093 - Enabling PPP ambiguity resolution in satellite and terrestrial frequency-varying carrier-phase signals

093 - Enabling PPP ambiguity resolution in satellite and terrestrial frequency-varying carrier-phase signals


Carrier-phase signals constitute the key observations in Global Navigation Satellite Systems (GNSS) for precise user positioning. To fully exploit these high-precision measurements, one needs to recover the integer nature of ambiguities. The Integer Ambiguity Resolution enabled Precise Point Positioning (PPP) concept, namely PPPAR, has proven to be capable of delivering centimetre-level positioning for CDMA based GNSSs, i.e., when the satellites transmit signals on identical frequencies. 

The recent developments of Low Earth Orbit (LEO) constellations for communication purposes (e.g., Iridium, Starlink) have raised an interest in the navigation domain. Due to their low altitude, the LEO satellites enable stronger signal reception levels on the ground and their fast geometry change can contribute to faster PPP convergence time. Furthermore, 5G provides new navigation opportunities, on ground and in space, also due to larger bandwidth and higher frequencies. Used as signals of opportunity, they can efficiently serve in aiding positioning users for improved performance or in realizing alternative positioning. 

However, this comes at the cost of processing carrier-phase signals with frequency diversity and different multiplexing schemes among terrestrial and satellite transmitters. The fact that the transmitters (LEO, 5G, etc.) transmit signals on different carrier frequencies prevents the users from forming the conventional double-difference and, therefore, integer ambiguities. Therefore, there is the need to tackle this challenge in order to be able to achieve rapid and ubiquitous centimetre-level positioning with: 

  • non-GNSS frequency-varying carrier-phase signals for alternative PPP-AR, and
  • GNSS/LEO/5G frequency-varying carrier-phase signals for augmented PPP-AR in challenging user environments


The objective of the activity is to define, implement and test algorithms for enabling high-accuracy positioning with IAR in LEO and 5G frequency-varying carrier-phase signals, and to develop a proof-of-concept demonstrator for a GNSS/LEO/5G PPP-AR user positioning setup.


The tasks to be performed shall include:

  • State-of-the-art review on the integer-estimability concept in transmitter-dependent carrier-phase measurement systems
  • Investigation, definition, design and trade-off analysis of the network and user
  • algorithms to support the full exploitation of frequency-varying carrier-phase signals for IAR-enabled positioning targeting the GNSS/LEO/5G user applications in challenging environments.
  • Development of a measurement generator for GNSS, LEO and 5G signals suitable for positioning applications.
  • Development of a software prototype for
    • network correction generation and,
    • PPP-AR positioning using integrated GNSS, LEO, 5G carrier-phase signals.
  • Prototype verification and performance assessment with representative synthetic measurements for various network configurations and challenging user environments
  • Definition, realization, and assessment of 5G and/or LEO test cases with real-world carrier-phase measurements, including identification and resolution of problem areas.


The main outputs of the activity will consist of:

  • Design Data package (reports, algorithms, results, etc.) providing a complete understanding of the achievable capabilities of IAR-enabled positioning based on frequency-varying carrier-phase signals.
  • Emulated-real-time post-processing software and user manual.
  • Potential Conference papers and patents.