1. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 1 Controlled Over the Air Test Methdology Update 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: 2005-03-15 Authors:

2. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 2 Objectives From PAR and 5 criteria: –Scope: The scope of 802.11T is to provide a set of performance metrics, measurement methodologies, and test conditions to enable measuring and predicting the performance of 802.11 WLAN devices and networks at the component and application level. (emphasis added) –Purpose: The purpose of 802.11T is to enable testing, comparison, and deployment planning of 802.11 WLAN devices based on a common and accepted set of performance metrics, measurement methodologies and test conditions.

3. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 3 Overview of Methodology Utilize setup that severely reduces any interference from outside sources –Screen room –Use a directional antenna and RF absorbent material to reduce multipath effects Take a channel measurement of the Open Air with no device present but place antenna in same position as where receive antenna would be in free space Utilize this measured free space channel loss to determine amount of received power as seen by the DUT –Measure transmitted power out to cabled portion add additional free space loss to determine rx channel power level Place DUT in place such that rx antenna is exactly in the place that was expected by step above

4. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 4 Topics of discussion Precision Throughput results Silent zone measurements

5. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 5 Precision Open air calibration measurements, requires precise placement (x,y,z) of the calibrated antenna and the actual DUT antenna. –Location of the RX calibrated antenna is key to a good measurement –Note the RX calibrated antenna can be a simple dipole. There is no need for a high-gain antenna like that used in the TX reference Items utilized during all measurements need to be placed precisely in the same locations in all measurements –TX directional antenna needs to be in same location

6. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 6 Laser positioners Usage of laser positioners allow for precise placement of calibrated antenna at the same location where the dut/sut antenna is located Lever used to control height screw used to control rotation screw used to control rotation of laser laser

7. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 7 Laser Positioners in Test Setup RF shielded screenroom directional antenna Inner Walls lined with RF absorbent material DUT laser positioner laser positioner Picture shows main components of items inside of the RF shielded enclosure Items outside of enclosure are not shown

8. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 8 Block Diagram Open Air Calibration AMP Network Analyzer Main beam pattern of tx antenna pointed toward open end of RF enclosure to minimize multi-path channel effects –Keeps channel frequency response flat –Directional antenna focuses the majority of energy in a particular direction Rx antenna is in the far field of the tx antenna Amplifier puts received signal within rx sensitivity of network analyzer Collect channel response to determine calibration Inner Walls lined with RF absorbent material RF shielded screenroom calibrated antenna directional antenna

9. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 9 Picture of Open Air Calibration with lasers on Diagram illustrates the usage of lasers to precisely place the calibrated antenna in the same spatial location as where the dut antenna will be Top laser cross hair Indicates top of antenna Bottom laser cross hair Indicates bottom of antenna vertical laser beam indicates that cross hairs Line up

10. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 10 Block Diagram Open Air Test REF Variable Attenuator DUT Use power meter to measure tx power Variable attenuator creates additional path loss for determining path loss sensitivity Power meter directional coupler Inner Walls lined with RF absorbent material RF shielded screenroom directional antenna

11. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 11 Picture of Open Air Test with lasers on Diagram illustrates the usage of lasers to precisely place the dut antenna in the same spatial location as where the calibrated antenna was Top laser cross hair Indicates top of antenna Bottom laser cross hair Indicates bottom of antenna vertical laser beam indicates that cross hairs Line up

12. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 12 Closeup Picture of Open Air Test with lasers on Diagram illustrates the usage of lasers to precisely place the dut antenna in the same spatial location as where the calibrated antenna was

13. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 13 System ready for over the air testing Note that lasers have been removed so as not to contribute to the channel Laser positioners constructed of materials to least effect RF channel –This effect still needs to be characterized

14. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 14 Throughput results conducted Results from running the tests in a conducted environment Baseline results

15. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 15 Throughput OTA results Results from running throughput results under the controlled OTA methodology Note that these results match fairly closely with conducted results

16. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 16 Quiet zone variation measurements For each point, multiple data points collected across multiple frequencies –Data collected across frequencies from 2402 – 2422 Mhz Each point represents a different location in a specific point in space –Points 1-27 are inside the test box –Points 28-36 are outside the test box 123 456 789 101112 131415 161718 192021 222324 252627 282930 313233 343536 light green outside of the box dark green inside of the box

17. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 17 Quiet zone measurement variation within the box These test results represent data collected for data inside the test box across various frequencies Rough variation between +/- 0.5 dB

18. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 18 Outside quiet zone measurement variation outside the box These test results represent data collected for data immediately outside the test box across various frequencies Note that the variation is larger outside of the box Variation between +/- 1 dB

19. doc.: IEEE 802.11-yy/xxxxr0 Submission March 2005 Kobayashi, Trachewsky, Dalton, Broadcom Corp.Slide 19 Conclusions Laser beam positioners have greatly enhanced the accuracy in which positioning the dut and the test antenna are placed For all systems, we will need a mechanical drawing to determine the location of the antennas embedded in these systems Initial throughput measurements show good correlation between conducted results and OTA results Variation between measurements in the test box are very tight while variation outside the test box vary a bit more