Definitions of ACK and CTS Timeout Month 1998 doc.: IEEE 802.11-98/xxx May 2002 Definitions of ACK and CTS Timeout Sunghyun Choi Philips Research USA sunghyun.choi@philips.com S. Choi, Philips

Definitions of ACK & CTS Timeout May 2002 Definitions of ACK & CTS Timeout In 802.11-1999, they are mentioned in the text while the actual value is never defined in the text. The values are defined in the SDL in Annex C TGe decided not to use Annex C as the reference. Therefore, TGe needs to define them in the text accordingly. S. Choi, Philips

May 2002 According to 802.11-1999 Annex C, p. 346 ACKTimeout = SIFS + ACK Transmission Duration + SlotTime Annex C, p. 348 CTSTimeout = SIFS + ACK Transmission Duration + SlotTime “ACK Transmission Duration” is determined based on the PHY rate expected based on the rules in 9.6. ACK length = CTS length S. Choi, Philips

Problem with Current Definitions May 2002 Problem with Current Definitions The transmitter of an MPDU or an RTS does not need to wait for the whole ACK or CTS transmission time as defined in certain cases When CCA stays idle after an MPDU or an RTS for PIFS, it implies that the MPDU or RTS was not received by the receiver correctly. We can define two different values for ACK/CTS Timeout depending on the situation! (See the resolution of Comment #1805 in 02/084r9) S. Choi, Philips

May 2002 New Definition After the transmission of an MPDU (or RTS), ACK Timeout (or CTS Timeout) will be: PIFS when CCA stays idle during the following PIFS interval SIFS + ACK Transmission Duration + SlotTime when CCA becomes busy within the following PIFS interval S. Choi, Philips

May 2002 Normative Text In Clause 9.2.8, add the following at the end of the third paragraph: ACKTimeout is determined by PIFS if no PHY-CCA.indication(busy) is detected from the PHY during a period with a duration of (aSIFSTime + aSlotTime) starting at the PHY-TXEND.confirm. ACKTimeout is determined by (aSIFSTime + ACK_Time + aSlotTime) if PHY-CCA.indication(busy) is detected from the PHY during a period with a duration of (aSIFSTime + aSlotTime) starting at the PHY-TXEND.confirm, where ACK_Time is the transmission duration of an ACK frame at the PHY rate determined according to the rule found in Clause 9.6. S. Choi, Philips

May 2002 Normative Text In Clause 9.2.5.7, add the following the first and second paragraphs: The source STA shall wait CTSTimeout amount of time without receiving a CTS before concluding that the RTS failed. CTSTimeout is determined by PIFS if no PHY-CCA.indication(busy) is detected from the PHY during a period with a duration of (aSIFSTime + aSlotTime) starting at the PHY-TXEND.confirm. CTSTimeout is determined by (aSIFSTime + CTS_Time + aSlotTime), where CTS_Time is the transmission duration of a CTS frame at the PHY rate determined according to the rule found in Clause 9.6, if PHY-CCA.indication(busy) is detected from the PHY during a period with a duration of (aSIFSTime + aSlotTime) starting at the PHY-TXEND.confirm. S. Choi, Philips