November 2016doc.: IEEE 802.11-16/1532r1

IEEE P802.11
Wireless LANs

Service Hash Response ANQP-element
Date: 2016-11-15
Author(s):
Name / Company / Address / Phone / email
Stephen McCann / BlackBerry Ltd / 200 Bath Road, Slough, Berkshire, SL1 3XE, UK / +44 1753 667099 /
9.4.5AccessNetworkQueryProtocol(ANQP)elements

9.4.5.1General

Insertnewrowsasfollowstotheendofthetable,withcorrespondingadjustmentto“Reserved”value:

Table9-271—ANQP-elementdefinitions

ANQP-elementname / InfoID / ANQP-element(subclause)
ServiceHashRequest / 288 / 9.4.5.27 (Service HashRequestANQP-element)
ServiceInformationRequest / 289 / 9.4.5.28 (Service Infor-mationRequest ANQP-element)
ServiceInformationResponse / 290 / 9.4.5.29 (Service Infor-mation Response ANQP-element)
Service Hash Response / 291 / 9.4.5.30 (Service Hash Response ANQP-element)

Insertthe newsubclauseasfollows:

9.4.5.29 ServiceInformationResponseANQP-element

TheServiceInformationResponseANQP-elementcontainsthedetailedserviceinformationinresponsetoaServiceHashRequestoraServiceInformationRequestANQP-element.

TheformatoftheServiceInformationResponseANQP-elementisshowninFigure9-625j(ServiceInfor-mationResponseANQP-elementformat).

Info ID / Length / Service Information Response Tuples

Octets:22variable

Figure9-625j—ServiceInformationResponseANQP-elementformat

TheInfoIDandLengthfieldsaredefinedin9.4.5.1(General).

TheServiceInformationResponseTuplesfieldcontainsoneormoreServiceInformationResponseTuplesubfields.

TheformatoftheServiceInformationResponseTuplesubfieldisshowninFigure9-625k(ServiceInforma-tionResponseTuplesubfieldformat).

ServiceNameLength / ServiceName / InstanceNameLength / InstanceName / ServiceInfor-mation QueryResponseLength / Service Informa-tion QueryResponse

Octets:1variable1variable2variable

Figure9-625k—ServiceInformationResponseTuplesubfieldformat

The Service Name Length subfield and the Service Name subfield are defined in 9.4.5.28 (Service Information Request ANQP-element).

The Instance Name Length subfield and the Instance Name subfield are defined in 9.4.5.28 (Service Information Request ANQP-element). The Instance Name Length subfield contains a nonzero value.

TheServiceInformationQueryResponseLengthsubfieldisthelengthoftheServiceInformationQueryResponsesubfield.IftheServiceInformationQueryResponseLengthsubfieldisequalto0,theServiceInformationQueryResponsesubfieldisnotincluded. When this subfield is included in the Service Hash Response ANQP-element it is set to 0 (also in the behaviour section below)

TheServiceInformationQueryResponsesubfieldisavariablelengthfield.ThecontentoftheServiceInformationQueryResponsesubfieldisservice-specificbasedontherequestedserviceinformationandisspecifiedin11.25a.3(SolicitedPADprocedure).

Insert new subclause as follows:

9.4.5.30 Service Hash Response ANQP-element

The Service Hash Response ANQP-element contains the detailed service information in response to a Service Hash Request ANQP-element.

The format of the Service Hash Response ANQP-element is shown in Figure 9-625xx (Service Hash Response ANQP-element format).

Info ID / Length / Service Information Response Tuples

Octets:22variable

Figure 9-625xx—Service Hash Response ANQP-element format

The Info ID and Length fields are defined in 9.4.5.1 (General).

The Service Information Response Tuples field is defined in 9.4.5.29 (Service Information Response ANQP-element)

11. MLME

11.25WLANinterworkingwithexternalnetworksprocedures
11.25.3Interworkingprocedures:genericadvertisementservice(GAS)

11.25.3.2ANQPprocedures11.25.3.2.1General

Insertnewrowstotableasfollows:

Table11-15—ANQPusage

BSS / IBSS
ANQP-elementname / ANQP-element(subclause) / ANQP-
element type / AP / Non-APSTA / STA
ServiceHash Request / 9.4.5.27
(ServiceHashRequest ANQP- element) / Q / R / T / —
Service InformationRequest / 9.4.5.28
(ServiceInformationRequest ANQP- element) / Q / R / T / —
Service InformationResponse / 9.4.5.29
(ServiceInformationResponse ANQP-element) / S / T / R / —
Service Hash Response / 9.4.5.30
(Service Hash Request ANQP- element) / S / T / R / —
11.25a.3SolicitedPADprocedure

Whendot11SolicitedPADActivatedistrue,anon-APandnon-PCPSTAmaytransmittoanAPorPCPaServiceHashRequestANQP-element.Thiselementincludesoneormoreservicehashesgeneratedfromtheservicename(s)ofthe service(s) that thenon-APandnon-PCPSTA issearching, as wellasvalid combina-tions of services of interest. AnAPorPCPmightadvertise support for the Solicited PADprocedureby set-tingtheSolicitedPADfieldoftheExtendedCapabilitieselementto1initsBeaconandProbeResponseframes.

Whendot11SolicitedPADActivatedistrue,anAPorPCPshallusetheinformationfromtheServiceHashRequestANQP-element(thatitreceivesfromanon-APandnon-PCPSTA)todetermineifitcanprovidetherequestedservice(s)orcombinationofservices.DeterminationisbasedontheservicehashvaluesintheService Hashes field ofthe receivedService Hash RequestANQP-element, andvalidservicecombinationsspecified through theFlagsand ServiceCombinationfieldsofthe Service Hash RequestANQP-element.IftheAPorPCPdeterminesthatitcanprovidetherequestedservice(s)orcombinationofservices,itshallrespondbytransmittingaServiceHashInformationResponseANQP-elementthatcontainsaServiceHashInformation ResponseTuplesubfieldforeachservicethatsatisfiestherequest.

NOTE—Forexample,anAPorPCPthatreceivesaServiceHashRequestANQP-elementframethatincludeshashval-uesfor4servicesS1,S2,S3andS4(inthatorder)andavalueof0xFEEEinitsServiceCombinationfield,respondstotherequestifandonlyifitcanprovideserviceS1orserviceS2orbothservicesS3andS4.TheServiceHash Information ResponseANQP-elementcancontainServiceHashInformationResponseTuplesubfieldsforanysetofavailableservicesthat satisfytheANQPrequest,e.g., S1,S3and S4.

Therequestingnon-APSTAshallprocesstheServiceHash Information ResponseANQP-elementinthereceivedANQPresponsetoselectaservicecombinationthatsatisfiesthenon-APandnon-PCPSTArequest.

Ifthereisamatchingservicename,thenon-APandnon-PCPSTAmightdecidetoproceedwiththeserviceinformationprocedure(see11.25.3.2.16(Serviceinformationprocedure)orauthenticationandassociationprocedure(see11.3(STAauthenticationandassociation))dependingonthenatureoftheservice(seeexam-plesillustratedinW.1(Pre-associationdiscoveryusagescenarios)).

B.4.30Pre-associationdiscoveryextensions

Item / Protocol Capability / References / Status / Support
PAD1 / Service Hint element / 9.4.2.217 (Service Hintelement) / CF33:M / YesNo N/A
PAD2 / Service Hash element / 9.4.2.218 (Service Hashelement) / CF33:M / YesNo N/A
PAD3 / ServiceHash Request ANQP-element / 9.4.5.27 (Service HashRequest ANQP-element) / (IW2.2.2ANDCF33):M / YesNo N/A
PAD4 / Service Information RequestANQP-element / 9.4.5.28 (ServiceInformation RequestANQP-element) / (IW2.2.2ANDCF33):M / YesNo N/A
PAD5 / Service Information ResponseANQP-element / 9.4.5.29 (ServiceInformation ResponseANQP-element) / (IW2.2.2ANDCF33):M / YesNo N/A
PAD4 / Service Hash Response ANQP- element / 9.4.5.30 (Service Hash Response ANQP- element) / (IW2.2.2 AND CF33):M / Yes No N/A 
PAD76 / UnsolicitedPADprocedure / 11.25a.2 (UnsolicitedPAD procedure) / CF33:M / YesNo N/A
PAD87 / Solicited PAD procedure / 11.25a.3 (SolicitedPADprocedure) / (IW2.2.2ANDCF33):M / YesNo N/A

AnnexW

(informative)

4.5.9BackgroundSearch

Applicationsthatruninthebackground(e.g.,automaticallyreceivingsalescouponsthatauserhasprevi-ouslysignedupfor)mightnotrequireimmediatediscoveryresultstobepresentedtotheuser.Itmaybeappropriatetopreventnon-APSTAs,runningsuchbackgroundapplications,fromperformingasolicitedPADsearch.Furthermore,asolicitedPADsearchinadenseWLANenvironmentcancausenetworkcon-gestion.Inthatcase,itismoreeffectivetoperformanunsolicitedPADsearch,inwhichanAPorPCPadvertisesmultiple services known to the SIR,while non-AP STAs need respond only if thereis a matchedservice.

TheAPorPCPcanelecttoadvertiseseveralservicesusingtheServiceHashelement,andadvertiseremain-ingservicesusingtheServiceHintelement,intheBeaconorDMGBeacon.Alternatively,theAPorPCPcanelecttoadvertisealloftheservicesusingeithertheServiceHashorServiceHintelementintheBeaconorDMGBeacon.UponreceivingaBeaconorDMGBeacon,anon-APSTAprocessestheServiceHashandServiceHintelementstoverifyifthereareanypotentialmatchingservices.FigureW-1(Exampleofaframeexchangeforbackgroundsearchwithhighprobabilityoffalsepositive)andFigureW-2(Exampleofaframeexchangeforbackgroundsearchwithlowprobabilityoffalsepositive)showtwocaseswherethereisamatchingServiceHint.

IftheprobabilityoffalsepositivesasindicatedintheFalsePositiveProbabilityRangefieldoftheServiceHintelementisconsideredrelativelyhighbythenon-APSTA(seeFigureW-1(Exampleofaframeexchange for backgroundsearchwithhighprobabilityof falsepositive)),thenon-APSTAcan sendaSer-vice Hash Request ANQP-element to confirm if theservice isreachablethrough the APor PCP.The APorPCPthenrespondswithaServiceHashInformationResponseANQP-elementwithServiceHashInformationResponseTuplesubfieldsthatcontainthecorrespondingServiceNameandInstanceNamefields.

Thenon-APSTAcanthensendaServiceInformationRequestANQP-elementcontainingtheServiceName,InstanceNameandspecificServiceInformationQuerytoobtainmoreinformationabouttheservicefromtheAPorPCP.TheAPorPCPrespondstotheANQPrequestwiththeANQPresponsewithServiceInformationResponseANQP-elementcontainingtheServiceName,InstanceNameandspecificService

Submissionpage 1Stephen McCann, BlackBerry

November 2016doc.: IEEE 802.11-16/1532r1

InformationQueryResponsefields.AftertheANQPrequestandANQPresponseexchange,thenon-APSTAcanobtainmoreinformationonavailableservicesafteritassociatestotheAPorPCP.

FigureW-1—Exampleofaframeexchangeforbackgroundsearchwithhighprobabilityoffalsepositive

IftheprobabilityoffalsepositiveasindicatedinFalsePositiveProbabilityRangefieldoftheServiceHintelementisconsideredrelativelylowbythenon-APSTA(seeFigureW-2(Exampleofaframeexchangeforbackgroundsearchwithlowprobabilityoffalsepositive)),thenon-APSTAcandirectlysendaServiceInformationQueryRequestANQP-elementcontainingaServiceNameandaSpecificServiceInformationQueryRequestfield toobtainmoreinformationabouttheservicefromtheAPorPCP.

FigureW-2—Exampleofaframeexchangeforbackgroundsearchwithlowprobabilityoffalsepositive

TheAPorPCPrespondstotheANQPrequestwithaServiceInformationResponseANQP-elementcon-tainingtheservicenameandinstancename.AftertheANQPrequestandANQPresponseexchange,thenon-APSTAcanobtaininformationonavailableservicesafterassociatingtotheAPorPCP.

Submissionpage 1Stephen McCann, BlackBerry

November 2016doc.: IEEE 802.11-16/1532r1

In ascenario wherethereis amatchingservicehash,thenon-APSTAcandirectly sendaServiceInforma-tionRequestANQP-elementcontainingtheservicenameandaspecificServiceInformationQueryRequesttoobtainmoreinformationabouttheservicefromtheAPorPCPasshowninFigureW-3(ExampleofframeexchangeforbackgroundsearchwithmatchingServiceHashelement).

TheAPorPCPrespondstotheANQPrequestwithaServiceInformationResponseANQP-elementcon-tainingtheservicename,instancenameandspecificServiceInformationQueryResponse.AftertheANQPrequestandANQPresponseexchange,thenon-APSTAcanmakeaninformeddecisionaboutchoosingtoassociatetotheAPorPCP.

Alternatively,thenon-APSTAmightchoosetoassociatebasedonthematchingServiceHashelement.

FigureW-3—ExampleofframeexchangeforbackgroundsearchwithmatchingServiceHashelement

4.5.10ImmediateSearch

Applicationsthatareinitiatedbyusers(e.g.,auserislookingforafastmoviedownloadservice)requireimmediatediscoveryresultstobepresentedtotheuser.Inthisscenario,anon-APSTAperformsasolicitedPAD procedure,wherebythenon-APSTAsendsaServiceHashRequestANQP-elementtoqueryspecificservicesimmediatelyafteruserinitiationoftheservice/application.TheAPorPCPrespondswithaServiceInformationResponseANQP-elementaccordinglyifthereisamatchedservice(seeFigureW-4(Exampleofframeexchangeforimmediatesearch)).TheServiceHashRequestANQP-elementcontainsaservicehashoftherequestedservice.TheAPorPCPrespondswithaServiceHashInformationResponseANQP-ele-mentwithaServiceHashInformationResponseTuplesubfieldcontainingthecorrespondingservicenameandinstancename.Thenon-APSTAthenmightperformaserviceinformationANQPrequestandANQPresponseexchangewiththeAPorPCP,asshowninFigureW-4(Exampleofframeexchangeforimmediate

Submissionpage 1Stephen McCann, BlackBerry

July 2016doc.: IEEE 802.11-16/1008r1

search),toobtainmoreinformationabouttheservice.AftertheANQPrequestandANQPresponseexchange,thenon-APSTAcanmakeaninformeddecisionaboutchoosingtoassociatetotheAPorPCP.

FigureW-4—Exampleofframeexchangeforimmediatesearch

Submissionpage 1Stephen McCann, BlackBerry