1. Asymmetric Digital Subscriber Line
ADSL
Asymmetric Digital Subscriber Line

2. What are the benefits of ADSL?
You can talk on the phone and use the Internet at the same time on a single phone line
You can connect to the Internet at up to 140 times faster than analog modems
Your connection to the Internet is always on
Your home has its own dedicated connection
Your connection is highly reliability
Your connection is highly secure
Asymmetric Digital Subscriber Line

3. Introduction
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 #1 Broadband Choice in the World with over 60% market share
ADSL is now available in every region of the world

4. 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, 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

5. Asymmetric Digital Subscriber Line
Dedicated Connection
Unlike a dial-up modem, ADSL gives you a dedicated line to the Internet.
Asymmetric Digital Subscriber Line

6. Asymmetric Digital Subscriber Line
ADSL Reliability
One strength of phone providers is their small number of service outages per year
Even if the power goes out, you will still be able to make phone calls.
Asymmetric Digital Subscriber Line

7. Asymmetric Digital Subscriber Line
ADSL Security
The dedicated connection that ADSL uses provides more security.
Asymmetric Digital Subscriber Line

8. ADSL Speed Comparison Pure Fibre Hybrid Fibre/Copper FTTH Enhanced
FTTC VDSL2,
ADSL2plus
ADSL
ISDN
Voice band Modem

9. ADSL Range
In general, the maximum range for ADSL 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 ADSL if your phone company has extended the local loop with optical fiber cable
Data Rate
Wire gauge
Wire size
Distance
1.5 or 2 Mbps
24 AWG
0.5 mm
5.5 km
26 AWG
0.4 mm
4.6 km
6.1 Mbps
3.7 km
2.7

10. ADSL Speed Factors The distance from the 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.

11. ADSL network components
The ADSL modem at the customer premises(ATU-R)
DSL access multiplexer (DSLAM)
Splitter - an electronic low pass filter that separates the analogue voice or ISDN signal from ADSL data frequencies DSLAM.

12. “Network” : ADSL ADSL Internet Broadband Network upto 8Mbit/s
Teöephon missing
Upto 1Mbit/s
Telephone
Network 8

13. ADSL Loop Architecture
Voice Switch
ISP
Central Office
Subscriber premises

14. Simple overview of ADSL in the phone network
POTS- Plain Old Telephone Service

15. ADSL Requirements Phone-line, activated by your phone company for ADSL
Splitter (filter) to separate the phone signal from the Internet signal
ADSL modem
DSLAM at exchange (central office)

16. Asymmetric Digital Subscriber Line
How does ADSL work?
One phone line delivers voice and a high-speed Internet connection
Voice/fax calls only use the frequencies below 4 kHz
Frequencies above 4 kHz are reserved for data transmission
ADSL
Voice/Fax
0 kHz
25 kHz
3.4 kHz
1100 kHz
Asymmetric Digital Subscriber Line

17. How does ADSL work
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 4 25
160
1104
KHz
PSTN
Downstream
Upstream

18. 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)

19. Carrierless Amplitude Phase
Carrierless Amplitude Phase (CAP) is an encoding method that divides the signals into two distinct bands:
The upstream data channel (to the service provider), which is carried in the band between 25 and 160kHz
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.

20. Discrete Multi-tone (DMT)
Discrete Multi-Tone (DMT) separates the DSL signal so that the usable frequency range is separated into 256 channels of kHz 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.

21. The DMT frequency bands
Frequency Division Multiplexing (FDM)

22. Asymmetric Digital Subscriber Line
Splitter
ADSL requires that a device, known as a splitter, be installed on your phone line (at customer end) where it enters your home in order to separate the voice service from the data service
Asymmetric Digital Subscriber Line

23. DSLAM
A DSLAM is a Network Device, usually placed at a Telephone Company Central Office, That Receives Signals from multiple customer of DSL Connections and puts the signals on a high-speed backbone line using Multiplexing Techniques.
A DSLAM takes connections from many customers and aggregates them onto a single, high-capacity connection to the Internet. The aggregated traffic is then directed to a telco's backbone switch,
DSLAM enables a phone company to offer business or home users the fastest Phone Line Technology (DSL) with the fastest backbone Network Technology (ATM).

24. Fibre Broadband (FTTC / FTTH)
Fibre broadband is a new type of broadband that is currently being deployed in the UK and other countries which uses fibre optic cables to help increase the speed of your broadband connection. It is often referred to as 'super-fast broadband' or 'next-generation broadband' as it offers faster speeds than have been available to date using older generation networks. It is available to both home and business users.
Fibre to the cabinet (FTTC)
Fibre-to-the-Cabinet (FTTC) involves running fibre optic cables from the telephone exchange or distribution point to the street cabinets which then connect to a standard phone line to provide broadband.
This is combined with a copper cable from the cabinet to the home or business which uses ADSL or similar technology that can deliver much faster speeds over shorter distances.

25. Fibre Broadband (FTTC )
Since Fiber has signal attenuation with respect to copper, Less prone to EMI and Higher bandwidth with light speed, FTTC broadband offer a downstream line speed upto 80Mbps.

26. Contention Ratio
 the contention ratio is the ratio of the potential maximum demand to the actual bandwidth. The higher the contention ratio, the greater the number of users that may be trying to use the actual bandwidth at any one time and, therefore, the lower the effective bandwidth offered, especially at peak times.
In other words The "contention ratio" is the maximum number of other people you will have to share the connection infrastructure with. So a contention ratio of 50:1 would mean that the maximum number of people you could be sharing the connection with at anytime is 49 other people.