Asymmetric Digital Subscriber Line Adsl

Asymmetric Digital Subscriber Line Adsl

1. Student: Milan Milicevic ,478/09
Supervisor: Prof. MilošD. Đurić
June 2010Faculty of Electrical Engineering,
University of Belgrade

2. What is ADSL?
ADSL (Asymmetric Digital
Subscriber Line, or DSL for short)
is a high-speed Internet access
service that utilizes existing
copper telephones lines to send
and receive data at speeds that far
exceed conventional dial-up
modems.

3. Dial-up/ADSL
The fastest dial-up modems are rated at 57
kilobits per second (Kbps), and usually
operate at about 53 Kbps under good
conditions. By comparison, ADSL allows
data stream speeds from 1.5 to 8 megabits
per second (Mbps).

4. ADSL
MODEM
ADSL Modem
is a device used to
connect a computer
or router to a
telephone circuit.

5. Frequency plan for ADSL
Red area is the
frequency range used by
normal voice telephony,
the green (upstream)
and blue (downstream)
areas are used for ADSL.

6. ADSL
ADSL uses standard telephone lines to
transmit upstream and downstream data on
a digital frequency, which sets these
datastreams apart from the analog signals
telephones and fax machines use.

7. Telephone use
Because the ADSL signal is operating on a
different frequency, the telephone can be
used normally, even when surfing the Web
with ADSL service.

8. ADSL connectors

9. ADSL download
The "asymmetric" in ADSL refers to the fact
that the downstream data rate, or the data
coming to your computer from the Internet,
is traveling faster than upstream data, or the
data traveling from your computer to the
Internet.

10. ADSL upload
Upstream data rates are slower because Web
page requests are fairly miniscule data
strings that do not require much bandwidth
to handle efficiently.

11. SDSL or SymmetricDigital Subscriber Line
Some businesses, however, may require matching
upstream rates for uploading large files. SDSL, or
SymmetricDigital Subscriber Line is an option.
"Symmetric" indicates that both datastreams are
operating at the same speed of 1.5 to 7 Mbps.
SDSL service requires a dedicated telephone line
because, unlike ADSL, telephone and fax services
cannot share a line with SDSL service.

12. ADSL requires
ADSL service requires an Internet service provider
(ISP), and ADSL modem. The modem is often
provided free of charge, and most ISPs that offer ADSL
service require subscriber contracts of one year. ADSL
is also more expensive than economical dial-up
service, which can cost less than $10 per month.

13. ADSL use
ADSL is especially suited for gamers, CAD use,
streaming multimedia and downloading large files.
Family members can share ADSL accounts, with a
basic monthly fee covering several mailboxes. Unlike
dial-up service, which stipulates only one session be
instigated at a time, multiple members can be using
ADSL service simultaneously on various computers in
the house without violating policy.

14. ADSL service
ADSL is an "always on" service, meaning
that as long as your computer is powered on,
it will automatically stay connected to the
Internet unless you manually disconnect via
software or hardware.
ADSL filter

15. ADSL providers
ADSL is not available to everyone. ADSL
providers, or even your local phone
company, can tell you if service is available
in your locale. Speeds will vary depending
upon your physical distance from local hubs.
ADSL speed

16. ADSL2 & ADSL2+
Some customers with close proximity may
be able to take advantage of newer varieties
of ADSL, called ADSL2 and ADSL2+, which
have even greater throughput rates, from 12
to 24 Mbps downstream and 1 to 3.5 Mbps
upstream.

17. ADSL Max
ADSL Maxis a cover term for the UK telco BT's
range of commercial ADSL services that are rate-
adaptive and are deployed over BT phone lines.
Such rate-adaptive services are intended to offer
the best possible speed attainable, which may vary
over time. BT's ADSL Max services were launched
in March 2006.
The highest speed ADSL Max services enable
customers to receive up to 7.15 Mbit/s

18. Rate-Adaptive Digital Subscriber Line(RADSL)
Rate-Adaptive Digital Subscriber Line(RADSL) is
a variation of Asymmetric Digital Subscriber Line
(ADSL) technology. In RADSL the DSL modem adjusts
the upstream bandwidth to create a wider frequency
band for the downstream traffic. Using this technique
the line is more tolerant of errors caused by noise and
signal loss.
As the frequency is adjusted, the upstream bandwidth
may be markedly decreased if there is a large amount
of line noise or signal degradation -this may reduce
the upstream bit rate to as little as 64 kbit/s -the same
speed as a single

19. Single-Pair High-speed Digital Subscriber Line(SHDSL)
Single-Pair High-speed Digital Subscriber Line
(SHDSL) is a form of DSL, a data communications
technology that enables faster data transmission over
telephone lines than a conventional voiceband modem
can provide.
An optional extended SHDSL mode allows symmetric
data rates up to 5696 kbit/s on one pair. Higher data
rates may be achieved using two or up to four copper
pairs.

20. Digital Subscriber Line Access Multiplexer
A Digital Subscriber Line Access Multiplexer
(DSLAM, often pronounced dee-slam) allows
telephone lines to make faster connections to the
Internet. It is a network device, located in the
telephone exchanges of the service providers, that
connects multiple customer Digital Subscriber Lines
(DSLs) to a high-speed Internet backbone line using
multiplexing techniques.By placing remote DSLAMsat
locations remote to the telephone exchange, telephone
companies provide DSL service to locations previously
beyond effective range.

21. Speed versus distance
25 Mbit/s at 1,000 feet (~300 m)
24 Mbit/s at 2,000 feet (~600 m)
23 Mbit/s at 3,000 feet (~900 m)
22 Mbit/s at 4,000 feet (~1.2 km)
21 Mbit/s at 5,000 feet (~1.5 km or ~.95 miles)
19 Mbit/s at 6,000 feet (~1.8 km or ~1.14 miles)
16 Mbit/s at 7,000 feet (~2.1 km or ~1.33 miles)
1.5 Mbit/s at 15,000 feet (4.5 km or ~2.8 miles)
800 kbit/s at 17,000 feet (~5.2 km or ~3.2 miles)

22. Advantages and disadvantages
Here are some advantages of DSL:
You can leave your Internet connection open and still use
the phone line for voice calls.
The speed is much higher than a regular modem
DSL doesn't necessarily require new wiring, it can use the
phone line you already have.
The company that offers DSL will usually provide the
modem as part of the installation.
But there are disadvantages:
A DSL connection works better when you are closer to the
provider's central office. The farther away you get from the
central office, the weaker the signal becomes.
The connection is faster for receiving data than it is for
sending data over the Internet.
The service is not available everywhere.

23. ADSL schematic

24. Thanking for attention
Electrical Engineering, University of Belgrade