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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
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