1. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 1 WRSS in 802.11p Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Date: 2005-07-20

2. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 2 Agenda – WRSS in 802.11p Progress since Cairns TGk and RCPI TGp and WRSS Proposed Definitions and Terms Responses / Direction

3. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 3 Progress Since Last Meeting in Cairns Face-to-face meetings and multiple conference calls to address WRSS issues among concerned parties. “Issues Related to RF Signal Strength Measurements in IEEE 802.11 Systems and Their Use in Kinematic State Estimation” white paper written (by Richard Roy) and distributed (11-04-0597-00-wave … how it got this number is interesting?). Document discusses the statistical characteristics of the signal strength measurements being proposed. Two questions posed were: –What RF signal strength measurement accuracies are required now and in the near future from original equipment manufacturers (OEMs) of otherwise IEEE 802.11p compliant radio receivers by designers of RF RSS-based location estimation applications? –What RF signal strength measurement accuracies are achievable now and in the near future by original equipment manufacturers (OEMs) of otherwise IEEE 802.11p compliant radio receivers? Invited 802.11 chipset / semiconductor manufacturers (email & phone follow-up) –Atheros, Conexant, Intel, Motorola and Texas Instruments. –No responses prior to this meeting.

4. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 4 TGk and RCPI Current definition of RCPI (P802.11k-D2.0 §17.3.10.6) –“The RCPI indicator is a measure of the received RF power in the selected channel. This parameter shall be a measure by the PHY sublayer of the received RF power in the channel measured over the entire received frame.” Current definition of RCPI accuracy UNDEFINED!!! –RCPI measurement accuracy in TGk is currently UNDEFINED!!! –There is, however, a specification that the UNDEFINED quantity must meet! In particular, RCPI measurement “accuracy for each measurement shall be ± 5 dB and resolution < 0.5 dB within the dynamic range of the receiver” (no mention of other operating conditions!).

5. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 5 TGk and RCPI PROPOSED DEFINITION: ACCURACY, when used to refer to statistical properties of RF received channel power (RCP) measurements made by a radio, shall refer to the (square-root of the) second moment of the probability density function (PDF) describing the statistics of the error in the RCP measurement in question over appropriate operating conditions (input powers, temperature, etc.). IMPORTANT: When specifying accuracy, the conditions under which the RCP measurement is made must be described for the specified accuracy to be meaningful (and measurable)! Thus, the term accuracy should not appear in the context of a numerical specification without an adjectival modifier referencing the underlying PDF.

6. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 6 TGp and WRSS WRSS measurement definition – Received RF power (in dBm) in the selected channel as measured at the antenna connector by the PHY sublayer. WRSS measurement statistics –With reference to the proposed definition of accuracy, the concept of short- term ( ~ secs) statistics (  fast and  slow respectively) should be included in TGk (and TGp if necessary). Estimating/Measuring Short-term and Long-term statistics – Short-term: Repeated WRSS measurements are made over a single burst at a fixed operating condition. – Long-term: The operating conditions are then varied over the entire range with multiple measurements made at each set point. Current WRSS draft specifications –Current WRSS measurement accuracy specification of ± 3 dB, as found in previous and current (D0.21) 11p drafts, is MEANINGLESS since there is NO DEFINITION OF ACCURACY!

7. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 7 Short-term (fast) Statistics P true is the true value of the received channel power (RCP) Mean(Z RCP ) is the mean value of the measured power (averaged over a large number of (consecutive) frames at a fixed operating point (eg. temperature, input power, AGC, etc.)) b fast is the bias in the short-term estimate of RSS at a fixed operating condition is the standard deviation of the measured power P true Mean(Z RCP )  fast b fast

8. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 8 Long-term (slow) Statistics Mean(b fast ) is the mean of the bias in the measurement of RCP (at a fixed operating point … temperature, input power, AGC, etc.), averaged over a large number of operating points within the operating region. is the standard deviation of the bias over all operating conditions (Mean(b fast )) 2 is the second moment of the bias over all operating conditions Mean(b fast )  slow 0 Bias (dB)  slow 2 +

9. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 9 WRSS-related Properties from a Potential WAVE Application WRSS used in threshold tests for initiating communications WRSS measurements made in line-of-sight conditions Very short distances (1-10 m) between transmitter and receiver Well-know communication zone (pre-calibrated) Interactions of short duration (< 1 sec) REMEMBER the definition of WRSS: –“Received RF power (dBm) in the selected channel as measured at the antenna connector by the PHY sublayer.”

10. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 10 RSSI, RCPI & WRSS (Reference Only) Parameter RSSI (from TGk) RCPI (from TGk) WRSS Proposed Measurement objectPreamble Preamble & Entire message Preamble & Entire Message ProtocolSimpleComplexSimple Set-up time002 ms Absolute accuracy *1 Not specified5 dbTBD Short-term accuracy *2 Not specified TBD Resolution *3 Not specified0.5 dBTBD Applicable signalOFDM, DSSS Applicable input rangeNot specified(-110 to 0 dbm)(-60 to -30 dbm) Bandwidth10 MHz11 MHz Measurement pointAntenna Connector * - Definitions

11. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 11 * Definitions for the RSSI, RCPI & WRSS Table 1.Absolute accuracy specification: upper bound on the square-root of the second moment of the WRSS measurement error (in db) made by any radio over all operating conditions. 2.Short-term accuracy specification: upper bound on the square-root of the second central moment of the WRSS measurement error (in db) made by any radio over all operating conditions. The second central moment is more commonly referred to as the standard deviation. 3.Resolution specification: the (maximum) value of the minimum increment in reported WRSS measurement values. This specification should be consistent with the short-term accuracy (i.e., on the same order). For example, IF the short-term accuracy specification is 1dB, a resolution of 0.5dB is appropriate … 0.1dB is overkill!

12. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 12 Desired Feedback from 802.11 Chipset Manufacturers and Radio Subsystem OEMs What values of absolute and short-term accuracies (in dB) measured over current WRSS proposed operating conditions do your current (and future) products achieve?

13. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 13 If Non-response from Chipset Manufacturers, Conduct Straw Poll in TGp 1.Should TGp concern itself with “WRSS”? __ Yes __ No __ Abstain 2.Should WRSS be mandated even if it has a considerable impact on product complexity? __ Yes __ No __ Abstain 3.Should TGp request TGk to address MAC poll/response latency issues for WAVE applications? __ Yes __ No __ Abstain 4.Should TGp address WRSS MAC poll/response effects and accept current accuracy/resolution values for absolute measurements from TGk? __ Yes __ No __ Abstain 5.Should TGp request that TGk incorporate short- and long-term statistical parameters in defining accuracy and setting limits (as described herein)? __ Yes __ No __ Abstain Reconfirmation: 1.Should TGp continue work on including WRSS (both MAC poll/response and accuracy/resolution)? __ Yes __ No __ Abstain 2.Should TGp eliminate WRSS entirely? __ Yes __ No __ Abstain

14. doc.: IEEE 802.11-05/0754-01-000p-r0 Submission Liu / Roebuck / Roy / Zhu July 2005 Slide 14 Desired Feedback from 802.11 Chipset Manufacturers and Radio Subsystem OEMs Present 802.11p draft (D0.21) specifies ± 3 dB accuracy and 0.2 dB resolution. Will you support a proposed 802.11p amendment to the 802.11 standard with these specifications?