Presentation on Proposed Normative Text for Management Cleanup

1. Presentation on Proposed Normative Text for Management Cleanup Authors: Steve Emeott, Ye Chen, Stephen Wang, Floyd Simpson Motorola, Inc. Date: January 11, 2004 Steve Emeott et.al Motorola,

2. Addresses Ballot Comments • APSD power management • Comment #16 thru #23 Steve Emeott et.al Motorola,

3. Issue Addressed • Clarification on issues relating to the 802.11e power management procedures specified in Clause 11.2 needed: • What power save mode the APSD mechanism should use during automatic delivery should be clarified • Limits in normative text on delivery behaviors during scheduled and unscheduled SP should be proposed • Facilitates co-existence of APSD (scheduled & unscheduled) and legacy power management, • Permits QAP to avoid pitfalls of delivering non-APSD traffic during APSD service periods • Refinements needed to text defining normative service period triggering behavior Steve Emeott et.al Motorola,

4. Relevant Clauses in 802.11e Draft (6.0) • Clause 11.2.1.4, defining means of engaging APSD, triggering both scheduled and unscheduled service periods and delivering frames • Clause 11.2.1.5, defining AP behaviors including buffering, delivering frames and signaling buffer status • Clause 11.2.1.9, defining operating mode for non-AP QSTAs transmitting and receiving frames via APSD Steve Emeott et.al Motorola,

5. APSD Power Mode Issue • In Clause 11.2.1.4, third paragraph, APSD is used only when the non-AP QSTA is in power-save mode, as indicated by the power management bit (set to 1). • However, in Clause 11.2.1.9, the non-AP QSTA transitions to Active mode prior to schedule/unscheduled service period • The two statements contradict to each other in terms of the power state at which APSD is operated. Steve Emeott et.al Motorola,

6. APSD Power Mode: Proposed Behavior • APSD is only used when a non-AP QSTA is in power-save mode. The non-AP QSTA wakes up prior to schedule/unscheduled service periods, but still in power-save mode as indicated by the power management bit • Benefits • QAP can continue to buffer non-APSD frames while delivering APSD traffic, avoiding potential pitfalls of transmitting non-APSD traffic (including unadmitted traffic) during APSD service periods • Non-AP can transition to Active mode, either at the beginning of the next SP or immediately, to retrieve such frames Steve Emeott et.al Motorola,

7. APSD Delivery Issue • Delivery behavior requiring QAP to attempt to transmit all frames destined for the non-AP QSTA during a scheduled/unscheduled SP is problematic • Such normative behavior is defined in clause 11.2.1.4 and in clause 11.2.1.5, bullet g. • Specified behavior potentially requires QAP to deliver frames addressed to a non-AP QSTA using multiple AC or even using multiple channel access functions (e.g. HCCA and EDCA) within one service period. • Such behavior required even when initiating HCCA SP during CFP Steve Emeott et.al Motorola,

8. Further Delivery Discussion • Some of the pitfalls in delivering all frames during a scheduled/unscheduled SP • If the QAP releases traffic to multiple channel access functions at the beginning of a SP, then properly setting the EOSP bit can be problematic • Difficult to predict which EDCA channel access function might finish accessing the channel first and when to set the EOSP bit to avoid Service Start Times of other QSTA • Complicates channel access implementation if new behaviors are required to feed back state of channel access function to scheduler • Complicates the scheduler for HCCA and EDCA because the HC should consider how much time to set aside for non-APSD traffic during SP • Permits the delivery of admitted EDCA traffic with schedule=1 at times not compatible with the schedule established by the admissions control module Steve Emeott et.al Motorola,

9. Delivery: Proposed Behavior • APSD downlink traffic delivery • The QAP shall deliver buffered frames associated with an admitted TSPEC having APSD=1 during appropriate scheduled/unscheduled service periods. The QAP shall not deliver non-APSD traffic (including unadmitted traffic) during scheduled/unscheduled SP. • Scheduled SP can be used to deliver all APSD traffic; unscheduled SP can be used to deliver only unscheduled APSD traffic. • Benefit • Straightens out most of the co-existence issue between legacy, scheduled and unscheduled power management mechanisms • Simplifies the issue of how to best set the EOSP bits at the end of a scheduled/unscheduled SP • Provides multiple power save delivery modes with which the non-AP QSTA may leverage to take full advantage of EDCA Steve Emeott et.al Motorola,

10. Triggering Issue • In Clause 11.2.1.4, sixth paragraph, it defines that any frame from a non-AP QSTA can trigger an unscheduled SP • Such behavior is problematic because • Control (e.g. PS-Poll) or management frame should certainly not trigger an unscheduled SP • Traffic sent in an AC with ACM=0 and frames associated with a TSPEC employing scheduled delivery should not trigger an unscheduled SP • The type of frame that can trigger an unscheduled SP should be redefined Steve Emeott et.al Motorola,

11. Triggering: Proposed Behavior • The only frames that can trigger an unscheduled SP (refer as trigger frame) shall be a QoS-Data or Null frame associated with an uplink TSPEC having its APSD subfield set to 1 and its schedule bit set to 0 by the non-AP QSTA • Benefit • Solves the problem that too many different types of frames can trigger an unscheduled SP Steve Emeott et.al Motorola,

12. Summary of Proposed Changes • During APSD scheduled/unscheduled service period, the non-AP QSTA is awake but not active • APSD is used for individual traffic flows and admitted traffic, not for the entire station • Downlink delivery • Deliver only APSD traffic during scheduled/unscheduled service period. Delivery of non-APSD traffic (including unadmitted traffic) during scheduled/unscheduled SP is not allowed • Scheduled SP can be used to deliver all APSD traffic; unscheduled SP can be used to deliver only unscheduled APSD traffic. • More Data bit and TIM are used to identify the presence of non-APSD traffic (including unadmitted traffic) in the power save buffer of a QAP. • Unscheduled SP are triggered by frames associated with a TSPEC the QAP has admitted with APSD=1, schedule=0 Steve Emeott et.al Motorola,

13. Proposed Normative Text Changes • All proposed changes as normative text are in document 11-04-0030-00-000e Steve Emeott et.al Motorola,

14. Q&A Steve Emeott et.al Motorola,

15. Motion To adopt the changes identified in document 11-04-0028-00-000e into the current TGe Draft Yes____ No____ Abstain_____ Steve Emeott et.al Motorola,