csc1100 - chapter07 - communications & networks
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ဆက်သွယ်ရေးနှင့်ကွန်ရက်များTRANSCRIPT
Discovering Computers 2008
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Chapter 7 Chapter 7 Chapter 7 Chapter 7
Communications Communications Communications Communications
and Networksand Networksand Networksand Networks
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Chapter 7 ObjectivesChapter 7 ObjectivesChapter 7 ObjectivesChapter 7 Objectives
Discuss the components required for successful communications
Discuss the components required for successful communications
Identify various sendingand receiving devices
Identify various sendingand receiving devices
Describe uses of computer communicationsDescribe uses of computer communications
Explain the purpose ofcommunications software
Explain the purpose ofcommunications software
Describe various types of lines for communications over the telephone network
Describe various types of lines for communications over the telephone network
Describe commonly usedDescribe commonly used
List advantages of using a networkList advantages of using a network
Differentiate among client/server,peer-to-peer, and P2P networks
Differentiate among client/server,peer-to-peer, and P2P networks
Describe the various network communications standards
Describe the various network communications standards
Describe commonly usedcommunications devicesDescribe commonly usedcommunications devices
Discuss different ways to set upa home network
Discuss different ways to set upa home network
Identify various physical and wireless transmission media
Identify various physical and wireless transmission media
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CommunicationsCommunicationsCommunicationsCommunications
What are computercommunications?� Process in which two or more computers/devices transfer
data, instructions, and information
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Sending device— initiates
instruction to transmit data, instructions, or
What is needed for successful communications?
CommunicationsCommunicationsCommunicationsCommunications
Communications device— connects
the sending device to the communications
channel
Communications channel— media
on which data, instructions, or
information travelinstructions, or information
Communications device— connects the communications
channel to the receiving device
Receiving device— accepts
transmission of data, instructions, or
information
channel information travel
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Uses of Computer CommunicationsUses of Computer CommunicationsUses of Computer CommunicationsUses of Computer Communications
What are some uses of communications technology?
WebWebWebWebInternetInternetInternetInternet EE--MailMailEE--MailMailInstantInstant
MessagingMessagingInstantInstant
MessagingMessaging
Internet Internet Internet Internet Internet Internet TelephonyTelephonyInternet Internet
TelephonyTelephonyNewsgroupsNewsgroupsNewsgroupsNewsgroupsChat RoomsChat RoomsChat RoomsChat Rooms
WebWebFoldersFolders
WebWebFoldersFolders
Fax Machine Fax Machine or Computer or Computer Fax/ModemFax/Modem
Fax Machine Fax Machine or Computer or Computer Fax/ModemFax/Modem
VideoVideoConferencingConferencing
VideoVideoConferencingConferencing
FTPFTPFTPFTP
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What are wireless messaging services?What are wireless messaging services?What are wireless messaging services?What are wireless messaging services?
TEXT MESSAGING� Limit messages to usually fewer
than 300 characters� Mobile to Mobile� Mobile to E-Mail� Web to Mobile� Mobile to Provider: use common
Text messagingText messagingallows users to send allows users to send and receive short and receive short
text messages text messages � Mobile to Provider: use common short code – 4 or 5 digit num assigned to specific content or wireless service provider, followed by message – e.g. vote for TV prg contestant
text messages text messages (SMS) on a phone (SMS) on a phone
or PDAor PDA
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What are wireless messaging services?What are wireless messaging services?What are wireless messaging services?What are wireless messaging services?
PICTURE MESSAGING� Video messaging: to send short video clips (about 15
seconds)� Smart phones & PDAs with picture/video messaging
also called MMS (multimedia message service)� Camera phone, video phone� Camera phone, video phone� Mobile to Mobile� Mobile to E-Mail
Picture messaging Picture messaging allows users to send allows users to send graphics, pictures, graphics, pictures, video clips, sound video clips, sound
files, and short text files, and short text messagesmessages
Video Video messagingmessaging
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What are wireless messaging services?What are wireless messaging services?What are wireless messaging services?What are wireless messaging services?
WIRELESS INSTANT MESSAGING (IM)�Real-time Internet communications service that allow
wireless mobile devices to exchange messages with one or more mobile devices or online users
�Some WISP provide IM service: smart phone & PDAs can be used to send & receive instant messagesPDAs can be used to send & receive instant messages
�AOL Instant Messenger (AIM), Yahoo! Messenger
�Mobile to Mobile�Mobile to PC�Web to Mobile
Wireless instant Wireless instant messagingmessagingallows allows wireless mobile wireless mobile
devices to exchange devices to exchange messagesmessages
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Uses of Computer CommunicationsUses of Computer CommunicationsUses of Computer CommunicationsUses of Computer Communications
What are wireless Internet access pointsand cybercafés?� Wireless Internet access
point allows wireless connection to Internet in public location� Hot sport, 3G network
� Cybercaféis coffee house that provides computers with Internet access – some are also hot spots
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Uses of Computer CommunicationsUses of Computer CommunicationsUses of Computer CommunicationsUses of Computer Communications
What is a global positioning system (GPS)?�Navigation systemconsists of one or more earth-based
receivers that accept & analyze signals sent by satellites in order to determine the geographical location
�GPS receiver: handheld, mountable or embedded device containing an antenna, a radio receiver and a processor –containing an antenna, a radio receiver and a processor –many include screen display showing an individual’s location on a map
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Uses of Computer CommunicationsUses of Computer CommunicationsUses of Computer CommunicationsUses of Computer Communications
What is a global positioning system (GPS)?
Step 1.GPS satellites orbit Earth. Every thousandth of a second, each satellite sends a signal that
Step 2.A GPS receiver (such as in a car, a wearable device, a smart phone, a handheld device, or a collar)sends a signal that
indicates its current position to the GPS receiver.
or a collar)determines its location on Earth by analyzing at least 3 separate satellite signals from the 24 satellites in orbit.
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Uses of Computer CommunicationsUses of Computer CommunicationsUses of Computer CommunicationsUses of Computer Communications
What are collaboration and groupware?
� A document management systemprovides for storage and
� Collaboration or work online is working with other users connected to a server
management of a company’s documents
� Groupware is software that allows people work together and share information over a network
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Uses of Computer CommunicationsUses of Computer CommunicationsUses of Computer CommunicationsUses of Computer Communications
What are voice mailand web services?� Voice mail is voice message
converted to digital form� Web servicesdescribe standardized
software that enables programmers to create applications that to create applications that communicate with other remote computers over the Internet or on an internal business network � doesn’t specific require prg lang,
OS, or Web browser� By sending properly formatted
XML (eXtensive Markup Language)files to Web services
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NETWORKNETWORKNETWORKNETWORK
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NetworksNetworksNetworksNetworks
What is a networknetwork?� Collection of
computers and devicesconnected via communications devicesand transmission mediatransmission media
What are the advantages of using a network?What are the advantages of using a network?
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NetworksNetworksNetworksNetworks
What is a local area network (LANLAN) and a metropolitan area network (MANMAN) ?� Network in limited geographical area such as
home or office building� Wireless LAN (WLANWLAN)
� Metropolitan area network (MAN) connects LANs � Metropolitan area network (MAN) connects LANs in city or town
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NetworksNetworksNetworksNetworks
What is a wide area network (WAN)?
� Network that covers large geographic area using many types of mediatypes of media
� Internet is world’s largest WAN
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NETWORK ARCHITECTURESNETWORK ARCHITECTURESNETWORK ARCHITECTURESNETWORK ARCHITECTURES
peer-to-peer &
P2PP2P
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NetworksNetworksNetworksNetworks
What is a client/server network?� One or more computers
act as serverand other computers, or clients, access serveraccess server
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NetworksNetworksNetworksNetworks
What is a peer-to-peernetwork?� Simple network
that connects fewer than 10 computerscomputers
� Each computer, or peer, has equal capabilities
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NETWORK TOPOLOGIESNETWORK TOPOLOGIESNETWORK TOPOLOGIESNETWORK TOPOLOGIESbus, ring & star
(layout of devices in network)
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NetworksNetworksNetworksNetworks
What is a bus network?� All computers and devices connect to central
cable or bus
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NetworksNetworksNetworksNetworks
What is a ring network?� Cable forms closed
ring, or loop, with all computers and devices arranged along ring
� Data travels from � Data travels from device to device around entire ring, in one direction
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NetworksNetworksNetworksNetworks
What is a star network?� All devices connect to
a central device (hub or switch)
� All data transferred from one computer to from one computer to another passes through hub or switch
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NetworksNetworksNetworksNetworks
What is an intranet?
Makes information accessible to employees
Internal network that uses Internet technologies
Extranetallows customers or suppliers to access part of company’s intranet
Typically includes connection to Internet
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IntranetIntranetIntranetIntranet
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NETWORK COMMUNICATIONS NETWORK COMMUNICATIONS NETWORK COMMUNICATIONS NETWORK COMMUNICATIONS
STANDARDSSTANDARDSSTANDARDSSTANDARDSEthernet, Token Ring, TCP/IP, 802.11 (Wi-Fi), Bluetooth,
UWB, IrDA, RFID, WiMAX, WAPUWB, IrDA, RFID, WiMAX, WAP
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Network Communications StandardsNetwork Communications StandardsNetwork Communications StandardsNetwork Communications Standards
What are Ethernet and token ring?
Ethernet technology allows computers to contend for access to network
If two computers send data at same time, a collision occurs and computers must send the data againcomputers must send the data again
Token ring technology controls access to network by requiring devices to pass a special signal,
called token
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Network Communications StandardsNetwork Communications StandardsNetwork Communications StandardsNetwork Communications Standards
What are TCP/IP and 802.11 (Wi-Fi )?� TCP/IP (Transmission Control Protocol/Internet
Protocol) technology transmits data by breaking it up into small pieces, or packets� Commonly used for Internet transmissions
� 802.11 (Wi-Fi) is family of standards for wireless LANs802.11 (Wi-Fi) is family of standards for wireless LANs
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Network Communications StandardsNetwork Communications StandardsNetwork Communications StandardsNetwork Communications Standards
What is Bluetooth?
Short-range radio waves transmitShort-range radio waves transmitdata between Bluetooth devices
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Network Communications StandardsNetwork Communications StandardsNetwork Communications StandardsNetwork Communications Standards
What are UWB, IrDA , RFID, WiMAX , and Wireless Applications Protocol (WAP)?
IrDAIrDAspecification allows data to be transferred wirelessly via infrared
IrDAIrDAspecification allows data to be transferred wirelessly via infrared
Worldwide Interoperability Worldwide Interoperability Worldwide Interoperability Worldwide Interoperability for Microwave Access (WiMAXfor Microwave Access (WiMAX
UWBUWBspecification allows data to be transferred wirelessly via short-range
UWBUWBspecification allows data to be transferred wirelessly via short-range wirelessly via infrared
light waveswirelessly via infrared light waves
Wireless Applications Wireless Applications Protocol (WAP)Protocol (WAP)allow wireless mobile devices to access Internet
Wireless Applications Wireless Applications Protocol (WAP)Protocol (WAP)allow wireless mobile devices to access Internet
Radio Frequency Radio Frequency Identification (RFID)Identification (RFID)uses radio signalsto communicatewith a tagplaced in an object
in a wide area
or 802.16)or 802.16)standard that specifies how wirelessdevices communicate over the airin a wide area
wirelessly via short-rangeradio waveswirelessly via short-rangeradio waves
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Communications SoftwareCommunications SoftwareCommunications SoftwareCommunications Software
What is communications software?
Programs that help users establish connectionto Internet, other network, or another computer Programs that help users
manage transmissionof
System softwareSystem software
Application Application softwaresoftwaremanage transmissionof
data, instructions, and information
Programs that provide an interface for usersto communicate with one another
Application software for communication:e-mail, FTP, Web browser, newsgroup/message boards, chat rooms, instant messaging, video conferencing, Internet telephony,…
softwaresoftware
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Communications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkDial-Up Lines, Dedicated Lines
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Communications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone Network
What is the public switched telephone network (PSTN)?
� Worldwide telephone system that handles voice-oriented telephone callstelephone calls
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Communications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone Network
What is a dial-up line?� Temporary connectionusing telephone line for
communications� Computers at any two locations can establish a
connection using modems and telephone network
� Costs no more than making regular call� Costs no more than making regular call
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Communications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone Network
What is a dedicated line?� Always-on connection
between two communications devices
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Communications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone Network
Dedicated lines:� 5 types:
1.ISDN (Integrated Service Digital Network) line
2.DSL (Digital Subscriber Line), ADSL (Asymmetric …)
3.FTTH & FHHB (Fiber to the Home/Building)
4.T-Carrier line (T1, fractional T1, T3)
5.ATM (Asynchronous Transfer Mode)ISDN line technique of carrying 3 or more
signals at once through the same line
multiplexingmultiplexing
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What are examples of communications devices?
Common types are dial-up modems, ISDN and DSL modems, cable modems, wireless modems,
network cards, wireless access points, routers, and hubs
ISDN and DSL modems send and receive data from ISDN
and DSL lines
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What is a dial-up modem?� A dial-up modem converts digital signals to analog signals
and vice versa� Usually in the form of an adapter card
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What are ISDN (Integrated Service Digital Network) and DSL (Digital Subscriber Line) modems?
Communications devices that send and receive digital ISDN and DSL signals
Communications devices that send and receive digital ISDN and DSL signalsreceive digital ISDN and DSL signalsreceive digital ISDN and DSL signals
Usually external devices in which one end connects to a telephone line and the other
end connects to a port on the system unit
Usually external devices in which one end connects to a telephone line and the other
end connects to a port on the system unit
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What is a cable modem?� Sends and receives data
over cable television (CATV) network
� Much faster than dial-up modem or ISDN; speed similar to DSLspeed similar to DSL
� Sometimes called a broadband modem
� Placed after cable splitter� System unit has network
card – e.g. Ethernet card
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What is a wireless modem?
� Allows access to the Web wirelessly from a notebook computer, a PDA, a smart phone, or other mobile deviceother mobile device
� Typically use the same waves used by cellular telephones� Has external or built-in antenna� Available as PC Cards, ExpressCard modules and flash
cards
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What is a network card?� Is an adapter card, PC Card,
ExpressCard module, USB network adapter, or flash cardthat enables computer or device to access networkaccess network
� Coordinates the transmissionand receipt of data, instructions & information to & from the computer or devices containing the network card
� Sometimes called network interface card (NIC)
Wireless network cardWireless network card
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What is a wireless access point?� Central
communications device that allows computers and devices to transfer devices to transfer data wirelessly among themselves or wirelessly to a wired network
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What is a router?� Connects computers and
transmits data to correct destination on network
� Routers forward data on Internet using fastest Internet using fastest available path
� Some routers have a built-in hardware firewall
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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices
What is a hub or switch?� Device that provides central
point for cables in network� Some hubs include routers –
hub receives data from many directions and then forwards it directions and then forwards it to one or more destinations
What are the differences between a hub & a switch & a router?What are the differences between a hub & a switch & a router?
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Home NetworksHome NetworksHome NetworksHome Networks
What is a home network?� Multiple computers
connected in home� Several types of home
networks� Ethernet — connect � Ethernet — connect
computers via cable
� Powerline cable—use electrical lines in house
� Phoneline— use telephone lines
Wireless Home NetworkWireless Home NetworkHomeRF network, Wi-Fi home network
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Communications ChannelCommunications ChannelCommunications ChannelCommunications Channel
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Communications ChannelCommunications ChannelCommunications ChannelCommunications Channel
What is a communications channel?� Transmission media on which data travels in
communications system
Bandwidth is amount of data that can travel over a communications
Transmission mediaare materials capable of over a communications
channelare materials capable of carrying one or more signals
Latency is the time it takes a signal to travel from one location to another on a network
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Transmission MediaTransmission MediaTransmission MediaTransmission Media
Transmission media category
Baseband media transmit only one
Broadband media transmit multiple signals transmit only one
signal at a time at much faster speed
Download transfer rates are faster than upload
DSL, cable television Internet service, satellites,…
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Communications ChannelCommunications ChannelCommunications ChannelCommunications Channel
How is a request sent over the Internet using a communications channel?
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Transmission MediaTransmission MediaTransmission MediaTransmission Media
Transmission media types
Physical transmission media Wireless transmission mediaPhysical transmission media Wireless transmission media
Twisted-Pair Cable, Coaxial Cable, Fiber Optic Cable
Infrared, Broadcast Radio, Cellular Radio, Microwave
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Physical Transmission MediaPhysical Transmission MediaPhysical Transmission MediaPhysical Transmission Media
What is physical transmission media?
� Wire, cable and other tangible materials used to send communications signals
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Physical Transmission MediaPhysical Transmission MediaPhysical Transmission MediaPhysical Transmission Media
What are twisted-pair cableand coaxial cable?� Twisted-pair cableis used for telephone systems and network cabling
(LAN)� Reduced noise– electrical disturbance that can degrade
communication
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Physical Transmission MediaPhysical Transmission MediaPhysical Transmission MediaPhysical Transmission Media
What are twisted-pair cableand coaxial cable?� Coaxial cableis often used for cable television wiring – long distance� Single copper wire surrounded by at least 3 layers: an insulation
material, a woven or braided metal, a plastic outer coating
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Physical Transmission MediaPhysical Transmission MediaPhysical Transmission MediaPhysical Transmission Media
What is fiber-optic cable?
� Capable of carrying significantly more data at faster speedsthan wire cables
� Less susceptible � Less susceptible to interference (noise) and, therefore, more secure
� Smaller size (thinner and lighter)
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Wireless Transmission MediaWireless Transmission MediaWireless Transmission MediaWireless Transmission Media
What is wireless transmission media?� Used when inconvenient, impractical, or impossible to
install cables� Includes Bluetooth and IrDA
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Wireless Transmission MediaWireless Transmission MediaWireless Transmission MediaWireless Transmission Media
What are broadcast radioand cellular radio?� Broadcast radiodistributes radio signals over long distances (btw
cities, countries,…)and short distances(within an office or home)- Flexible & portable but slower, more susceptible to noise- used by Bluetooth, UMB, HomeRF, Wi-Fi, and WiMAX* Bluetooth & UMB are alternatives to infrared communications* Hot spots use Wi-Fi & WiMAX networks* Hot spots use Wi-Fi & WiMAX networks
� Cellular radiois form of broadcast radio used for mobile communications – wireless modems & cellular telephones (use high-frequency radio waves to transmit voice & digital data messages)- 1G, 2G & 3G
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Wireless Transmission MediaWireless Transmission MediaWireless Transmission MediaWireless Transmission Media
What is a microwave station?� Earth-based reflective dishcontains antenna, transceivers
and other equipments for microwave communications� Microwave: radio waves at high-speed signal transmission
(fixed wireless)
� Must be transmitted in � Must be transmitted in straight line with no obstructions
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Wireless Transmission MediaWireless Transmission MediaWireless Transmission MediaWireless Transmission Media
What is a communications satellite?� Space station that receives microwave
signals from earth-based station, amplifies (strengthens)signals, and broadcasts signals back to any number of earth-based stations(microwave stations, smart phones & GPS)- uplink down link& GPS)- uplink down link
� Air navigation, television and radio broadcast, & Internet connections use communications satellites
� Satellite Internet connection needs a satellite dish & a satellite modem card
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Summary of Communications and NetworksSummary of Communications and NetworksSummary of Communications and NetworksSummary of Communications and Networks
Communications terminology and applications
Communications terminology and applications
Various communications devices, media, and procedures
Various communications devices, media, and procedures
Chapter 7 Complete
How to join computers into a networkHow to join computers into a network
devices, media, and proceduresdevices, media, and procedures