Siemens IEEE802.11 Tutorial page 45

Scanning
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Scanning required for many functions.
– finding and joining a network
– finding a new AP while roaming
– initializing an Independent BSS (ad hoc) network
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802.11 MAC uses a common mechanism for all PHY.
– single or multi channel
– passive or active scanning
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Passive Scanning
– Find networks simply by listening for Beacons
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Active Scanning
– On each channel
• Send a Probe, Wait for a Probe Response
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Beacon or Probe Response contains information
necessary to join new network.
WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 45 © Siemens, 2002