Communications Starting Along the Information Highway

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Communications Starting Along theInformation
Highway
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Communications and the Cyberspace

• Communications (telecommunications) is the
  electronic transfer of information from one
  location to another.
• Connectivity refers to the ability to connect
  devices by communications technology to other
  devices and sources of information.
• Cyberspace, coined by William Gibson in his
  novel Neuromancer to refer to a futuristic
  computer network that people use by plugging
  their brains into it, has come to mean the
  computer online world and the Internet in
  particular, and the whole wired and wireless
  world of communications in general.

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Telephone-related communications services

• Fax messages
• Dedicated fax machines
• Fax modems
• Voice mail
• analog signal ? digital signal ? analog signal
• E-mail (Electronic mail)

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Video/voice communication

• Videoconferencing V-mail (video mail)
• Picture phones

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Online Information Service

• Three big companies
• America Online (AOL)
• CompuServe
• Prodigy

• Service
• People connections--email, bulletin boards, chat
  room
• Research and news
• Games,entertainment,clubs
• Travel services
• Downloading
• Shopping

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Bulletin board systems (BBSs)

• An electronic bulletin board (BBS) is a
  centralized information source and
  message-switching system for a particular
  computer- linked interest group.

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The Internet

• The internet the world biggest networks, uses a
  protocol called TCP/IP to allow computer to
  communicated.
• TCP/IP, for Transmission Control
  Protocol/internet Protocol, is the standardized
  set of guidelines (protocols) that allow
  different computers on different networks to
  communicate with each other efficiently.
• Applications over the Internete-mail, FAQ files,
  FTP, Archie, telnet, gopher, WAIS, Web browsers.

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Internet Addresses

• Domain Name system

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Features of the Internet

• E-mail
• Usenet newsgroups-electronic discussion groups
• Mailing lists E-mail-based discussion groups
• FTP for copying all the free files you want
• Telnet to connect to remote computers
• Gopher including Veronica and Jughead
• WAIS ways of searching by content
• World Wide Web for multimedia and hypertext
  information retrieval

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Shared resources

• Workgroup Computing Groupware Workgroup
  computing (collaborative computing) enables teams
  of co-workers to use networks of microcomputers
  to share information and cooperative projects.
  Groupware is a software that allows two or more
  people on a network to work on the same
  information at the same time. Two popular
  groupware
• Lotus Notes (purchased bu IBM in 1995)
• Microsoft Exchange Server
• Electronic Data Interchange (EDI) EDI is the
  direct electronic exchange between organizations
  computer systems of standard business documents
  such as purchase orders, invoces, and shipping
  documents.
• Intranets Intranets are internal corporate
  networks that use the infrastructure and
  standards of the Internet and the WWW.

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A Security Program Firewall
A firewall is a security program that connects
the intranet to external networks such as the
Internet. It blocks unauthorized traffic from
entering the intranet and can also prevent
unauthorized employees from accessing the
intranet.
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Portable Work Telecommuting and virtual office

• Telecommuting working at home with computer and
  communications connections between office and
  home.
• Virtue office a nonpermanent and mobile office
  run with computer and communications technology.

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Information or Internet appliance

• The TV/PC (picture)
• The multifaceted Net
• Telephone on the Net (e.g., internet phone)
• Radio on the Net (e.g., Real Audio)
• Television on the Net (e.g., Real Video)
• 3-D on the Net (e.g., VRML)
• The information/Internet appliance
• Set-top box Internet PCs
• Network PDAs
• Network Computers

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Modems

• Why needs a modem?
• How modems work?
• External modem vs internal modem
• Transmission speed (e.g., 9600, 14,400, 28,800,
  56K bps)
• bps bits per second

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Review of analog and digital signals
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Modifying an Analog Signal

• Frequency Modulation

Amplitude Modulation
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How modems work ?
Demodulate (converts analog signals back to
digital form)

• Modulate (converts digital pulses to analog
  form)

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ISDN lines Cable modems

• ISDN (Integrated Services Digital Network)
• Cable modems

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Communications software

• Error correction Noise is anything that causes
  distortion in the signal when it received.
• Data compression Data compression reduces the
  volume of data in a message, thereby reducing the
  amount of time required in transmission.
• Remote control Remote-control software allows
  you to control a microcomputer from another
  microcomputer in a different location.
• Terminal emulation Terminal emulation software
  allows you to use your microcomputer to simulate
  a mainframes terminal.

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The electromagnetic spectrum
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The Conduits of Communications

• Twisted-pair wire
• Coaxial cable
• Fiber-optic cable

• Microwave and satellite systems
• Other wireless communications

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Microwave Satellite Systems
Satellite systems

• Microwave systems

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Other Wireless Communication

• One-way
• The Global Positioning systems (GPS)
• Pagers
• Two-way
• Analog cellular
• packet radio
• Cellular Digital Packet Data

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Cellular connections

• 
  

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The next generation of wireless communications

• Digital cellular phone
• Personal communications services
• Specialized mobile radio
• Satellite-based systems

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Type of network

• Wide area network (WAN)
• Metropolitan area network (MAN)
• Local area networks (LANs)

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Advantages of networks

• Sharing of peripheral devices
• Sharing of programs and data
• Better communications
• Security of information
• Access to databases

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Client/server LAN

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Peer-to-peer LAN

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Components of a LAN

• Connection or cabling system
• Microcomputers with interface cards A network
  interface card, which is inserted into an
  expansion slot in a microcomputer, enables the
  computer to send and receive messages on the LAN.
• Network operating system e.g., Novells NetWare.
• Other shared devices
• Bridges and gateways A bridge is an interface
  that enables similar networks to communicate. A
  gateway is an interface that enables dissimilar
  networks to communicate, such as a LAN with a WAN.

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Factors Affecting Data Transmission

• Transmission rate frequency, bandwidth
• Line configurations point-to-point vs.
  multipoint.
• Serial parallel transmission
• Direction of transmission simplex, half-duplex,
  full-duplex.
• Transmission mode asynchronous vs. synchronous.
• Packet switching A packet is a fixed-length
  block of data for transmission. Packet switching
  is a technique for dividing electronic messages
  into packets for switching.
• Multiplexing Multiplexing is the transmission of
  multiple signals over a single communications
  channel. A multiplexer is a device that merges
  several low-speed transmissions into one
  high-speed transmission.
• Protocols A protocol is a set of conventions
  governing the exchange of data between sender and
  receiver in a communication network.

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Transmission mode

• Asynchronous transmission
• Synchronous transmission

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Some topologies of LANs
Star
Ring
Bus

• Others
• Hybrid network
• FDDI (Fiber Distributed Data Interface) network

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Controversial material Censorship

• Filtering software
• Browsers with ratings
• The V-chip

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Cyberethics

• Netiquette (Net etiquette)
• Controversial Material
• Censorship
• Privacy Issues