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Indoor Positioning System

Indoor Positioning System . Tony Offer, Christopher Palistrant. Basic Concept. Function Make mobile device aware of its location within a building Use location awareness to provide location-dependent services Usefulness Many applications for devices that know where they are

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Indoor Positioning System

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  1. Indoor Positioning System Tony Offer, Christopher Palistrant

  2. Basic Concept • Function • Make mobile device aware of its location within a building • Use location awareness to provide location-dependent services • Usefulness • Many applications for devices that know where they are • Provision of services based on the context of locality • Target Users • Businesses with large office buildings • Maintenance workers

  3. Example Scenario Start out in office Locate coworker Head out toward coworker’s office After print stop, continue on to coworker’s office Arrive at coworker’s office Notice automatic change in mobile device

  4. User Interest • User’s degree of automation is increased • Enhanced machine autonomy • Reduced dependence on user input • Device state can change based on location • Current tasks simplified by our system • Selecting the closest office printer • Finding a person in the office building • Changing desktop environment based on inhabited room

  5. Architecture • Components • Server beacon • Speakers • 802.11 capability • Mobile client • Microphone • 802.11 capability • Process • Server beacons emit simultaneous 802.11 and ultrasound broadcasts • Clients listen for ultrasound • Clients determine location • No centralized management • Uses pre-existing hardware

  6. Indoor Positioning System In Action • iPAQ receives 802.11 room-identifying message • iPAQ hears ultrasound from nearby server beacon • iPAQ identifies its location • Human is not disturbed by inaudible ultrasound

  7. Expected Effort • Remaining components • No additional hardware needed • Need software to communicate over 802.11 • Need software to sample and analyze incoming sound • Minimum requirements • Single beacon with 802.11 card • Implement location-awareness • Desired Functionality • N beacons with less than or equal to N 802.11 broadcast points • Implement interactive map application

  8. Expected Effort (continued) • Unknowns • Reliability of ultrasound broadcast • Capabilities of the iPAQ recording system • Processing power of the iPAQ • Contingencies • If iPAQ is not sufficient • Recording system: Attach external microphone • Processing power: Use simpler DFT library • Anything else: Use laptop as mobile client • If ultrasound is unreliable • Experiment with different hardware arrangements

  9. Related Work • Cricket (MIT) • Similarities • Uses a combination of radio waves and ultrasound to determine location • No central management • Differences • Uses specialized $10 beacons and receivers • Determines 4x4 ft region within a room • Active Bat (AT&T) • Similarities • Uses a combination of radio waves and ultrasound to determine location • Differences • Uses a central management server to perform computations • Uses specially made hardware for tags and sensors • Determines location within a room to an accuracy of 9 cm

  10. Related Work (continued) • Context-Aware Computing With Sound (Intel Research, Cambridge) • Similarities • Uses standard computer speakers and microphones to generate and detect ultrasound • Differences • Modulates ultrasonic sound waves to carry data • Does not provide positioning capabilities

  11. Distinctiveness • Ideas borrowed from other projects • Emission and detection of ultrasound to signify room-level activity • Production and sampling of ultrasonic frequencies using standard computer speakers and microphones • Unique aspects of our project • Utilizes pre-existing, standard office hardware to accomplish its goals • Distinguishes itself from the Cricket and Active Bat projects • Trades high-level accuracy for simplicity and ease of deployment

  12. Burning Questions • Will the iPAQ and other standard mobile devices be able to perform fast Fourier transforms? • Is our system crippled by the inability of a mobile client device to be made aware of its location in hallways?

  13. Evaluation • Major evaluation metrics • Cost • Our system should only use readily available hardware • Reliability • Our system should provide accurate and consistent location determinations • The rate of error for false positives and negatives should be as low as possible • Desired information from user studies • Usefulness of the system • Reliability of the location determination • Speed of update when transitioning between rooms

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