Coherent Integration of Future GNSS Signals

R.T. Ioannides, L.E. Aguado, G. Brodin

Abstract:	Indoor GNSS positioning suffers from low received CNR values due to the reduction of the signal strength penetrating through buildings and also due to the increased interference from sources usually present indoors. This situation imposes new more stringent requirements to the design of GNSS sensors for both the acquisition and tracking functions. Acquisition of low CNR signals is the most demanding task for indoor positioning applications, since the tracking loops have a greater dynamic range. Once the satellite signals have been acquired the tracking loops can be set to track these signals by increasing the integration period, or dwell time, of the correlation totals. Furthermore, the loss of tracking of weak signals in indoor environments is another aspect that has to be tackled by designing a faster reacquisition algorithm that overcome today´s limitations in the use of GNSS sensors indoors. In the past years a number of different methods have been introduced improving the performance of indoor positioning, such as assisted GNSS, where the reference network provides assistance in terms of the navigation message, initial position and time estimate. This allows the GNSS sensor to increase the coherent integration times within the receiver with the consequent sensitivity gains. However, such techniques rely on the availability of an assistance network. The new modernized GPS signals and the Galileo signals will provide the user with an additional opportunity to achieve accurate and reliable indoor positioning, without relying on such assistance data. Since each of the modernized GPS and Galileo satellites will be transmitting two or more signals at different carrier frequencies, there is an opportunity to increase the overall received signal energy by appropriately combining the energy of each of these, which can improve signal acquisition.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	1253 - 1268
Cite this article:	Ioannides, R.T., Aguado, L.E., Brodin, G., "Coherent Integration of Future GNSS Signals," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 1253-1268.
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