Overview on DSL & ADSL along with its working mechanism

1. Presented by:
Bina Gupta
BIM 7th sem
Under the supervision of:
Sameer Gautam
BIM Department
Hetauda School Of Management
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2.  History
 Overview of DSL
 DSL Requirement
 How DSL works?
 Overview of ADSL
 ADSL Requirements
 How ADSL works?
 Distance Limitations
 Other types of DSL
 References
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3. 1. Started with phones
◦ During last decades internet was accessed through
modems connected through Plain Old Telephone
System
◦ Modems were extremely slow by today's standards
◦ Plain Old Telephone System (POTS) was designed
for voice transmission, at frequencies below 3kHz
◦ Limitation for obtainable data rates of the system
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4. 2. ISDN
◦ Alternative to Plain Old Telephone System(POTS)
◦ Improved internet access speed
◦ Transfer of both audio and video
◦ Require special cabling
◦ Require expensive setup
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5. 3. Broadband & DSL
◦ In 1980, Joseph Lech discovered the idea of
broadband to transfer the data
 Broadband:
 Broadband is a fast, permanent Internet connection, which
is 10 to 100 times faster then a dial-up connection.
◦ With the idea of broadband, came up with the idea
of DSL & ADSl.
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6.  DSL(Digital Subscriber Line) is a very high-
speed connection that uses the same wires as
a regular telephone line
 Replacement of ISDN
◦ Integrated Services Digital Network (ISDN): ISDN is a
digital transmission system, which is used to
transmit voice and data through copper telephone
wires
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7.  DSL technology allows Internet and
telephone service to work over the same
phone line without requiring customers to
disconnect either their voice or Internet
connections.
 DSL Internet services are used primarily in
homes and small businesses.
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8.  DSL Internet service only works over a limited
physical distance and remains unavailable in
many areas where the local telephone
infrastructure does not support DSL
technology.
 xDSL refers to different variations of DSL,
such as ADSL, HDSL, and VDSL
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9. 1. Ethernet cables
2. Telephone
3. Modems
4. Filter
5. Phone jack
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10. 1. Data is generated by your computer (such as a
request for a Web page or for your email)
2. Flows over Ethernet cable to the DSL modem
3. Passes through the DSL modem and continues
over a phone cable to the jack
4. Travels to your outside phone box via the
phone cabling inside your house’s walls
5. On to the Central Office building in your
neighborhood
6. Then goes to your ISP’s network
7. Then goes out to the Internet
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11. 12/26/2014 11
Figure: Working mechanism of DSL

12. ADSL(Asymmetric Digital Subscriber Line)
◦ Asymmetric - The data can flow faster in one
direction than the other. Data transmission has
faster downstream to the subscriber than upstream
◦ Digital - No type of communication is transferred in
an analog method. All data is purely digital, and
only at the end, modulated to be carried over the
line.
◦ Subscriber Line - The data is carried over a single
twisted pair copper loop to the subscriber premises
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13.  ADSL is a form of DSL, a data communications
technology that enables faster data transmission
over copper telephone lines
 ADSL is capable of providing up to 50 Mbps, and
supports voice, video and data.
 ADSL is the popular Broadband Choice in the
World with over 60% market share
 ADSL is now available in every region of the
world
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14.  Designed to suit the standard pattern of use
of data networks
 ADSL implementation gives the incoming
stream a large slice of bandwidth, and a
smaller amount is dedicated to duplex
communications.
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15.  Phone-line, activated by your phone company
for ADSL
 Filter to separate the phone signal from the
Internet signal
 ADSL modem
 Subscription with an ISP supporting ADSL
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16.  To create ADSL, there must be a pair of
ADSL modems, one at the subscriber site and
the other at the network operator site (i.e.
Central Office or nearest access node).
 During an Internet connection, the two ADSL
modems communicates, converting signal to a
format that can be transferred over telephone
line.
 DSLAM (Digital Subscriber Line Access
Multiplexer) is a device at the operator site that
contains ADSL modems and interfaces to
backbone network.
 Backbone network: A network that aggregates traffic from
smaller networks and transports traffic between networks.
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17.  ADSL signal from each subscriber is split
into voice and data signals by a splitter
(filter) that's usually contained in the same
rack with the DSLAM.
 The voice (telephone) signal is forwarded to
a telephone switch (Local Exchange) for
further connection to the telephone network
(PSTN).
 The data signal that carries Internet traffic is
sent to the ISP over backbone network for
connection to the Internet.
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18.  At a subscriber site, a splitter (filter)
separates the telephone signal from the data
signal.
 Therefore the subscriber can receive or make
telephone calls during an Internet connection
without interference. The presence of a
separate splitter is required only in Full Rate
ADSL. In the case of splitterless ADSL (also
known as G.Lite, ADSL Lite, or Universal
ADSL), an external splitter is not required.
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19. 12/26/2014 19
Figure: Working mechanism of ADSL

20.  ADSL is a distance-sensitive technology
 The limit for ADSL service is 18,000 feet
(5,460 meters)
 At the extremes of the distance limits, ADSL
customers may see speeds far below the
promised maximums
 customers nearer the central office have
faster connections and may see extremely
high speeds
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21.  High-bit-rate DSL (HDSL)
 Symmetric DSL (SDSL)
 Very high bit-rate DSL (VDSL)
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22.  High-bit-rate DSL (HDSL)
◦ HDSL technology was developed in the early 1990s,
making it one of the oldest forms of DSL.
◦ HDSL service provides equal bandwidth for both
downloads and uploads, offering data rates up to
2,048 Kbps.
◦ HDSL requires multiple phone lines to accomplish
this.
◦
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23.  Symmetric DSL (SDSL)
◦ Replacement of alternatives like HDSL since it
requires one phone line and offer similar
performance and reach.
◦ Symmetric types of DSL connections provide equal
bandwidth for both uploads and downloads.
◦ Symmetric DSL technology is popular for business-
class DSL services as companies often have greater
needs for transferring data.
◦ Typical symmetric DSL connections support 1.5
Mbps for downloads and uploads.
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24.  Very high bit-rate DSL (VDSL)
◦ VDSL was developed to support exceptionally high-
bandwidth applications such as High-Definition
Television (HDTV).
◦ VDSL can achieve data rates up to approximately
51,840 Kbps, making it the fastest available form of
DSL.
◦ The technology was originally named VADSL ('A' for
asymmetric), but VDSL but later on it was improved
since it can operate in either symmetric and
asymmetric modes
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25.  To perform at this speed, VDSL relies on fiber
optic cabling.
 VDSL supports both voice and data
communication on the same line, like other
forms of DSL.
 Also like most DSL technology, the
performance of VDSL depends significantly
on the physical distance traversed by wires:
Shorter distances mean faster networking.
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26.  http://www.adsl.com/general_tutorial.html 12/26/2014
 The ADSL Forum, FAQ http://www.adsl.com/faq.html 12/26/2014
 ADSL - Asymmetric Digital Subscriber
Line http://murray.newcastle.edu.au/users/staff/eemf/ELEC351/SProjec
ts_98/Wang/351_adsl.html 12/26/2014
 http://www.telstra.com.au/adsl 12/26/2014
 Netcomm Home Page http://www.netcomm.com.au 12/26/2014
 Aztech ADSL modem
http://www.aztech.com.sg/support/spec/spec_dsl900e.html
12/26/2014
 Aztech ADSL modem specs
http://www.aztech.com.sg/products/adsl_modem/dsl900e.html
12/26/2014
 List of modem manufacturers
http://www.hardwaresite.net/drvmodem.html 12/26/2014
 PCTEL G. Lite modems www.pctel.com/media/data_sheets/txt_GLite.htm
12/26/2014
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