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Wi-Fi

Wi-Fi. Jason Orgill John Bodily Scott Rowberry. Background. Purpose Develop MAC and PHY layer for wireless connectivity of fixed, portable and moving stations within a fixed area

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Wi-Fi

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  1. Wi-Fi • Jason Orgill • John Bodily • Scott Rowberry

  2. Background • Purpose • Develop MAC and PHY layer for wireless connectivity of fixed, portable and moving stations within a fixed area • The higher OSI-layers are the same as in any other 802.X standard, this means that at this level there is no perceptible difference between wired and wireless media. • When • 1997 standard first published

  3. Background – cont. • Wi-Fi Alliance • Major industry players formed an alliance in 1999 under the name of Wireless Ethernet Compatibility Alliance (WECA) to create interoperability standards • Coined the term Wi-Fi • Renamed to Wi-Fi Alliance in 2003 • Establish the standards

  4. 802.11 Standards • 802.11b • Ratified in December 1999 • Operates at 2.4 GHz • Maximum throughput of 11 Mbps • Actual throughput of 6.5 Mbps • Typical Range of ~100 feet • Uses Complementary Code Keying (CCK)

  5. 802.11 Standards – cont. • 802.11a • Ratified in January 2000 • Operates at 5 GHz • Maximum throughput of 54 Mbps • Actual throughput of 25 Mbps • Typical range of ~100 feet • Uses Orthogonal Frequency Division Multiplexing (OFDM)

  6. 802.11 Standards – cont. • 802.11g • Ratified in January 2003 • Operates at 2.4 GHz • Maximum throughput of 54 Mbps • Actual throughput of 25 Mbps • Typical range of ~100 feet • Uses Orthogonal Frequency Division Multiplexing (OFDM) • Interoperable with 802.11b

  7. 802.11 Standards – cont. • 802.11n • Yet to be ratified • Operates at 2.4 GHz and 5 GHz • Maximum throughput of 540 Mbps • Actual throughput of 200 Mbps • Typical range of ~165 feet • Added Multiple Input – Multiple Output (MIMO)

  8. Connectivity Modes • Ad-Hoc • Create Peer-to-peer networks • Access Point • Used to create hotspots where wi-fi devices can connect to the network • Must have ethernet cable run to router/switch to access the network • The router and switch will use this link for the wireless activity

  9. Link Layer Architecture: MAC • Medium Access Control links the nodes • Wi-fi nodes have transmission “gears” BPSK – (for weakest signals) – 6-9 Mbps QPSK – (for weak signals) – 12-18 Mbps QAM-16 – (for good signals) – 24-36 Mbps QAM-64 – (for strongest signals) – 48-54 Mbps Data Link (MAC) - Frames

  10. Wi-Fi Security • WEP – Wired Equivalency Privacy • Easy to break • WPA – WiFi Protected Access • WPA2 • MAC – Media Access Control • Uses list of MACs to grant access

  11. Any Questions?

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