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CHAPTER 5 : COMMUNICATION SYSTEM & COMPUTER NETWORK - Coggle Diagram
CHAPTER 5 : COMMUNICATION SYSTEM & COMPUTER NETWORK
Computer communications
Process in which two or more computers or devices transfer data, instructions, and information
Needed for successful communications
Sending device — initiates instruction to transmit data, instructions, or information
Communications device — connects the sending device to the communications channel
Receiving device — accepts transmission of data, instructions, or information
Communications channel — media on which data, instructions, or information travel
Communications device — connects the communications channel to the receiving device
Uses of Computer Communications
wireless messaging services
Text messaging
Wireless instant messaging
Picture/video messaging
Global positioning system (GPS) - In order to determine the receiver’s geographic location . Navigation system that consists of one or more earth-based receivers
Collaboration and Groupware
-Collaboration is working with other users connected to a server
-Groupware is software that allows people work together and share information
Voice mail and web services
-Voice mail is voice message converted to digital form
-Web services describe standardized software that enables programmers to create applications that communicate with other remote computers over the Internet or on an internal business network
NETWORK
Collection of computers and devices connected via communications devices and transmission media.
Networks Classifications
Local area network (LAN) &Metropolitan area network (MAN) -
-A LAN is a network in limited geographical area such as home or office building
-Metropolitan area network (MAN) connects LANs in city or town
Wide area network (WAN) - Network that covers large geographic area using many types of media
Networks Architecture
Client/server network
-One or more computers act as server and other computers, or clients, access server
Peer-to-peer network
Simple network that connects fewer than 10 computers
-Each computer, or peer, has equal capabilities
Internet peer-to-peer (P2P)
-Sometimes called a file sharing network
-Enables users to connect to each other’s hard disks and exchange files directly
NETWORK TOPOLOGY
Star network
All devices connect to a central device (hub or switch)
-All data transferred from one computer to another passes through hub or switch
Bus network -
-All computers and devices connect to central cable or bus
-Example of network topology (layout of devices in network)
-Popular topologies are bus, ring, and star
Ring network -
-Cable forms closed loop (ring), with all computers and devices arranged along ring
-Data travels from device to device around entire ring, in one direction
Intranet
Makes information accessible to employees
Typically includes connection to Internet
Internal network that uses Internet technologies
Extranet allows customers or suppliers to access part of company’s intranet
Network Communications Standards
Bluetooth - Short-range radio waves transmit data between Bluetooth devices
UWB - specification allows data to be transferred wirelessly via short-range radio waves
IrDA- specification allows data to be transferred wirelessly via infrared light waves
Worldwide Interoperability for Microwave Access (WiMAX or 802.16) - standard that specifies how wireless devices communicate over the air in a wide area
Radio Frequency Identification (RFID) - uses radio signals to communicate with a tag placed in an object
Wireless Applications Protocol (WAP) -allow wireless mobile devices to access Internet
Communications Software
Programs that help users establish connection to Internet, other network, or another computer
Programs that help users manage transmission of data, instructions, and information
Programs that provide an interface for users to communicate with one another
Communications Over the Telephone Network
Public switched telephone network (PSTN) - Worldwide telephone system that handles voice-oriented telephone calls
Dial-up line - Temporary connection using telephone line for communications
Communication devices
Dial-up modem
-A dial-up modem converts digital signals to analog signals and vice versa
-Usually in the form of an adapter card
ISDN and DSL modems
Usually external devices in which one end connects to a telephone line and the other end connects to a port on the system unit
Cable modem -
Sends and receives data over cable television network
Much faster than dial-up modem or ISDN
Sometimes called a broadband modem
Wireless modem
-Allows access to the Web wirelessly from a notebook computer, a smart phone, or other mobile device
Network card
Adapter card, PC Card, Express Card module, USB network adapter, or flash card that enables computer or device to access network
Wireless access point
-Central communications device that allows computers and devices to transfer data wirelessly among themselves or wirelessly to a wired network
Router
Connects computers and transmits data to correct destination on network
-Routers forward data on Internet using fastest available path
Hub or switch
Device that provides central point for cables in network
Home Networks - Multiple computers connected in home
-Several types of home networks.
EXAMPLE : phone line, powerline cable,ethernet
Physical Transmission Media
Wire, cable, and other tangible materials used to send communications signals
Twisted-pair cable and coaxial cable
Twisted-pair cable is used for telephone systems and network cabling
-Coaxial cable is often used for cable television wiring
Fiber-optic cable - Capable of carrying significantly more data at faster speeds than wire cables
Wireless Transmission Media
-Used when inconvenient, impractical, or impossible to install cables
-Includes Bluetooth and IrDA
Broadcast radio - Broadcast radio distributes radio signals over long and short distances
Cellular radio
Use widely for mobile communications, specifically wireless modems and cell phones.
Microwave station - Earth-based reflective dish used for microwave communications
communications satellite - Space station that receives microwave signals from earth-based station, amplifies signals, and broadcasts signals back to any number of earth-based stations