Network and Systems Laboratory nslab.ee.ntu.edu.tw Energy-Accuracy Trade-off for Continuous Mobile Device Location Kaisen Lin, Aman Kansal, Dimitrios Lymberopoulos, and Feng Zhao Archiang
Network and Systems Laboratorynslab.ee.ntu.edu.tw
Energy-Accuracy Trade-off for Continuous Mobile Device Location
Kaisen Lin, Aman Kansal, Dimitrios Lymberopoulos, and Feng Zhao
Archiang
Network and Systems Laboratorynslab.ee.ntu.edu.tw
OutlineIntroductionSystem OverviewSystem DesignExperiments and EvaluationConclusions
Network and Systems Laboratorynslab.ee.ntu.edu.tw
IntroductionPopular mobile localization resource
GPS, WiFi, Cell-tower ID, BluetoothContinuous and ubiquitous location access aren’t
available due to energy constraint
Using multiple location sensors simultaneously to make up for this variability in accuracy would further increase energy use.Tradeoff between energy and accuracy
Network and Systems Laboratorynslab.ee.ntu.edu.tw
Goal: a system that automatically manages location sensor availability, accuracy, and energy.GPS, WiFi, Cell-tower ID, BluetoothOpen sky view locations, availability and accuracy.Static and mobile
ExamplePizza stores in PortlandShoppingFinding friends
a - Loc
Network and Systems Laboratorynslab.ee.ntu.edu.tw
System Overview Bayesian estimation
Combine the sensor data and predicted location to provide a ML estimation
Discretization A-Loc uses a 10m step size for space
discretization. A-Loc uses time granularity of 1 minute
Training
Network and Systems Laboratorynslab.ee.ntu.edu.tw
System DesignGPS, WiFi, Bluetooth, and cell-tower
on Android G1 and AT&T Tilt phones
Accuracy Models
Network and Systems Laboratorynslab.ee.ntu.edu.tw
Selection Algorithm The goal of the selection algorithm
is to determine the most energy efficient sensor to be used, such that the required location accuracy can be achieved.
This algorithm also maintains an estimate of the user’s location that is based on a prediction of user movements.
Use Hidden Markov Model (HMM)
Network and Systems Laboratorynslab.ee.ntu.edu.tw
Experiments and EvaluationPrototype Implementation
Android’s LocationManager API
Application Accuracy Requirement
Network and Systems Laboratorynslab.ee.ntu.edu.tw
System PerformanceAccuracy requirement
A-Loc compares withStatic
Least energy consumptionPeriodicPerfect Models
Best resolution
Network and Systems Laboratorynslab.ee.ntu.edu.tw
ConclusionsThe authors present a-Loc system that can automatically
tunne the location energy and accuracy trade-off by continually adapting to the dynamic location sensor characteristics and application needs.
A-Loc provides significant energy savings that go beyond existing techniques.