1. Multi Level Power Control
Multi Level Power Control
Date:
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Floyd Backes, AutoCell Laboratories, Inc.

2.
Abstract
Abstract
This presentation summarizes a submission on multi-level power control, v-multi-level-power-control.
Floyd Backes, AutoCell Laboratories, Inc.

3. Presentation Overview
Presentation Overview
Review of Transmit Power Control
AP Power Control
STA Power Control
Simulation Explanation
Simulation Results
Multi Level Power Control
Overview of Contribution
Floyd Backes, AutoCell Laboratories, Inc.

4. Transmit Power Control
Transmit Power Control
Unlike TPC for regulatory purposes, this submission is intended to allow for increased performance
A variety of algorithms for performance based TPC exist
This submission does not specify an algorithm
Floyd Backes, AutoCell Laboratories, Inc.

5. Simple Example 2007-5-15 AP 1 AP 2 Non-AP 1 Non-AP 2
Floyd Backes, AutoCell Laboratories, Inc.

6.
Simple Example
Transmissions from AP2 interfere with Non-AP 1
AP 1
AP 2
Non-AP 1
Non-AP 2
TPC Reduces Interference
Floyd Backes, AutoCell Laboratories, Inc.

7. What About the non-AP STAs?
What About the non-AP STAs?
AP 1
AP 2
Non-AP 1
Non-AP 2
Non-AP 1 still interferes with AP2
Non-AP STA TPC can additionally reduce interference
Floyd Backes, AutoCell Laboratories, Inc.

8. Simulation Results Bear This Out
Simulation Results Bear This Out
Custom network simulation tool used to investigate performance impact of TPC
No TPC
AP only TPC
AP + non_AP TPC
4 runs for each combination
b/g environment
8 Detached Homes
2 Video streams (3.5 Mbps) in each homes
Floyd Backes, AutoCell Laboratories, Inc.

9.
Physical Layout
Floyd Backes, AutoCell Laboratories, Inc.

10. Network Configuration
Network Configuration
Floyd Backes, AutoCell Laboratories, Inc.

11.
Traffic
Floyd Backes, AutoCell Laboratories, Inc.

12. Simulation Results 2007-5-15 Percent PDU Error Rate
Floyd Backes, AutoCell Laboratories, Inc.

13. Other Considerations Clearly, TPC can improve performance
Other Considerations
Clearly, TPC can improve performance
There can be a down side…
Floyd Backes, AutoCell Laboratories, Inc.

14. Previous Example 2007-5-15 AP 2 coverage before TP reduction
New station now appears in what is now a coverage hole
AP 1
AP 2
Non-AP 1
Non-AP 2
Floyd Backes, AutoCell Laboratories, Inc.

15. Eliminating TPC induced Coverage Holes
Eliminating TPC induced Coverage Holes
If TP of both data and management frames from an AP are reduced, a non-AP STA within “range” of that AP may not hear its Beacons
Multi Level Power Control allows Management frames to be transmitted at a higher TP than data
Floyd Backes, AutoCell Laboratories, Inc.

16. Previous Example 2007-5-15 Range of Beacons Range of Beacons
Newly arrived Non-AP STA
Can hear AP2’s beacons
AP 1
AP 2
Non-AP 1
Non-AP 2
Floyd Backes, AutoCell Laboratories, Inc.

17. Summary of Submission Provides:
Summary of Submission
Provides:
The ability to signal control of the transmit power of data frames independently of management frames coming from non-AP STAs
The ability to control all of the STAs in a BSS simultaneously, or on a per-STA basis.
The ability to signal the management power setting before joining a BSS
Signal the management power setting immediately upon joining a BSS
The ability for a non-AP STA to signal whether or not it can adopt the transmit power limit and if not, what its limit is.
Floyd Backes, AutoCell Laboratories, Inc.

18. What this is not Dynamic TPC
What this is not
Dynamic TPC
This submission does not specify a power control algorithm
May be used even when transmit power is adjusted manually
Floyd Backes, AutoCell Laboratories, Inc.

19. Rationale Adjustment of Transmit Power common in 802.11 deployments
Rationale
Adjustment of Transmit Power common in deployments
Spatial reuse enhancements in dense deployments
Enhanced privacy
Power savings
Redundancy
Transmit Power may be adjusted as a result of:
Manual planning
Assisted site surveys
Automatic power adjustment algorithms
Floyd Backes, AutoCell Laboratories, Inc.

20. Approach Create new IE for “Relative Power Limit Request”
Approach
Create new IE for “Relative Power Limit Request”
Represents a reduction in power limit (relative to country and local power constraint), in dB
Not possible to extend existing power constraint IE
Relative Power Limit Request IE to be carried in
Beacons
Association Responses
Reassociation Responses
Probe Responses
Relative Power Limit Request frame
Floyd Backes, AutoCell Laboratories, Inc.

21. Approach (continued) Create new IE for “Relative Power Limit Response”
Approach (continued)
Create new IE for “Relative Power Limit Response”
Represents the power limit actually in use
A “Status”, one of:
Accept
Reject (requested relative power limit out of bounds due to HW limitations, regulatory limitations, or management configured limitations)
If “Reject”, what maximum relative power limit can be supported
Relative Power Limit Response IE to be carried in:
Relative Power Limit Response frame
Floyd Backes, AutoCell Laboratories, Inc.

22. Approach (continued) 2007-5-15
New Wireless Network Management Action frame for “Relative Power Limit Request”
New action field value for “Relative Power Limit Request”
Carries the Relative Power Limit IE
May be broadcast or unicast
A directed Transmit Power Limit frame overrides any value carried in a Management frame
If the non-AP STA cannot support the requested Relative Power Limit, it responds with the actual value that can be supported using the Relative Power Limit Response element.
STA must use the lower of:
the maximum transmit power level specified for the channel in the Country element minus the relative power limit specified for the current channel (from the MIB) in the Relative Power Limit Request element
the maximum transmit power level specified for the channel in the Country element minus the local power constraint specified for the channel (from the MIB) in the Power Constraint element.
Floyd Backes, AutoCell Laboratories, Inc.

23. Summary of Submission 2007-5-15
New Wireless Network Action frame “Relative Power Limit Request“
Carries Relative Power Limit Request IE
New Wireless Network Action frame for “Relative Power Limit Response“
Carries Relative Power Limit Response IE
May be sent in response to a
Relative Power Limit request frame
Association Response
Reassociation Response
Define Relative Power Limit Request and Relative Power Limit Response IEs.
Add relative Power Limit Request IE to:
Beacon Frame Body
Association Response Frame
Reassociation Response Frame
Probe Response Frame
Floyd Backes, AutoCell Laboratories, Inc.

24. Summary of Submission (continued)
Summary of Submission (continued)
Added Relative Power Limit to the BSS Description table in MLME-SCAN.confirm
Added Relative Power Limit Request to the parameter Lists of:
MLME-ASSOCIATE.confirm
MLME-ASSOCIATE.response
MLME-REASSOCIATE.confirm
MLME-REASSOCIATE.response
Floyd Backes, AutoCell Laboratories, Inc.

25.
Summary of Submission
Define Relative Power Limit Request Protocol Exchange
Define primitives:
MLME-POWERLTREQUEST.request
MLME-POWERLTREQUEST.confirm
MLME-POWERLTREQUEST.indication
MLME-POWERLTRESPONSE.request
MLME-POWERLTRESPONSE.confirm
MLME-POWERLTRESPONSE.indication
Define Relative Power Limit Request and Response Procedure
Floyd Backes, AutoCell Laboratories, Inc.

26. Motion Move to include the substantive text in document
Motion
Move to include the substantive text in document
11-07/0465r0 into the TGv draft.
Moved:
Seconded:
Floyd Backes, AutoCell Laboratories, Inc.