DATA COMMUNICATION

DATA COMMUNICATION

Data communication refers to all the methods by which computers and other devices in a network send data to each other.What is a network?A network is a set of computers that are linked together so that they can share facilities such as printers, files, memory space and so on.

2005 Prentice-Hall, IncSlide 3- Reduced hardware costs-Users share equipmentConnected people-People can work together without being at the same location-Groupware software enables sharing of schedules and communicationsAdvantages of NetworkingShared applications-Users share software-File server enables all users to work with the same application program Building information resources-Users create common pools of data that can be accessed by employees

2005 Prentice-Hall, IncSlide 4Disadvantages of NetworkingThe organization has to pay technical staff to maintain the network.The network fail occasionally then no one in the organization can use the computers.As more users long on to the network the servers have to share there time among them and the system may slow down.Additional work is given when the users forget their passwordTypes of networksThere are three (3) main types of networks:

1. LAN Local Area Network: this is a network of computers that are connected by cables over a fairly small area, usually within one building, such as an office or school.

2. MAN - Metropolitan Area Network: this is a computer network run by one organization that connects together several LANs across a larger area such as a city. A MAN uses both cables and wireless connections.

2. WAN - Wide Area Network: this is a network that connects computers over a wide area or even across the world. A WAN uses satellite and other wireless connections rather that cables.

Check your progressAnswer the following question in your notebooks:Which of the networks (LAN, MAN, WAN) is used here in the I.T. lab? Give reasons for your answer.Is the internet a type of network? If yes what type of network is it (LAN, MAN, WAN)? Give reasons for your answers

Transmission mediaThese are cables and signaling methods that carry data from one place to another in a network. Transmission media fall into two (2) groups: wired transmission media and wireless transmission media.

Wired transmission media-These consists of cables and wires used for transmission.

1. Twisted Pair cables: this consist of two insulated wires twisted around each other; the same type of wire as that used for telephones.

2. Coaxial cables: these consists of an insulated copper wire surrounded by a layer of braided wire; the same type of wire as that used for cable TV.

3. Fibre optic cable: this consist of a type of fiber glass cable that transmits data in the form of light impulses. They can carry more data for longer distances than other wired medias.

Wireless transmission media-This refers to the methods of carrying data through the air or space using signals.

Infrared : is a wireless transmission medium that carries data via light beams. It includes a transmitter and receiver for sending and receiving signals.

Transmitter and receiver must be in line of sight.

2. Radio Wave: this is a wireless transmission medium that carries data via radio frequency signals.

Wireless LANs in a home or business are one type of radio technology.Radio signals can be long range (between cities or regions) and short range (within a building).Radio signals are susceptible to noise and electrical interference.

3. Microwaves: are high-frequency radio waves.

Much of long-distance telephone service is carried by microwaves.Microwaves travel in a straight line.Microwave relay stations are built about 30 miles apart.

4. Satellites: are microwave relay stations suspended in space. Satellites use microwave signals to transmit data to and from earth-based relay stations.

Wireless network technology-These are used to connect laptops and other mobile devices to a network. These are:

WI-FI(wireless fidelity): is a wireless method of data transmission used in LANs and for internet access. Some cell phones can use WI-FI technology to access the internet.

Bluetooth: is similar to WI-FI but only works over short distances and is slower. It is mainly used to send data between devices such as a cell phone, camera, laptop and so on.

Group activityStudents will be placed into groups based on the type of transmission medium they choose. They will then give advantages and disadvantages of the transmission medium selected.

Read up on the following for the next class:

-Modem-Hotspot-Bandwidth(narrowband, voiceband, broadband)-Communication modes(simplex,half-duplex,duplex)