1. Alternate EDCA Parameter Set
July 2009
doc.: IEEE /0048r2
Jan 2010
Alternate EDCA Parameter Set
Date:
Authors:
Alex Ashley, NDS Ltd
Alex Ashley, NDS Ltd

2. July 2009
doc.: IEEE /0048r2
Jan 2010
Abstract
This proposal fulfils the PAR objective of the 11aa task group:
Intra-Access Category prioritization of transport streams by modifying EDCA timing and parameter selection without any requirement for deep packet inspection
This proposal allows the creation of up to 2 extra EDCA parameter sets to facilitate intra-access category prioritization.
Alex Ashley, NDS Ltd
Alex Ashley, NDS Ltd

3. Jan 2010
Use Cases
Prioritize all packets in a video stream above/below another video stream
In EDCA and EDCA-AC modes
The higher priority video has a greater chance of channel access
Alex Ashley, NDS Ltd

4. Jan 2010
Comments
“There should be extra ACs or some other solution, but not per frame parameter changing. The backoff is a post-backoff which comes after the frame, not before it. Parameter changing makes no sense.”
“How do the new AACs work? I see the two level queuing, so I'm expecting that there is a first round of internal contention say between AAC_VI and AC_VI … what parameters are used for over-the-air contention?”
How do I know if a STA implements the extra EDCA timing parameters?
Don’t we need to specify the scheduler for consistent performance?
Alex Ashley, NDS Ltd

5. Changes from r0 proposal
Jan 2010
Changes from r0 proposal
Shorter Alternate EDCA Parameter Set
AAC_BE and AAC_BK removed. AAC_VI / AAC_VO only included in element when supported
Removed need for extra EDCAF
Makes it possible to implement on existing h/w
Removed requirement to use CL for AAC_VI
Controlled Load (CL) has defined meaning in enterprise networks
Added default EDCA parameters for AAC_VI and AAC_VO
Same as AC_VI and AC_VO (to allow for implementation on existing h/w that can’t support extra EDCA timing parameters)
Alex Ashley, NDS Ltd

6. Changes from r2 proposal
Jan 2010
Changes from r2 proposal
Reduced down to 2 options:
6 queues -> 4 EDCAF, using existing EDCA timing
6 queues -> 6 EDCAF, using existing + alternate param set
dot11RobustAVStreamingAlternateEDCAFEnabled MIB variable if 6 EDCAF supported & enabled
“Alternate EDCAF” extended capabilities bit for STAs to signal support
Alex Ashley, NDS Ltd

7. Capability Signalling
Jan 2010
Capability Signalling
Two bits in Extended Capabilities information element to signal enhanced EDCA capabilities.
Table 7-35a—Capabilities field
Bit(s)
Information
Notes
<ANA>
Alternate EDCA
The STA sets the Alternate EDCA field to 1 when the MIB attribute dot11RobustAVStreamingAlternateEDCAEnabled is set to true, and sets it to 0 otherwise. See (HCF contention-based channel access)
Alternate EDCAF
The STA sets the Alternate EDCAF field to 1 when the MIB attribute dot11RobustAVStreamingAlternateEDCAFEnabled is set to true, and sets it to 0 otherwise. See (HCF contention-based channel access)
Alex Ashley, NDS Ltd

8. Alternate EDCA Parameter Set
Jan 2010
Alternate EDCA Parameter Set
Up to two extra EDCA parameter records
AAC_VI, AAC_VO
Signalled in beacon, probe response, (re)association response
Similar structure to EDCA (WMM) Parameter Set
Alternate Priority Info field used to indicate presence of AAC VI/VO
Alex Ashley, NDS Ltd

9. Jan 2010
Alternate EDCA Parameter Set (dot11RobustAVStreamingAlternateEDCAFEnabled false)
User Priority -> AC mapping expanded to use these extra queues, when supported
Frames are still sent using existing four EDCAF
Extra ACs map to existing EDCAF for transmission
Uses existing EDCA Parameter Set timing
Alex Ashley, NDS Ltd

10. Jan 2010
Alternate EDCA Parameter Set (dot11RobustAVStreamingAlternateEDCAFEnabled true)
Frames are sent using six EDCAF
User Priority -> AC mapping expanded to use these extra EDCA queues and EDCAF
Allows use of Alternate EDCA Parameter Set timing
Table 9-1aa – UP-to-AC mappings (dot11RobustAVStreamingAlternateEDCAFEnabled true)
Priority
UP (Same as 802.1D user priority)
802.1D designation AC
Alternate AC
EDCAF
Designation (informative)
Lowest 1 BK
AC_BK
Background 2 - BE
AC_BE
Best Effort 3 EE
AAC_VI
AVI
Video (alternate) 4 CL
AC_VI 5 VI
Video 6 VO
AC_VO
Voice
Highest 7 NC
Alex Ashley, NDS Ltd

11. Frames sent using existing four EDCAF
Jan 2010
Frames sent using existing four EDCAF VO VI BE BK
Mapping to
Access Category
Transmit queues
for ACs
EDCA functions with internal collision resolution
(MSDU, UP)
AC_BK
AC_BE
AC_VI
AAC_VI
AC_VO
AAC_VO
Scheduler gives higher priority to MSDU from the highest UP
Standard EDCA timing used for transmission
Figure 9-17—Reference implementation model
Alex Ashley, NDS Ltd

12. Frames sent using six EDCAF
July 2009
doc.: IEEE /0048r2
Jan 2010
Frames sent using six EDCAF
AVO
AVI BE BK
Mapping to
Access Category
Transmit queues
for ACs
EDCA functions with internal collision resolution
(MSDU, UP)
AC_BK
AC_BE
AC_VI
AAC_VI
AC_VO
AAC_VO VO VI
Figure 9-17aa—Reference implementation model
Alex Ashley, NDS Ltd
Alex Ashley, NDS Ltd

13. Stream Classification Service Interaction
July 2009
Month Year
doc.: IEEE yy/xxxxr0
doc.: IEEE /0048r2
Jan 2010
Stream Classification Service Interaction
The Intra-Access Category Priority element can be used to select use of the alternate EDCA parameter set for a classified stream
Removes need to always use table 9-1 mapping
For an accepted SCS,
the AP shall process subsequent unicast MSDUs that match the classifier specified in the SCS Descriptor. The processing of matching MSDUs depends upon the access policy assigned to the MSDU:
For MSDUs that are not part of a TS, the User Priority subfield of the Intra-Access Priority element is used as the UP of these MSDUs.
If dot11RobustAVStreamingAlternateEDCAFEnabled is true, matching MSDUs that are not part of a TS (as described in 11.4), or MSDUs that are part of a TS that uses EDCA or HEMM as the Access Policy, the Alternate Priority subfield of the Intra-Access Priority element is used to select whether the EDCA Parameter Set or Alternate EDCA Parameter Set is used for these MSDUs.
All matching MSDUs are tagged with their drop eligibility using the value from the Drop Eligibility subfield of the Intra-Access Priority element
Slide 13
Alex Ashley, NDS Ltd
Page 13
Alex Ashley, NDS Ltd
John Doe, Some Company

14. July 2009
doc.: IEEE /0048r2
Jan 2010
Conclusions
This proposal fulfils the PAR objective of the 11aa task group:
Intra-Access Category prioritization of transport streams by modifying EDCA timing and parameter selection without any requirement for deep packet inspection
Creation of up to two extra EDCA parameter sets to facilitate intra-access category prioritization
This proposal scales from existing h/w that just add prioritized queuing in front of existing EDCA, to implementations providing full per-AC queuing and timing
Alex Ashley, NDS Ltd
Alex Ashley, NDS Ltd

15. “The art of a good compromise is to upset everyone.”
Jan 2010
Conclusions
“The art of a good compromise is to upset everyone.”
My work is done.
Alex Ashley, NDS Ltd

16. July 2009
doc.: IEEE /0048r2
Jan 2010
Motion
Move to incorporate the text changes in aa-alternate-edca-parameter-set.doc into the TGaa draft
Moved:
Seconded:
Result:
Alex Ashley, NDS Ltd
Alex Ashley, NDS Ltd

17. References 11-09-0850r3 “Alternate EDCA Parameter Set”
Jan 2010
References
r3 “Alternate EDCA Parameter Set”
r0 “Stream Classification Service”
11-09/0022r0 “Implementation for Intra-AC Differentiated Services”
11-08/0764r1 “Using packet drop precedence for graceful degradation”
11-09/0264r0 “Drop Precedence in wireless, wired-wireless networks”
11-09/0371r0 “TGaa minutes for Vancouver”
Alex Ashley, NDS Ltd

18. History Implementation for Intra-AC Differentiated Services
Jan 2010
History
Implementation for Intra-AC Differentiated Services
IEEE /0022r0
Using packet drop precedence for graceful degradation
IEEE /0764r1
Drop Precedence in wireless, wired-wireless networks
IEEE /0264r0
Thursday March 12 TGaa AVB meeting
IEEE /0371r0
Stream Classification Service
IEEE /0725r0
Alex Ashley, NDS Ltd