Signal Processing and Speech Communication Laboratory
hometheses & projects › Carrier Phase-Based Ranging for Smart Car Access Systems

Carrier Phase-Based Ranging for Smart Car Access Systems

Master Thesis
Announcement date
17 Jun 2019
Johanna Kerber
Research Areas

Modern cars are equipped with a passive keyless entry & start (PKES) system which allows users to access and start the car without actively using the key fob. Existing systems use a combination of two technologies: a low-frequency (LF) magnetic field to determine the location of the fob (ranging), and an ultra-high radio frequency (UHF/RF) link to establish communication between fob and car. Because LF magnetic fields remain largely undisturbed by environmental factors including human body effects, the fob location can be accurately determined by measuring the received field strength (RSSI).

Given the ubiquity of smart devices (phones, watches, etc.) there is a shift towards smart car access systems, with LF/UHF being replaced by existing RF technologies. Due to its wide availability in smart devices, Bluetooth is one of the potential RF technologies for a PKES system where it will be used for both ranging and communication between device and car. In addition to using RSSI and time of flight, ranging information can be obtained from phase shifts induced at multiple carrier frequencies.

In this master thesis you will investigate algorithms for carrier phase-based ranging and assess their applicability to smart car access using Bluetooth.


  • Review literature on carrier phase-based ranging algorithms (MUSIC, ESPRIT, maximum likelihood, sparse Bayesian learning, …)
  • Develop and implement algorithms in Matlab using existing RF transceiver model and compare algorithm complexity
  • Evaluate impact of different channel models and transceiver imperfections (IQ phase/gain imbalance, phase noise) on ranging performance
  • Perform measurements in a real-world car access scenario using Bluetooth devices and evaluate algorithm performance on measurement data

Your Profile:

  • Master student in electrical engineering, software engineering, or similar studies
  • Interest in development and Matlab implementation of signal processing algorithms
  • Basic knowledge in Matlab programming
  • Eager to interact with an international team of system, hardware, and software engineers