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IT for Communication Systems

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					        MIS 2000


         Class 14
Information Technology for
 Communication Systems
                                      Outline
      Telecommunications Model
      Transmission speed
      Computer network and typologies
      Internet (TCP/IP & HTTP) and how it works
      Voice over IP (VoIP)
      Wireless Networks




IT for Celecommunication Systems   Information Systems for Management
                   Telecommunications Model
    Similar to the way we sometimes think about human communication

                        electronic signal (data, message)
             sender                                 channel        receiver


  Sender & Receiver – special devices (cell phone, email client computer, etc.). Similar
to people talking to each other, one talks, the other listens.
  Technical standards (protocol) that define sender and receiver and how they
communicate (establish connection, ensure transmission, etc.). People also use rules:
self-introduction, language or vocabulary selection, watching reactions to speech…
   Data – the content transmitted. People: the content of speech.
 Channel - The form of energy by which data travel (electrical signal in wire, electro-
magnetic wave, light…). People: voice via air waves. *see Note




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                                  Transmission Speed
                  The amount of data transmitted through a channel in unit of time.

                  Used as a measure of a capacity of telecommunications channel.*

                               Channel                                         Speed
         Fiber optic cable                                    Trillions of bits/sec

         Coaxial cable used for Internet access at            Billions of bits/sec
         home
         Radio Frequency Wave used for cell                   Thousands of bits/sec
         phone

                  Notice that the measure of data transmission speed is bits per
                second. In contrast, the measure for computer storage uses the
                term bytes (and larger measures, like megabyte).


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                     Computer Network
    Computer Network is a set of nodes (computers, printers, and other
    equipment) linked via a communication channel.
    Two kinds: Local and Wide Area networks


    Local Area Network (LAN)
         Covers a smaller area (one or more buildings like the campus)
         Example: Ethernet – the bus network software by Xerox corp.
         (different than “Internet”); see next slides




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Celecommunication
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Systems                 Information Systems for Management               3 of 12
                      Computer Network

• Wide Area Network (WAN)

     • Covers a larger area (a region, across continents)

     •   Examples:

           • Proprietary software l(e.g., IBM’s global corporate network)

           • Internet (not proprietary, but a set of rules for connecting
             different proprietary networks across – see next slides)




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Systems                   Information Systems for Management            4 of 12
             LAN Typologies: Star Network

                                       All computers are connected to a
                                            central point.

                                       All communications between computers
                                            must pass through the central node
                                            – centralized network.

                                       Better communications control, but if
                                           central node goes down – the whole
                                           network is down (high-risk).




                                                                            More

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                       Bus Network

                                              All computers are linked on the same
                                                   open channel.

                                              All messages are broadcast to the entire
                                                  network – decentralized network.

                                              Simple to set up and manage, but
                                                 collision between messages possible
                                                 (if that happens, all senders must
                                                 send again). Collision detection
                                                 feature reduces the problem.



                                                                            More

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Systems             Information Systems for Management                    6 of 12
                          Ring Network

                                                  All computers are linked by a circular
                                                       channel.

                    Message
                    container                     Message is passed in one direction from
                                                     one node to another

                                                  Better control and no collision, but
                                                      management more complex than
                                                      with bus.




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                              Internet (TCP/IP)
      TCP/IP is a set of rules (or a network protocol or standard) that define
      communications rules. These rules are implemented in network software of
      different vendors and operating systems. Two LANs that “support TCP/IP” are
      said “to be on the Internet”.
      Internet standard defines 4 “layers” that work together both on the sender and
      receiver side:                  Sender                Receiver

               Email (SMTP),
            file transfer (FTP,
                        HTTP)

                           TCP

                             IP




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                            How Internet Works

                                    SENDER          RECEIVER
SMTP to TCP:
“Take this message                                                    SMTP restores original format
and send it to this                                                   of message and presents it.
email address”.

TCP Breaks message into
packets and passes these                                              Put reassembles packets
to IP.                                                                in proper orders and checks
                                                                      sum of data received vs.
                                                                      sum sent.
IP scans Internet
addresses and                                                         Accepts packets and
routers on the way to                                                 reports back to routers.
receiver. IP puts address
on each packet and
passes them to Network.
                                                                      Gets packets off com-
Network physically puts                                               munication medium.
packets onto the com-
munication medium.


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                               Voice over IP (VoIP)

          Using Internet as telephone network (voice and text & video;
          example: Skype)

          Based on new Internet protocol – VoIP

          Computers act as VoIP phones or special VoIP phones used

          VoIP phone has an Internet address and can act as Internet
          node anywhere without changing its “number” (IP address)

          Big savings in comparison to classical phone




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                               Wireless Networks
            This is the future! *
            Use RF waves (see Note to slide on Telecommunications model)

                                  (1) WiFi Standard
            Used in wireless LANs (PCs, laptops support WiFi)
            Cell phones have WiFi capability and thus can be a LAN node
            When LAN is linked to the Internet, a WiFi laptop or cell phone
            connects to the Internet (e.g., LAN in Drake Ctr. with “hot
            spots”); see Note **
            WiMAX version of this standard covers 50 km range




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                                 Wireless Networks

                               (2) Personal Area Network Standards

              Example: Bluetooth
              Covers 10m in diameter, 10 devices connected
              Used for connecting:
                 microphone and headphones to cell phone
                 keyboard & mouse to CPU
                 computer to printer




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