{"id":14137,"date":"2025-08-06T13:30:33","date_gmt":"2025-08-06T11:30:33","guid":{"rendered":"https:\/\/www.uni.lu\/research-en\/?post_type=events&p=14137"},"modified":"2025-09-24T08:49:44","modified_gmt":"2025-09-24T06:49:44","slug":"doctoral-defence-alejandro-gonzalez-garrido","status":"publish","type":"events","link":"https:\/\/www.uni.lu\/research-en\/events\/doctoral-defence-alejandro-gonzalez-garrido\/","title":{"rendered":"Doctoral Defence: Alejandro GONZ\u00c1LEZ GARRIDO"},"content":{"rendered":"\n
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The Doctoral School in Science and Engineering<\/a> is happy to invite you to Alejandro GONZ\u00c1LEZ GARRIDO\u2019s defence entitled<\/p>\n\n\n\n

\nContributions to Hybrid 5G and GNSS for PNT applications<\/h5>\n\n\n\n

Supervisor:<\/strong> Dr Jorge QUEROL<\/a><\/p>\n\n\n\n

Abstract<\/strong>:<\/p>\n\n\n\n

The thesis provides a  global navigation satellite systems (GNSS)-independent system  leveraging 5G new radio (NR) as an integrated communications and positioning platform within non-terrestrial networks (NTN). A key contribution is a statistical interference model for the use of the positioning reference signal for navigation services in  multi-satellite low Earth orbit (LEO) deployments. By using Monte Carlo analyses the  aggregate interference is well described by a generalized extreme value (GEV) distribution, yielding practical interference bounds for link-budget design and system dimensioning.<\/p>\n\n\n\n

Building on this characterization, two joint communication and positioning (JCAP) payload architectures for 5G-NTN are developed and optimized: (i) a so called \u201cshared-beam\u201d scheme that multiplexes a direct spread spectrum sequence (DSSS) for navigation with 5G signal for data within the same beam, and (ii) an \u201cindependent-beam\u201d scheme that separates navigation and communications signals in different beams, where a wide navigation beam overlap all data beams, therefore a user will receive the signal from both services. Then, a Pareto analysis quantifies the tradeoff between spectral efficiency and positioning accuracy, demonstrating consistent meter-level accuracy with minimal spectral efficiency degradation.

Finally, a hybrid receiver for the JCAP waveform designed can offer the navigation observables and the data by using  an extended Kalman filter for Doppler estimation, maintaining reliable tracking under strong interference from the data service and an uncoded bit error rate (BER) similar to dedicated data receivers.
Collectively, the results show that current NTN infrastructures, with modest modifications and full backward compatibility, can deliver resilient GNSS-independent PNT and lay groundwork for 6G convergence of communication and positioning.<\/p>\n\n\n\n