Introduce Data Communication - Computer Science -Networking

INTRODUCE

data communication

Basic Requirements for Successful Communication

– Two or more parties (Sender & Receiver)

 – Communication medium (Channel)

 – Use of compatible standards (Protocols)

For data communication to occur, the communicating devices must be part of a communication system made up of a combination of hardware and software.

Characteristics of Data Communication System

• Delivery–

 The system must deliver data to the correct destination. Data must be received by the intended device or user and only by that device or user.

 • Accuracy–

The system must deliver data accurately.  The data that had been altered in transmission and left uncorrected are unusable.

 • Timelines–

 The system must deliver data in a timely manner.  Data delivered late are useless.  Timely deliver means delivering data as they are transmitted, in the same order they are sent, and without significant delay.

•  Data is encoded and transmitted as signals in the transmission media.

•  Based on the bit pattern of data, the sending side generates a signal on the selected transmission medium and then this signal propagates to the receiving end.

•  The receiving side extracts data from this signal and reproduce in its original format.

•A signal is generated by changing the strength (or any other property) of a particular form of energy with respect to time on a suitable medium.

• Form of energy used can be Electrical, Light or Electromagnetic .

• The medium used can be Copper, Optical Fiber or Free Space.

1.Electrical  ;

Copper

     2.Light ;

      Optical Fiber

       3.Electromagnetic;

        Free space

Physical Media

•  Properties –Bandwidth, Delay, Cost, Ease of installation & maintenance, etc.

•  Media

          * Guided (wire-line)

      * Media Unguided (wireless) -signal is always analog

•  Characteristics and quality determined by medium and signal .

•  For guided, the medium is more important.

•  For unguided, the bandwidth produced by the antenna is more important.

•  Key concerns -data rate and distance .

• Design Factors –Bandwidth (Higher bandwidth gives higher data rate), Transmission impairments, Interference, Number of receivers.