Performance Evaluation of the RF Receiver for Precision Positioning System

One of the major drivers for developing integrated navigation systems is the vision to provide first responders and healthcare providers, critical information where and when they need it. These integrated wireless devices of the future will assist the user with communications and incident management operations in the field in real time. The most important piece of such a system is clearly a ability to track and locate these wireless devices with high precision in a high-multipath environment. A previous paper presented a novel method for precise geolocation in indoor environments using an orthogonal frequency domain multiplexed (OFDM) signal consisting of many sinusoidal sub-carriers [1]. Unlike the ultra wideband signals that are often proposed for performing precision location in high multipath environments, the proposed signal structure is easily adapted to conform to existing spectral allocations. Further, the signal structure is capable of being used in coded orthogonal frequency domain multiplexing (COFDM) systems for supporting communications and navigation concurrently on the same radio channel. This technique is also well suited for use on ad hoc wireless networks, allowing the precision location of wireless nodes with respect to one another. This OFDM-based technique was first demonstrated using audio frequency signals rather than RF signals and is currently being implemented at RF. The focus of this paper is the design and performance evaluation of the RF front end receiver structure being developed for precision location system using this multicarrier technique. The effect on the precision of the location estimate due to RF receiver design imperfections will be assessed and design issues for future receiver design improvements will be reviewed.