Indoor GPS theory & implementation

A Global Positioning System (GPS) that works in cell-phones, and indoors, is the key to consumer applications that will dramatically improve our quality of life. GPS applications will do this by increasing two priceless resources: our security and our time. In this paper we outline the key applications of GPS in cell-phones and similar wireless devices. Most of these applications require the GPS to work indoors, and we provide an outline of the theory of indoor GPS, showing that GPS can indeed be made to work in most places that cell-phones work. Indoor GPS, or more precisely high-sensitivity GPS, is a combination of assisted-GPS (A-GPS) and massive parallel correlation. This paper describes both these components, with examples of each, and provides test results showing the theory in practice.