10:00 AM on Thursday, May 2, 2013
Location: 430 Durham
M.S. Thesis Defense for Zachary BISKADUROS
Graduate Advisory Committee:
Dr. R. Michael Buehrer, Chair
Dr. Jeffery H. Reed
Dr. R. Michael Ruohoniemi
The localization of wireless devices, i.e. mobile phones, laptops, and handheld GPS receivers, has gained much interest due to the benefits it provides, including quicker emergency personnel dispatch, location-aided routing, as well as commercial revenue opportunities through location based services. GPS is the dominant position location system in operation, with 31 operational satellites producing eight line of sight satellites available to users at all times making it very favorable for system implementation in all wireless networks. Unfortunately when a GPS receiver is in a challenging environment, such as an urban or indoor scenario, the signal quality often degrades causing poor accuracy in the position estimate or failure to localize altogether due to satellite availability.
Our goal is to introduce a new solution that has the ability to overcome this limitation by improving the accuracy and availability of a GPS receiver when in a challenging environment. To test this theory we created a simulated GPS receiver using a MATLAB simulation to mimic a standard GPS receiver with all 31 operational satellites. Here we are able to alter the environment of the user and examine the errors that occur due to noise and limited satellite availability. Then we introduce additional user(s) to the GPS solution with the knowledge (or estimate) of the distances between the users. The new solutions use inter-receiver distances along with pseudoranges to cooperatively determine all receiver location estimates simultaneously, resulting in improvement in both the accuracy of the position estimate and availability.