Integrated NAV/COM digital receivers for indoor performance improvement

It is well known that in indoor environment performance of GNSS-based positioning are strongly limited by several factors. Acquisition of weak signals is critical, visibility of a sufficient number of satellite is not granted, and the SIS received at the antenna propagates via multiple paths. Indoor signal acquisition can be aided by external elements providing augmentation signals through dedicated links or by means of communication channels (e.g. Assisted GPS). On the other hand several techniques are being developed to integrate positioning capabilities within communication system (namely GSM, UMTS and WLAN), that cannot provide suitable accuracy when performance comparable with the dimension of the building are required. In order to provide the user of reliable positioning solutions, the synergies among different positioning information sources must be exploited, and a suitable receiver dealing both with navigation and communication signal is required. In this paper the implementation of a reconfigurable receiver integrating both navigation and communication capabilities for the specific positioning application is discussed with a particular reference to a project being developed at Politecnico di Torino aiming at the implementation of a digital receiver based on Software Defined Radio (SDR) techniques for GPS and Galileo.