Design and Test Results of a Software Defined Radio for Indoor Navigation

NAVSYS has developed a Software Defined Radio (SDR) test-bed with the capability of navigating inside of buildings. This test-bed combines Global Positioning System (GPS), wireless communications, and Time-ofArrival (TOA) “Pseudolite” technology to provide location indoors for applications such as first responders, warfighters, and location-based services. The system uses network assistance over a wireless 802.11 link to enhance GPS and TOA in low-signal and degraded-signal environments (e.g. tunnels, buildings, under tree canopy, and within proximity to RF transmissions). The network assistance information includes differential pseudorange, ephemeris, and navigation data bit aiding. Each system node is capable of navigating using GPS and can switch over to TOA in areas where GPS reception is impossible using strategically located TOA transmitter nodes. The design incorporates a frequency flexible transceiver. Since the system is based on an SDR architecture, it is easily upgraded for additional capabilities including inertial integration and mesh enhancements using wireless and TOA. In addition, the system can leverage silicon economics and Moore’s Law as new computing technologies evolve to further reduce size, weight, and power. This paper presents the design and operational results of the SDR indoor navigation test bed.