DSL TECHNOLOGIES

RTTC,HYDERBAD

2Apr 18, 2023

Different technologies

NarrowBand

2.4 kbps – 128kbpsBroadband

256kbps – 8000kbpsLAN

1000kbps – 100Mbps / Giga Ethernet

3Apr 18, 2023

Broadband Technologies

Wireless Wireline

DSL (Digital Sub’s Line)

Cable Modem

Optical Fibre Technologies

PLC (Power Line Communication)

3G Mobile

Wi-Fi (Wireless Fidelity)

LMDS & MMDS

FSO (Free Space Optics)

Satellite

WiMAX

TECHNOLOGY OPTIONS FOR BROADBAND SERVICES

4Apr 18, 2023

Advantages and Disadvantages of ADSL

AdvantagesAlways on

No usage charge

Inexpensive

Fast

No engineer install

“Easy” to set up

Wider coverage as almost every house has a copper pair!

Can use telephone at the same time as being online

Minimum 3 month contract with some providers

Wide choice of products within the ADSL portfolio

Easy to migrate

DisadvantagesMust have a BSNLtelephone line to use ADSL (At the moment!)

Not suitable for servers

Contention issues

Distance limits

Local exchange must be ADSL enabled

DACS can cause problems

Alarms that contact authorities via phone line can be problematic with an ADSL installation

5Apr 18, 2023

Digital Subscriber Lines (DSL) on copper loop

DSL has proved to be an important technology for provisioning of Broadband services through the copper loop. The owners of copper loop have to be given a high priority because their role is critical as key drivers in the Broadband service market using DSL.

BSNL and MTNL as well as other access providers are expected to aggressively use their copper loop infrastructure for providing Broadband services through this technology

6Apr 18, 2023

DSL provides dedicated bandwidth that can be up to 278 times faster than a 28.8 Kbps modem, 143 times faster than 56Kbps modem, 62 times faster than ISDN and up to 4 times faster than a E1 (T1) connection.

That's really fast!

Even better, DSL uses your ordinary phone line but doesn't tie it up -- you can access the Internet while you are using the same line for conversation or faxing.

In addition, you stay connected -- there's no dialing up or waiting for busy signals.

WHAT IS DSL

7Apr 18, 2023

DSL may offer more than 100 times the network performance of a traditional analog modem

DSL uses the same telephone line as traditional modem

DSL remains always-on all the time

Customer no longer need to physically dial up to the ISP to “log in to the internet”

DSL Technology

8Apr 18, 2023

DSL can also be implemented with PPoE (Point to Point Protocol over Ethernet) that does not support always-on. This is required when authentication is necessary.

DSL Technology

9Apr 18, 2023

xDSL-Families

•ADSL- Asymmetric Digital Subscriber Line

•HDSL-High Data Rate DSL

•VDSL-Very high data rate DSL

•IDSL-ISDN DSL

•RADSL-Rate adaptive DSL

•SDSL-Symmetric DSL

10Apr 18, 2023

ADSL

Asymmetric Digital Subscriber Line

ADSL FamilyFamily Description Upsteream

Rate

Downstream Rate

Maximum

range

ADSL G,992.1 / G.DMT 640 KBps 8 MBps 5.5 Km

ADSL Lite G.992.2 / G.Lite 384 KBps 2 MBps 6Km

ADSL2 G.992.3 / G.dmt.bis 1-1.5 MBps 12-16 MBps 5.7 Km

ADSL2 Lite G.992.4 / G.lite.bis

ADSL2 + G.992.5 / ADSL 2 plus 1 MBps 26 MBps 5.7 Km

ADSL2 RE G.992.3 Reach Extended 1MBps 12 MBps 7Km

11Apr 18, 2023

12Apr 18, 2023

ADSL

Asymmetric Digital Subscriber Line

G.DMT / G.992.1 standard

Used for applications which require greater download bandwidth but require relatively little in opposite direction like Web browsing; File downloads

An ADSL circuit connects an ADSL modem on each end of a twisted pair telephone line creating three information channels

A high speed downstream channel

A medium speed duplex channel

A basic telephone service channel

13Apr 18, 2023

ADSL

The basic telephone service channel is split off from the digital modem by splitter at client site

Allows simultaneous access to the line by the telephone and the computer

In case of power/ADSL failure, data transmission is lost but basic telephone service will be operational

Provides

16-640 kbps upstream

1.5-8 mbps downstream

Can work up to a distance of 3.7 to 5.5 kms depending upon the speed required

14Apr 18, 2023

ADSL rates and channel frequency

band allocation in local loop

15Apr 18, 2023

Data Rate - Wire Size – Distance

ADSL

Data Rate Wire Size Distance

1.5-2.0 Mbps 0.5 mm 18000 Feet

5.5 Kms

1.5-2.0 Mbps 0.4 mm 15000 Feet

4.6 Kms

6.1 Mbps 0.5 mm 12000 Feet

3.7 Kms

6.1 Mbps 0.4 mm 9000 Feet 2.7 Kms

ADSL

16Apr 18, 2023

ADSL Transceiver

MUX

ErrorControl

D/A & A/D

LineCoupler

ChannelSeparation

FDMOr

ECH

OutputTo line

DEMUX

ErrorControl

DownstreamChannel(s)

DuplexChannel(s)

DuplexChannel(s)

RCVR

XMTR

BasicTelephone

ServiceSplitter

BasicTelephone

Service

17Apr 18, 2023

HDSL

High bit/data rate DSL

Can be viewed as equivalent of PCM stream

Offers the same bandwidth both upstream and downstream

Can work up to a distance of 3.66 to 4.57 kms depending upon the speed required

Can deliver 2048 kbps

On 2 phone lines, each line carrying 1168 kbps

On 3 phone lines, each line carrying 784 kbps

18Apr 18, 2023

HDSL

No provision exists for voice because it uses the voice band

HDSL-2 is proposed as next generation HDSL over single phone line

Requires more aggressive modulation, shorter distance and better phone line

19Apr 18, 2023

SDSL

Symmetric Digital Subscriber Line

Rate adaptive version of HDSL

Does not support analog calls

Works up to 3.7 kms on 0.5 mm dia cable

Affordable alternative to dedicated leased lines

SHDSL-Symmetric High-bit-rate Digital Subscriber Line is an further improvement over HDSL/SDSL and uses single phone line

20Apr 18, 2023

VDSL

Very-high Data-rate DSL

Also known as BDSL

Originally named VADSL (A –Asymmetric) but was later extended to support both symmetric & asymmetric

Requires one phone line

Supports voice & data

Works between 0.3-1.37 kms depending on speed

21Apr 18, 2023

Upstream data rate of 1.6-2.3 mbps

Downstream data rate of 13-52 mbps

Data Rate - Wire Size – Distance

VDSL

Downstream Upstream Distance

12.96 Mbps 1.6-2.3 mbps 4500 Feet 1.37 Kms

25.82 Mbps 1.6-2.3 mbps 3000 Feet 0.91 Kms

51.84 Mbps 1.6-2.3 mbps 1000 Feet 0.30 Kms

22Apr 18, 2023

IDSL

ISDN DSL-a hybrid DSL/ISDN solution

Works over existing ISDN connection

Increases ISDN speed from 128 kbps to 144 kbps

23Apr 18, 2023

XDSL Modulation

Two types of modulation techniques are used in xDSL Technologies

CAP - Carrierless Amplitude and Phase

DMT - Discrete Multi-Tone modulation

24Apr 18, 2023

CAP Modulation

Carrierless Amplitude and Phase

Closely related to QAM (Quadrature Amplitude Modulation)

QAM generates a DSSC (Double Sideband Suppressed Carrier) signal constructed from two multi-level PAM (Pulse Amplitude Modulated) signals applied in phase quadrature to one another

CAP modulation produces the same form of signal as QAM without requiring in-phase and quadrature components of the carrier to first be generated

25Apr 18, 2023

CAP Transmitter

ConstellationEncoder

+

In-PhaseFilter

QuadratureFilter

D/APassbandLine Filter

BinaryInput

OutputTo line

an

bn

26Apr 18, 2023

CAP Receiver

A/D

In-PhaseAdaptive filter

QuadratureFilter

DecisionDevice

DecoderLineInput

DataOut

an

~

bn

~

27Apr 18, 2023

DMT Modulation

Discrete Multi-Tone modulation

Evolved from the concept of operating an array of N relatively low-rate transceivers in parallel to achieve an overall high rate on one line

The N low-rate information streams are kept separated from one another by sending them over N separate frequency sub-bands or sub-channels

DMT achieves this sub-channel arraying by utilising the IFFT (Inverse Fast Fourier Transform) and it counterpart, the FFT (Fast Fourier Transform)

28Apr 18, 2023

DMT Transmitter

Serial toParallelInputData

Buffer

D/ALineFilter

DataInput

OutputTo lineDMT

SymbolEncoder

IFFT

DMTSymbols

Transmitted SeriallyN (Complex)

Sub-channelSymbols

1

2

N

29Apr 18, 2023

DMT Receiver

ParallelTo SerialOutputData

Buffer

A/DFilterDataOut

line DMTSymbolDecoder

FFT

DMTSymbolsReceivedSerially N (Complex)

Sub-channelSymbols

1

2

N

30Apr 18, 2023

ADSL DMT Modulation

Upstream

Frequency (KHz)

DownstreamVoice

0 4

256 frequency bands of sub-carriers of4 KHz bandwidth and spacing of 4.3 KHz.Each sub carrier can support maximum15 bits/Hz. Depending on signal to noiseRatio for that sub carrier a decision is takenHow many bits that particular sub carrier canSupport. Each carrier can carry 0-15 bits/sec/HzCarriers 1-6 for voice and guardband

25 138 139

No

of

Bit

s

15

1104

7 31

16

69 kHzUpstreamPilot Tone

64

276 kHzDownstreamPilot Tone

32 255

31Apr 18, 2023

ADSL DMT Modulation

Upstream DownstreamVoice

0 4 25

Frequency (KHz)138 139

No

of

Bit

s

15

dB

1104

Downstream

Signal to noise ratio

32Apr 18, 2023

ADSL2+ DMT Modulation

Frequency

DownstreamVoice

0 4

No

of

Bit

s

157 31 32 255

ADSL/ADSL2

0.14MHz 1.1MHz 2.2MHz

ADSL2+

ADSL2+ Doubles the bandwidth used toCarry data

512

Upstream

33Apr 18, 2023

ADSL 2/2+

ADSL 2/2+ are further improvement over ADSL and provide greater download speed and better range.

Due to better modulation efficiency, more download speed is possible.

ADSL 2/2+ can re-synchronize on line at different speed without interrupting the communication if SNR changes due to external interference. This is not possible with ADSL.

When no communication is taking place ADSL2/2+ can go in sleep/power saving mode and come back to live mode automatically when data transmission starts.

34Apr 18, 2023

NIB-II Broadband DSL Deployment

Broadband RAS

480 PortDSLAM

SDH RINGGigE

GigE

GigE

Tier2 LAN Switch

NOTE: Items indicated in dottedline boxes are not part of Project 2.2

Corerouter

Gig E & FE

FE FE

FE

B1 city

ADSL terminals

ADSL terminals ADSL terminals

FE

GE

ADSL terminals

GigE

FE

GigE

24 PortDSLAM

FE

BB•

•ContentServer

•

SSSS

FE

B2 city

MPLS Core Network

Splitter

ADSL

From MDFMax 40 KM

Dark Fibre

Max 10/20 KMDark fiber

Tier1 Layer2GigE Aggregation

Switch

ADMADM

ADM

ADM ADM

48 PortDSLAM

64 PortDSLAM

120 PortDSLAM

FE FE

240 PortDSLAM

35Apr 18, 2023

DSL Deployment : MDF Wiring

Ex Side Line SideMDF

InternetGE/FE

Normal Line

Normal LineDSL Line

Normal Line

Normal Line

Normal Line

DSL Line

DSL Line

Telco Switch

DSLAM

POTS Line

36Apr 18, 2023

SPLITTERS

Central OfficeHome/Office

ADSLCPE

Curb

ADSL up to 5Km

SHDSL (PAM16) up to 5Km

SHDSL

SplitterDSLAM

Data switch

Voice Switch

ADSL Deployment Today

DSL Technologies Evolution of Network

SPLITTERS

Central OfficeHome/Office

ADSLCPE

Curb

ADSL up to 5Km

SHDSL (PAM16) up to 10Km

SHDSLIAD

VDSLIAD

Splitter

SPLITTERS

ONU OLT

DSLAMMSAP

VDSL up to 1.5Km

Fiber

VoDSL

VOICE

Fiber

Multicast

TV

Splitter

4-wireSHDSL

Voice SwitchIP Phone

POTS

IP Phone

POTS

38Apr 18, 2023

DSL BROADBAND DEPLOYMENT

BB

Broadband RAS

480 Port DSLAM

SDH RINGLayer 2 GigEAggregation

SW

GigE

GigE

GigE

LAN Switch

Corerouter

Gig E & FE

FE FE

FE

B1 city B2 city

120 Port DSLAM

48 Port DSLAM

ADSL terminals ADSL terminals ADSL

terminals

FE

64 Port DSLAM

GE

240 Port DSLAM

ADSL terminals

GigE

FE

GigE

24 Port DSLAM

FE

• Content• Server

FE

SSSS

THANK YOU