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Digital archive of theses discussed at the University of Pisa


Thesis etd-04202012-125157

Thesis type
Tesi di dottorato di ricerca
Thesis title
Signal design and Theoretical bounds for Time-Of-Arrival estimation in GNSS applications
Academic discipline
Course of study
relatore Prof. Morelli, Michele
tutor Prof. Luise, Marco
  • Binary Offset Carrier (BOC)
  • Continuous Phase Modulation (CPM)
  • Cramér-Rao Bound (CRB)
  • Filtered Multitone (FMT)
  • Gaussian MSK (GMSK)
  • GNSS
  • Modified Cramér-Rao Bound (MCRB)
  • Modified Ziv-Zakai Bound (MZZB)
  • Multicarrier
  • ranging
  • spread-spectrum
  • theoretical bounds
  • time delay estimation (TDE)
  • tracking
  • Ziv-Zakai Bound (ZZB)
Graduation session start date
Positioning accuracy in satellite navigation systems depends on time-delay estimation (TDE) between satellite transmitted codes and local receiver replicas.
This thesis is specifically focused on the problem of improving time delay estimation (TDE) accuracy of SS signals, focusing on the fundamental issue of estimation theory and on the properties of the transmitted signal.
TDE fundamentals limits are deeply investigated, encompassing the Cram´er Rao Bound and the Ziv-Zakai Bound, and their modified versions to lighten their computation in presence of unknown parameters, in addiction to the time delay. The adoption of the ZZB as benchmark for both acquisition and tracking stage performance is addressed, analyzing innovative or standard signalling waveforms such as Galileo SIS.
The main contributions of this thesis are dealt with the analysis of applicability of spread spectrum continuous phase-modulated (SS-CPM) and spread spectrum filtered multitone (SS-FMT) as ranging signals. A special subset of CPM, labeled as “Semi-integer MSK (SiMSK)” obtained by properly setting the modulation parameters, is revealed easily adaptable to the requirements on emissions, intrinsically constant envelope and spectral efficient, while still allowing good tracking performance. Besides, an ad hoc encoding of the SS-SiMSK enables the design of a constant envelope signal bearing two different rate services, without any approximation at the transmitter side. The analysis of the multicarrier (MC) signal revealed the high degree of freedom in its design, proposing the special Filtered Multitone (FMT) modulation as possible candidate for ranging signals. The strictly bandlimited property and the full spectral flexibility possessed by the FMT are exploited in some cases of study to adapt the system to channel conditions or in particular to emulate existing or innovative spectra. For both the SSCPM and SS-FMT modulation schemes investigated, some estimation algorithms are tested and their performance are compared to the correspondent theoretical bound.