Timing Measurement Date: 2008-07-16 Authors: July2008 November 2007 doc.: IEEE 802.11-07/2752r1 July2008 Timing Measurement Date: 2008-07-16 Authors: Ganesh Venkatesan, Intel Corporation Peter Ecclesine, Cisco Systems

November 2007 doc.: IEEE 802.11-07/2752r1 July2008 Abstract This submission summarizes the Timing Measurement feature in 802.11v in general and specifically addresses two LB133 comments on Timing Measurement (268, 1280). Note: There are more LB133 comments on Timing Measurement that are not directly addressed by this submission and will be addressed later. Ganesh Venkatesan, Intel Corporation Peter Ecclesine, Cisco Systems

Timing Measurement motivations November 2007 doc.: IEEE 802.11-07/2752r1 July2008 Timing Measurement motivations Use the measurement data in a higher layer algorithm to: Synchronize clocks between two STAs or synchronize systems to a common clock Non-AP STA-based determination of location Researching the motivations further demonstrated that accuracy requirements on the time measurement data are too tight (resulting in complex implementation(s)) in order to determine location. Hence the ‘non-AP STA-based location determination’ goal is now dropped. Ganesh Venkatesan, Intel Corporation Peter Ecclesine, Cisco Systems

Timing Measurement Support July2008 Timing Measurement Support Ganesh Venkatesan, Intel Corporation

Timing Measurement Frame July2008 Timing Measurement Frame Category Action Dialog Token Follow Up Dialog Token Timestamp Difference (optional) Timestamp Timestamp Accuracy Optional sub-elements Octets 1 0 or 4 0 or 10 0 or 1 Variable Ganesh Venkatesan, Intel Corporation

Frame Exchanges to Get the Required Data July2008 Ganesh Venkatesan, Intel Corporation

Timestamps Time of Departure July2008 Timestamps Time of Departure Time of Arrival (discussed in this submission) Ganesh Venkatesan, Intel Corporation

Receive PLCP (example Clause 15 PHY) July2008 Receive PLCP (example Clause 15 PHY) Ganesh Venkatesan, Intel Corporation

What happens in the PLCP? July2008 What happens in the PLCP? If the MIB variable dot11MgmtOptionTimingMsmt exists and is set to TRUE, the PLCP shall do the following: Save the value of the Timestamp counter corresponding to the time when the first PMD_DATA.Indication for the incoming frame was received from the PMD, ta, Estimate timestamp offset between when the first PMD_DATA.Indication occurred and when the PCLP header will be fully received and determined to be valid, toffset, Save the value of the Timestamp counter corresponding to the actual time when the PCLP header is received and determined to be valid, tactual Determine timestamp error = tactual – (ta + toffset), and Forward tactual, timestamp error values within RXVECTOR Ganesh Venkatesan, Intel Corporation