Some Additional TPC Aspects to Consider March 2002 March 2002 Some Additional TPC Aspects to Consider Peter Larsson Ericsson Research peter.larsson@era.ericsson.se Peter Larsson, Ericsson Research, Sweden

Motivation Three concerns: March 2002 Motivation Three concerns: TPC Request/Report frames in conjunction with 802.11 Power Management need to be addressed. TPC Request/Report frames works fine for downlink power control, but would benefit from additional support in the uplink. AP centric radar detection would benefit from additional TPC support in the uplink. Peter Larsson, Ericsson Research, Sweden

Power Management and TPC (1) March 2002 Power Management and TPC (1) N.B CF-Pollable STAs not considered Beacon Beacon ACK TPC Report AP Time Pwr Mgt=0 Pwr Mgt=1 Channel busy STA TPC Request ACK Awake Awake Power is consumed when being awake. Why bother, one is anyway sending data immediately after the TPC frames? Not entirely true! Implementation specific. E.g. after long silence, the first frame should be able to determine a sensible power level. Peter Larsson, Ericsson Research, Sweden

Power Management and TPC (2) March 2002 Power Management and TPC (2) N.B Ack response on PS poll not considered Beacon Beacon TIM ACK TPC Report AP Time Pwr Mgt=1 Pwr Mgt=0 STA TPC Request PS Poll ACK Awake Awake Awake Peter Larsson, Ericsson Research, Sweden

March 2002 The Proposal Beacon Beacon AP Time Transmit Power indication Transmit Power indication STA Awake Awake Exploit 802.11 power save philosophy , i.e. wake up at TBTT, wait for beacon, do what is needed, then go back to sleep. Complement with transmit power indication in Beacon in addition to existing TPC frames Peter Larsson, Ericsson Research, Sweden

TPC UL/DL UL DL TPC Req./ Rep. Not useful TPC Beacon March 2002 TPC UL/DL N.B Commonly, not all STAs do TPC in one frame time UL DL Message complexity = O(N) Active and precise TPC Message complexity = O(N) Active and precise TPC Beacon ACK Beacon Beacon ACK Beacon TPC Rep ACK TPC Rep TPC Req ACK TPC Req TPC Req./ Rep. AP Time AP Time ACK ACK ACK TPC Req TPC Req TPC Rep ACK TPC Rep STA STA STA 1 STA 2 STA N STA 1 STA 2 STA N Message complexity = O(1) Passive TPC. Reduced power consumption. Not useful TPC Beacon Beacon Beacon AP Time STA STA 1,2,…N STA 1,2,…N Peter Larsson, Ericsson Research, Sweden

AP Centric Radar Detection March 2002 AP Centric Radar Detection 2 complementary mechanisms for radar detection. Medium silencing TPC in UL Regular TPC updates, in addition to on demand updates (i.e. TPC Req/Rep) will ease radar detection. Peter Larsson, Ericsson Research, Sweden

Proposed alternatives March 2002 Proposed alternatives Alternative 1. 8 bit IE payload containing transmit power indication. Alternative 2. 16 bit IE payload containing 8 bit transmit power indication and 8 bit estimated interference level Alternative 1+2=3. 8 bit IE payload containing two fields in alt 2 added together. See 02/069 p.9. N.B. this is compatible with alt 1. Peter Larsson, Ericsson Research, Sweden

March 2002 Conclusion It was suggested that beacons contain transmit power information. The beacon TP indication will complement the TPC request/ report method. The proposal provides: A 802.11 power management compatible TPC mechanism for UL. Improved medium efficiency for UL Improved means for radar detection. Peter Larsson, Ericsson Research, Sweden

March 2002 Two Ways Forward Consider the power save, UL complexity & radar detection issues in conjunction with TPC later in the LB process. Including TP level indication in the beacon may then be a recommended amendment. Consider this issue this meeting and amend necessary beacon IE format/text in the draft. Peter Larsson, Ericsson Research, Sweden