Basics Of Data Communication Part: 1

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Introduction and Basics of Data Communication Model

Data Communications is the transfer of data or information between a source and a receiver. The source transmits the data and the receiver receives it. Data communication involved the following like communication networks, different communication services required, the kind of networks available, protocol architectures, OSI models, TCP/IP protocol models etc. Data Communication is interested in the transfer of data, the method of transfer and the preservation of the data during the transfer process.

In Local Area Networks, we are interested in "connectivity", connecting computers together to share resources. Even though the computers can have different disk operating systems, languages, cabling and locations, they still can communicate to one another and share resources.

The purpose of Data Communications is to provide the rules and regulations that allow computers with different disk operating systems, languages, cabling and locations to share resources. The rules and regulations are called protocols and standards in Data Communications.



It is the generator of data that will pass on the destination using networks. Without any request source never passes the data to destination. So, if source is passing the data means any of the destinations is requesting for data using some query languages.


It is simply a device used to convert the data as per the destination requirement. For example a modem, converts the analog (telephonic signals) signal to digital (computer signals) signals and alternatively digital to analog also.

Transmission System

To transmit the data on different connected systems we use different transmission systems. Data transmission using transmission system means the physical transfer of data over point-to-point or point-to-multipoint communication channels. Example of such channels are copper wires, optical fibers even wireless communication channels etc.


This receives the signals from the transmission system and converts it into a form that is suitable to the destination device. For example, a modem accepts analog signal from a transmission channel and transforms it into digital bit stream which is acceptable by computer system.


It is simply a device for which source device sends the data.

Data Communication System Tasks

There are some tasks performed by the communication systems are

Signal Generation

To transmit the data over the transmission system, communicating device must be able to generate and receive these signals. The generation of the signals should be in such a way that the resultant signal can be acceptable by the transmission mediums.


Device must interface with the transmission system to communicate or transfer the data over network.

Data Synchronization

It is the process of establishing consistency among data from a source to destination devices and vice versa and continuous harmonization of the data over time.

Exchange Management

For meaningful data transaction there should be some management of data being exchanged. Both the transmitter and receiver should adhere to some common convention about the format of data, amount of data, time required, data format etc.

Transmission System Utilization

Due to the importance of Data transmissions without interruptions or failures the transmission systems is usually well dimensioned and are being operated with margins that minimize the possibility of outages. Various techniques are available to allocate the total capacity of a transmission channel among connected devices like Digital, Analog, Multiplex, Simplex, Duplex, Half-Duplex etc.

Error Detection and Correction

In any communication system transmitted data is prone to error. Either it is because of transmitted signal getting distorted in the transmission medium leading to misinterpretation of signal or errors introduced by the intermediate devices. Error detection and correction is required in cases where there is no scope for error in the data transaction. We can think of file transfer between two computers or even on remote network computers where there is a need for this. But in some cases it may not be very important as in the case of telephonic conversation.

Flow Control

At the time of transmission of data, source computer is generating data faster than receiver device capable to receive it. To handle such problem, there is some kind of flow control mechanism used. Before getting started the transmission of data they have to agree upon between two communication devices.


When more than two devices share a transmission facility, a source system must somehow indicate the identity or address of the destination. Addresses are in form of IP or we can say ftp address and there are used lots of credentials.


Routing means to send data to appropriate destinations. In this process the evolved computer ensures that the data is being sent on destination system only or any other hacking happening. To eliminate such problem developers uses SSL level security.

Communication Network and Services

Communication Network is set of equipment or say facilities that provide a communication services like to transfer of data between two or more nodes located in any of its geographical point. Example of such networks includes computer networks (LAN/WAN), intranet networks, telephone networks, television broadcasting networks, cellular networks etc.

Radio and Television Networks

These networks are very common network usage various stations to transmit an ensemble of signals simultaneously over network of cables. Aside from selecting the station of interest, the role of the user in these services is passive. Relatively high audio and video quality is expected here but a significant amount of delay (fraction of second) can be tolerated even in live broadcasting.

Telephone Networks

This service is real-time service provided by a network. Two persons are able to communicate by transmitting their voice across the network. These services is called connection-oriented service because to establish such communication users must first interact with the network.

Cellular Networks

These networks extends the normal telephone service to mobile users who are free to move within a regional area covered by an interconnected array of smaller geographical areas called cells. Each cell has a radio transmission system that allows it to communicate with users in its area. Cellular provides also support a roaming service where a subscriber is able to place calls while visiting regional area other than the home.

There are many other network services like Video on Demand, Streaming Audiovisual, and Audio-Video Conferencing etc available.