Asymmetric Digital Subscriber Line ADSL Asymmetric Digital Subscriber Line Manoj Kumar Piyush Mishra

What Is ADSL ADSL – Asymmetrical Digital Subscriber Line, is a broadband communication technology that creates high-speed access to the Internet and remote networks using the phone lines that are already present in your home. ADSL is superior to analog modems in many respects.

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

Total Subscribers Middle East & Africa 0.25% North America 29.5% Latin America 2.0% Western Europe 22.7% Eastern Europe 0.28% South East Asia 2.7% Asia Pacific 42.5%

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

Simultaneous Connections Talk on the phone and surf the Internet at the same time on the same phone line! You do not have to disable call waiting to connect to the Internet.

ADSL standards : Standard name Common name 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 ITU G.992.3/4 Annex J 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 ITU G.992.5 Annex L RE-ADSL2+ ITU G.992.5 Annex M 28 Mbit/s

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

OPTICAL FIBRE

What is fiber optics? We're used to the idea of information travelling in different ways. When we speak into a landline telephone, a wire cable carries the sounds from our voice into a socket in the wall, where another cable takes it to the local telephone exchange. Cellphones work a different way: they send and receive information using invisible radio waves—a technology called wireless because it uses no cables. Fiber optics works a third way. It sends information coded in a beam of light down a glass or plastic pipe. It was originally developed for endoscopes in the 1950s to help doctors see inside the human body without having to cut it open first. In the 1960s, engineers found a way of using the same technology to transmit telephone calls at the speed of light (186,000 miles or 300,000 km per second).

ISDN Integrated Services Digital Network: the CCITT standard that defines a completely digital telephone/telecommunications network which carries voice, data, and video over existing telephone network infrastructure. ISDN provides two 64 Kbit/s channels, which can be combined or used independently for both voice and data. It is designed to provide a single interface for hooking up a phone, fax machine, PC, etc.

The ISDN subscriber will have full connectivity, nationally, to other analog telephone subscribers. At present ISDN services are available to and from India for the following countries: Australia Austria Belgium  Canada  Denmark  France  Germany  Ireland  Italy  Israel  Japan  Malaysia  Netherland  Norway  Phillipines  Singapore Switzerland  Thailand  U.A.E  United Kingdom  U.S.A

Variety of supplementary Services supported by ISDN. Calling Line Identification Presentation(CLIP) Calling Line Identification Restriction(CLIR)  Multiple Subscriber Number(MSN) Terminal Portability(TP) Call Hold(CH) Call Waiting(CW)

DIAL-UP Dial-up Internet access is a type of Internet connectivity that operates through a standard telephone line.

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

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.

ADSL hardware equipments DSLAM (Digital Subscriber Line Access Multiplexer) - DSL Access Multiplexer, a mechanism at a phone company's central location that links many customer DSL connections to a single high-speed ATM line. CPE (Customer Premise Equipment) - communications equipment that resides on the customer's premises. For example, DSL modem is Customer Premise Equipment (CPE).

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

ADSL-based Reference Diagram

ADSL Loop Architecture Voice Switch ISP Central Office Subscriber premises

The role of the DSLAM The path of data along the ADSL from its commercial or residential source, via the local loop, to the CO (Central Office). The local loop here terminates at the Main Distribution Frame (MDF), to be picked up by one of the CO's many ADSL modems. If the form of ADSL allows for the carrying of both analog and digital signals, a POTS splitter will separate out the signals. The analog signal will follow its time-honored path along the copper-wire infrastructure. For the digital signal, however, one step before the signal can be shot along to its destination.

Using DSLAM

Splitter Full-rate ADSL requires that a device, known as a splitter, be installed on your phone line where it enters your home in order to separate the voice service from the data service

RJ 45 CABLE

STRAIGHT CONNECTIONS

ADSL Modem Connections RJ 45 RJ11 Power Supply CAT 5

PPPoE Connection The Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol for encapsulating Point-to-Point Protocol (PPP) frames inside Ethernet frames. It is used mainly with ADSL services where individual users connect to the ADSL modem over Ethernet.

PPPoE - How it works PPPoE - enables establishing PPP sessions and encapsulating PPP packets over Ethernet. It has two distinct stages - A discovery stage and a Session stage. The discovery stage identifies the Ethernet MAC address of the peer with which the PPP session is to be established. The session stage gets a PPPoE session ID for the PPP session and encapsulates PPP packets.

To make an PPPoE connection Configuration

To open Network Connections Click Start, Click Control Panel, Click Network and Internet Connections, Click Network Connections. 

Under Network Tasks, Click Create a new connection, Click Next. Click Connect to the Internet,

If you already have an account with an Internet service provider (ISP), click Set up my connection manually and then click Next. If you have a CD from an ISP, click Use the CD I got from an ISP and then click Next.  If you do not have an Internet account, click Choose from a list of Internet service providers (ISPs) and then click Next.

Set up my connection manually •If you are connecting to your ISP using a standard 28.8 Kbps, 56 Kbps, or ISDN modem, click Connect using a dial-up modem, click Next, and follow the instructions in the wizard. If your DSL or cable modem ISP connection requires a user name and password, click Connect using a broadband modem that requires a user name and password, click Next, and then follow the instructions in the wizard. If your DSL or cable modem ISP connection is always on and does not require you to type a user name and password, click Connect using a broadband connection that is always on, Click Next, and then click Finish.

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

How DSL divide bandwidth

Observations Three Channels: VOICE channel Voice channel is split off from the digital modem by filters, thus guaranteeing uninterrupted POTS. High speed downstream channel Its data rate depends on length of the copper line, its wire gauge, presence of bridged taps, cross talk, etc. Medium speed upstream channel

Modulations Used in ADSL Modulation is the key of ADSL technology; it is a process in which one signal modifies properties of another. Several modulation technologies are used by various kinds of ADSL.

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)

Carrierless Amplitude Phase CAP used for ADSL divides the available space into three bands. The range from 0 to 4 kHz is allocated for POTS transmissions. The range of 25 kHz to 160 kHz is allocated for upstream data traffic and the range of 240 kHz to 1.5 MHz is allocated for downstream data traffic.

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.

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 25,875 138 1104 KHz VOICE Downstream Upstream

Discrete Multi-tone (DMT) high-bit rate services carried by ADSL must not interfere with other services, particularly plain old telephone service , that are being transported simultaneously over the same lines.

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.

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 25,875 138 1104 KHz VOICE Downstream Upstream

Point-to-Point Protocol over Ethernet over ATM (PPPoEoA)

Features Appropriate for Internet requirement Convenient downstream data rate of up to 6-8Mbps upstream data rate of up to 640kbps to 1Mbps Convenient always on Parallel with voice service no need to unplug telephone line Secure access to Internet no need to worry about your noisy neighbors

Pros & Cons Why ADSL? ADSL disadvantages: 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 ADSL disadvantages: Distance-sensitive Slower upload speeds Phone line required

Conclusion ADSL was born of the need for speed coupled with the desire for low cost dedicated remote network access. It will revolutionize the way we see the World Wide Web. ADSL emerge heralding the coming of a new age of remote multimedia. With the internet influencing our lives more and more each day, it will be high speed ADSL connections that power the revolution. In the future people will view ADSL like they view cable TV. That such a small object as an ADSL card may wield such an influence over our lives.

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