1. doc.: IEEE 802.11-06/0385r0 Submission March 2006 A. Kapur, et al, Broadcom CorporationSlide 1 EVM Specification Issues for TGn 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://stuartpatcom Date: 2006-03-DD Authors:

2. doc.: IEEE 802.11-06/0385r0 Submission March 2006 A. Kapur, et al, Broadcom CorporationSlide 2 Comment on EVM Specifications At first glance, the tx EVM requirement doesn’t appear to depend on the type of impairment at the transmitter. A closer look leads to different conclusions. Three (nonlinear) tx impairments were considered: –PA IMD due to choice of PA output back-off (OBO), using RAPP model –I-Q imbalance (gain and phase) –Phase noise, varying the close-in density level in dBc/Hz We assume that the receiver is “perfect” (i.e., free from nonlinear impairment). –Clearly, this is not the case. –I-Q imbalance and phase noise will be present. EVM limits must be specified assuming the mandatory TGn configuration for the number of spatial streams, e.g. 2x2 for 2 spatial streams. –ZF, MLD, other (?) receiver types may be considered.

3. doc.: IEEE 802.11-06/0385r0 Submission March 2006 A. Kapur, et al, Broadcom CorporationSlide 3 Comments on EVM Specification Varying the tx impairments, we want to determine the EVM values at which a target FER floor or maximum sensitivity degradation is reached. –It is possible that EVM values resulting from different combinations of tx impairment levels will result in different levels of rx degradation. Since the specification does not break out EVM due to each type of tx impairment, we must “assume the worst” and select the lowest EVM number which ensures compliance with our FER floor and senstivity degradation requirements. –Some number around 0.5 to 1 dB degradation in rx sensitivity is probably o.k.

4. doc.: IEEE 802.11-06/0385r0 Submission March 2006 A. Kapur, et al, Broadcom CorporationSlide 4 EVM Test System Model PA OBO I-Q imb PN TX ZF or MLD RX {H k } ZF RX 1 1 -1 Vary channel model (ch. B, D NLOS) Record sensitivity, FER floor for each receiver type. Record EVM. Vary PA OBO, PN

5. doc.: IEEE 802.11-06/0385r0 Submission March 2006 A. Kapur, et al, Broadcom CorporationSlide 5 Tx EVM vs. Tx Impairments EVM (dB) Nominal impairments: PA OBO11.0 dB -33.0 PN-100.0 dBc/Hz CFO31.0 ppm I-Q imb0.1 dB / 0.9 deg. Increased impairments: Nominal + PN-97.5 dBc/Hz-31.9 PN-95.0 dBc/Hz-30.7 PN-92.5 dBc/Hz-29.1 PN-90.0 dBc/Hz-28.1 PA OBO10.0 dB-31.2 PA OBO9.0 dB-28.7 PA OBO8.5 dB-27.3 PA OBO8.25 dB-26.6 PA OBO8.0 dB-26.0

6. doc.: IEEE 802.11-06/0385r0 Submission March 2006 A. Kapur, et al, Broadcom CorporationSlide 6 ZF Rx, Effect of Different Tx Impairments on EVM, Rx Sensitivity Note that the input SNR requirements are excessively high. However, MLD, which achieves 1% FER at a reasonable input SNR is more sensitive to the tx- side nonlinear impairments.

7. doc.: IEEE 802.11-06/0385r0 Submission March 2006 A. Kapur, et al, Broadcom CorporationSlide 7 Conclusions PN close-in density of -92.5 dBc/Hz results in -29 dB EVM but an unacceptable loss in rx sensitivity. It looks like -33 dB is a more reasonable EVM limit for MCS 15 if PN is the dominant source of impairment (ZF degrades 0.7dB w.r.t. ideal case). PA OBO has a large effect on tx EVM, and -31 dB EVM appears to be an acceptable limit if only PA IMD is considered (ZF degrades 0.7dB w.r.t. ideal case).

8. doc.: IEEE 802.11-06/0385r0 Submission March 2006 A. Kapur, et al, Broadcom CorporationSlide 8 Motion Motion to adopt text in document 11-06/0446r0 into the TGn draft