digital data transmission techniques

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Digital Data Transmission

Techniques

Today's Presentation is On Digital Data Transmission

Techniques Used Nowadays


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DIGITAL DATA TRANSMISSION TECHNIQUES

Now in modern age there are several techniques used

for transmission of data/informations.

Today is the era of digital technology so the basic need

of transmission of data is SPEED.

Along with several facilities alot of techniques of digital

data transmission are present.

Several types of techniques are being used.

The most common type of technique being used are as

under:


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Several types of techniques being used are:

Asymmetric Digital SubscriberLine (ADSL)

Asynchronous Transfer Mode(ATM)

Bluetooth

Digital Subscriber Line Lite(DSL Lite)

Fixed Radio Access (FRA)

Frame Relay

General Packet Radio System

(GPRS)

High speed Digital SubscriberLine (HDSL)

Mesh systems

Optical fibre

SuperJANET

Wi-Fi

WiMax

ZigBee


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Asymmetric Digital Subscriber Line (ADSL)

A digital transmissiontechnique for enhancingthe information-carryingcapacity of traditionalcopper pair cables in the

local access network. Since the bandwidth of

the return channel is lessthan that of the outgoingchannel, the technique is

described as asymmetric. Its speed was originally at

512 kilobits a second, butnow up to 8 Megabits asecond. It is widely used

nowadays

ADSL


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TYPES OF ADSL:

ADSL2

ADSL services typicallyoperate at a maximum speed of

1.5 megabits per second

(Mbps), supporting e-mail, Webaccess, Voice over Internet

Protocol (VoIP) and some

multimedia applications.

ADSL2 is an enhanced version

delivering speeds of up to 12Mbps

ADSL2


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TYPES OF ADSL(contd.)

ADSL2+ADSL2+ reached consent at theInternationalTelecommunications Union(ITU) in January 2003, joiningthe ADSL2 standards family.

The result is a significantincrease in data rates onshorter phone lines, doublingthe downstream bandwidth andincreasing the downstream datarate to as much as 24 Mbps.


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Asynchronous Transfer Mode (ATM)

This is a digital transmissiontechnique which uses packetswitching technology.

These packets are of auniform, short fixed length

called cells, so that ATM issometimes called Cell Relay.

Each packet contains 48 bytesof the information to betransported and 5 bytes ofcontrol information - called the

header. Its has speed upto 155 Mbps.

It is expected to have speedupto 622Mbps.


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Bluetooth

This is a wirelesscommunications system It is aradio frequency networkingsystem that enables a host ofelectronic devices to connect

to and communicate withvarious networks including theInternet.

Such devices can includedomestic equipment likeheating, lighting and ventilation

systems and personalequipment like handheld andnotebook computers, mobiletelephone and personal stereo.


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Digital Subscriber Line Lite (DSL Lite)

This operates at same principle as Asymmetric Digital

Subscriber Line (ADSL)

It is faster but at lower speeds than ADSL.

Downstream speeds are between 64 kilobits

1.5megabits a second, while upstream speeds are between

32 kilobits 512 megabits a second.

Although speeds are slower than for ADSL, installation

costs are lower too.


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Fixed Radio Access (FRA)

A radio technique to provide local access between a

local telephone exchange and a local telephone

customer.

It was used by Ionica

The frequency used was between 3,425 - 3,490 MHz.

Each base station could service up to 2,000 users.


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Frame Relay

Like (ATM), it uses packet switching technology to

provide fast data transmission.

However, Frame Relay uses a variable length unit of

data called a frame

Public frame relay services are much more prominent in

the USA than Europe (with the notable exception of

Finland) and such services have been used in the Asia-

Pacific region.


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General Packet Radio System (GPRS)

It is a technology for permitting mobile telephones and

other devices to access the Internet.

it is a packet-based system which enhances the capacity

of existing digital mobile networks by creating packets.

GPRS has data rates of 144 kilobits a second


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General Packet Radio System (GPRS)


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High speed Digital Subscriber Line (HDSL)

It is used by publictelecommunications operatorsto provide advanced servicesto business premises using thecopper access cable.

Unlike (ADSL), it provides thesame bit rate in each direction,operating at up to 2 megabits asecond.

Therefore it can be used forWeb/email hosting as well asfast Internet access and otherapplications.


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Mesh systems

Wireless mesh networks are multi-hop systems in whichdevices assist each other in transmitting packets throughthe network, especially in adverse conditions.

They provide a reliable, flexible system that can beextended to hundreds of devices over a widegeographical area. What mesh networks have incommon is that any time mesh-enabled devices are inclose proximity to each other, they automatically create awireless mesh network.

On such systems, data can 'hop' up to 2 Km from

rooftop to rooftop.


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Optical fibre

It involves the generation of lightsignals by miniature lasers whichthen travel along glass fibres to bereceived by tiny diodes.

The main advantage of opticalfibre is the enormously greater

capacity or bandwidth.

Optical fibres are smaller, lighter,far more reliable, are not affectedby electrical interference, and donot cause interference with otherequipment

Optical fibre systems can carrysignals far greater distanceswithout the need for the signal tobe boosted.

Cost of fibres usually of silica arelow but that of opto-electronic

devices is high.


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SuperJANET

It was originally called the JointAcademic Network (JANET).Later it was developed into thefaster SuperJANET.

It is a data network linking

British universities and uses(ATM) technology.

At most sites, the operatingspeed is 10 Mbps but in somecases access is only 4 Mbps oras much as 16 Mbps.


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Wi-Fi

This is a wirelesscommunications systemformally known as IEEE802.11b.

It is also known as "wirelessEthernet" or "Wi-Fi" (Wireless

Fidelity). It operates in the 2.4 GHz

band and since this is lowpower, the spectrum isunlicensed.

Wi-Fi is a means of providing

wireless connectivity in anoffice or a home for computers(or other devices) withinaround 50-100 metres (150-300 feet) of a base station.


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WiMax

Wireless communicationssystem based on a newstandard called IEEE 802.16a

It is supported by a groupcalled the World Inter-

operability for MicrowaveAccess (WIMAX). WiMax is awireless metropolitan areanetwork (MAN) technologywith a bandwidth of around 75Mbps across a distance of

about 30 miles and operatesmainly in the 2.4, 3.5 and5.8GHz range.


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ZigBee

Like Wi-Fi, WiMax, this is awireless communicationssystem, but it is slower (250kilobits a second) and hasshorter range than the othersystems

It requires less power (sobatteries can last up to 10years).

It is designed for wirelesscontrols and sensors in thehome or office such as lights,

switches, doors andappliances.

It has the IEEE standard802.15.4 and, like Wi-Fi andBluetooth, it operates at 2.4GHz.


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Designed And Presented by:

Armaghan Zafar

Syed Asad Ali Kazmi

Waseem AbbasSection D

Electrical (Communication)

Main Campus UET Peshawar

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