Indoor Positioning Kalid Azad Advisor: Prof. Littman (MAE dept) Co-advisor: Prof. Cook Cs398 Project Proposal

Problem Description What is indoor positioning? Find your location accurately indoors (like GPS) Why is it important? Unsolved problem Indoor robots, underground surveying, detailed maps/directions…

Why is it hard? GPS doesn’t work indoors! No line of sight… No obvious alternative Previous approaches: Psuedo-GPS, IR signal strength, RF, ultrasonic/acoustic… Indoor radio propagation not well studied Reflection, absorption from obstacles Walls/windows/doors have different delays Cost! No $100,000 atomic clocks allowed. Light travels ~ 1 ft/ns Hard to measure propagation delays w/o good clocks Resolution Want ~ 1 ft resolution (not room-level granularity)

Approaches My approach: use phase differences Multiple transmitters send sine waves Receiver notes relative phase differences Calculates how many wavelengths away from transmitter Receiver solves for its position Or, transmit data to central server, which calculates position and sends it back (via wireless network)

My Approach T1 T2 = Possible location 1 wavelength

My Approach Advantages No atomic clock/synchronization, works on RF, good resolution, phase easy to detect Done before? On google, only found 1 paper describing use of phase differences Not done in hardware

Methodology, milestones, and deliverables Steps Extensive survey of current technology Create a method Develop algorithm, order hardware Develop software Proof-of-principle Web-based, GUI Implement in hardware

Methodology, milestones, and deliverables By checkpoint (~1 month) Thoroughly examined existing technology Created algorithm Ordered hardware Begin coding software Deliverables Report Detailed description of algorithm Hardware Requirements Portion of software implementing algorithm

Methodology, milestones, and deliverables Remaining steps for semester Implement algorithm in hardware If possible, use on a vehicle Deliverables by end of semester Detailed algorithm Software implementation Hardware implementation

Methodology, milestones, and deliverables Difficulties A good algorithm is… Cost-effective, precise, easy to implement, without atomic clocks/synchronization, robust… Getting hardware to work properly No specialized hardware for my algorithm Method may not be as precise as planned

Methodology, milestones, and deliverables Fall-back plan Explain what I found with my algorithm Benefits, drawbacks, tradeoffs Measure position with the precision I can Find limitations, sources of errors, effect of various obstacles (walls, doors, windows) If it doesn’t work… Document what doesn’t work, and why Lesson for others =)