From the thesis abstract: "The Global Positioning System (GPS), a satellite navigation system, is critical to the United States' (U.S.) national and homeland security. The U.S. has made GPS resilient to interruption by flying more satellites than required, dispersing its infrastructure, and increasing its signals. Despite these efforts, there is concern the U.S. may not be able to overcome disturbances in GPS's operations. Limitations in GPS data and the policy literature prevent the full quantification of exactly how vulnerable GPS is to service interruption. This thesis used constant comparison analysis to examine how a shift in conceptual lens from viewing GPS as public utility to viewing it as a software platform has changed our understanding of its criticality, resilience, and vulnerability. This methodology overcomes research limitations by using GPS system design, operations, and policies as its data sources. The public utility lens reveals the U.S. has increased GPS resilience through system design and redundancies. The software platform lens shows the U.S. further increased GPS resilience by adding navigation signals. Together, the lenses indicate manufacturers, applications developers, and users are constraints to increasing GPS's resilience. Additional data, models, and research are required to inform policies and decisions to further improve GPS's resilience."
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