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Hi Murali,

Criss missed a couple of your questions, so I thought I would finish up.

4)In an 11b/g AP when Beacons are sent out in 1 Mbps does it use OFDM preamble or short preamble or long preamble? (When there are no stations)?

5) 11b stations cannot decode ERP element, how do they know what network is using? (Physical may undertsand preamble, then what is the use of barker bit ?)

4) An AP Beaconing at 1 Mbps will use long preambles for the Beacons themselves.

5) Since the AP is sending Beacons out usually using 1 Mbps (DSSS), the long-preamble-only, DSSS or HR-DSSS stations will be able to read it. If it sees information fields or elements that are unfamiliar to it, they will be ignored. To answer your question, HR-DSSS (802.11b) stations will only decode what they understand - everything else is seen as RF interference. ERP APs and STAs have to deal with things in the right way (ERP procedures) to allow for this. The ERP IE is only meant for ERP STAs to read/decode. It lets APs and STAs know when to use protection and when to use long or short preambles when using DSSS or HR-DSSS PHYs.

Devinator