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

doc.: IEEE 802.11-10/0079r0

Submission

Interference Signalling Enhancements

Date: 2010-03-xx

Mar 2010

Allan Thomson, Cisco SystemsSlide 1

Name Affiliations Address Phone email Allan Thomson Cisco Systems 170 W. Tasman Drive, San

Jose, CA95134 +1-408-853-5570 [email protected]

Brian Hart Cisco Systems 170 W. Tasman Drive, San Jose, CA95134

+1-408 [email protected]

Dave Stephenson Cisco Systems 170 W. Tasman Drive, San Jose, CA95134

+1 408 [email protected]

Emily Qi Intel Corporation 2111 NE 25th Ave, Hillsboro, OR

+1-503-264-7799 [email protected]

Oren Kaidar Intel Corporation 2111 NE 25th Ave, Hillsboro, OR

+1-503-712-3494 [email protected]

Authors:

doc.: IEEE 802.11-10/0079r0

Submission

Mar 2010


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

doc.: IEEE 802.11-10/0079r0

Submission

Mar 2010


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

doc.: IEEE 802.11-10/0079r0

Submission

Mar 2010


ProblemThe 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

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

doc.: IEEE 802.11-10/0079r0

Submission

Solution IntroductionExtend 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 frames2) Absolute AP transmission based on TSF offset to 0

Solution aspects:

1) Advertisement2) Client Reporting Mechanism3) AP Mediation Mechanism

Mar 2010


doc.: IEEE 802.11-10/0079r0

Submission

Mar 2010


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 periodAP 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 Frames1.25 1.25

Optional AP EOS U-APSD Frame

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 periodAP transmits buffered frames to client after receiving trigger frame until end of

adjusted duration calculated based on interval of interference and offset from TSF

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


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


Order IE1 Category

2 Action

3 Dialog Token

4 TSPEC

5 TCLAS

6 TCLAS Processing

7 Coexistence (optional)

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


Element ID Length TSF 0 Offset Interval/Duration

Optional Subelements

Octets: 1 1 8 4 variable

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


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


Order IE Value1 Category QoS (1)

2 Action ADDTS request (0)

3 Dialog Token N

4 TSPEC QoS Flow #1 Parameters

5 TCLAS QoS Flow #1 Traffic

6 TCLAS Processing QoS Flow #1 Processing

7 Coexistence Duration = 2ms

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




3 Dialog Token N





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




3 Dialog Token N





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




3 Dialog Token N





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


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


doc.: IEEE 802.11-10/0079r0

Submission

Questions ?

Mar 2010


Documents

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