1. doc.: IEEE 802.11-10/0079r0 Submission Interference Signalling Enhancements Date: 2010-03-xx Mar 2010 Allan Thomson, Cisco SystemsSlide 1 Authors:

2. doc.: IEEE 802.11-10/0079r0 Submission Mar 2010 Allan Thomson, Cisco SystemsSlide 2 Abstract As part of the implementation evaluation of the current collocated interference feature in TGv SB, several significant issues were raised about the viability of the feature This proposal highlights a solution to resolve TGv SB Recirc #1 CIDs 2 and 13

3. doc.: IEEE 802.11-10/0079r0 Submission Mar 2010 Allan Thomson, Cisco SystemsSlide 3 An Example Use Case: WiFi Voice Client with BT Headset The client wants to use voice over wifi and BT headset at the same time. BT is periodic at 3.75ms intervals with 1.25ms active and 2.5ms silence, AP has to transmit after the U-APSD trigger frame and before the BT transmission by the handset Client AP 3.75ms Client U-APSD Trigger Frame AP U-APSD Voice Frames

4. doc.: IEEE 802.11-10/0079r0 Submission Mar 2010 Allan Thomson, Cisco SystemsSlide 4 Problem The currently defined collocated interference feature has the following issues: 1) Requires the AP implement some form of scheduling and when combined with all interactions and services the AP has to provide for BSS operation becomes a significantly complex task 2) Does not make use of existing 802.11 frames and AP interactions and therefore requires additional complexity on both AP and client 3) Does not take into account important state such as power save provided by U-APSD

5. doc.: IEEE 802.11-10/0079r0 Submission AP Guiding Principles/Objectives Maximize over-the-air throughput in the BSS –Minimize wasted transmissions to absent clients Provide scalable solution for up to 100’s of clients in the BSS Provide solution such that existing performance is not negatively impacted Transmit packets in order received subject to priority –Don’t give devices reporting collocated interference greater priority than devices without interference Minimize development

6. doc.: IEEE 802.11-10/0079r0 Submission Solution Introduction Extend the U-APSD signalling that takes place to allow the client to report interference free intervals and have the AP integrate that logic into the delivery of frames Provide two mechanisms 1) Immediate AP transmission based on trigger frames 2) Absolute AP transmission based on TSF offset to 0 Solution aspects: 1)Advertisement 2)Client Reporting Mechanism 3)AP Mediation Mechanism Mar 2010 Allan Thomson, Cisco SystemsSlide 6

7. doc.: IEEE 802.11-10/0079r0 Submission Mar 2010 Allan Thomson, Cisco SystemsSlide 7 Example #1: WiFi Voice Client with Periodic BT Interference every 3.75ms with 1.25ms active BT Client setup (not shown): Sends ADDTS coexistence for 2ms duration Client sends U-APSD trigger frame after each BT interference period AP transmits buffered frames to client after receiving trigger frame until end of duration Client AP 3.75ms Client U-APSD Trigger Frame AP U-APSD Voice Frames BT Frames 1.25 Optional AP EOS U-APSD Frame

8. doc.: IEEE 802.11-10/0079r0 Submission Mar 2010 Example #2: WiFi Voice Client with Periodic BT Interference every 3.75ms with 1.25ms active BT Client setup (not shown): Sends ADDTS coexistence for 3.75ms interval with TSF 0 Offset = 2 Client sends U-APSD trigger frame after each BT interference period AP transmits buffered frames to client after receiving trigger frame until end of adjusted duration calculated based on interval of interference and offset from TSF

9. doc.: IEEE 802.11-10/0079r0 Submission Advertisement Add new bit to Extended Capabilities IE to indicate U- APSD Coexistence service Both AP and non-AP STA would set the bit when supporting the feature If either does not support the feature then coexistence while using U-APSD is not available Mar 2010 Allan Thomson, Cisco SystemsSlide 9

10. doc.: IEEE 802.11-10/0079r0 Submission Client Reporting Mechanism Include in ADDTS Request frame an optional “coexistence” IE The client receives a ADDTS response that acknowledges positive acceptance by the AP that coexistence will be provided for the Duration requested Mar 2010 Allan Thomson, Cisco SystemsSlide 10 OrderIE 1Category 2Action 3Dialog Token 4TSPEC 5TCLAS 6TCLAS Processing 7Coexistence (optional)

11. doc.: IEEE 802.11-10/0079r0 Submission Coexistence IE TSF 0 Offset only used if non-AP STA wants AP to adjust for TSF drift of interference Interval/Duration defines how long the AP is able to transmit to the non-AP STA after receiving a U-APSD trigger frame TSF 0 Offset field is microseconds since TSF time 0 –0 indicates unused Interval/Duration field is measured in microseconds and defined in 4 octets –0 is a reserved value Mar 2010 Allan Thomson, Cisco SystemsSlide 11 Element IDLengthTSF 0 OffsetInterval/Duratio n Optional Subelements Octets:1184variable

12. doc.: IEEE 802.11-10/0079r0 Submission Client Advertisement Behavior If the non-AP STA has advertised support for U-APSD Coexistence feature in the Extended Capabilities IE then it has the capability to detect interference and request use of the coexistence feature The non-AP STA shall not include the Coexistence IE in the ADDTS frame unless the AP has also advertised support for the Coexistence feature in the Extended Capabilities IE Mar 2010 Allan Thomson, Cisco SystemsSlide 12

13. doc.: IEEE 802.11-10/0079r0 Submission Client Behavior – Interference Detected Upon determination that interference is occurring the non-AP STA shall include the Coexistence IE in the ADDTS frame indicating the preferred Duration when the AP should transmit frames to the non-AP during the U-APSD service period ADDTS frame with Coexistence requested: Mar 2010 Allan Thomson, Cisco SystemsSlide 13 OrderIEValue 1CategoryQoS (1) 2ActionADDTS request (0) 3Dialog TokenN 4TSPECQoS Flow #1 Parameters 5TCLASQoS Flow #1 Traffic 6TCLAS ProcessingQoS Flow #1 Processing 7CoexistenceDuration = 2ms

14. doc.: IEEE 802.11-10/0079r0 Submission Client Behavior – Interference Changes Upon determination that interference is changing, the non-AP STA may issue another ADDTS frame to update the Duration field as necessary ADDTS frame with Coexistence modified: Mar 2010 Allan Thomson, Cisco SystemsSlide 14 OrderIEValue 1CategoryQoS (1) 2ActionADDTS request (0) 3Dialog TokenN 4TSPECQoS Flow #1 Parameters 5TCLASQoS Flow #1 Traffic 6TCLAS ProcessingQoS Flow #1 Processing 7CoexistenceDuration = 4ms

15. doc.: IEEE 802.11-10/0079r0 Submission Client Behavior – No Interference Detected Upon determination that interference has stopped and the non-AP STA no longer needs the AP to provide coexistence protection but continues to use QoS Services for U-APSD SP the non-AP STA may transmit a ADDTS frame without the Coexistence IE ADDTS frame sent to stop interference protection without CoexistenceIE Mar 2010 Allan Thomson, Cisco SystemsSlide 15 OrderIEValue 1CategoryQoS (1) 2ActionADDTS request (0) 3Dialog TokenN 4TSPECQoS Flow #1 Parameters 5TCLASQoS Flow #1 Traffic 6TCLAS ProcessingQoS Flow #1 Processing 7CoexistenceDuration = 2ms

16. doc.: IEEE 802.11-10/0079r0 Submission Client Behavior – No QoS Required & No Interference Detected Upon determination that interference has stopped and the non-AP STA no longer needs the AP to provide QoS services or coexistence protection for U-APSD SP the non-AP STA may transmit a DELTS frame without the Coexistence IE DELTS frame sent to stop interference protection without CoexistenceIE Mar 2010 Allan Thomson, Cisco SystemsSlide 16 OrderIEValue 1CategoryQoS (1) 2ActionADDTS request (0) 3Dialog TokenN 4TSPECQoS Flow #1 Parameters 5TCLASQoS Flow #1 Traffic 6TCLAS ProcessingQoS Flow #1 Processing 7CoexistenceDuration = 2ms

17. doc.: IEEE 802.11-10/0079r0 Submission AP Behavior If the AP has advertised support for U-APSD Coexistence feature in the Extended Capabilities IE then it shall process U-APSD Coexistence IE otherwise it shall ignore –AP should never receive a Coexistence IE from a non-AP STA is the AP has not already advertised support for this feature Upon reception the AP shall associate the Duration field for the non-AP STA such that any frames transmitted during the U-APSD SP to that non-AP STA should be transmitted during that period Mar 2010 Allan Thomson, Cisco SystemsSlide 17

18. doc.: IEEE 802.11-10/0079r0 Submission U-APSD SP Termination Normal behavior for AP is that it sets the EOSP bit in the last frame transmitted in the U-APSD service period If the AP determines that the frame to be transmitted cannot be transmitted before the Duration field expires then it needs to notify the non-AP STA somehow Explicit Termination: –New normative behavior required to define that the AP transmits a QoS null frame in this circumstance with the EOSP bit set to terminate the U-APSD SP Implicit Termination: –New normative behavior required to defined that both the AP and non-AP STA will implicitly terminate the SP after the Duration time has expired after reception of the U-APSD Trigger frame at the AP Mar 2010 Allan Thomson, Cisco SystemsSlide 18

19. doc.: IEEE 802.11-10/0079r0 Submission Questions ? Mar 2010 Allan Thomson, Cisco SystemsSlide 19