The
effective throughput for the 11g user will drop, because the 11g standard
requires the use of a "protection mechanism" whenever an 11b client is
associated at the AP or at an overlapping AP that is on the same channel.
The reason that a protection mechanism is required is that an 11b station cannot
decode frames sent at 11g data rates. At best 11g frames seem like noise
to an 11b station.
The
protection mechanism does require that an 802.11 control frame (usually a CTS
frame that is addressed to the sender of the data frame, i.e., a "CTS to self")
is sent before the data frame. This control frame must be sent using an
11b data rate, so that 11b stations will be able to receive it and stay off the
air while the 11g data frame is transmitted.
So
because this extra frame needs to be transmitted with every data frame, the
overall throughput will drop, even when the data frames are sent at the 11g data
rates. There is no requirement that the data frames use 11b data rates
when 11b stations are present, as is often claimed.
-Bob
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mary
Sent: Tuesday, January 04, 2005 10:22 PM
To: wireless@lists.bawug.org
Subject: [BAWUG] throughput question
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mary
Sent: Tuesday, January 04, 2005 10:22 PM
To: wireless@lists.bawug.org
Subject: [BAWUG] throughput question
If I have a .11g
access point and a user using a .11g card and another user associates with
a .11b card does the transfer rate drop for the user using the .11g card?
Thanks so
much...
_______________________________________________ BAWUG's general wireless chat mailing list [unsubscribe] http://lists.bawug.org/mailman/listinfo/wireless
