Caraoke
Omid AbariDeepak Vasisht, Dina Katabi, Anantha Chandrakasan
An E-Toll Transponder Network for Smart Cities1Electronic Toll Transponders80% of the cars in US have themSome states are making it mandatory
2Opportunities
1234576Localization3Opportunities
Adjust traffic-light timingSmart street-parkingDetect red-light runnerOne infrastructure for many smart services
4Challenge: No MAC to Prevent Collision
Physical Isolation
Interference Wireless queryOne car respondsWireless queryAll cars respond at the same timeWhat can we do?5
I don't care 'Cause I've never been so high Follow me to the dark Let me take you past our satellites 6CaraokeA system that delivers smart services using existing e-toll transponders despite interference
Software-Hardware solution: Count carsLocalize carsDecode transponders
Built and evaluated on our campus streets with existing e-toll transponders7Count cars: How to count despite interference? Localize cars
Decode transponders
8Counting Despite InterferenceTime-DomainFreq-Domain
CarrierDataSpike
9Counting Despite InterferenceTime-DomainFreq-Domain
CarrierDataSpike
Caraoke can count transponders despite interference Toll transponders have difference in their carrier frequency10Count cars
Localize cars: How to localize despite interference?
Decode transponders
11Localizing TranspondersLocalization requires knowing the channelHow to extract channels in the presence of interference?
12
Localizing TransponderTime-DomainFreq-Domain
SpikeUse the channel to find the Angle-of-Arrival13Localizing Transponder
14Localizing TransponderCars are always on the road planeIntersect spatial angle with road planeHyperbola
Intersects hyperbolas across multiple readers to find the exact location of the car15Count cars
Localize cars
Decode transponders: How to decode despite interference?
16Solution: Coherent CombiningRealImag17Solution: Coherent Combining
RealImag18Solution: Coherent Combining
RealImag++=Caraoke uses channel information to combine responses coherently and decode the ID19Custom Hardware DesignSelf-SustainingHarvest Solar Energy
20Custom Hardware DesignSelf-SustainingHarvest Solar EnergyLow-CostReplace TX chain with simple PLLPower: 9mW; Cost: $40
21Experimental Results22EvaluationMIT campus- four streetsCaraoke readers were placed on 12.5-feet polesStandard E-ZPass transponders on the cars
23Accuracy of Counting TranspondersHigher accuracy and significantly lower cost than camera-based systems [R.L., JEI13; J.M. Urbana08 ]24Accuracy of Localizing TranspondersCaraoke enables enough accuracy to detect occupied versus available parking spots25Speed Detection AccuracyCaraoke detects the speed to within 8%26Required Time for DecodingCaraoke enables real-time smart city services27Related WorkWireless InterferenceThey require changing transmitter or leverage intrinsic asynchrony in protocols (S. G. Sigcomm12, J. W. Sigcomm08, etc.)Automated PaymentThey require a gate and physical isolation (McDonalds drive-through)Smart ParkingThey require sensors on parking spots or Wi-Fi devices in cars (Street Line, S. M. MobiSys10, S. N. Mobicom13, etc.)28ConclusionA system for delivering smart services using existing e-toll transponders
Can count, localize and decode transponders in the presence of interference
We built it into a small PCB29Omid AbariDeepak Vasisht, Dina Katabi, Anantha Chandrakasan
An E-Toll Transponder Network for Smart Cities30