1. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 1 STA receiver performance indication 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-XX-XX Authors:

2. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 2 Abstract This presentation introduces the mechanism to carry STAs receiver performance information to other STA.

3. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 3 STA receiver performance information - background Minimum sensitivity levels are already specified –14.6.15.4 –15.4.8.1 –17.3.10.1 –Typically implementations are better Currently STAs does not have a mechanism to exchange receiver performance information –11-05-1599-02-000k-measurement-frame-normative-text introduces measurement frame where Transceiver Noise Floor is carried –However, this is only AP => STA.

4. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 4 STA receiver performance information A mechanism that enables STA to indicate receiver performance could be useful. –Can indicate minimum required signal level in reception –Can indicate better performance than mandated by the specification –Can be used to finetune APs rate adaptation algorithms –Can indicate ‘interference slots’

5. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 5 Sudden changes in STA receiver performance In multiradio devices it is possible that activity of other radio causes degradation in STA WLAN receiver performance –For example, GSM/GPRS TX may increase the noise floor by 10- 20 dB –WLAN - BT may collide –Other radios may cause similar effects Typically these are not continuous degradations and typically they have certain characteristics –For example, GSM/GPRS TX has certain slot structure and degraded performance is experienced periodically.

6. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 6 GSM interference mechanism: WLAN front-end GSM front-end GSM wideband noise desensitizes 2.4GHz ISM band GSM transmission 3 rd harmonic in 5GHz ISM band TRX switch causes harmonics that can’t be filtered out Wideband noise passes transmitter front-end without specific filters

7. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 7 Example: GSM/GPRS TX and WLAN GSM TX WLAN band interference GPRS TX 2 UL slots 0,577 ms 4,038 ms 1,154 ms 3,461 ms WLAN band interference

8. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 8 Example: WLAN - BT Simultaneous WLAN and BT usage is causing big problems. 802.15.2 is not solving the problem –Can control STA side but cannot control AP side, i.e., cannot control WLAN DL transmissions => collisions occurs. BT HV3 SCO TX RX 2 x 625 us 2500 us

9. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 9 Proposal: Enhanced Link Measurement Report Define new element: STA Performance Indicator Information element The Transceiver Noise Floor field is a signed integer and is 1 octet in length. It shall indicate the noise floor of the receiver used by the STA transmitting the frame in which it appears in units of dBm. The transceiver noise floor is referenced to the connector of the currently in-use receiving antenna The Interference Characteristic field enables the STA to indicate periods of degraded receiver performance due to local interference. The inclusion of this field shall be optional. Details: See next slide.

10. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 10 Interference Characteristic field The Receive Interference bit-field shall be set to 1 to report degradation in WLAN receiver performance The Transmit Interference bit-field shall be set to 1 to report that the WLAN radio is causing interference to other radio systems at the reporting STA The Periodic Interference bit-field shall be set to 1 to indicate that reported Receive Interference is periodic in nature with known timing The Interference Noise Floor shall indicate the degraded receiver noise floor during the reported interference in units of dBm. The Interference Interval field indicates the interval between two successive periods of interference in microseconds. The Interference Burst Length field indicates the duration of each period of interference in microseconds. The Interference Start Time field contains the lower 4 bytes of the TSF timer at the start of the next interference burst.

11. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 11 Usage of STA receiver performance information AP can request the information or non-AP STA can autonomously send report if its performance is degraded. If Interference Characteristic fields are not present then it can be used directly for e.g. rate adaptation purposes If Interference Characteristic fields are present then AP can: –Keep the rate same (even if there are lost frames) and try to avoid ‘Interference’ slots –Use more robust rate. However, this is not preferred as it will make the situation in many cases even worse. If interference does not exist anymore, STA can update its performance information by sending frame with no Interference Characteristics fields

12. doc.: IEEE 802.11-05/0583r0 Submission May 2005 Simon Black et al, NokiaSlide 12 Conclusion STA receiver performance information provides valuable information for the AP –STA can indicate that its performance is degraded STA can specify interference characteristic AP can try to avoid ‘interference’ slots –STA can indicate that its performance is better that mandated by the specifications Direct input for APs rate adaptation logic