Overview of telecom networks

OVERVIEW OF TELECOMMUNICATION NETWORKS

Today’s telecommunication technologies have evolved from the earliest smoke signals to almost instant global transmission of large amounts of data.

EVOLUTION OF TELECOM TECHNOOGY

Telephone subscriber

Distribution point

Pillar

Cabinet

Main distribution frame

Telephone exchange

The way how transmission line reaches from subscriber to exchange.

WORKING OF BASIC TELECOMMUNICATION N/W

MAIN PARTS OF TELECOMMUNICATION N/W

Telephone Exchange Switching RoomMDF

TELEPHONE EXCHANGEThe switching centre, which houses the terminating and switching equipment and is called telephone exchange.

EVOLUTION OF TELEPHONE EXCHANGES

Manual exchange Automatic

exchangeElectronic exchange

MAIN DISTRIBUTION FRAME

•M.D.F. is a media between switching network and subscriber’s line. •It is a termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires.

SWITCHING ROOMSwitch room consists of

BM(Benjamin Moore) and CM cabinets mounted in standard switch.

These cabinets are fastened to a switch Room and interconnected by cables.

DIGITAL SWITCHINGA Digital switching system, in general, is one in which signals are switched in digital form.

These signals may represent speech or data.

Switch is the key device in PSTN.

SPACE DIVISION SWITCH

TIME DIVISION SWITCH

DIGITAL SWITCH

BROADBANDAn ‘always-on’ data connection that is able to support interactive services including Internet access and has the capability of the minimum download speed of 256 kilo bits per second (kbps) to an individual subscriber from the Point Of Presence (POP) of the service provider.

Applications of Broadband

MULTIPLEXING

There are basically two types of multiplexing techniques.

In telecommunications and computer networks, multiplexing  is a method by which multiple analog or digital signals are combined into one signal over a shared medium.

FDM TDM

FREQUENCY DIVISION MULTIPLEXINGFDM is an analog technique.In this, the transmission bandwidth is divided in frequency.FDM uses analog modulation and filtering to multiplex narrow band signals into a broadband channel.

TIME DIVISION MULTIPLEXINGTDM is a digital technique.In this, the available bandwidth is shared on a time slot basis in a round robin fashion.TDM can be implemented in two ways:i. Synchronous TDM.ii. Asynchronous TDM.

TDM multiplexing process

CONCEPTS OF PCMA pulse modulation technique in which the amplitude of an analogue signal is converted to a binary value represented as a series of pulses

To develop a PCM signal from several analogue signals, the following processing steps are required .

i. Filteringii. Samplingiii. Quantizationiv. Encodingv. Line Coding

SIGNALINGA signaling system uses a language which enables two

switching equipments to converse for the purpose of setting up calls.

Basically there are 2 types of signaling.

CHANNEL ASSOSCIAT

ED SIGNALING

CHANNEL CONTROLL

ED SIGNALING

SIGNALING CONTINUED....

CAS CCSSpeech and Signal

going along same path.Dedicated Signal

channel TS16 is used.Signal channel is not

used during speech, hence not effective utilization of signaling channel.

Not message based.

Speech and Signal going in different paths.

Same signal channel can carry signals of many speech channels

Signalling channel will be effectively utilized, hence efficient signaling system

Message based signaling system with variable lengths.

OPTICAL FIBRE CABLE

Optical Fiber is new medium, in which information (voice, Data or Video) is transmitted on the principle of Total Internal Reflection through a glass or plastic fiber, in the form of light.

OPTICAL FIBRE CABLE CONTINUED....

ADVANTAGES AND DISADVANTAGES OF OFC

ADVANTAGES DISADVANTAGESOperates at high

speeds.Wider bandwidth.Less transmission

losses.Small size and weight.High signal security.

Expensive.Difficult to install.OFC cables are more

difficult to solder.

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