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Network Technologies and Connectivity

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									Internet Technologies
   and Connectivity
                  Dial-up

   Dial-up access is just like a phone
    connection – normal telephone lines
   Quality of connection is not always good
    and data rates are limited.
   Up to 56Kbps data transfer rate until the
    ISDN (Integrated Services Digital
    Network) provided a much faster rate – up
    to 64Kbps
              Leased Line

   Permanent telephone connection between
    two points set up by a telecommunications
    common carrier – It is always active.
   Leased lines are used by businesses to
    connect distant offices.
   Data transfer rate depends on the type of
    channel used (up to 2Mbps)
                    DSL

   Digital Subscriber Line
   Uses a sophisticated modulation scheme
    to pack data onto copper wires.
   Uses two copper wires to avoid the tie-up
    on your phone line
   No need to dial – connection is always on
           DSL Categories

   ADSL (Asymmetric)
     Common in North America
     Downstream rate: 1.5 to 9Mbps

     Upstream rate: 16 to 640 Kbps

   SDSL (Symmetric)
     Common in Europe
     Data rata: 3Mbps
                   Cable
   Uses cable modem – designed to operate
    over cable TV lines.
   Uses TV channel space for data
    transmission – for both upstream and
    downstream

   Note: coaxial cables provides much
    greater bandwidth than telephone lines
                   Cable vs DSL
   Speed
       Ideally, cable connection is 2x faster than that of the
        DSL’s, however, it uses a shared bandwidth that
        causes speed fluctuations.
   Security
       Cable connection creates security issues – you are
        automatically in a network when connected.
   Cost
       Primarily depends on the broadband services you
        need and place where you live.
                  Wireless

   Wi-Fi – Wireless Fidelity
   Uses radio frequency to communicate
   Specifically refers to 802.11 network
   802.11 came from IEEE (Institute of
    Electrical and Electronics Engineers) – sets
    standards for a range of technological
    protocols
             Wireless

 Describes the underlying technology
  of wireless local area network
  (WLAN)
 It was developed to be used by
  mobile computing devices (ex.
  Laptops, Pocket PCs, etc.)
  Some Radio Frequencies

 AM  radio – 535 KHz to 1.7 MHz
 FM radio - 88 to 108 MHz

 Television Stations (Ch. 2 – 6) –
  54 to 88 MHz
 Television Stations (Ch. 7 – 13) –
  174 to 220 MHz
        Wi-Fi Specifications

   802.11a
     Release Date: 1999
     Op. Frequency: 5.15 to 5.35/5.47 to
      5.725/5.725 to 5.875 GHz
     Data Rate: 25 Mbps to 54 Mbps

     Range (indoor): 25 meters

     Range (outdoor): 75 meters
    Wi-Fi Specifications

 802.11b

  Release Date: 1999
  Op. Frequency: 2.4 to 2.5 GHz

  Data Rate: 6.5 Mbps to 11 Mbps

  Range (indoor): 35 meters

  Range (outdoor): 100 meters
    Wi-Fi Specifications

 802.11g

  Release Date: 2003
  Op. Frequency: 2.4 to 2.5 GHz

  Data Rate: 25 Mbps to 54 Mbps

  Range (indoor): 25 meters

  Range (outdoor): 75 meters
    Wi-Fi Specifications

 802.11n

  Release Date: 2007*
  Op. Frequency: 2.4 or 5 GHz

  Data Rate: 200 Mbps to 540 Mbps

  Range (indoor): 50 meters

  Range (outdoor): 125 meters
                Bluetooth
   Industrial specification for Wireless
    Personal Area Networks (WPANs)
   Provides a way to connect and exchange
    information between devices over a short-
    range radio frequency (10 meters)
   Communicates at a frequency of 2.5 GHz
   Sends weak signals – 1mW
   Uses spread-spectrum frequency hopping
                Bluetooth

   Applications
     Transfer files between devices
     Communication between two devices

     Wireless controllers for game consoles

     Networking between two PCs in a
      confined space and where little
      bandwidth is required

								
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