Daniel Gonzalez, Avery Lamp, Ethan Weber, and Moin Nadeem

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AREALYTICS

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DanielGonzalez,AveryLamp,EthanWeber,andMoinNadeem

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Our Team

EthanWeber

Hardware,Microcontrollers,Software,Web

http://ejweber.scripts.mit.edu/

AveryLamp

Software,iOSDeveloper,Web

http://averylamp.me/PortfolioLinks.pdf

Daniel“Gonzo”Gonzalez

Design,Software,Hardware,Web

http://gonzo.mit.edu/resume.pdf

MoinNadeem

Software,Systems,Web

http://moinnadeem.com/

AnIntroduction

Forplacesthathavealargeflowofhumantrafficthroughoutthedaysandnights,suchas

universitiesandconventioncenters,it’shelpfulforpeoplerunningthoseinstitutionstohaveagood

ideaofwherepeopletravelmostandhowtheymoveincertaintimesofthedays.Therewasno

efficient,simplewaytoaccomplishthistaskuntilArealyticscametolife.Nowweareableto

passivelytrackpeople’sdevicesthroughoutvariousbuildingsandspaces.Wecandisplaythis

informationonadashboardsystemtailoredtowardsacustomer’sneeds:real-timedataabout

customers,maxflowratesofwalkways,locationhotspots,andwearecurrentlyleveragingthe

millionsofdatapointsavailabletocreateapredictiveanalyticssolution.

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Howweaccomplishthistaskissimple:wehavereconfiguredWiFichipsintoanetworkof

microcontrollersthatdetectDNSProbeRequests.DNSproberequestsareessentiallysignalsthat

WiFidevicesbroadcastouttotheroutersnearbywiththeirMACaddresssaying,“Hey,I’mhere!

Allowmetobuildaconnectionwithyou.”WestorealloftheseproberequestsbyloggingMAC

addresses,timestamps,signalstrengths,andmore.Withthisinformation,wecanmodelthepaths

thatpeopletookthroughouttheday.Wewillalsoprovidevitalinformationtobusinessesand

institutionsaboutwheretocreatenewworkingspaces,wheretoperformconstruction,andwhereto

relocatesitestooptimallocations.

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 

SystemInfrastructureDiagram

Thisisadiagramdepictingthemajorcomponentsofoursystem.WehaveanetworkofESP8266

microcontrollerswithpowersourceslocatedwithinsomegeographicalregion.Wecallthese

modulesESPs.ThesedevicesconnecttoWiFiaccesspointsnearbyandcontinuallysendthedatato

ourserver.Theserverthenprocessesallofthedatatocreatedynamicvisualizations.TheiOS

applicationactsabridgebetweentheESPsandtheserverallowingustoeasilydeploytheESPsin

locationsandupdatethedatabasewithease.

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StateMachineDiagram

ESPs

1. AutomaticallyconnecttoWiFi.

2. SynchronizeESP8266timewithanNTP(NetworkTimeProtocol)server.

3. Listenforallproberequests.

4. Sendproberequestswithtimestampinbatchesof5tothedatabase.

5. Send“keep_alive”GETrequestevery30secondstosignifythedeviceisonline.

6. TestconnectionandreconnecttoWiFiifneeded.

7. Repeatfromstep2.

Server

AllofourserverapplicationsarewritteninFlask.OurbackendisinMySQL.

1. Website

1.1. UseApachetolistenforHTTPrequestsandservetheappropriatefiles.

1.2. Useclient-sideJStocontinuallypingtheserver,checkingfornewdata.

2. Database

2.1. ObtainPOSTrequestswithnewMACaddresses.

2.2. Validatethedatatypes.

2.2.1. Ifvalid,insertthedata,timestamp,andsignalstrengthinatableofmac

addresses.

2.3. ReturnvalidorinvalidHTTPstatuscodes.

3. iOSEndpoint

3.1. ListenforHTTPrequestandupdate“keep_alive”tableaccordingtothe

microcontrollersbeingdeployed.

4. Notifications

4.1. TwilioapplicationinFlaskthatsendstextswheneverthereisadeployeddeviceis

unreachableduetosomeunforeseencircumstance.

iOSApplication

1. CallsaGETrequesttogetthelistofESPsinthe“keep_alive”tableanddisplaythelistinthe

app.

2. ClickonESPofscanQRcodeofESPbox.

3. WaitsforusertoenternicknameandthentheapplicationautomaticallyassignsGPS

coordinatesbasedoffoflocationreadingsfromthephone.

4. LocationsareupdatedeffectivelyandaccuratelywithanHTTPrequestincludingcoordinates,

nickname,theMACaddress,andtimeofmovement

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Deployment

Objectives

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Deploymentisoneofthekeyconceptsbehindourproject.TheabilitytodeployanadditionalESP

quickly,cheaply,andeffectivelyshouldbeanintegralpartofthecustomerexperience.Therefore,as

weconsideredhowweshoulddeploydevices,wehadafewcoreconceptsinmind.

1. Eachdeploymentshouldrequireminimalconfiguration.ThemoretheESPcouldinitialize

on

it’sown

,thebetterexperiencewecouldprovide.

a. ThismeansthattheESPshouldconnecttoWiFiautomatically,astheusershouldn’t

havetoconsiderthis.

2. Eachdeploymentshouldbemodular.Informationsystems—particularlyinformation

visualizationsystems—shouldbeaccommodativeofthemwithoutadditionaleffortonthepart

oftheuser.

3. Uptimeiskey—ifonenodegoesdown,thenourdatabecomesexponentiallylessvaluable.

Therefore,weshouldbeabletomonitoruptimefordevicesandbealertedwhenonedevice

goesonlineoroffline.ThedeviceshouldalsoreconnecttoWiFiinthecaseofalost

connection.

4. Quickandeffectivedeploymentisanecessity,sowedecidedtousecreateaniOS

companionapptospeeduptheprocess.WecansimplysnapapictureoftheQRcodeon

eachmoduleandourdatabasewillbeupdatedwiththecoordinates,timeoflastupdate,and

thenicknameofthelocation.Thisisthenusedtoautomaticallycreategraphsandmapsfor

ourwebsite.

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StepsforDeployment

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1. Chargebatteriesorgatherpowersupplies.Oursystemcurrentlyneedseithercharged

batteriesorUSBpowersuppliesthatplugintooutlets.

2. InstalltheiOScompanionapp.Theappiscurrentlynotontheappstore,butwehaveplans

tofurtherdeveloptheappforbothiOSandAndroidandmakeitpublicallyavailablewithour

product.

3. PlacethemodulesindesiredlocationsandsnapapictureoftheQRcode.SettheGPS

coordinateswitheitheryourcurrentlocationorbymovingthemapwithyourfingers.Typein

thenicknameforeachlocation,hitsubmit,andyouaredone.

4. Simplyheadtodomecrawl.ustoviewyourdataandandouranalysisofyourlocationdata.

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PortableModules

Hardware

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ThehardwareinoursystemconsistsofanESP8266WiFimodulemicrocontroller(here) andsource

ofpower.WecurrentlypowerourdevicesviaamicroUSBcableoraLiPobattery(here) .Thepower

sourcesplugconvenientlyintoourpowerbreakoutboard(here) ,andthefootprintofeachunitis

designedtobeverycompact,modular,andportable.Withpartsprovidedbythe6.S08class,our

teamsoldered8protoboardsmeetingthesegoals.



Thisimagedepicts3ofour8modules.Our

prototypeboardshavefemaleheaderssothatwe

caneasilydisconnectandreconnecttheESPsand

powerboards.Thisprovedveryimportantbecause

wecanprogramourESPsonaseparate

breadboard,movethemtotheprotoboards,and

thendeploythemoduleswithease.Bydoingitthis

way,weeliminatedtheneedforextrahardwareon

eachprotoboard.



WechosetousetheESP8266WiFimoduleinstead

ofaTeensymicrocontrollertosavemoney,reduce

size,andenhanceperformance.TheESPis

cheaper,smaller,andmorepowerfulthantheTeensy.Furthermore,itcanbeusedasoftaccess

point,meaningitcanactasbothaWiFistation(router)andasaclientforourdatabase.Withthese

capabilities,wehavetheESPsettoconstantlyreceiveproberequestsanduploadthedatatothe

ourdatabaseevery5entries.



Aftercompletingthe8hardwareunits,wecreatedaclean-lookingboxtoencloseeachunitfor

deploymentacrossMIT’scampus.Welabelledtheboxesinawaythatensuredtheprojectwouldbe

safelydistributedandnotdisrupted.Furthermore,weaddedaQRcodetoeachboxsignifyingthe

MACaddressofeachESP.TheseQRcodesareusedwiththeiOScompanionapptoquicklydeploy

anetworkofmoduleswithcorrespondingGPScoordinates.



http://www.electrodragon.com/product/esp8266-smd-adapter-board/

https://www.adafruit.com/product/258

https://www.adafruit.com/product/2465

ESPSoftware



ThesoftwareontheESPsworksbycollectinginformationaboutnearbydevices(phones,laptops,

etc.)andsendingittoourserver.Thedatathatwearesendingtothedatabaseconsistsofthe

epochtime(millisecondssinceJanuary1,1970),theuniqueMACaddressoftheESP,theprobe

requestfromadevicesearchingforWiFi,andthesignalstrengthofthatdevice.Thedatais

convenientlypackagedintoastringontheESPclientsideandsentviaaPOSTrequesttotheserver.

Furthermore,weadjustedtheserversidetohandlebatchposting,meaningwecansendmultiple

databaseentriesinthesamestringtoreducetimespentsendingthetheserver.Weaddedthis

featureinhopestoreducepowerconsumption,butwelearnedthatmostofthepowerwas

consumedbyactingasanaccesspointregardlessofthetimespentonHTTPrequests.



SomeveryimportantfeaturesofourESPsoftwareincludethefollowing:

1. AutomaticWiFiConnection

a. Whenpoweredup,theESPautomaticallysearchesforunencryptedWiFinetworks

nearby.Withthelistofnetworksorderedinstrength,thefunctioniteratesthrough

connectingtoeachnetworkandpinginggoogle.com.Ifthereisasuccessfulresponse

fromGoogle,theESPwillremainconnectedtothenetwork.Ifthereisn’tasuccessful

response(meaningnointernetconnectivity),theESPwillrepeatbytestingthenext

unencryptednetworkandsoon.

2. SSIDIncludesMACaddress

a. WehaveprogrammedtheESPtosetitsSSIDtoourteamnameincludingthelasttwo

digitsoftheESP’sMACaddress.Thisallowsustouseourphonesforquickdebugging

andchecktoseewhetherthenetworkisbroadcastingaWiFisignalasanaccesspoint.

Furthermore,thispermitsustoensurethatourWiFisignalsdon’toverlap,suchthat

devicesdon’treporttobeinmultipleplacessimultaneously.

3. Sendinga“keepalive”GETrequestevery30seconds

a. TheESPsendsaGETrequesttoourserverevery30secondssignifyingthattheESPis

stillonlineandfunctional.Thisisimportantbecauseweusethisinformationtokeepup

todateonwhichESPsandlocationsareoperational.Whentheservernoticesthatone

hasgoneoffline,thedashboardonourwebsite(domecrawl.us)willupdateandthe

teammembersshouldreceivetextnotifications.

4. HTTPPostRequestswithMACaddressInformation

a. TheESPisconstantlysendingapostrequestwith“BATCH_NUMBER”ofMAC

addressesperpost.Furthermore,inthecasewhereverylownumbersofMAC

addressesarebeingcollected,thepostrequestwilldefaulttopostingataminimum

rateofPOST_UPDATE_MINIMUM.

5. AutomaticWiFiReconnect

a. IFtheESPgoeswithoutasuccessfulresponsefromtheserverfor

SUCCESSFUL_RESPONSE_INTERVALmilliseconds,theESPwillautomatically

reconnecttotoWiFi.



6. ESPBlinkingLED

a. TheESPmodulewillblinkeverytimethatitexecutesanHTTPrequest.Thisallowsus

toquicklyknowifthedeviceisworkingwhiledebugging.

7. SynchronizeTime

a. WeuseanNTPclientlibrarytosynctheESPclockwiththerealtime.Wethenusethe

epochtimeinsecondsassociatedwitheachMACaddresswhenuploadingthe

database.



Inthenearfuture,weplantoimplementawaytochangealloftheESPparametersremotely.We

willalsoimplementawaytoremotelyflash(overWiFi)theESPwithfirmware.Thiswillhelpmakethe

networkofdevicesmuchmorescalablebecausecurrentlyeachdeviceisprogrammedindividually,

whichwouldn’tbefeasibleforanythinggreaterthan20devices,forinstance.



HardwareLibrariesandDependencies



Thefollowinglibrarieshavebeenveryimportanttooursoftwaredevelopmentonthehardwareside:

1. ESP8266WiFi.handESP8266HTTPClient.h

a. ThesetwolibrariesaidinsettinguptheESPsassoftaccesspoints,connectingtothe

internetandourserver,findingnearbyWiFinetworks,collectingMACaddresses,and

displayingeachESP’suniqueMACaddress.

2. elapsedMillis.h

a. ThislibraryisvitaltokeepingourESPprocess’stimely.Wehavemanytimersand

intervalsforeachprocesssothatwecanconductGET/POSTHTTPrequestsatthe

correcttimespresetbyconstants.Eventuallytheseconstantswillbeadjustableover

theyearviaourwebsite.

3. NTPClient.handWiFiUdp.h

a. TheselibrariesareusedtosynctheESPclockwiththetimeinUTC.Wearethenusing

thisdatatosendtheepochtimewitheachMACaddressthatiscollected.



EnergyManagement



Inordertostayportable,ourteamworkedhardtotestpossiblewaystoconserveenergyinour

system.Onewaythatwetriedtosaveenergywasbyusingbatchposting,meaningwesend

multipleMACaddressesclusteredinanextendedstringinanHTTPrequest.Weaccomplishedthis

taskonboththeclientandserversidesothatwecouldsendagroupofcollectedMACaddresses

uptosomepredefinedlimit.



Withthissoftwareinplace,weranatestrunwithour8devices.Theresultsfromourtestare

summarizedbelow.TheMACAddressrepresentstheESPmodules,thebatchnumberisthenumber

ofcollectedMACaddressesbeforesendingthedatabase,andthetimealiveisthetimeinhours

(roundedtothenearesthour)beforetheESPdiedwhenstartingwithpowerfromafullycharged

1200mAh3.7Vbattery.



MACAddresses

BatchNumber

TimeAlive(hours)

A0:20:A6:00:EC:E0

5

8

A0:20:A6:0F:29:0F

5

7

A0:20:A6:04:62:4A

5

8

A0:20:A6:14:D9:28

5

8

A0:20:A6:01:56:52

10

0(b/cofbrokenESP)

A0:20:A6:0F:26:15

20

7

A0:20:A6:0F:2C:91

30

8

A0:20:A6:01:56:F4

50

8



Fromthisdata,weconcludedthattheHTTPrequestsdidn’ttakeupmuchpowercomparedtothe

otherprocessesonboardtheESPmicrocontroller.Forexample,because50batchpostsis10times

fewerthan5batchpostsandyettheESPslivedforroughlythesameamountoftime,itissafeto

concludethatbroadcastingtheESPasanaccesspointistakingupthemajorityofthepower.

Accordingtoourcalculations,theESPappearstodrawonaverage150mA(1200mAH/8H).Thisis

aconstantpowerconsumptionof0.555W(150mA*3.7V).



Afterconductingtwoteststhatlastedaround8hourseach,theteamdecidedthatitwouldbemost

efficienttouseapoweroutlettocollectdataforalongertimeinterval.Forourthirdandfinaltestin

thisclass,wehavedeployed8devicesthatarepluggedintomicroUSBwallplugs.Weplantoleave

theserunningforafewweekstocollectalargedatasetthatwecanusetoperformdatascienceand

datavisualizationon.



Althoughwalloutletsworkwithoutlimits,theteamisactivelyworkingonfindingwaystoimprove

powerefficiency.Wewouldliketohaveasystemthathastwooptions:usebatteriesandlastaweek

inanylocationoruseoutletstolastindefinitely.



SoftwareOverview

ServerSoftware

● Database

○ OurdatabaseisusingMySQLandishostedlocallyonourteam’sLinodeserver

instance.Wecurrentlyhavetwomaintablesthatweareusinginourdatabase:

“keep_alive”and“mac_addresses.”OurserverisconstantlylisteningforHTTP(both

GETandPOST)requestsandupdatingthesetablesaccordingly.Theserveris

multithreadedtohandlemanyrequestsatonce.

○ WeareusingaMySQLdatabaseonourLinodebox,withthefollowingtables:

■ keep_alive

● Thistablestoresallofourdevices,thetimedeployed,thelasttime

communicationoccurredbetweenourdeviceandtheserver,the

nicknameofthedeploymentlocation,andgeographiccoordinatesofthe

deploymentlocation.MostofthesearesetthroughouriOSapp!

■ mac_addresses

● Thistablestoresallproberequestsfromdevices.Theseentriesforprobe

requestsincludetimecaptured,RSSIsignalstrength,andtheassociated

ESPthedevicewascapturedfrom.

○ With8devicesconstantlyrunningfor3days,wereceiveonaverage1,000,000entries

ofMACaddressesfromMIT’strafficoncampus.

● FlaskApp

○ Endpoints

■ WehavecreatedmanyendpointstohandallofourHTTPrequests.Wehave

endpointsforthedatabasetokeepitupdated.Wehavemanyendpoints

createdfornavigatingourwebsite,creatinggraphsbehindthescenes,and

keepingthewebsiteuptodate.WealsocreatedanendpointfortheiOS

companionapp.Thisallowsustoeasilydeployourdevices--givingthemunique

namesandlocationsforeachmodule.

○ Challenges

■ Multithreading

● Wefoundthatmultithreadingourserverwasextremelyimportant.When

wehave8devicesrunningwithover5requestsasecondfromeach,we

mustrunprocessesinparallel.Originallywedidn’thavethisenabledin

Flaskwhichcausedourservertocrashmultipletimes.However,our

problemwasfixedassoonasfixingthisproblem.

■ ClosingMySQLconnection

● Ourteamranintosomeproblemsontheserverwhenopeningtoomany

MySQLconnectioninourFlaskApp.Ourserverwouldcrashonoccasion

becausewewerenotterminatingouropenedconnection.Thiswasfixed

byclosingaconnectionaftereachquerythatismadeinFlask.

WebsiteSoftware

● StatusPage

○ Thestatuspageisaconvenientwaytodisplaythenumberofdevicesonlineand

offline.Italsokeepsusupdatedwiththenumber“uniqueMACaddresses”thathave

beendetectedsinceourlastdeployment.

● GraphsPage

○ Onthehttp://domecrawl.us/graphs.htmlwebpageweareutilizingBokehplotsin

Pythontogenerategraphsthatdisplaythenumberofproberequestsataspecific

locationovertime.ThispageiscreateddynamicallyusingJavascript.Assoonasthe

HTMLpageloads,theJavascriptsendsaGETrequesttoaFlaskendpointtogetthe

listofdevicesonlinefromour“keep_alive”table.Thisreturnedlististhenparsedasa

JSONlistandusedtocreateaboxforeachBokehplottobedisplayed.Afterthisis

runontheinitialpageload,ausercanselectatimeintervalfromthe“MinuteInterval”

dropdown.ThisisthenusedtosendaGETrequesttoanotherPythonendpoint,

generateaBokehplotgiventhetimeinterval(whichcountsthenumberofprobe

requestsineachinterval),andthenreturntheHTMLandJavascripttextforthe

correspondingBokehplot.Finally,theBokehplotisinsertedintothecorrectdivtag

andisdisplayedonthescreen.Asourdatasetbecomeslarger,thegraphtakesmore

andmoretimetoload.Wewillworkonspeedingupourgraphingalgorithmsinthe

futuretoreducetimedelaysandimprovelargedatamanagement.

● MACAddressSearchPage

○ ThispageisusedtosearchforindividualMACaddressesthathavebeensavedinour

database.WecreateanddisplayanimageforthecorrespondingMACaddressandlog

thepathofthedeviceasitmovedthroughoutthelocationofdeployment--MITinour

case.TheimageiscreatedbymakinguseofthelibrariesNetworkXandMatplotlib.

● MapPage

○ GoogleprovidesaverynicemapJavascriptAPI.WeareutilizingthisAPItoadd

clusteringvisualizationsandgraphicalanimationsoffoot-traffic.



iOSSoftware

● IntuitiveInterface

○ TheiOSappwascreatedinordertohelpspeeduptheprocessofdeployingthe

hardwaretocollectdata.Inour“keep_alive”table,eachESPhasarow.TheESPhas

alocation,nickname,aswellasotherrelevantinformationaboutwhereitwasplaced.

WhenproberequestshitthatESP,thekeep_aliveinformationforthatESPiscopied

intorelevantfieldsinthe“mac_addresses”tablewherealloftheproberequestsare

storedwiththeirlocationsandtimes.TheiOSappmakesiteasytoupdatethe

“keep_alive”tablewiththenewGPScoordinatesofwhereitwasdeployedaswellasa

nicknameforthedevice. 

○ TheiOSappisverysimple,butitgetsthejobdone.Itstartswithalistofallofthe

ESPsinthe“keep_alive”table,displayingtheirMACaddressandnickname.Inorder

tomodifythedataintherowforaESP,youcaneitherclickontheroworusetheQR

scannerbuttontoscantheQRcodeconvenientlyplacedontopofeachoftheESPs.

Afterscanning,apageforeditingtheinformationfortheESPappears.Ithasamap

andanicknamefield.Inthemap,theprevioussavedlocationoftheESPismarked

withapin,andthenewsavedlocationiswhereverasecondpinonthemapisdragged

to.Thenicknamefieldcanbeeditedeasilybyclickingonit.Afterchangesaremade,

ausercanclickthesavebutton,andthenewinformationfortheESPissentuptothe

servertoupdatethe“keep_alive”table. 

○ Insummaryallthatisneededtodeployamodule:

■ ScantheQRCode

■ Dragthemaptothenewlocation

■ TypeinthenewESPnickname(userfriendlynameforlocation)

■ ClickSave

● ServerConnection

○ TheserverhasacoupleendpointsbuildintomaketheiOSappfunction

○ KeepAliveEndpoint:Thekeepaliveendpointserversonefunction.TogettheiOS

appthelistofESPsinsidethe“keep_alive”table,withtherelevantinformationtoeach

ESP.Todothis,itsimplypullsthewhole“keep_alive”table,packsitintoaJSONwith

acustomJSONencoder,thensendsittotheiOSapplication.TheiOSapplication

thendisplaystheinformationinatable.

○ SetLocationEndpoint:Thesetlocationissimple.Itupdatesthelocation(latitudeand

longitude)foragivenMACaddressinsidethe“keep_alive”table.IttakesintheMAC

addresswiththelatitudeandlongitudeURL-Encodedandsavesitinsidethe

“keep_alive”tablewiththecorrespondingMACaddress.

○ SetNicknameEndpoint:Thesetnicknameisalsosimple.Itupdatesthenicknamefor

agivenMACaddressinsidethe“keep_alive”table.IttakesintheMACaddresswith

thenicknameURL-Encodedandsavesitinsidethe“keep_alive”tablewiththe

correspondingMACaddress.

ChallengesandObstacles

1. ProgrammingtheESPs:Oneofourfirstchallengeswastofigureouthowtoprogramthe

ESPs.Afterdoingalotofresearchonline,wefoundthatpeoplehavecreatedwaysto

reprogramtheESPsusingArduinoandreflashingtheESP.Wehadalotofdifficulty

comparingtheESP8266tothetutorialsonlinebecausethepinswerenameddifferentlyon

ourESP.Afterreadingthroughalotoftutorialsandtryingdifferentwirings,wewereableto

findawiringthatallowedustoflashtheESP.Wehadtodosomeexperimentationwithpin

numberstoreverseengineerwhichpinscontrolledthebuilt-inLEDandwhichpinscrashed

theexamplecode.SoonenoughwewereabletosettheESPupasanaccesspointand

receiveallproberequeststothataccesspoint.

2. Connectingtotheinternet:Oneofthebiggestchallengeswehadonthehardwaresidewas

disconnectingfromtheinternetandnotsendingreceivedproberequests.Whenaspecific

ESPgoesoffline,itisoftenverydifficulttofigureoutwhyanditwouldalsonotreconnect.In

ordertosolvethisproblem,wewrotecodeforthemodulesthatimmediatelydetectswhenit

isnotconnectedtointernet.Afteritdetectsaproblemwithinternet,theESPscansforall

availablewirelessnetworksandsequentiallytriestoconnecttoanunsecurednetwork.Ifthe

connectionissuccessful,theinternetistested,andifitfails,ittriesthenextunsecured

network.Usingthisstrategy,evenifaESPlosesconnectiontointernet,itisabletoreconnect

quicklyandkeepsendingdatatotheserver.

3. Batterylife:Anotherissuewehadwaswithlimitedbatterylife.Withthe1200mAHlipo

batteries,theESPlastedabout8hours.EachESPneedsacurrentofabout150mAbecause

theESPsneedtoactasawifirouteraswellaspostproberequestswhenthebatchnumberis

reached(5proberequestssentatatime).Becausewewantedlongcontinuoussetsofdata,

wehadonlyacoupleoptionsinordertomakeourESPslastlonger.Wecouldplaywiththe

batchsize(discussedinenergysection),wecouldgetbiggerbatteries,orwecouldsimply

plugthemdirectlyinwalls.Aftertryingthethreeoptions,weendedupdecidingtoplugthe

ESPsdirectlyinwallstogetcontinuoussetsofdata.

4. MultipleHTTPrequests:Achallengethatwehadontheserversideisthatwithnumerous

ESPsdoingpostrequeststotheserveratthesametime.Afterweincreasedthenumberof

ESPsinourtestsetfrom4to8,wenoticedthattheservergetsbackedupandsometimes

crashesduetothenumberofpostrequests.Inordertofixthisissue,wemadetheFlaskApp

thathandlesallpostrequestsandinsertsthemintotheSQLdatabasemultithreaded. 

5. MACAddressRandomization:Oneissuewehavethatwespendsignificanteffortstotryand

solveistherandomizationofMACaddresses.IniOS7,Appleintroducedsoftwarethat

randomizestheMACaddressusedtosendproberequestseverysooften.Becauseofthis,

peoplewithiPhonesthatwalkbyESPsmaynotbepickedupinmultiplelocations,astheir

MACaddresscouldchangeinbetweenthoselocations.Inordertodealwiththis,weonly

considertheproberequeststobevalidifthesameMACaddressappearsinmorethanone

location,signifyingthattheMACaddresswasprobablynotarandomizedspoofedMAC

address.ThisaddedanotherleveltoourSQLquerieswhichsignificantlyslowedsomeofour

graphing.

6. LocationAnimations:WiththecurrentSQLdatabasestructure,itisverydifficulttoforma

querytocreateanimations.Ouroriginalgoalforanimationswastobeabletoanimatea

singularMACaddressasitwalksacrosscampusbetweenthedifferentESPs.Inordertofilter

MACaddressandtheirproberequests,wehadtocreateincrediblycomplicatedqueries,

sometimesfilteringmanytables.Weendedupusingqueriesthatfilterthedatabaseand

requerywithtablesuptofourtimesinordertogetgoodusabledata.Thisendeduptakinga

significanthitinourendpoint’sresponsetime.Forsomeendpoints,itrequiresover10

secondstofullyquerythedata.

7. Scalability:Anissuewearecurrentlyhavingwithourprojectisscalabilityforthefuture.Asof

now,wearestoringabout1millionproberequestrowsstoredinourdatabaseevery3days.

Withsuchalargedatabase,ourcomplexqueriesaregettingslowerandslower.Thequeries

neededtodoanimationsonthedatabasehavestartedtakingalongtime,sowearelooking

foramoreoptimalsolution.

What’sNext?



Goals

OurteamishopingtobringArealyticsoutsideoftheclassroomandintotheretailspace.Wehave

beendevelopingourtechnologyinclassinsuchthatitwillbeeasilytransferabletobebuiltintoa

realproduct.Themarketwearetargetingisdataanalyticsforthingslikemallsandalsoevents. 



Currentlytherearenoefficientmethodsofgettingdataonwherepeoplegowhenwalkingaround

througheventsorbuildings.However,thisdatacanbeextremelyvaluabletoeventhostsand

buildingowners.Eventhostscouldkeeptrackofwhichareasarevisitedmostfrequentlytoimprove

theefficiencyoffutureevents.Forexample,conferencescouldspendmoretimepreparingthe

eventswithgreatestinterest/attendance.



Furthermore,mallscouldplacestoresinmoreefficientlocationsdependingonthetrendsof

customermovements(ConsumersaftervisitingstoreA,arelikelytovisitstoreBandC.A,B,andC

shouldbelocatedneareachother).Mallscanfigureoutwhichlocationsaremoreprofitable,and

chargemoreforleaseforthoselocations.Mallscandoahealthanalysisontheircurrentnumbersof

customersandhowthatvariesthroughouttheday.



Outsideofretailspace,thereisalsopotentialoutsideoftheretailspaceandinthehomespace.Our

teamcompetedinahackathonattheMITMediaLabtoprototypethistechnologycateringtothe

elderly.Wedesignedasystemthatcouldlocatewheresomeoneisintheirhome.Wewouldputour

MACaddresstrackerdevicesineachroomofthehouseandthenwecouldmonitorthepathofan

elderlypersonastheytraversedthroughtheirhome,forexample.Usingthisdata,isitpossibleto

tellwhensomeoneisspendingtoolonginagivenlocation.Forexample,ifanelderlypersonwas

spendinganhourinthebathroom,oursystemcouldalerttheirchildrenthatsomethingmaybe

wrong.Thisisjustanotherapplicationofourtechnologyincasewewouldexpandoutsideofthe

retailspace.Alinktoourprojectpresentationishere.



Inordertomakeourproductmarketreadythereisalotthatneedstobedone.Wehopetocreate

PCBdesignsforourESPsandfigureouthowtoproducethematalargerscale.Wewantthemto

plugdirectlyintoanoutletaswellaslookniceandunsuspicious.WeenvisionthattheESPscould

beassmallasa3x3x2inchboxthatsimplyplugsintoawalloutlet.Wealsodonotwanttolose

outontheeventspace,whereoutletsmaybelimited.Inordertodealwiththispotentialissue,we

wouldliketoalsobuildaversionoftheESPthatcanbebatterypoweredanddistributedanywhere

onthefly.



Wealsoplantoexpandtremendouslywiththedataanalytics.Duetothescalabilityissueswe

encounteredwhiledoingthe6.S08project(slowingovertime),wehopetocreateanefficientwayto

storeandaccessdata.WemayswitchourdatabaseovertoaMongoDatabaseratherthanSQL,

anddostrategicinsertionwithonlyproberequeststhatmatter(potentiallyreducingredundancies

20x).Wealsoneedtooptimizeourgraphingalgorithmsandanalyticsalgorithmssothatwecan

quicklycrunchnewstatisticsforourcustomers.



Furthermore,wewouldliketoaddalottotheanalyticssideoftheproberequests.Inordertomake

Arealyticsmarketviable,weneedtobringdatathatisusefulforourcustomerstotheirfingertips.In

ordertodothis,wemayneedtotalktoourpotentialcustomersandfigureoutwhattypesofgraphs

andthingswouldbehelpfultothem.