D ETECTING D RIVER P HONE U SE L EVERAGING C AR S PEAKERS Jie Yang, Simon Sidhom, Gayathri Chandrasekaran, Tam Vu, Hongbo Liu, Nicolae Cecan, Yingying Chen, Marco Gruteser, Richard P. Martin MobiCom Sowhat

O UTLINE Introduction System design Experiment Results Conclusion Discussion

O UTLINE Introduction System design Experiment Results Conclusion Discussion

M OTIVATION I NTRODUCTION M OTIVATION Cell Phone Distraction Hands-free Phone Operation Driving Mode Route incoming calls to voic Delay incoming text notification Driving Mode Route incoming calls to voic Delay incoming text notification Driver? Passenger?

O BJECTIVE I NTRODUCTION O BJECTIVE Classify phone which seat Bluetooth + Audio infrastructure Phone Transmit Signal Car Head Unit Speaker Play Signal Phone Record Processing

C HALLENGES I NTRODUCTION C HALLENGES Unobtrusiveness Robustness to Noise and Multipath Computational Feasibility

O UTLINE Introduction System design Experiment Results Conclusion Discussion

O VERVIEW S YSTEM D ESIGN O VERVIEW Acoustic Relative-Ranging System Avoid Interfere Distinguish speakers

R ELATIVE R ANGING S YSTEM D ESIGN R ELATIVE R ANGING

B EEP S IGNAL S YSTEM D ESIGN B EEP S IGNAL Unobtrusiveness Robustness to Noise Frequency Android developer phone 2 – 16~18kHz iPhone 3G – 18~20kHz Length – 10ms

P ROCESSING S YSTEM D ESIGN P ROCESSING

D ETECT B EEP S YSTEM D ESIGN D ETECT B EEP Sequential change-point detection : sequence of recorded audio signal Requirement: known distribution Cumulative sum μ : mean value of noise from t 0 to t 1, time of transmitting > Threshold for W samples

P ROCESSING S YSTEM D ESIGN P ROCESSING

C LASSIFICATION S YSTEM D ESIGN C LASSIFICATION 2-channel > -5 4-channel if  Front Check Else  Back Check

O UTLINE Introduction System design Experiment Results Conclusion Discussion

P HONES & C ARS E XPERIMENT P HONES & C ARS Phones Android Developer Phone 2, Phone I iPhone 3G, Phone II Cars Honda Civic Si Coupe, Car I Acura Sedan, Car II 2 channel sound system with fader system

P ROCEDURE E XPERIMENT P ROCEDURE Create Beep 4 beep audio files, For { Phone I, Phone II } x { 2 channel, 4 channel } Each file with 4 beeps for each channel Create uniformly distributed white noise  Bandpass filter {16~18, 18~20} kHz Transmit Laptop to car’s head unit via Bluetooth Record Audio recorder app. on phone for offline analysis

S CENARIOS E XPERIMENT S CENARIOS Phone I, Car I

S CENARIOS E XPERIMENT S CENARIOS Phone II, Car II

S CENARIOS E XPERIMENT S CENARIOS Phone I, Car 60 MPH Highway

O UTLINE Introduction System design Experiment Results Conclusion Discussion

M ETRICS R ESULTS M ETRICS Accuracy Detection Rate False Positive Rate Measurement Error

D RIVER VS. P ASSENGER R ESULTS D RIVER VS. P ASSENGER 2-Channel is OK

P OSITION A CCURACY R ESULTS P OSITION A CCURACY

L EFT VS. R IGHT R ESULTS L EFT VS. R IGHT

F RONT VS. B ACK R ESULTS F RONT VS. B ACK

R ELATIVE R ANGING R ESULTS R ELATIVE R ANGING

C OMPUTATIONAL C OMPLEXITY R ESULTS C OMPUTATIONAL C OMPLEXITY Filtering, Short-time Fourier transform n recorded samples, moving window size After filtering, Average processing time 0.5s for 2-channel 1s for 4-channel

O UTLINE Introduction System design Experiment Results Conclusion Discussion

C ONCLUSION Driver mobile phone use detection system Leverage existing infrastructure of car speaker for ranging via Bluetooth Acoustic relative-ranging Over 90% detection rate

O UTLINE Introduction System design Experiment Results Conclusion Discussion

D ISCUSSION Strengthens Clear motivation, system design description Real implement Weakness Different setting for different hardware  not comparable How to set calibration value

T HANKS FOR L ISTENING ~