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1.Wireless Lan Organization
IEEE802.11 include infrastructure and ad-hoc
2. Basic in infrastructure
1) power on AP
AP advertise its presence by send beacons at a regular interval , about 10 times a second.
And in one channel.
2) Sta scanning
Because there is a number of different radio frequencies(channels), so the STA must tune into each channel in turn and listen for beacon messages.
3) Sta probing
Because scanning is too slow, so if we want to accelerate the process , we can send probe message.
4) authentication
Sta AP
authenticate request msg
------------------------>
authenticate response
<------------------------
5) Association
Sta AP
association request
-------------------->
assoication response
3. IEEE 802.11 messages
1) Control:
2) Management:
Sta and AP used to negotiate and control their relationship.
3) Data
4. General Frame Formats
Preamble + pldp + mac + user date + crc
1) Mac
ad-hoc
SA+DA
AP -> Sta
SA + TA + DA
Sta -> AP
SA + RA + DA
2) Management Frame
Fixed Fields + Elem1 + Elem2 ... + Elemn
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