Monterey: Update of Proposed Over the Air Test Methodology Jan 2005 doc.: IEEE 802.11-05/1622r0 Jan 2005 Monterey: Update of Proposed Over the Air Test Methodology Date: 2005-01-19 Authors: 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 <http:// ieee802.org/guides/bylaws/sb-bylaws.pdf>, 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 <stuart.kerry@philips.com> 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 <patcom@ieee.org>. Kobayashi, Trachewsky, Victor, Broadcom Corp Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 doc.: IEEE 802.11-05/1622r0 Jan 2005 Abstract An update on progress made in the area presented in 802.11-04/1476r0, “A Proposed Open Air Test Methodology” Basic updates are: Demonstration of repeatability in two different setups (one screenroom located on one floor to another located on a different floor Show ability to run test in different frequency bands Kobayashi, Trachewsky, Victor, Broadcom Corp Kobayashi, Trachewsky, Victor, Broadcom Corp

Agenda Objective Background Goals Block Diagram of setup Jan 2005 doc.: IEEE 802.11-05/1622r0 Jan 2005 Agenda Objective Background Goals Block Diagram of setup Picture of setup Methodology Old and NEW Test results Recommendations Kobayashi, Trachewsky, Victor, Broadcom Corp Kobayashi, Trachewsky, Victor, Broadcom Corp

Objective From PAR and 5 criteria: Jan 2005 Objective 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. Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 Background The objective of TGT is to come up with a repeatable measurement methodology and to provide set of metrics measurement methodologies test conditions to enable measuring and predicting Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 Goals Propose a controlled open air environment to help achieve the goals and objective of TGT Allows for complete system evaluation including antenna and effects of all components of DUT Kobayashi, Trachewsky, Victor, Broadcom Corp

Controlled Open Air Test Jan 2005 Controlled Open Air Test REF Open Air Channel DUT platform channel DUT Open air channel can be broken into two components The open air channel by itself The DUT platform channel Create an environment where open air channel is virtually flat reduce multipath channel response System Under Test (SUT) * = REF Open Air Channel DUT DUT platform channel System Under Test (SUT) * = Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 Overview 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 Kobayashi, Trachewsky, Victor, Broadcom Corp

Block Diagram Open Air Calibration Jan 2005 Block Diagram Open Air Calibration RF shielded screenroom 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 calibrated antenna directional antenna AMP Network Analyzer Kobayashi, Trachewsky, Victor, Broadcom Corp

Block Diagram Open Air Test Jan 2005 Block Diagram Open Air Test RF shielded screenroom Use power meter to measure tx power Variable attenuator creates additional path loss for determining path loss sensitivity Inner Walls lined with RF absorbent material DUT directional antenna REF Variable Attenuator Power meter directional coupler Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 Picture of setup Picture shows main components of items inside of the RF shielded enclosure Items outside of enclosure are not shown RF shielded screenroom Inner Walls lined with RF absorbent material DUT directional antenna Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 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 Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 Results First results are provided as a reference to results from previous presentation First plot in this series shows conducted results Second plot shows initial measurements made over the air Second set of results shows Result of moving from one screenroom on one floor to another Similar results were achieved as compared to runs shown in previous presentation Repeatability of this methodology is shown Third set of results show initial work in the 5.7Ghz band Second plot shows some initial measurements made over the air Kobayashi, Trachewsky, Victor, Broadcom Corp

Product 2 PER Channel 1-13 conducted Jan 2005 Product 2 PER Channel 1-13 conducted Controlled experiment running conducted Kobayashi, Trachewsky, Victor, Broadcom Corp

PER Channel 13 DUT channel with open air losses calibrated out Jan 2005 PER Channel 13 DUT channel with open air losses calibrated out Note that after channel effects of air and DUT platform are calibrated out the curves line up similar to conducted results of previous slide Kobayashi, Trachewsky, Victor, Broadcom Corp

PER Channel 1-9 DUT channel with open air losses calibrated out Jan 2005 PER Channel 1-9 DUT channel with open air losses calibrated out Note that these results line up closely with results shown in previous 2 slides Same Product 2 was used in similar test platform in a different screenroom Kobayashi, Trachewsky, Victor, Broadcom Corp

Conducted PER results on channel centered at 5765Mhz Jan 2005 Conducted PER results on channel centered at 5765Mhz Controlled experiment as basis Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 PER results on channel centered at 5765Mhz with open air losses calibrated out Note that these results line up with results shown in previous slide Kobayashi, Trachewsky, Victor, Broadcom Corp

Issues to be Considered Jan 2005 doc.: IEEE 802.11-05/1622r0 Jan 2005 Issues to be Considered Requires a very accurate positioner Requires knowledge of the exact location of the antenna(s) in the DUT (sometimes enclosed in the chassis) Do not currently have a good proposed technique for testing diversity systems (TBD) Have not yet checked that the procedure works at all incident azimuth angles Do not have solution to run the test easily over a variety of elevation angles The resulting RF channel isn’t completely flat; so, while we are calibrating the rx power at a point in space, we really want to calibrate capacity (integral of the logarithm of SNR at high SNR) Kobayashi, Trachewsky, Victor, Broadcom Corp Kobayashi, Trachewsky, Victor, Broadcom Corp

Jan 2005 Recommendation TGT should continue to explore this methodology (as alluded to in slide 7) for doing full system characterization via Open Air Testing Kobayashi, Trachewsky, Victor, Broadcom Corp