Enhancing Bluetooth Location Services with

Direction Finding

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table of contents1.0 Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.0 Bluetooth Location Services . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.1 Bluetooth Proximity Solutions 5 a. Point of Interest Information Solutions 5 b. Item Finding Solutions 6

3.2 Bluetooth Positioning Systems 6 a. Real-time Locating Systems 6 b. Indoor Positioning Systems 7

4.0 Bluetooth Direction Finding. . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.1 Direction Finding Using Angle of Arrival Method 9

4.2 Direction Finding Using Angle of Departure Method 10

4.3 BluetoothProfileswithDirectionFinding 10

4.4 Enhancing Bluetooth Location Services Solutions Using Direction Finding 11

5.0 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Executive SummaryThe market opportunity for Bluetooth® locationserviceshasgrownrapidlyoverthelastfewyears,withindustryforecastsnowpredictingover400millionproductsinthissolutionareashippingperyear by 2022¹.

Today,Bluetoothpointofinterest(PoI)informationsolutions are enhancing the visitor experience withinmuseumsandretailstoresaroundtheworld.MillionsofpeoplerelyonBluetoothitemfindingsolutionstotrackdownlostkeysandother personal items. Bluetooth indoor positioning systems(IPS)arehelpingmillionsoftravelersnavigate through busy airports and shoppers throughmalls.Andwarehousesandfacilitiesaround the globe are using Bluetooth real-timelocatingsystems(RTLS)tobettermanageresourcesandoptimizetheflowofmaterials.

Despitethistremendoussuccess,theBluetoothcommunity does not remain idle and continually seeks to enhance the technology. The community recentlyaddedadirectionfindingfeaturethathasthepotentialtosignificantlyenhancetheperformance of Bluetooth location services solutions.

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1 Source: ABI Research.

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Introduction One key reason for the incredible success of Bluetooth is its unique approach to market. With Bluetooth,developersgetmorethanjustaradiotechnology,theygetcomplete,full-stack,globallyinteroperablesolutionsthataddressvariouswirelessconnectivityneeds.

Bluetoothdoesnotseektobethebestsolutionforallwirelessconnectivityneeds,butifyouareadeveloperbuildingasolutionthatneedstostreamaudiobetweentwodevices,asolutionthatneedstotransferdatabetweentwodevices,alocationservicessolution,orasolutionwhereyouneedtohavetens,hundreds,oreventhousandsofdevicescommunicatingwitheachotherinasecure,reliablemeshnetwork,thenBluetoothstrivestobethebesttechnologyavailable.Thisfocusondeliveringcomplete,globallyinteroperablesolutionsforspecificsolutionareashasplayedasignificantroleinestablishingBluetoothasthetechnologyofchoiceformanydevelopercommunities.AndtheBluetoothcommunityiscontinuallyworkingtoenhancethetechnologytobetter meet developer needs in these various solution areas.

The introduction ofBluetoothLowEnergy in 2010 gave developers the ability to start leveraging Bluetooth to createpowerful,low-costreal-timelocatingsystems,indoor positioning systems,itemfindingsolutions,point of interest (PoI)informationsolutions,andmore.Injustafewyears,location

serviceshasbecomeoneofthefastestgrowingsolutionareasforBluetooth,anditisexpectedthatover400millionBluetoothdevicessupportinglocationservicessolutionswillbeshippingperyearby2022.

point-to-point point-to-point broadcast mesh

locationservices

devicenetworks

datatransfer

audiostreaming

solu

tion

topo

logy

Bluetooth BR/EDR Bluetooth Low Energy

radi

o

Bluetooth Location ServicesUntilnow,allstandardBluetoothlocationservicessolutionshavebeendevelopedusingthesamebasicbuildingblock.TheyleveragetheBluetoothLowEnergyradiotodetermineiftwoBluetoothdevicesareinrangeofeachotherand,inmanycases,usereceivedsignalstrength(RSSI)measurementstoestimatethedistancebetweenthetwodevices.ThatbasicabilitytodeterminewhetheranotherdeviceisnearbyandapproximatelyhowcloseasledtothecreationofanumberofcompellingBluetoothlocationservicessolutions.Thesesolutionsgenerallyfallintotwocategories:proximity solutions and positioning systems.

Bluetooth Proximity SolutionsProximitysolutionsarethesimplerofthetwocategories and leverage Bluetooth to determine thelocationoftwodevicesrelativetoeachother.OneBluetoothdevice,generallyasmartphone,isusedtodetermineifanotherBluetoothdeviceiswithinrangeand,inmanycases,approximatelyhowfaraway.Pointofinterestinformationanditemfindingaretwoofthe most popular Bluetooth proximity solutions.

PoI Information Solutions

Point of interest information solutions wereoneofthefirstBluetoothlocation

services to come to market. In a PoIinformationsolution,small,

battery-poweredBluetooth

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Bluetooth Location Services

proximity solutions

item finding solutions(e.g. personal property tags)

point of interest information solutions

(e.g. proximity marketing)

positioning systems

real time locatingsystems (RTLS)(e.g. asset tracking)

indoor positioningsystems (IPS)(e.g. wayfinding)

Many museums support smartphone apps that provide visitors with additional information about nearby exhibits.

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transmitters,oftenreferredtoasbeacons,are deployed throughout facilities to improve the visitor experience. Beacons deployed inmuseumscanprovidevisitorswithmoreinformationaboutexhibitswhilebeaconsinretailestablishments can provide nearby shoppers withadditionalproductinformation.Inthesesolutions,thevisitortypicallydownloadsanapplication to their smartphone that enables the Bluetooth radio in their phone to listen for nearby beacons and then presents more information to the user based on the beacon or beacons it hears.

Item Finding Solutions

Itemfindingsolutionshavebeenexperiencingtremendousgrowthoverthelastfewyears.Thesesolutionsinvolvesmall,battery-poweredBluetoothdevices,oftenreferredtoaspersonalpropertytags,thatcanbeattachedtomovableobjectslikeasetofkeysorawallet.TheyalsoincludeanapplicationthatenablestheBluetoothradioinsmartphonestolistenforandestimatethedistanceofspecifictags.

Bluetooth Positioning SystemsPositioning systems use Bluetooth to determine the physical location of devices and involve more sophisticatedinfrastructuredeployments.Real-timelocatingsystems(RTLS)andindoorpositioningsystems(IPS)aretwoofthemostpopulartypesofBluetoothpositioningsystems.

Real-time Locating Systems

Bluetooth RTLS solutions are used for both asset trackingaswellaspeopletracking.Forexample,these solutions can locate and track the position ofpallets,forklifts,andworkersinawarehouse,or ultrasound machines and patients in a

hospital,helpingtoensuresafetyandoptimize response time in an emergency.

Bluetooth RTLS solutions are based on the deployment of Bluetooth

receivers,oftenreferredtoas

Item finding solutions help consumers locate misplaced items. So long as the item is connected to a Bluetooth tag, an app on their smartphone will let them know if the item is nearby and approximately how close.

Using a Bluetooth RTLS solution, key resources in a warehouse, like pallets, forklifts and workers, can be easily located and tracked.

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locators,infixedlocationsthroughoutafacility.The locators connect back to a centralized server,oftenreferredtoasalocationengine.Low-power,battery-operatedBluetoothtransmitters,commonlycalledtags,arethenattachedtoallassets(orpeople)thatthesystemis intended to track.

The tags are programmed to transmit a signal onaperiodicbasis,thefrequencyofwhichisdeterminedbasedonhowmobilethetrackedassetsareexpectedtobe,aswellashowreal-time location estimates need to be. Each locator continually reports back to the location engine alltagsitcanhear,aswellasthereceivedsignalstrength(RSSI)fromeach.Thelocationengineusesthatinformation,aswellastheknownpositionofeachlocator,toestimatethepositionof tags based on a process called trilateration. Trilaterationdeterminesthepositionofanobjectbyunderstandingitsdistancefromthreeknownreferencepoints.InthecaseofBluetooth,locatorsestimate their distance to any given asset tag based on the received signal strength from the tag.

Theaccuracyoflocationestimatesisinfluencedbyseveralfactors,includingthefloorplanofthefacility and the number of locators deployed. Current standard Bluetooth RTLS solutions can providemeter-levelaccuracy(~1to10meters).

Indoor Positioning Systems

Bluetoothindoorpositioningsystemspowerwayfindingsolutionsthathelpvisitors,suchasshoppersinamall,travelersinanairport,or

workersinalargeofficebuilding,navigate theirwaythroughoutafacility.

BluetoothIPSsolutionsworkintheoppositewayasRTLSsolutions.InsteadofBluetoothreceivers,Bluetoothtransmitters,commonlyreferredtoaslocatorbeacons,are

deployedinfixedlocationsthroughoutafacility.Visitorsthenuseanappontheir

tag

Locator

Locator Locator

LocationEngine

Bluetooth asset tracking system based on RSSI and trilateration.

LocatorBeacon

LocatorBeacon

LocatorBeacon

Bluetooth IPS system based on RSSI and trilateration.

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smartphone that enables the Bluetooth radio in the phone to listen for locator beacons. Based onwhichbeaconstheappcanhear,alongwiththereceivedsignalstrength(RSSI)fromeachandtheirknownlocations,theappisabletousetrilateration,thesameprocessusedinRTLSsolutions,tocalculateitscurrentposition.

LikeRTLSsolutions,thelocationaccuracyofBluetoothIPSsolutionsisinfluencedbyseveralfactorsincludingthefloorplanofthefacility,aswellasthenumberoffixedlocatorbeaconsdeployed,butcurrentsystemscanprovidemeter-levelaccuracy(~1to10meters).

Bluetooth IPS solutions, such as those for wayfinding, are helping travelers find their way through airports around the world.

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Bluetooth Direction FindingWhile Bluetooth location services have seen tremendous success based on current capabilities,thereismarketdemandforsolutionsthat can provide even greater performance. Forexample,insomeRTLSdeployments,itisimportant for the system to provide location accuracydowntocentimeter-level.Fortunately,awell-establishedcapabilityhasrecentlybeenaddedtoBluetoothtechnologythatwillenablethe development of location services solutions that can achieve these advanced performance requirements.

Radiodirectionfindingreferstothepracticeofdeterminingthedirectionfromwhichareceivedsignalwastransmitted.Radiodirectionfindinghasbeeninpracticesincetheearlytwentiethcentury and is used in systems to support everything from aviation and nautical navigation towildlifetracking.

Inversion5.1oftheBluetoothCoreSpecification,Bluetoothaddedanoptionaldirectionfindingcapability.Usingthisnewfeature,aBluetoothdevicecandeterminethedirectionofasignalbeingtransmitted from another Bluetooth device. This seemingly basic capability has the potential to significantlyenhanceBluetoothlocationservicessolutions.

Asdiscussedabove,BluetoothlocationservicesarecurrentlyusingRSSItoestimatethedistancebetweentwodevicesand,inthecaseofRTLSandIPSsolutions,usethosedistanceestimatesandtrilaterationtodeterminethepositionofadevice.Now,withdirectionfinding,thosesamedevicescanalsouseinformationaboutthedirectionofanotherdeviceand,forRTLSandIPSsolutions,usetriangulation to improve location accuracy.

TheBluetoothdirectionfindingfeaturesupportstwomethodsfordeterminingthedirectionofaBluetoothsignal,bothofwhicharebasedontheuseofanantennaarray;angleofarrival(AoA)and

angleofdeparture(AoD).

Direction Finding Using Angle of Arrival MethodIntheangleofarrival(AoA)method,thedevicetowhichdirectionisbeingdetermined,

suchasataginanRTLSsolution,transmitsaspecialdirectionfindingsignalusingasingleantenna.Thereceivingdevice,suchasalocatorinthatsameRTLSsolution,

Since the early twentieth century, radio direction finding has been used to support everything from aviation and nautical navigation to wildlife tracking.

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hasmultipleantennaarrangedinanarray.Asthetransmittedsignalcrossesthearray,thereceivingdeviceseesasignalphasedifferenceduetothedifferenceindistancefromeachoftheantennainitsarraytothetransmittingantenna.ThereceivingdevicetakesIQsamplesofthesignalwhileswitchingbetweentheactiveantennainthearray.BasedontheIQsampledata,thereceivingdevicecancalculatetherelativesignaldirection.TheAoAmethodofdirectionfindingisintendedforusewithRTLS,itemfinding,andPoIinformationlocationservicessolutions.

Direction Finding Using Angle of Departure MethodIntheangleofdeparture(AoD)method,thedevicetowhichdirectionisbeingdetermined,suchasalocatorbeaconinanIPSsolutions,transmitsaspecialsignalusingmultipleantennaarrangedinanarray.Thereceivingdevice,suchasamobilephoneinthatsameIPSsolution,hasasingleantenna.Asthemultiplesignalsfromthetransmittingdevicecrosstheantennainthereceivingdevice,thereceivingdevicetakesIQsamples.BasedontheIQsampledata,thereceivingdevicecancalculatetherelativesignaldirection.TheAoDmethodofdirectionfindingisintendedforuseinIPSsolutions,suchasthoseusedforwayfinding.

Bluetooth Profiles with Direction FindingFormanyBluetoothfeatures,profilespecificationsarepublishedthatdefinehowtodevelop

interoperableBluetoothproductsthatimplementthefeature.Forexample,theBluetoothHeadsetProfiledefineshowtodevelopinteroperableaudioheadsetsusingBluetooth.

ThisisalsotrueforthenewBluetoothdirectionfindingfeature.Severalnewprofilesareintheirfinalstagesofdevelopmentandareexpectedtobereleasedsoon,

AoA Method AoD Method

AoA AoD

Transmitter Receiver

Receiver Transmitter

Bluetooth direction finding using angle of arrival (AoA) Bluetooth direction finding using angle of departure (AoD)

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includingaprofileforproductsimplementingdirectionfindingusingtheAoAmethodandaprofileforproducts implementing it using the AoD method.

Enhancing Bluetooth Location Services Solutions Using Direction FindingTheBluetoothcommunityaddeddirectionfindingcapabilityinresponsetomarketdemandforBluetooth based location services solutions that could deliver even greater performance. By adding thedirectionfindingfeature,BluetoothproximitysolutionscanadddirectionalcapabilitieswhileBluetooth positioning systems can improve location accuracy.

Item Finding Solutions–ShouldsmartphonevendorschoosetoincludeBluetoothdirectionfindingwithAoAsupportintheirproducts,itemfindingsolutionscouldbeenhancedtoprovidedirectionalinformation.Withdirectionfindingsupport,inadditiontoidentifyinghowcloseamisplaceditemis,anitemfindingapplicationonasmartphonecouldalsodeterminetheitem’sdirection,improvingtheuser experience.

PoI Information Solutions–PoIinformationsolutionscouldalsobenefitfromdirectionfindingwithAoAbeingaddedtosmartphones.Imaginearoominamuseumwithmultipleexhibitsthathaveassociatedbeacons.Withdirectionfindingsupport,aPoIinformationapplicationonasmartphonecouldnotonlyinformauserofalltheexhibitsintheroomandallowthemtoselectonetoreceiveadditionalinformation,buttheusercouldsimplypointtheirsmartphoneataspecificexhibittogetmore information on that item.

RTLS Solutions –Byimplementingdirectionfinding,RTLSsolutionscouldimprovelocationaccuracydowntocentimeter-level,dependingondeploymentconsiderations.BydeployingaRTLSsolutionwithdirectionfindingsupport,afactorycouldtrackthelocationandflowofmaterialswithgreaterprecision,aswellastrackandalertworkersbeforetheygointounsafeworkareas.

IPS Solutions –IPSsolutionswithdirectionfindingsupportdeployedinhospitalsorshoppingmallscould provide even greater positioning accuracy to improve the navigation experience or require the deploymentoffewerlocatorbeacons.

ConclusionTheBluetoothcommunityiscontinuallyenhancingthetechnologytoaddressnewmarketopportunitieswhilemeetingtheever-expandingneedsofthemarketsinwhichitalreadyparticipates.WiththeintroductionoftheBluetoothLowEnergyradio,thecommunitysoughttoaddressthemarketopportunityforstandardized,lower-costlocationservicessolutions.WithBluetoothlocationservicessolutionsnowpredictedtobeshipping400millionproductsperyearby2022,itwouldappear the community has been successful in achieving that goal.

However,thecommunityneversitsstill.DespitethesuccessBluetoothlocationservicessolutionshaveseenbasedoncurrentcapabilities,thecommunitysawmarketdemandforsolutionsthatcoulddeliverevengreaterperformance,suchasBluetoothRTLSsolutionsthatcouldachievetruecentimeter-levellocationaccuracy.Tomeetthisneed,thecommunityaddedadirectionfindingfeature to Bluetooth.

Theadditionofdirectionfindingbringsestablished,time-testedmethodsfordeterminingsignaldirectiontoaproven,trustedradio.ThisfeaturewillenableBluetoothproximitysolutionstoadddirectionalcapabilitiesthatenhancetheuserexperienceaswellasBluetoothpositioningsystemsthatcanaddressthefullspectrumofpositioningusecases,fromcommonlowresolutionsystemstothemost precise.

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