Computer application: Chapter #9 Networks and Communications

COMMUNICATIONS

Computer communications describes a process in which two or more computers or devices transfer data, instructions, and information.

USES OF COMPUTER COMMUNICATIONS

Users can send and receive wireless messages using wireless messaging services.
Wireless Internet access points allow people to connect wirelessly to the Internet from home, work, school, and in many public locations.
A cybercafe 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.
Groupware

Helps groups of people work together on projects and share information over a network.
Component of workgroup computing.
Major feature is group scheduling.

Allows someone to leave a voice message for one or more people.
Computer in voicemail system converts an analog voice message into digital form.
A voice mailbox is a storage location on a hard disk in the voice mail system.

Many programs provide a means to collaborate, or work online, with other users connected to a server.
Collaboration software includes tools that enable users to share documents via online meetings and communicate with other connected users.
Web services enable programmers to create applications that communicate with other remote computers over the internet or on an internal business network.
A mashup is a web application that combines services from two or more sources.
A network is a collection of computers and devices connected together via communications devices and transmission media.

NETWORKS

A local area network (LAN) is a network that connects computers and devices in a mimited 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 geographical area.
The design of computers, devices, and media on a network is sometimes called the network architecture.
P2P describes an Internet network on which users access each other's hard disks and exchange files directly over the Internet.
A network topology refers to the layout of the computers and devices in a communications network.
An internet is an internal network that uses Internet technologies.
An extranet allows customers or suppliers to access part of its intranet.

Network Communications Standards

Ethernet is a network standard that specifies no computer controls when data can be transmitted.
The token ring standard specifies that computers and devices on the network share or pass a special signal (token).
TCP/IP is a network standard that defines how messages are routed from one end of a network to another.
Wi-Fi identifies any network based on the 802.11 standard that facilities 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 places in or attached to an object, animal, or person.
WiMAX (802.16)

Communications Software

Communications Over the Telephone Network

Communications Devices

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 form a notebook computer, a smart phone, or other mobile device.
A network card enables a computer or device to access a network.
Available in a variety of styles.
Wireless network cards often have an antenna.
A wireless access point is a central communications device that allows computers and devices to transfer data wielessly among themselves or to a wired network.
A router connects multiple computers or other routers together and transmits data to its correct destination on a network.
Many are protected y a hardware firewall.
A hub or switch connects several devices in a network together.

Home Networks

Communications Channel

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.

Wireless Transmission Media

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 satellites is a space station that receives microwaves signals from an earth-based station, amplifies it, and broadcasts the signal over a wide area.

Computer application