doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 1 Stream Classification Service Date: Authors:

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 2 Abstract This proposal fulfils two of the PAR objectives of the 11aa task group: 1.Graceful degradation of audio video streams when there is insufficient channel capacity, by enabling packet discarding without any requirement for deep packet inspection, 2.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 4 extra EDCA parameter sets to facilitate intra-access category prioritization and a method to subdivide AIFS. This proposal also creates a new service called the “stream classification service” that allows the establishment of streams with higher layer signaling of packet drop eligibility and allows classification of streams in to an access category.

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 3 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 Allow some packets in a flow to be tagged as drop eligible –Not all packets, as some packets are more important than others –In EDCA, EDCA-AC and HCCA modes Both of the above at the same time And in combination with 802.1AVB –Allows AVB flows to use these prioritisation features

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 4 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

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 5 Feedback from 802.1* Q: How many priority levels? A: There is a difference between number of supported priorities and the maximum number of priorities that can be signalled. There is not much point in having more than 8 priority signalling levels, as this is the number of priorities provided by The minimum number of supported priorities is two, so that AV traffic can be prioritised over best effort traffic. Q: How many drop precedence levels? A: Drop precedence is a planned for the next version of the AVB spec. You could reserve two stream IDs and use one for the lower priority (droppable) packets. You could reserve more stream IDs if you wanted more levels of drop priority. *See IEEE /0371r0 – TGaa minutes from Vancouver

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 6 Drop Eligibility indicator “The DEI subfield is 1 bit in length and is used by the STA to indicate that the corresponding MSDU, or fragment thereof, is eligible for discarding if there are insufficient resources at the destination STA” Placeholder text in QoS Control field clause until we know what other signalling bits 11aa requires. Two extra retry limits, to allow for less retries when DEI=1 –dot11ShortDEIRetryLimit, dot11LongDEIRetryLimit

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 7 Intra-Access Category prioritization “Intra-Access Category prioritization of transport streams by modifying EDCA timing and parameter selection” We cannot break current EDCA (WMM) timing and parameter selection. We cannot do intra-AC prioritization just using the 4 existing EDCA parameter records.

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 8 Alternate EDCA Parameter Set Up to four extra EDCA parameter records –AAC_BK, AAC_BE, AAC_VI, AAC_VO Signalled in beacon, probe response, (re)association response –Identical structure to existing EDCA (WMM) Parameter Set –Reserved octet in EDCA PS used to indicate presence of AAC_??

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 9 Alternate EDCA Parameter Set Table 9-1 – UP-to-AC mappings PriorityUP (Same as 802.1D user priority) 802.1D designation ACAlternate AC (if supported [1] ) [1] Designation (informative) Lowest1BKAC_BK Background 2-AC_BKAAC_BKBackground (alternate) 0BEAC_BE Best Effort 3EEAC_BEAAC_BEBest Effort (alternate) 4CLAC_VIAAC_VIVideo (alternate) 5VIAC_VI Video 6VOAC_VO Voice Highest7NCAC_VOAAC_VOVoice (alternate) [1] [1] Support for an alternate AC is defined as dot11RobustAVStreamingAlternateEDCAEnabled set to true and the appropriate Alternate AC_?? Present bit it is set in the Alternate Priority Info field of the Alternate EDCA Parameter Set element (see aa). User Priority -> AC mapping expanded to use these extra EDCA parameters, when supported

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 10 Fractional AIFS AIFS must be a multiple of slot time –but AIFSN for AC_VI is 2 and AC_BE is 3* –It would be useful if we could have an AIFSN of 2½ We can achieve a mean AIFSN of 2½ without breaking slot times –E.g. AIFSN = 2,3,2,3,2,3 AIFS[AC] = (AIFSN[AC] + (AIFSF[AC] & dot11QosTransmittedFrameCount [AC])) × aSlotTime + aSIFSTime * Default parameters for EDCA and WMM Reserved field in baseline & WMM

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 11 Intra-Access Priority IE Intra-Access Priority IE can be used in ADDTSPEC and QosMap Configure frames to signal use of drop eligibility and EDCA alternate priority –However, only defines one priority level per TID/UP –Stream Classification Service can be used to select packets within a TS

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 12 Stream Classification Service (SCS) An optional service implemented by an AP that allows a stream to be classified to a User Priority, EDCA AC and Drop Eligibility Uses existing TCLAS processing used by TS, FMS, DMS, TFS Each stream is assigned an ID (SCSID) by non-AP STA requesting classification –Used by AP in responding to request and by STA to modify/delete stream Using two SCSIDs (or TS + SCSID) allows a flow to be configured with selected frames drop eligible

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 13 Stream Classification Service (SCS) Overview STA advertises Stream Classification Service (SCS) Capability Non-AP STA sends a request to specify traffic classes for classification and the priority to assign to matching frames AP may accept or reject the traffic class specified by the non-AP STA If the service is accepted by the AP, –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. For MSDUs that are not part of a TS, 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 the EDCA Parameter Set for these MSDUs, if the MIB attribute dot11RobustAVStreamingAlternateEDCAEnabled is true. All matching MSDUs are tagged with their drop eligibility using the value from the Drop Eligibility subfield of the Intra-Access Priority element See doc 09/0726r0

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 14 Non-AP STA request SCS SMEMLME Non-AP STAAP MLMESME MLME-SCS.requestSCS Request FrameMLME-SCS.indication SCS Response FrameMLME-SCS.confirmMLME-SCS.response Process SCS Request SCS Frame Exchange Sequence

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 15 SCS Frame Exchange Sequence AP can terminate SCS at any time SCS Response FrameMLME-SCS.terminationMLME-SCS.termrequest SMEMLME Non-AP STAAP MLMESME AP decides to terminate SCS

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 16 TSPEC + SCS Intra-Access Priority IE can be used in ADD TSPEC request to signal UP, EDCA AC and DEI of the stream A subsequent SCS can be used to select some packets in the TS –E.g. to select packets for DEI=1 MLME-SCS.requestSCS Request FrameMLME-SCS.indication SCS Response Frame MLME-SCS.confirm MLME-SCS.response Process SCS Request

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 17 SCS Request and Response frames CategoryActionDialog TokenRequest Type (“Add”, “Change” or “Remove”) SCS Descriptor List Octets : 1111 variable SCSIDLengthIntra-Access Category Priority Element TCLAS Elements (optional) TCLAS Processing Element (optional) Octets : or 3variable0 or 3 SCS Descriptor CategoryActionDialog TokenSCS Status List Octets:1111 SCSIDSCS Status Octets : 1 1 SCS Status SCS Request frame: SCS Response frame:

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 18 Pure Example, no SCS AP UP & DEI passed via MAC-SAP interface AV stream The AP can use the UP value to choose EDCA AC and the DEI tagging to choose packets to discard if conditions deteriorate. AV stream

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 19 Mixed Wired/Wireless Example, SCS AP Source device L2/L3 tags UDP packets with priority and drop eligibility. Wired connection to AP. Request SCS Destination makes an SCS request to the AP to inform it that the stream has DEI and the method of tagging. AV stream When SCS active, the AP can use the DEI tagging to choose packets to discard if conditions deteriorate. AV stream

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 20 Mixed Wired/Wireless Example, Destination SCS AP Source device L2/L3 tags UDP packets with priority eligibility. Request SCS Destinations make SCS requests to the AP to select the UP of each AV stream. The UP used by each destination is a management (configuration) decision. AV stream 1 When SCS active, the AP can use the UP (and EDCA params) to provide intra-AC prioritization. AV stream 2 AV stream 1 Request SCS

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 21 Another Wireless Example, Source SCS AP Source device L2/L3 tags UDP packets with priority eligibility. Source makes SCS requests to the AP to select the UP of the AV streams Request SCS AV stream 1 When SCS active, the AP can use the UP (and EDCA params) to provide intra-AC prioritization. AV stream 2 AV stream 1

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 22 Conclusions This proposal to fulfils two of the PAR objectives of the 11aa task group: 1.Graceful degradation of audio video streams when there is insufficient channel capacity, by enabling packet discarding without any requirement for deep packet inspection, Drop Eligibility Indicator SCS to allow non-AP STA to configure DEI signaling from upper layers 2.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 4 extra EDCA parameter sets to facilitate intra-access category prioritization and a method to subdivide AIFS. AIFSF to provide finer grained medium access probability SCS to allow selection of UP and EDCA Parameter Set.

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 23 References 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”

doc.: IEEE /0725r0 Submission July 2009 Alex Ashley, NDS LtdSlide 24 Motion Move to incorporate the text changes in aa-stream-classification-service.doc into the TGaa draft Moved: Seconded: Result: