Enhanced GNSS Signal Tracking in Fading Environments Using Diversity Reception
Engineering--Electronics and Electrical
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AbstractThis research focuses on improving GNSS signal tracking performance in multipath fading environments through diversity combining. Despite the remarkable amount of research already reported in the literature, the concept of diversity combining at the correlator level to enhance tracking and measurement performance is not broadly discussed. To this end, two types of diversity combining, namely spatial and frequency diversity combining are investigated. The first phase of the research characterizes spatial diversity reception in harsh fading environments. The signal power, delay spread and Doppler spread characteristics of GNSS signals are investigated. As a consequence of exploiting the spatial diversity behavior, a closed-loop tracking architecture is proposed. The proposed method is tested on data collected in indoor static and urban kinematic scenarios. The carrier and code loop tracking errors between single antenna and dual antenna spatial diversity reception for different scenarios are compared. Results show improved performance in the latter case. In the second phase, the characteristics of frequency diversity reception with those of spatial diversity in a harsh fading environment are compared. The frequency diversity reception is characterized in terms of temporal C/N0 fluctuations, correlation coefficients and other metrics. The SNR enhancement obtained from frequency diversity combining is compared with that of spatial diversity combining. The correlation peak distortion reduction resulting from the two diversity combining methods is also investigated. By exploiting the frequency diversity behavior, the third phase proposes two closed-loop tracking approaches to enhance carrier and code tracking robustness in fading environments. The first approach is targeted to harsh fading environments. It performs carrier Doppler and code phase tracking using a dual-frequency diversity combined signal. The tracking and navigation solution performance evaluated in dense foliage and residential environments show reduced errors and improved continuity and availability of navigation solution. The second approach is targeted to moderate fading environments which achieves carrier phase tracking with PLLs using diversity combined signal. The proposed method is tested on data sets collected in static and kinematic scenarios in terms of reduction in carrier Doppler error and carrier phase cycle slips.
CitationSIddakatte, R. K. (2016). Enhanced GNSS Signal Tracking in Fading Environments Using Diversity Reception (Unpublished doctoral thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/25900
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