CHAPTER-9 NETWORK AND COMMUNICATION

Computer communications describes a process in which two or more computers or devices transfer data, instructions, and information. Users can send and receive wireless messages using wireless messaging services. Mostly used for blog, chat room, Email, Fax.

  

Process of communication :-

·       Sending device

·       Communication channel

·       Receiving data

Wireless Internet access points allow people to connect wirelessly to the Internet from home, work, school, and in many public locations.

A Cybercafé is a coffeehouse, restaurant, or other location that provides personal computers with Internet access to its customers.

A global positioning system (GPS) is a navigation system that consists of one or more earth-based receivers that accept and analyze signals sent by satellites in order to determine the GPS receiver’s geographic location.

GPS receiver are available in :-

·       Built into mobile device

·       Available as handheld device

·       Available in new vehicles

A Network is a collection of computers and devices connected together via communications devices and transmission media

Advantages of a network include :-

·     Facilitaing communication

·     Sharing hardware

·     Sharing data and information

·     Sharing software

·     Transferring funds

A local area network (LAN) is a network that connects computers and devices in a limited geographical area.

A wireless LAN (WLAN) is a LAN that uses no physical wires.

A metropolitan area network (MAN) connects LANs in a metropolitan area.

A wide area network (WAN) is a network that covers a large geographic area.

The design of computers, devices, and media on a network is sometimes called the network architecture.

A network topology refers to the layout of the computers and devices in a communications network. Example – Ethernet , Token ring, Wi-Fi, Bluetooth, WAP.

Wi-Fi identifies any network based on the 802.11 standard that facilitates wireless communication. Sometimes referred to as wireless Ethernet.

Bluetooth defines how two Bluetooth devices use short-range radio waves to transmit data.

UWB (ultra-wideband) specifies how two UWB devices use short-range radio waves to communicate at high speeds.

IrDA transmits data wirelessly via infrared (IR) light waves.

RFID uses radio signals to communicate with a tag placed in or attached to an object, animal, or person.

Communications software consists of programs that are :-

• ·  Helps users establish a connection to another computer and network.
• ·          Manage the transmission of data , instructions, and information.
• ·           Provide an interface for users to communicate with one another.

A communications device is any type of hardware capable of transmitting data, instructions, and information between a sending device and a receiving device.

A dial-up modem converts signals between analog and digital.

A digital modem sends and receives data and information to and from a digital line.

A wireless modem uses the cell phone network to connect to the Internet wirelessly from a notebook computer, a smart phone, or other mobile device.

A network card enables a computer or device to access a network.

A router connects multiple computers or other routers together and transmits data to its correct destination on a network. Many are protected by a hardware firewall.

The amount of data that can travel over a communications channel sometimes is called the bandwidth.

Latency is the time it takes a signal to travel from one location to another on a network.

 Transmission media carries one or more signals.

Broadband media transmit multiple signals simultaneously.

Cellular radio is a form of broadcast radio that is used widely for mobile communications.

Microwaves are radio waves that provide a high-speed signal transmission.

A communications satellite is a space station that receives microwave signals from an earth-based station, amplifies it, and broadcasts the signal over a wide area.