3. Introduction
Past decade has seen extensive growth in the
telecommunicaton industry.
Popularity of Internet & other data communication
services has increased.
Majority of Internet users access their service VIA
Modems connected to P.O.T.S.
P.O.T.S was designed for voice transmission at
frequencies below 3 KHz.
4. To increase performance of new online services, the
bandwidth hungry public must consider other options.
Technologies, such as I.S.D.N. or cable connections,
require special cabling.
A P.O.T.S. connection provided an adequate medium
for relatively small amounts of data that required to be
transmitted.
So the existing system was the logical choice over
special cabling.
5. DIFFERENT VARIANTS OF DSL
H.D.S.L.
It is the pioneering high speed
format,
But not commercially viable
option due to its need for 2
Twisted pairs,
Doesn’t have support for normal
Tele Phone Services.
S.D.S.L.
It is symmetric DSL,
Operates over a single twisted
pair,
Limited to short distances,
Suffers N.E.X.T.
I.S.D.L.
Stands for I.S.D.N. DSL,
Sımılar to I.S.D.N. Technology,
Lacks support for analog voice.
V.D.S.L.
Very high bit rate D.S.L.
Requires shorter
connections than are
generally practical.
A.D.S.L.
Most promising
technology,
Suitable for personal
broadband requrements,
Allows same channel to
still act as a traditional
service.
6. WHAT IS A.D.S.L.
A modem technology,
Converts existing twisted pair telephone lines into access
paths for multimedia & high speed data communications,
Can transmit upto 6Mbps to subscriber,
832 Kbps in both directions,
Expands access capacity by a factor of 50 or more.
It allows more bandwidth downstream than for upstream.
Users of these applications
download more information than they
send.
A Gateway is commonly used to
make an ADSL Connection.
7. What does ADSL mean:
O Asymmetric - The data can flow faster in one direction
than the other. Data transmission has faster
downstream to the subscriber than upstream
O 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.
O Subscriber Loop - The data is carried over a single
twisted pair copper loop to the subscriber premises
8.
9. BENEFITS OF A.D.S.L.
Provides high speed Internet access using regular telephone
lines,
Connectivity-always on
Data security,
Ease of use
No Dial-Up is required
Speed is upto 25 times faster than analog modems.
10. FUTURE of A.D.S.L.
ADSL will play a crucial role over the next decade or more
as telephone companies enter new markets for delivering
information in video and multimedia formats.
New broadband cabling will take decades to reach all
prospective subscribers.
Success of these new services will depend on reaching
as many subscribers as possible during the first few
years.
By bringing movies, television, video catalogs, remote
CD-ROMs, corporate LANs, and the Internet into homes
and small businesses.
ADSL will make these markets viable and profitable for
telephone companies and application suppliers alike.
12. ADSL CAPABILITIES
ADSL Modem connected to each end of twisted pair telephone line.
3 Information channels are created :
1. High speed downstream channel
2. A medium speed duplex channel
3. A basic telephone service channel
ADSL Guarantees uninterrupted telephone service even if ADSL fails.
Downstream rates depend on:
1. Length of copper line
2. Its wire gauge,
3. Presence of bridged gaps,
4. Cross coupled interference
Line attenuation increases with line length & frequency,
Line attenuation decreases with increase in wire diameter.
13. ADSL TECHNOLOGY
Depends upon advanced digital signal processing
technology & algorithms,
Outside - ADSL Looks Simple,
Inside – Miracle of Modern Technology,
It Consists of : Transmitter & Receiver
1) Telephone exchange
2) Splitter (Low Pass Filter)
3) DSLAM , ISP
4) Splitter
5) ADSL Modem
6) Computer
7) Phone, Fax
14. FDM : One band to upstream other to downstream,
DOWNSTREAM : TDM; High & Lowchannels
UPSTREAM : Corresponding low channels
Overlapping removed by echo cancellation
BLOCK
DIAGRAM
16. FREQUENCY RESPONSE OF
ADSL
ADSL= Broad Bandwidth
ADSL exploits the unused analogue bandwidth available in the
wires.
ADSL works by using a frequency splitter device to split a
traditional voice telephone line into two frequencies.
17. LIMITATIONS
It is a distance sensitive technology.
Limit for ADSL service is 5490 metres.
Maximum downstream speed is 8 mbps at a distance of
about 1830 metres.
Maximum upstream speed is 640 kbps.
ADSL can’t be received using bridge tapes, fiber optic
cables and loading coils.
18. ADSL EQUIPMENTS
DSL
EQUIPMENT:DSLAM
It uses two pc’s of equipments
one at the customer end and one
at the internet services provider .
At the customer location there is
DSL transceiver also called as
“DSL MODEM” and ATU-R too.
DSL service provider has a DSL
access multiplexer (DSLAM ) to
receive customer connection.
The transceiver can connect to
the customer equipment by using
USB or 10 base –T Ethernet
connections.
The devices used by businesses
may combine network routers
network switches or other
networking equipments.
It really allows DSL to happen.
It takes connection from many
customers and aggregates them
on to a single high capacity
connection to the internet.
It is flexible and able to support
multiple types of DSL in a
single central office.
19. ADSL REQUIREMENTS
Phone line , activation by
your phone company for it
Filter to separate the
phone signal from the
internet signal
ADSL modem
Subscription with an
ISP supporting ADSL
20. ADSL RANGE
ADSL
SPEED FACTORS
Maximum range for DSL
without a repeater is 5.5
km
As distance decreases
towards the telephone
company office , the data
rate increases.
For larger distances ,
DSL service is provided
only when phone
company has extended
the local loop with optical
fiber cable.
The distance from local
exchange,
The type and thickness of
wires used,
The number and type of
joins in the wire,
The proximity of the wire
to other wires carrying
ADSL, ISDN and other
non voice signals,
The proximity of the wires
to radio transmitters.
21. 1) HIGH SPEED INTERNET ACCESS
2) E-COMMERCE
3) DISTANCE LEARNING
4) VIDEO CONFERENCING
5) ENTERTAINTMENT-ONLINE GAMING
APPLICATION
22. O ADSL advantages:
Simultaneous Internet and voice/fax capabilities
over a single telephone line
Uninterrupted, high-speed Internet access that's
always on-line
Cost-effective solution for society
Data Security that exceeds other technologies
Fast download speeds
O ADSL disadvantages:
Distance-sensitive
Slower upload speeds
Phone line required
23. It is ASYMMETRIC.
Allows more bandwidth for downstream than upstream
data flow.
ADSL modems create multiple channels using FDM or
echo cancellation.
It is ideal for those who download much more data than
they send.
CONCLUSION
