Sensing Meets Mobile Social Networks:Sensing Meets Mobile Social Networks:The Design, Implementation and The Design, Implementation and

Evaluation of the Evaluation of the CenceMe ApplicationCenceMe Application

Emiliano Miluzzo†, Nicholas D. Lane†, Kristóf Fodor†, Ronald Emiliano Miluzzo†, Nicholas D. Lane†, Kristóf Fodor†, Ronald Peterson†, Hong Lu†, Mirco Musolesi†, Shane B. Eisenman§, Peterson†, Hong Lu†, Mirco Musolesi†, Shane B. Eisenman§,

Xiao Zheng†, Andrew T. Campbell†Xiao Zheng†, Andrew T. Campbell†

††Computer Science, Dartmouth CollegeComputer Science, Dartmouth College

§Electrical Engineering, Columbia University§Electrical Engineering, Columbia University

Presented by Amre ShakimovCompSci 215

MotivationMotivation

• Text messaging: Text messaging: •““Where R U?” Where R U?” •““What R U doing?”What R U doing?”

• Mobile phones are virtually always ON and with usMobile phones are virtually always ON and with us• Sensors in mobile phone: GPS, accelerometers, Sensors in mobile phone: GPS, accelerometers,

microphone, camera … etcmicrophone, camera … etc• Data collection through sensorsData collection through sensors

Introduction of CenceMeIntroduction of CenceMe

• People-centric sensing applicationPeople-centric sensing application• Implementation on Nokia N95; Implementation on Nokia N95;

Symbian/JME VM platformSymbian/JME VM platform• Share user presence information Share user presence information

(Facebook)(Facebook)

ContributionsContributions

• Design, implementation and evaluationDesign, implementation and evaluation• Lightweight classifierLightweight classifier• Trade-off: time fidelity v.s. latencyTrade-off: time fidelity v.s. latency• Complete User studyComplete User study

Mobile Phone limitationsMobile Phone limitations

• OS LimitationsOS Limitations• API and Operational LimitationsAPI and Operational Limitations• Security LimitationsSecurity Limitations• Energy Management LimitationsEnergy Management Limitations

Architecture Design IssuesArchitecture Design Issues

• Split-Level Classification (primitives, facts)Split-Level Classification (primitives, facts)– Customized tag Customized tag – ResiliencyResiliency– Minimize bandwidth usage/energyMinimize bandwidth usage/energy– Privacy/data integrityPrivacy/data integrity

• Power Aware Duty-Cycle (~6 hours)Power Aware Duty-Cycle (~6 hours)

CenceMe ImplementationCenceMe Implementation

Operations (Phone):Operations (Phone):• Sensing Sensing • Classification to produce primitives Classification to produce primitives • Presentation of people's presence on the phone Presentation of people's presence on the phone • Upload of primitives to backend servers Upload of primitives to backend servers

Classifications (Backend Server):Classifications (Backend Server):• classifying the nature of the sound collected from the microphone classifying the nature of the sound collected from the microphone • classifying the accelerometer data to determine activity (sitting, standing, classifying the accelerometer data to determine activity (sitting, standing,

walking, running) walking, running) • scanned Bluetooth/MAC addresses in range scanned Bluetooth/MAC addresses in range • GPS readings GPS readings • random photos random photos (!!!)(!!!)

Phone SoftwarePhone Software

ClickStatusClickStatus

Backend SoftwareBackend Software

Phone classifiers (1/2)Phone classifiers (1/2)

• AudioAudio– Feature extractionFeature extraction– ClassificationClassification

Phone classifiers (2/2)Phone classifiers (2/2)

• ActivityActivity

Backend ClassifierBackend Classifier

• ConversationConversation• Social ContextSocial Context

– Neighborhood conditionsNeighborhood conditions– Social StatusSocial Status

• Mobility Mode DetectorMobility Mode Detector• LocationLocation• ““Am I Hot”Am I Hot”

– Nerdy, party animal, cultured, healthy, greenyNerdy, party animal, cultured, healthy, greeny

System PerformanceSystem Performance

• Classifier accuracyClassifier accuracy• Impact of mobile phone placement on bodyImpact of mobile phone placement on body

– 8 users8 users– Annotations as ground truth for comparison with Annotations as ground truth for comparison with

classifier outputsclassifier outputs

• Environmental conditionsEnvironmental conditions• Sensing duty cyclesSensing duty cycles

General ResultGeneral Result

Phone placement on bodyPhone placement on body• Pocket, lanyard, clipped to beltPocket, lanyard, clipped to belt• Insignificant impact conversation v.s. Non-conversationInsignificant impact conversation v.s. Non-conversation

Environmental impactEnvironmental impact• Independent of activity classificationIndependent of activity classification• More important: transition between locationsMore important: transition between locations

Duty Cycle (1/2)Duty Cycle (1/2)• Problem detecting short term eventProblem detecting short term event• Experiment: 8 people. Reprogram different duty cycles.Experiment: 8 people. Reprogram different duty cycles.

Power BenchmarksPower Benchmarks• Measuring battery voltage, current, temperatureMeasuring battery voltage, current, temperature• Battery lifetime: 6.22+/- 0.59 hoursBattery lifetime: 6.22+/- 0.59 hours

Memory and CPU BenchmarksMemory and CPU Benchmarks

User StudyUser Study• Survey user experienceSurvey user experience• Feedback:Feedback:

– Positive from all usersPositive from all users– Willing to share detail status and presence information Willing to share detail status and presence information

on Facebookon Facebook– Privacy not an issuePrivacy not an issue– Stimulate curiosity among usersStimulate curiosity among users– Self-learning on activity patterns and social statusSelf-learning on activity patterns and social status

Rooms for improvementRooms for improvement

• Battery life to up to 48 hoursBattery life to up to 48 hours• Finer grained privacy policy settings.Finer grained privacy policy settings.• Shorter classification timeShorter classification time

ConclusionConclusion

• A complete design, implementation and evaluationA complete design, implementation and evaluation• First application to retrieve and publish sensing presenceFirst application to retrieve and publish sensing presence• A complete user study and feedback for future A complete user study and feedback for future

improvementimprovement