Subject: Re: Multirate and 802.11

From: [email-masked]
Date: Wed, 30 Jan 2002 10:15:33 -0500

Hi Vikram,

Basically, RTS/CTS and all other control frames (e.g., ACK) frames
should be transmitted at one of rates in the BSS Basic Rate Set.
In the typical 802.11b network, the BSS Basic Rate Set is 1 & 2 Mbps.
That means RTS/CTS will be transmitted at either 1 or 2 Mbps typically.

At the same time, the BSS Basic Rate Set is really up to the station,
which initiates each particular BSS, which would be an AP in case of 
infrastructure BSS,
and the first station in case of independent BSS used for MANET, I 
believe.

BTW, the BSS Basic Rate Set includes all the rates, which should be 
supported
(i.e., receivable and transmittable) by all the stations in the particular 
BSS.
That is, a station which does not support any of the rates in the BSS 
Basic Rate Set
will not be allowed to be part of the BSS.
This will ensure that all the stations will receive all the control frames 
including RTS/CTS.

When 802.11g (a higher rate version of .11b) comes to the market, the 
whole 802.11b rates, i.e.,
1, 2, 5.5, and 11 Mbps, may be used for the BSS Basic Rate Set, in many 
cases.

FYI.

Sunghyun

------------
Sunghyun Choi, Ph.D.
Senior Member Research Staff
WiCAN - Wireless Communications and Networking Department
Philips Research USA, Briarcliff Manor, New York, USA
Tel: (914) 945 6506    Fax: (914) 945 6580
E-mail: [email-masked]
URL 1: http://www.philabs.research.philips.com/~szc - Philips internal
URL 2: http://www.eecs.umich.edu/~shchoi - Personal Homepage
** My opinions do not necessarily reflect those of my employer **

Vikram Kanodia <[email-masked]>
Sent by: [email-masked]
01/29/2002 04:48 PM

        To:     [email-masked]
        cc:     (bcc: Sunghyun Choi/BRQ/RESEARCH/PHILIPS)
        Subject:        Multirate and 802.11
        Classification: 

Hi,

I had a couple of questions about multirate support of IEEE 802.11. I
will be gratefuil if someone can provide pointers etc...

(*) I know that the PHY preamble and headers are all sent at a basic rate
(1Mbps?). Is the RTS/CTS exchange also done at the basic rate ?

(*)....if not then how do other overhearing nodes latch onto the
RTS/CTS.. ?

Thanks,
-Vikram

-- 

Department of ECE, Rice University | 713 348 3786 (O)| 713 664 5650(H)
WWW: http://www.ece.rice.edu/~kanodia