Roman Lesjak

Mr. Roman Lesjak


Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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20 December 2023 in Engineering Proceedings
Verified
Conference Paper
Open access
PDF file
RLRoman Lesjak
Roman Lesjak
SSSusanne Schweitzer
Susanne Schweitzer
JVJosé M. Vallet
José M. Vallet
KDKarl Diengsleder-Lambauer
Karl Diengsleder-Lambauer
Selim SolmazSelim Solmaz
Selim Solmaz
To realize the societal need for greener, safer, and smarter mobility, ambitious technical challenges need to be addressed. With this aim, the H2020-EUSPA project ESRIUM investigates various aspects of highly accurate, reliable, and assured EGNSS localization information for road vehicles with a particular focus on automated vehicles. To analyze the achievable accuracy, reliability, and availability of multi-frequency and multi-GNSS mass-market receivers, we have conducted test drives under different GNSS reception conditions. In the tests, special focus was placed on using the Galileo Open Service Navigation Message Authentication (OSNMA) service, offering an additional feature for assured PVT (position, velocity, and time) information with respect to spoofing. We analyzed the performance of three Septentrio Mosaic-X5 receivers operated with different OSNMA settings. It could be shown that strict use of OSNMA provides very good positioning accuracy as long as sufficient suitable satellites are available. However, the overall performance suffers from a reduced satellite number and is therefore limited. The performance of a receiver using authenticated Galileo with GPS signals (final status of Galileo OSNMA) is very good for a mass-market receiver: 92.55% of the solutions had a 2D position error below 20 cm during 8.5 h of driving through different environments.

14 October 2021 in IEEE Transactions on Antennas and Propagation
Verified
Journal Article
Open access
FFFernando Perez Fontan
Fernando Perez Fontan
VSVicente Pastoriza Santos
Vicente Pastoriza Santos
FMFernando Machado
Fernando Machado
FPFrancisco Poza
Francisco Poza
NWNorbert Witternigg
Norbert Witternigg
RLRoman Lesjak
Roman Lesjak
In this article, we present implementation details of a generative satellite maritime propagation channel model at L-band. In an earlier paper, we presented the parameterization of the channel model for the narrowband case based on recordings of GPS L1 $C/N_{0}$ time-series in different sea state conditions. Additionally, we performed wider band measurements using GPS E5a (≈10 Mcps—chips per second— > 20 MHz bandwidth) and obtained estimations of power delay profiles. Due to lack of dynamic range and delay resolution, in these measurements, no conclusive information was gathered on the time spreading caused by the channel. What was clear is that the time spreading was not significant outside the first signal chip, i.e., $\approx 0.1~\mu \text{s}$ . Still wideband modeling is required within this spreading range. Now, we want to extend the model to the wideband case. To achieve this goal, we have used a rough surface scattering model applicable to sea surfaces and employed it to characterize the time dispersion to be expected. Additionally, we also used this scattering model to help verify the validity of the existing Doppler spread model. Furthermore, ship movements in the waves play a role. We try and analyze this issue. Finally, we present a detailed discussion on various implementation issues we came across when coding the simulator.

26 January 2021 in IEEE Transactions on Antennas and Propagation
Verified
Journal Article
Closed access
FFFernando Perez Fontan
Fernando Perez Fontan
VSVicente Pastoriza Santos
Vicente Pastoriza Santos
FMFernando Machado
Fernando Machado
NWNorbert Witternigg
Norbert Witternigg
RLRoman Lesjak
Roman Lesjak
In this article, we present a statistical narrowband mobile satellite maritime propagation channel model at the L-band based on empirical observations using GPS C/N 0 measurements from a receiver onboard a vessel in different sea conditions. The model is fully parameterized for all possible elevation angles. In the measurements, we have used a low-gain, 6.2 dBi, hemispherical antenna. The parameters provided, thus, are valid for this and similar antenna gains.

23 April 2022
Verified
Book Chapter
Closed access
PDF file
WBWerner Bailer
Werner Bailer
HFHermann Fürntratt
Hermann Fürntratt
MKManfred Klopschitz
Manfred Klopschitz
DLDominik Lampel
Dominik Lampel
RLRoman Lesjak
Roman Lesjak
GSGerald Steinbauer-Wagner
Gerald Steinbauer-Wagner

7 April 2026 in Engineering Proceedings
Verified
Conference Paper
Open access
PDF file
JHJulia I. M. Hauser
Julia I. M. Hauser
RLRoman Lesjak
Roman Lesjak
HGHamid Kavousi Ghafi
Hamid Kavousi Ghafi
Intentional and unintentional GNSS interference can greatly affect the performance of precise timing and localization in areas such as automated driving or aviation. Nevertheless, reports show that jamming occurs near many European airports that are located close to a highway or in heavy industry areas due to broadcasting of interfering signals. To assess the impact of such potential risks, we investigated interference occurring on a section of highway located both near to an airport and close to logistics centers as part of the Austrian Security Research Program project CATCH-IN. This section of highway is of particular interest, as the highway runs in parallel to the approach path of aircraft and crosses the approach path 3.7 km before the aircraft touches down (the flight altitude is only 200 m above the ground). For this experiment, we distributed six Septentrio Mosaic x5 GNSS receivers as sensors along the highway and monitored this section for five months. We analyzed the data with AGC monitoring, CN0 monitoring, and baseband sample monitoring to identify interference along the highway that could affect sensors along the descending flight trajectory. During the period of this experiment, we saw events that we believe could cause potential safety risks and problems for aviation safety. In our analysis, we focused on the statistical evaluation of the temporal repetitions, in particular the times of day that see more interference and the frequencies at which more interference occurs. Additionally, we analyzed the performance of different algorithms for dealing with large datasets. The results provide new insight into potential monitoring stations near airports and raise awareness of potential risks and vulnerabilities in aviation safety as well as automated driving along highways.

24 April 2026 in Engineering Proceedings
Verified
Conference Paper
Open access
PDF file
SSSusanne Schweitzer
Susanne Schweitzer
RLRoman Lesjak
Roman Lesjak
HGHamid Kavousi Ghafi
Hamid Kavousi Ghafi
MSMichael Schönhuber
Michael Schönhuber
VMVolker Marterer
Volker Marterer
JKJosef Kaufmann
Josef Kaufmann
GNSS-based navigation is commonly used in aircraft as a source of localization. As reports of pilots about jamming during flights are becoming more frequent, we performed jamming tests with a parked passenger aircraft to assess the criticality of jamming events. We observed the reaction of the aircraft GPS position display in the cockpit and the ADS-B availability during jamming. We analyzed the relative power levels at which the GPS-receivers and the ADS-B broadcasting show negative effects. Beyond other factors, we observed significantly long recovery times for the GPS position display and the ADS-B system. The results give unique detailed facts about the vulnerability of one type of commercial passenger aircraft and emphasize how important it is to raise awareness of this vulnerability in aviation.