A Seminar Topic on ADSL Asymmetric digital subscriber line
Slide 2
Contents Introduction xDSL and ADSL Other DSL Technology What
does ADSL mean ADSL Speed Factors ADSL Network Components ADSL
Requirements How does ADSL work? ADSL Modulation CAP(Carrierless
Amplitude Phase) DMT(Discrete Multi Tone) ADSL vs Cable Modem
Features of ADSL What can you do with ADSL Pros & Cons An
Insight Conclusion
Slide 3
Introduction This era of competition among communication
service provider provides all the services their customers needs.
They position their networks in such a way that they can provide
all the services the customer wants. This paper addresses an
important component of the network which is capable of providing
both broadband and narrowband services which is ADSL.
Slide 4
xDSL and ADSL xDSL or Digital Subscriber Line collectively
refers to a group of technologies that utilize the unused bandwidth
in the existing copper access network to deliver high-speed data
services from the distribution center, or central office, to the
end user. Asymmetric Digital Subscriber Line (ADSL) is one such
form of the Digital Subscriber Line technology. It is a data
communication technology that enables faster data transmission over
copper telephone lines than a conventional voice-band modem can
provide.
Slide 5
Other DSL Technologies ADSL: Asymmetric DSL SDSL: Single line
DSL HDSL: High-bit-rate DSL VDSL: Very High-bit-rate DSL R-ADSL:
Rate Adaptive DSL
Slide 6
What does ADSL mean : 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. Subscriber Line - The data is carried over a single
twisted pair copper loop to the subscriber premises.
Slide 7
ADSL Speed Factors The distance from the local exchange The
type and thickness of wires used The proximity of the wire to other
wires carrying ADSL, ISDN and other non-voice signals The proximity
of the wires to radio transmitters.
Slide 8
ADSL Network Components The ADSL modem at the customer
premises(ATU-R) The modem of the central office (ATU-C) DSL Access
Multiplexer (DSLAM) Broadband Access Server (BAS) Splitter - an
electronic low pass filter that separates the analogue voice or
ISDN signal from ADSL data frequencies.
Slide 9
ADSL Requirements 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
How does ADSL work ADSL exploits the unused analogue bandwidth
available in the wires 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 ADSL works by using a frequency splitter device to
split a traditional voice telephone line into two frequencies
425,8751381104KHz PSTNDownstreamUpstream
Slide 14
ADSL Modulation Modulation is the overlaying of information (or
the signal) onto an electronic or optical carrier waveform There
are two competing and incompatible standards for modulating the
ADSL signal: Carrierless Amplitude Phase (CAP) Discrete Multi-Tone
(DMT)
Slide 15
Carrierless Amplitude Phase Carrierless Amplitude Phase (CAP)
is an encoding method that divides the signals into two distinct
bands: 1. The upstream data channel (to the service provider),
which is carried in the band between 25 and 160kHz. 2. The
downstream data channel (to the user), which is carried in the band
from 200kHz to 1.1MHz. These channels are widely separated in order
to minimize the possibility of interference between the
channels.
Slide 16
Discrete Multi-tone (DMT) Discrete Multi-Tone (DMT) separates
the DSL signal so that the usable frequency range is separated into
256 channels of 4.3125kHz each. DMT has 224 downstream frequency
bins (or carriers) and 32 upstream frequency bins. DMT constantly
shifts signals between different channels to ensure that the best
channels are used for transmission and reception.
Slide 17
ADSL Standards : Standard name Common name Downstream rate
Downstream rate Upstream rate ITU G.992.1 ADSL (G.DMT) 8 Mbit/s 1.0
Mbit/s ITU G.992.2 ADSL Lite (G.Lite) 1.5 Mbit/s 0.5 Mbit/s ITU
G.992.3/4 ADSL2 12 Mbit/s 1.0 Mbit/s ITU G.992.3/4 Annex J ADSL2 12
Mbit/s 3.5 Mbit/s ITU G.992.3/4 Annex L RE-ADSL2 5 Mbit/s 0.8
Mbit/s ITU G.992.5 ADSL2+ 24 Mbit/s 1.0 Mbit/s ITU G.992.5 Annex L
RE-ADSL2+ 24 Mbit/s 1.0 Mbit/s ITU G.992.5 Annex M ADSL2+ 28 Mbit/s
3.5 Mbit/s
Slide 18
ADSL Range In general, the maximum range for DSL without a
repeater is 5.5 km As distance decreases toward the telephone
company office, the data rate increases For larger distances, you
may be able to have DSL if your phone company has extended the
local loop with optical fiber cable Data RateWire gaugeWire
sizeDistance 1.5 or 2 Mbps24 AWG0.5 mm5.5 km 1.5 or 2 Mbps26 AWG0.4
mm4.6 km 6.1 Mbps24 AWG0.5 mm3.7 km 1.5 or 2 Mbps26 AWG0.4
mm2.7
Slide 19
ADSL vs Cable Modem Pro: Secure. Point to point connectivity of
ADSL ensures the security of the service. Cable, by contrast, is
shared media and is not secure at all. Bigger coverage area. Cheap.
ADSL uses existing twisted pair, hence is cheap in installation and
also cheap in monthly payment. Cons: Bandwidth. ADSL has about
1.1MHz BW due to loop limitations, while cable modem has about
745MHz BW. Bridge taps, DLCs, load coils can lead to problems.
Mutual noise among different DSL lines.
Slide 20
Features of ADSL :
Slide 21
What can you do with ADSL? Conventional uses: Surf or browse
the web Send or receive electronic messages or e-mails Business
uses: Promote a company, product or service (advertising online)
Retrieve information using search engines Download files (software;
media; etc.) Buy and sell (online shopping/comparing offers and
prices) Financial transactions (banking operations, stock exchange,
etc.) E-services (e-learning, telemedicine, etc.) Other uses: ADSL
access to TV programmes Telephony(VoIP)
Slide 22
Pros & Cons Why ADSL? 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 Better Data Security Fast download speeds ADSL Limitations:
Distance-sensitive Slower upload speeds Phone line required
Slide 23
An Insight Into the Improved ADSL ADSL2 Approved by ITU-T as
G.992.3 July 2002 Features Improved rate up to 12Mbps by 1Mbps
Improved reach around 600ft / 180m Better modulation efficiency
Bonding of lines ADSL2+ Approved by ITU-T as G.992.5 January 2003
Features Much increased rates up to 28Mbps by 1Mbps Doubled
downstream frequency band to 2.2Mhz Reduced cross talk Builds on
all ADSL2 features
Slide 24
Conclusion Future is bright for the improvements in this
technology. Users mainly everybody has a craze or need for internet
which has made ADSL a part of human life to certain extent and it
is trying to succeed.If it does the human life will change for
ever.