Project Name:

“Data Communication” Group:

Sundas :62

Awais ch :67

Saddique: 81

Hussnain :74

Meesha :57 Subject:

“Business It”

Beginning……

Data communication :

Data communication :

It is refers to the exchange of data between a source and a receiver. Data communication

is said to be local if communicating devices are in the same building or a similarly

restricted geographical area.

Datum:

It means the facts information statistics or the like derived by calculation or

experimentation. The facts and information so gathered are processed in accordance

with defined systems of procedure. Data can exist in a variety of forms such as numbers,

text, bits and bytes. The Figure is an illustration of a simple data communication system.

Components of data communication system:

1. Message:

It is the information or data to be communicated. It can consist of text, numbers,

pictures, sound or video or any combination of these.

2. Sender:

It is the device/computer that generates and sends that message.

3. Receiver:

It is the device or computer that receives the message. The location of receiver

computer is generally different from the sender computer.

Medium:

It is the channel or physical path through which the message is carried from

sender to the receiver

Protocol:

It is a set of rules that govern the communication between the devices. Both

sender and receiver follow same protocols to communicate with each other.

Protocol

It performs the following functions:

Data sequencing.

Data routing.

Data formatting.

Flow control.

Error control.

Precedence and order of transmission.

Connection establishment and termination.

Data security

Log information

Network Modes:

The way in which data is transmitted from one place to another is called data transmission mode. It is also called the data communication mode. It is indicates the direction of flow of information.

Sometimes, data transmission modes are also called directional modes.

Types of Data Transmission Modes:

1. Simplex mode

2. Half-duplex mode

3. Full-duplex mode

Simplex Mode: In simplex mode, data can flow in only one direction. In this mode, a sender can only send data and cannot receive it. Similarly, a receiver can only receive data but cannot send it. Data

sent from computer to printer is an example of simplex mode. In simplex mode, it is not possible to confirm successful transmission of data. It is also not

possible to request the sender to re-transmit information. This mode is not widely used. However, this mode is used in business field at certain point-of-sale terminals. The other

Examples:

Radio T.V transmissions.

Half-Duplex Mode: In half-duplex mode, data can flow in both directions but only in one direction at a time. In

this mode, data is sent and received alternatively. It is like a one-lane bridge where two-way traffic must give way in order to cross the other.

Example:

The Internet browsing is an example of half duplex mode. The user sends a request to a Web

server for a web page. It means that information flows from user's computer to the web server. Web server receives the request and sends data of the requested page. The data flows the Web server to the user's computer. At a time a user can a request or receive the data of web page.

Full-Duplex Mode: In full duplex-mode, data can flow in both directions at the same time. It is the fastest directional mode of data communication.

Example:

The telephone communication system is an example of full-duplex communication mode. Two persons can talk at the same time. Another example of fully-duplex mode in daily life is automobile traffic on a two-lane road. The traffic can move in both directions at the same time.

Data Transmission Network: LAN

WAN MAN

PAN VPN

Types of Data Transmission

Network:

Local Area Network (LAN)

LAN stands for Local Area Network. It covers, as the name suggests, a local area. This usually includes a local office and they're also pretty common in homes now, thanks to the spread of Wi-Fi. LAN is based on Ethernet. There are two ways to implement Ethernet.

Wide Area Network (WAN)

It refers to a wide area network. The name is exactly what it sounds like: a network that covers an area wider than a LAN. Beyond that, the definition is less clear. Distances can range from a network connecting multiple buildings on a corporate or college campus to satellite links connecting offices in different countries. The most popular WAN is the one you're using to read this article: the Internet.

It's actually a collection of other networks, including other LANs and WANs.

Example: WANs can be wired, using fiber-optic cable, for example, or wireless. A wireless WAN might use

microwave or infrared (IR) transmission technology, or even satellite.

Virtual Private Network (VPN)

Another method that has become popular in recent years is the use of a virtual private network, or VPN. It uses the Internet to allow people to log into a network remotely and access its resources, but

encrypts the connection to thwart eavesdroppers. If your company sets you up with a VPN, you can access your corporate intranet, file servers or email from home or a coffee shop - just as if you were using it in your office. This makes VPN a popular way to support remote workers, especially in fields where privacy is paramount, such as healthcare. Windows, Mac OS X and many Linux distributions can act as VPN clients right out of the box.

Personal Area Network (PAN)

PAN stands for personal area network, and again, it's exactly what it sounds like: a network covering a very small area, usually a small room. The best known wireless PAN network technology is Bluetooth, and the most popular wired PAN is USB. You might not think of your wireless headset,

your printer or your smartphones as components in a network, but they are definitely talking with each other. Many peripheral devices are actually computers in their own right. Wi-Fi also serves as a PAN technology, since Wi-Fi is also used over a small area.

Metropolitan Area Network (MAN)

A metropolitan area network (MAN) connects nodes located in the same metro area. For example, a

company located in the San Francisco Bay Area might have its buildings in San Francisco, Oakland

and San Jose linked together via a network.

One of the most common ways for organizations to build this kind of network is to use microwave

transmission technology. You might have seen a microwave antenna on a TV news van, extended

high in the air, beaming video and sound back to the main TV studio.

Network Topologies:

Think of a topology as a network's virtual shape or structure. This shape does not

necessarily correspond to the actual physical layout of the devices on the

network.

Example:

The computers on a home LAN may be arranged in a circle in a family room, but

it would be highly unlikely to find a ring topology there.

Network topologies are categorized into the following basic types:

Bus

Ring

Star

Tree

Mesh

More complex networks can be built as hybrids of two or more of the above basic

topologies.

Bus Topology

Bus networks (not to be confused with the system bus of a computer) use a

commonbackbone to connect all devices. A single cable, the backbone functions

as a shared communication medium that devices attach or tap into with an

interface connector. A device wanting to communicate with another device on the

network sends a broadcast message onto the wire that all other devices see, but

only the intended recipient actually accepts and processes the message.

Bus Topology Diagram

Ring Topology

In a ring network, every device has exactly two neighbors for communication

purposes. All messages travel through a ring in the same direction (either

"clockwise" or "counterclockwise"). A failure in any cable or device breaks the

loop and can take down the entire network.

Ring Topology Diagram

Star Topology:

Many home networks use the star topology. A star network features a central

connection point called a "hub node" that may be a network

hub , switch or router . Devices typically connect to the hub with Unshielded

Twisted Pair (UTP) Ethernet.

Compared to the bus topology, a star network generally requires more cable.

Star Topology Diagram

Tree Topology:

Tree topologies integrate multiple star topologies together onto a bus. In its

simplest form, only hub devices connect directly to the tree bus, and each hub

functions as the root of a tree of devices. This bus/star hybrid approach supports

future expandability of the network much better than a bus (limited in the number

of devices due to the broadcast traffic it generates) or a star (limited by the

number of hub connection points) alone.

Tree Topology Diagram

Mesh Topology:

Mesh topologies involve the concept of routes. Unlike each of the previous

topologies, messages sent on a mesh network can take any of several possible

paths from source to destination. (Recall that even in a ring, although two cable

paths exist, messages can only travel in one direction.) Some WANs , most

notably the Internet, employ mesh routing.

A mesh network in which every device connects to every other is called a full mesh. As

shown in the illustration below, partial mesh networks also exist in which some devices

connect only indirectly to others.

ADVANTAGES OF COMMUNICATION:

Speeds the sending of information: Communication technology tools like electronic mail and text messaging systems speed up

the sending of information within and outside of the organization.

Improves organizational communication:

Communication technology helps in the creation of a shared information environment in an organization. Organization information is organized in one central location, allowing any one access that information as they need.

Speeds decision making in an organization:

Since communication technology speeds the transfer of information, employees in an organization can easily consult each other and analyze information in a shortest period and make a decision.

Increases participation in organizational processes:

Every employee will have a specific task to complete and all this can be monitored remotely by the manager. So all parties will be active since their work is being made simple by easy communication.

Influences the way people interact in organizations:

An organization were you only see the operations manager twice a week, by the time he comes, everyone will need to speak to them and they will have less time for each of you. But with electronic mail, you can simply draft an email and send it to your superior or workmate.

Structures organizational life:

Communication technology puts everything where it is supposed to be. No need to see papers and files every where in the office. All data is stored on the database, and you will have less paper work in the organization which makes life easier at work.

Supports open discussions:

Most organization have used the internet to create organizational forums where members of the organization can discuss about various issues and get a solution. In this case members can suggest on areas of improvement within the organization.

Eliminates stereotypical classifications: It reflects a selected few of the racial demographics. With communication technology, all this will be eliminated because there is no face-to-face communication. Stereotyping of employees can result into poor performance and lack of self-esteem amongst employees, so it is a wrong character.

Provides a voice to those who normally would not speak up in

groups:

Face-to-face communications tends to be difficult to some people, so the use of communication technology will help them communicate effectively at work.

DISADVANTAGES OF COMMUNICATION TECHNOLOGY IN

AN ORGANIZATION:

Poor substitute for face-to-face communication:

Since employees are using machines to communicate, they get less time to talk to each

other and know each other better. This has resulted into increased bad relationships at work.

Difficulty Training Employees:

If an organization deploys a new communication technology system, they will have to pay an extra fee to train employees in the organization to use that technology effectively.

Expensive:

It can be very expensive to install a new communication technology system in a very big organization.

Not Safe:

Information has been centralized less than one database; it is exposed to people with wrong intention within the organization.

Communication Devices:

Communication device is a hardware device capable of transmitting

an analog or digital signal over the telephone, other communication

wire, or wirelessly. The best example of a communication device is a

computer Modem, which is capable of sending and receiving a signal to

allow computers to talk to other computers over the telephone. Other

examples of communication devices include a network interface

card(NIC), Wi-Fi devices, and an access point. Below is a picture of

some of the different types of Wi-Fi devices that are all examples of a

communication device.

Communication device examples

Below is a full listing of all the different types of communications devices you

may encounter when dealing with a computer.

Bluetooth devices Infrared devices

Modem (over phone line) Network card (using Ethernet)

Smartphone Wi-Fi devices (using a router)

Physical Transmission:

It uses wire, cable, and other physical materials to send communications signals.

Examples of physical transmission media are

Twisted-pair cable

Coaxial cable

Fiber-optic cable

Fiber optic:

Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials. It transmits lights rather than electronic signals thus eliminating

electrical interference, this makes it suitable for areas that contain large amount of electrical interferences. In addition it has the ability to transmit signals over much

longer distance, carry more information at a faster speed than coaxial and twisted pair. More over cables are much thinner and light weighted.

Coaxial cable:

Coaxial cabling has a single conductor as it center. A plastic layer provides insulation between the center conductor ad the braided mental shield. The metal shield help to block any outside interference from fluorescent lights, motors, and other computers . Its difficult to install, but its highly resistant to signal interference, it supports greater

cable length between network devices than twisted pair. Two type of coaxial cable are: thick coaxial and thin coaxial.

Twisted-pair cable:

The cable has four pairs of wires inside the jacket. Each pair is twisted with a different number of twists per inch to help eliminate interference from adjacent pairs

and other electrical devices. The tighter the twisting, the higher the supported transmission rate and the greater the cost per foot.

Wireless Transmission Media –

Send communications signals through air or space. Used when inconvenient,

impractical, or impossible to install cables.

Types Wireless Transmission Media

Broadcast Radio

Bluetooth:

Cellular Radio

Personal Communication Services (PCS)

Microwaves

Uses line-of-sight transmission

Communications

Infrared

Thank You