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Wi-FiWi-FiJason OrgillJason Orgill

John BodilyJohn Bodily

Scott RowberryScott Rowberry

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BackgroundBackground

PurposePurposeDevelop MAC and PHY layer for wireless Develop MAC and PHY layer for wireless connectivity of fixed, portable and connectivity of fixed, portable and moving stations within a fixed areamoving stations within a fixed areaThe higher OSI-layers are the same as in The higher OSI-layers are the same as in any other 802.X standard, this means any other 802.X standard, this means that at this level there is no perceptible that at this level there is no perceptible difference between wired and wireless difference between wired and wireless media. media.

WhenWhen1997 standard first published1997 standard first published

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Background – cont.Background – cont.

Wi-Fi AllianceWi-Fi AllianceMajor industry players formed an Major industry players formed an alliance in 1999 under the name of alliance in 1999 under the name of Wireless Ethernet Compatibility Alliance Wireless Ethernet Compatibility Alliance (WECA) to create interoperability (WECA) to create interoperability standardsstandards

Coined the term Wi-FiCoined the term Wi-Fi

Renamed to Wi-Fi Alliance in 2003Renamed to Wi-Fi Alliance in 2003

Establish the standardsEstablish the standards

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802.11 Standards802.11 Standards

802.11b802.11bRatified in December 1999Ratified in December 1999

Operates at 2.4 GHzOperates at 2.4 GHz

Maximum throughput of 11 MbpsMaximum throughput of 11 Mbps

Actual throughput of 6.5 MbpsActual throughput of 6.5 Mbps

Typical Range of ~100 feetTypical Range of ~100 feet

Uses Complementary Code Keying (CCK)Uses Complementary Code Keying (CCK)

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802.11 Standards – cont.802.11 Standards – cont.

802.11a802.11aRatified in January 2000Ratified in January 2000

Operates at 5 GHzOperates at 5 GHz

Maximum throughput of 54 MbpsMaximum throughput of 54 Mbps

Actual throughput of 25 MbpsActual throughput of 25 Mbps

Typical range of ~100 feetTypical range of ~100 feet

Uses Orthogonal Frequency Division Uses Orthogonal Frequency Division Multiplexing (OFDM)Multiplexing (OFDM)

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802.11 Standards – cont.802.11 Standards – cont.

802.11g802.11gRatified in January 2003Ratified in January 2003

Operates at 2.4 GHzOperates at 2.4 GHz

Maximum throughput of 54 MbpsMaximum throughput of 54 Mbps

Actual throughput of 25 MbpsActual throughput of 25 Mbps

Typical range of ~100 feetTypical range of ~100 feet

Uses Orthogonal Frequency Division Uses Orthogonal Frequency Division Multiplexing (OFDM)Multiplexing (OFDM)

Interoperable with 802.11bInteroperable with 802.11b

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802.11 Standards – cont.802.11 Standards – cont.

802.11n802.11nYet to be ratifiedYet to be ratified

Operates at 2.4 GHz and 5 GHzOperates at 2.4 GHz and 5 GHz

Maximum throughput of 540 MbpsMaximum throughput of 540 Mbps

Actual throughput of 200 MbpsActual throughput of 200 Mbps

Typical range of ~165 feetTypical range of ~165 feet

Added Multiple Input – Multiple Output Added Multiple Input – Multiple Output (MIMO)(MIMO)

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Connectivity ModesConnectivity Modes

Ad-HocAd-HocCreate Peer-to-peer networksCreate Peer-to-peer networks

Access PointAccess PointUsed to create hotspots where wi-fi Used to create hotspots where wi-fi devices can connect to the network devices can connect to the network

Must have ethernet cable run to Must have ethernet cable run to router/switch to access the networkrouter/switch to access the network

The router and switch will use this link The router and switch will use this link for the wireless activityfor the wireless activity

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Medium Access Control Medium Access Control linkslinks the the nodesnodes

Wi-fi nodes have transmission “gears”Wi-fi nodes have transmission “gears”

Link Layer Architecture: MACLink Layer Architecture: MAC

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

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Wi-Fi SecurityWi-Fi Security

WEP – Wired Equivalency PrivacyWEP – Wired Equivalency PrivacyEasy to breakEasy to break

WPA – WiFi Protected AccessWPA – WiFi Protected Access

WPA2WPA2

MAC – Media Access ControlMAC – Media Access ControlUses list of MACs to grant accessUses list of MACs to grant access

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Any Questions?Any Questions?