Initial Rate Settlement Just After Association.

Anand S. Katti askatti at ece.iisc.ernet.in
Sat May 29 14:42:34 EDT 2004


Hi,

	We had a long discussion here about this Initial rate settlement.
As said by Jouni, THE MAX RATE SUPPORTED BY BOTH ENDS IS TRIED FIRST,
Immediatly after the Association is established.

I conducted a series of Experiments in testing this, and following is the
result.

a) I wrapped a thick sheets of CU foil over the Client Access
Card(orinoco), so that its signal level is reduced to almost -84dBM.
I put this card in to client 20Mtrs away from the HostAP Acces Point.
Im running winxp on the client, it has an icon that gives me the
connection speed. Immmdiately after sliding the card in , i see that it
gets assocaited with the hostap and the connection speed is displayed as
11Mbps. And immediately the connection speed goes down to 1Mbps through
6Mbps in no time.

Same is the case observed when the HostAP card is wrapped in thick CU
foils.

The above experiments shows that in HostAP driver during the
Association SNR or SIR of the
signals is not considered for choosing the INITIAL RATE.
 Its considered immediately ONLY after starting with the
HIGHEST RATE(11Mbps) first and decreasing down to lower rates to suit the
current SNR/SIR of the signal.
As I saw this behaviour in the client.

Kindly correct me if the above set of results comply with the
implementation of the HostAP driver.

If above results HOLDS good. Then the supported rates exchanged during the
Association are used just to make sure that the STAs support atleast
1,2Mbps(BASIC RATE SET), cause many are multirate cards.(Vendor
interoperability)

Desperately waiting for the reply,

Warm Regards,
Anand





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