Subject: [manet] Request for clarifications on 802.11 4-way handshake

From: "Kostas Voulgaris" <[email-masked]>
Date: Mon, 22 Aug 2005 23:31:33 +0100

Dear all,

Reading the standards on 802.11 I have a few of questions regarding the
4-way handshake and the PHY operation. 

More specifically, it seems that a PLCP header and Preamble is added to the
MPDU at the beginning of any data transmission. 

If this is correct, does the same rule apply for RTS / CTS and ACK packets?
i.e. are a Preamble and PLCP Header added any time one of the aforementioned
packets is to be transmitted?

Also, does the transmission of any control packet starts at the beginning of
a slot?

As an example, a slot duration according to the standards for DSS system is
20us. A SIFS duration is 10us. 

Omitting PLCP Header and Preamble, an RTS packet duration is 160us (1Mbps
transmission), occupying 8 slots.

When should CTS transmission begin? Right after the SIFS (i.e. at the middle
of the slot), or wait for the beginning of the next slot?

Your prompt reply is highly appreciated. 

Best regards, 

Kostas Voulgaris

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---

From: "Farrag, Osama" <[email-masked]>
Date: Mon, 22 Aug 2005 19:25:54 -0400

Kostas,        

          PLCP is added to any 802.11 MAC frame transmitted, yes
including RTS, CTS and ACK control frames. And CTS and ACK frames
transmission starts right after SIFS, even when it is middle of a slot.

Best Regards

Osama Farrag 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Kostas Voulgaris
Sent: Monday, August 22, 2005 6:32 PM
To: [email-masked]
Subject: [manet] Request for clarifications on 802.11 4-way handshake

Dear all,

More specifically, it seems that a PLCP header and Preamble is added to
the MPDU at the beginning of any data transmission. 

If this is correct, does the same rule apply for RTS / CTS and ACK
packets? i.e. are a Preamble and PLCP Header added any time one of the
aforementioned packets is to be transmitted?

Also, does the transmission of any control packet starts at the
beginning of a slot?

As an example, a slot duration according to the standards for DSS system
is 20us. A SIFS duration is 10us. 

Omitting PLCP Header and Preamble, an RTS packet duration is 160us
(1Mbps transmission), occupying 8 slots.

When should CTS transmission begin? Right after the SIFS (i.e. at the
middle of the slot), or wait for the beginning of the next slot?

Best regards, 

Kostas Voulgaris