This document provides an overview of digital subscriber line (DSL) technology. It discusses how DSL uses existing telephone lines to provide high-speed internet access simultaneously with phone service. The document outlines the different types of DSL standards, how DSL works by separating voice and data signals, and its advantages like faster speeds and ability to use internet and phone simultaneously. Potential disadvantages discussed include reduced speeds over long distances from the provider and faster download than upload speeds.

1. DSL
Digital Subscriber Line
Presented by :
AL-Maqashi Saleem (49)
Patkar college

2. Agenda
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Aim of DSL
What is DSL?
PROs & CONs
Block diagram
DSL standards
Conclusion
References

3. The Need for Speed
 Explosive Growth of the Internet
 Increase Demand for High-Speed Access
 By Businesses & Individuals
 Increase Demand for New Applications
 Real-time interactive multimedia
 Video conferencing
 Distance learning

4. What is DSL?
 Digital Subscriber Line
 A technology which uses the existing
transmission medium (telephone wire) to
provide high-speed transfer of information
across the internet.
 DSL simply uses more of the bandwidth.
 DSL
 allows simultaneous voice and high-speed
data services such as super fast Internet access
 over a single pair of copper telephone wires.

5. Common Types of DSL

6. How It Works
 A. Over the Wire: You are
connected to another ADSL
modem which also has a POTS
splitter, which separates voice calls
from data.
 B. Telephone Calls: Voice calls
are routed to the phone company's
public switched telephone network
(PSTN) and proceed on their way
as usual.
 C. Internet Requests: DSL Access
Multiplexer links many ADSL lines to
a single high-speed asynchronous
transfer mode (ATM) line, which in
turn connects to the Internet.
Plain old telephone
 D. Back at You: The requested
data is retrieved from the Internet
and routed back to you.

7. Advantages of DSL
The following are some advantages of DSL service:
 Broadband Internet and Phone at the same time: You
can be online on facebook and twitter and at the same
time talk to your friend on your landline connection.
This was not possible with dial- up connection as going
online meant you could not use your landline phone.
 Faster Internet: It is was faster than the 52 kbps dial up
connection. DSL internet provides speed of above
2mbps
 No wiring: Since DSL broadband connection uses phone
line to connect to the net no special wiring is required

8. Con,,,,
 No Dropped Connections: A major problem with
dial up connection was that it would disconnect all of
a sudden leaving you high and dry. DSL connections
do not have these problems and seldom is there a
disconnection.
 Faster Downloads: Faster DSL network means, that
downloads are faster. Now you can download more
files in the same time.
 Multiple Computers on Single DSL Line: More
computers can be connected to internet using the
same DSL connection. That means no need to take
special connection for an extra computer or laptop.

9. disadvantages of DSL
The following are some disadvantages of DSL:
 Your DSL connection works faster if you live closer
to the provider’s central office. The farther your
home is from the ISP’s office the more your speed
will reduce.
 Data being received is faster than data being sent
over the Internet.
 DSL availability is limited to certain cities, not
everyone can get this service

10. DSL Architecture
 Digital Subscriber Line (DSL) is the newest technology
being used for Internet access. DSL connects your home
or office to the Internet through the same telephone wire .
Like ISDN, with DSL, user can make and receive
telephone calls while connected simultaneously to the
Internet .
 To use DSL you will need a DSL modem (also called a
router), a Network Interface Card (NIC), and a telephone
line. DSL is also relatively new technology that is just
being introduced in many places . Hardware developers
are working with service providers to make the service
cost affordable for consumers. As time goes by, the
service should become more widely available at a
reasonable price.

11. DSL BLOCK DIAGRAM

12. Two standards for DSL
1- Discrete multitone (DMT) : is a form of FDM that divide data
into 256 downstream and 32 as upstream channels .
Discrete Multi-Tone (DTM), a multi-carrier modulating
technology, is generally used as the modulation standard
for ADSL. DTM is very resistant to noise.
2- Carrierless amplitude/phase (CAP) : is a version of QAM
by dividing the signals into three part ,, voice , upstream
and downstream .

13. Conclusion
It is highly likely that xDSL will become widely adopted
particularly among high-speed Internet "power users" as
well business requiring fast access to various networks,
provided naturally that the prices come down.
xDSL technology offers a viable interim solution to the
bandwidth problem while fiber optic cables are being
installed.

14. References
Data Network Design -Selected pages (3rd Edition) darren L. Spohn
ADSL Forum, "General Introduction to Copper Access Technologies",
http://www.adsl.com/adsl/general_tutorial.html
The Need for Speed",
http://www.kentrox.com/product/cellworx/nspeed/xDSLprimer.html

15. Thank you
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