F INDING M I M O : T RACING A M ISSING M OBILE P HONE USING D AILY O BSERVATIONS Hyojeong Shin, Yohan Chon, Kwanghyo Park and Hojung Cha MobiSys Sowhat

O UTLINE Introduction System Design Evaluation Discussion Conclusion

O UTLINE Introduction System Design Evaluation Discussion Conclusion

M OTIVATION Missing handheld device problem Existing solution MobileMe, provided by Apple Inc. and Skyhook GPS, cell tower ID, WiFi fingerprints Drawbacks - Inaccurate location estimations in indoor GPS signal not reachable Pre-learned database for radio fingerprints not available

C HALLENGES 1. Efficient - limited battery duration 2. Indoor environment challenge GPS, floor plan, pre-learned radio map, non-standard hardware not generally available 3. Room-level accuracy 4. Not necessary with additional hardware functionality or infrastructure

O UTLINE Introduction System Design Evaluation Discussion Conclusion

I DEA OF F INDING M I M O ~ Warn / Cold Game ~ Sim() = Tanimoto coefficient function =

P LACE - MATCHING P ROBLEM Input Initial known position Logged observations Live observations Output Moving path of missing mobile Moving path of the chaser

S YSTEM A RCHITECTURE Missing Mobile LifeMap Missing mobile app. Chaser SmartSLAM Chaser app.

L IFE M AP Functionality Monitor user ’ s physical location with ambient features Construct nodes (places) & edges (paths) Sensing GPS, GSM, WiFi Activity-based sensor selection (move / stationary) Detection of movement – Tanimoto Coefficient > threshold Known place Stationary state continuously maintained Role movementknown places Provide information of movement and known places Missin g Mobile LifeMap Missing mobile app. Chaser SmartSLAM Chaser app.

M ISSING M OBILE : D AILY A MBIENT L OGGER Role Record ambient radio logs on the path, from last known place to current unknown place Functionality Log WiFi vectors, LifeMap detect movement & no GPS signal Sleep state, otherwise Minimize stored information Collection period < 1 Day Reset when 1. revisit a known place 2. GPS signal available Missin g Mobile LifeMap Missing mobile app. Chaser SmartSLAM Chaser app.

S MART SLAM: I NDOOR P EDESTRIAN T RACKING Role Provide indoor floor plan & location of the user Functionality – floor plan construction Path Accelermeter  step count Digital compass  heading direction Location Use WiFi observation to identify locations Adjust path while revisting identified locations Missin g Mobile LifeMap Missing mobile app. Chaser SmartSLAM Chaser app.

C HASER : D EVICE T RACKING C HASING I NFORMATION Circumstantial evidence Approximate missing time & previous known place Indoor pedestrian tracking Display map & location of the user Log similarity Similarity of current and logged observations Trace similarity – Target similarity – Chasing progress - Missin g Mobile LifeMap Missing mobile app. Chaser SmartSLAM Chaser app.

C HASER : D EVICE T RACKING C HASING I NFORMATION Missin g Mobile LifeMap Missing mobile app. Chaser SmartSLAM Chaser app. If no specific location (GPS) in log data Visit all possible entrances of last place to find the one with largest similarity Indoor Chasing

O UTLINE Introduction System DesignEvaluation Discussion Conclusion

M ISSING M OBILE Energy consumption space complexity Energy consumption & space complexity Setting Similarity threshold = students collect 2 weeks Energy consumption RateActivateInterval GPS?30sec2min WiFi move5sec-- stationary10sec30sec2min

M ISSING M OBILE Space complexity AP – 367 ~ 1573 Record – 50160~ ~ 22.3MB Reduction: ABCBD  ABD

C HASING A HIDDEN DEVICE

V ERTICAL L OCALIZATION

H IDE - AND -S EEK G AME Goal: check if chaser could chase with only the information from chaser app. Setting 4 games at 4 different buildings 36 people 1 participant hide, chaser group chase

C ASE S TUDY : S HOPPING MALL Real environment & case Setting m 2 shopping mall 3 hours log Extract 6 possible missing place  generate logs User chase at the next day

O UTLINE Introduction System Design EvaluationDiscussion Conclusion

D ISCUSSION User guide Move slow while chasing Places with similar radio signal may be on different floor Erroneous data GPS may be read via window Open space

O UTLINE Introduction System Design Evaluation DiscussionConclusion

C ONCLUSION FindingMiMo with ambient observations to help to trace missing mobile device Not clear descriptions for detail settings

T HANKS FOR L ISTENING ~