing
Process of translating individual speech circuits into pre assigned frequency slots within the bandwidth of the transmission medium
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TIME DIVISION MULTIPLEXINGTDM Involves Sharing of the Transmission medium by a Number of Circuits in TIME DOMAINThis can be achieved by establishing a sequence of Time Slots (periods) during which Individual channels (circuits) are Transmitted
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Modulation
Modulation is the process of varying one waveform in relation to another waveform
Three types of modulation are Analogue modulation Digital modulation Pulse modulation
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Modulation of Digital Signal
ASK (Amplitude Shift Keying) FSK (Frequency Shift Keying) PSK (Phase Shift Keying) QAM (Quadrature Amplitude Modulation)ASK:Amplitude Shift Keying)
The amplitude of the carrier is changed with respect to the input digital signal [ 0 or 1 ].Similar to ON/OFF Keying.Causes more errors
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Amplitude Shift Key Modulation
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Frequency Shift Key, Phase shift keying
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Pulse Code Modulation(PCM) Conversion of Analog signal into Digital
Binary format is called PCMStages of PCM: Filtering..................limiting freq band to 4khz Sampling...............PAM sampling 8000/SE
Quantizing.............Assigning quantity to amplitudes read.
Encoding/Decoding Binary conversion Line Coding.............HDB3+/AMI/CMI
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Frame & MultiframeFrame The Collection of one sample from each channel
is called a Frame. Total frames :15 Thus the set of first Samples of all channels is
one frame, the set of Second Samples is Second frame, and so on.
The duration of a frame is 125 micro seconds One additional frame to carry sync data(MFAW)Multi frame A group of 16 frames is formed to make a
Multiframe. The duration of a multi frame is 2 milliseconds.
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2 Mbps Frame Structure
Signaling information
32 Time slots in 125 s
Frame Alignment Word (FAW)
Samples from Channels 1 to 15 Samples from Channels 16 to 30
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
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Multi Frame Structure
Ch 30
Ch 16
S Ch 30
S Ch 15
Ch 15
Ch 2
Ch 1
ALM &
Supy
F15
Ch 30
Ch 16
S Ch 29
S Ch 14
Ch 15
Ch 2
Ch 1FAW
F14
Ch 30
Ch 16
S Ch 18S Ch 3
Ch 15
Ch 2
Ch 1
ALM &
SupyF3
Ch 30
Ch 16
S Ch 17S Ch 2
Ch 15
Ch 2
Ch 1FAWF2
Ch 30
Ch 16
S Ch 16S Ch 1
Ch 15
Ch 2
Ch 1
ALM &
SupyF1
Ch 30
Ch 16
MFAW ALMMFAW
Ch 15
Ch 2
Ch 1FAWF0
B5-B8B1-B4TS31TS17
TS16TS15TS2TS1TS0
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Frequency 2048Kbps 50ppm. (HDB3 coded)
Pulse shape All masks of a valid signal conform to the pulse mask given in ITU-T G.703, irrespective of the sign. The value V corresponds to the nominal peak value.
Type of pair Symmetrical pair.
Test load impedance 120 Ohms resistive.
Nom, peak voltage of a mark (pulse) 3.0 V.
Peak voltage of a space (no pulse) 0 0.3 V.
Nominal pulse width 244 ns.
Ratio of the amplitudes of positive and negative pulses at the centre of the pulse interval
0.95 to 1.05
Ratio of the widths of positive and negative pulses at the nominal half amplitude.
0.95 to 1.05
Max. peak to peak jitter at an output port
As per Para 2 / ITU-T Rec. G.823.
2.048 MBPS G.703 INTERFACE
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O F System Composition
Fibre Optics Transmission System (FOTS) comprises of the following sub systems
Digital multiplex sub systemOptical line transmission systemCentral supervisory systemTrans multiplexer sub systemAlarm sub systemPower supply sub system
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C 12 VC 12 TU 12 TUG 2X 3
X 7
2 Mb
C26.3 Mb VC 2 TU 2X 1
X 7
X 3
C 3 VC 3 TU 3 TUG 334 Mb
C 4 VC 4 AU 4 AUG STM-NX N140 MbX 1
C 3 VC 3 AU 3X 334 Mb
SDH Multiplexing
C111.5 Mb VC 11 TU 11
X 4
SDH Multiplexing
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SDH Frame Structure
1
3
5
9
4
270270 Columns (Bytes)
1 9transmitrow by row
RSOH
MSOH
AU Pointer Payload(transport capacity)
RSOH: Regenerator section overheadMSOH: Multiplex section overheadPayload: Area for information transport
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SDH System Types
TypesSTM-1 ----
STM-4 ----
STM-16 --
STM-64 --
Bit Rates Chl. Capacity155.520 Mb/s --- 1890 Chls
622.080 Mb/s --- 7560 Chls
2488.32 Mb/s --- 30240 Chls
9953.28 Mb/s --120960 Chls
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IntegratedIntegrated
DWDM Mux
G.692G.692
OpenOpen
OTU
G.692G.692155MSDH155MSDH622MSDH622MSDH2.5G SDH2.5G SDH10G SDH10G SDH
PDHPDHIP
ATMATM
155MSDH155MSDH622MSDH622MSDH2.5G SDH2.5G SDH10G SDH10G SDH
PDHPDHIP
ATMATM
DWDM System inputTransponderTransponder
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Mainframe
Mainframe
Server
Server
Storage
Storage ESCON/FICON
Metro DWDM
DWDM Application for Data Centre
Data Centre Interconnection
Fiber Channel
Storage Area Network (SAN ) on DWDM
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Basic Working Process of MPLS
Core LSR
IP IP L1 IP L2 IP L3 IP
Traditional IP forwarding
Traditional IP forwarding Label forwarding
Edge LSR Edge LSR
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Architecture of a MLLN
V-MUX MODEMDACC
Provides fully secure data communication serviceEnd to end circuit creation and monitoringcircuit loop test and fault isolation,Alternate re-routing of traffic,Software programmability of NTUsFully Managed Access Network
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MLLN Network
DACC
DACC
DACC
V-MUX
V-MUX CUSTOMER
CUSTOMER
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Summary We have seen different Transmission Technologies and media
Transmission is in transition phase where we are migrating from circuit switching technologies like SDH to Packet switching technology like MPLS Future transmission system will be based on optical switching like OTN ( Optical Transport Networks )
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