Narrowband interference rejection studies for Galileo signals via Simulink

Four Global Navigation Satellite System (GNSS) are scheduled to be fully operational orbiting the Earth in the coming years. A considerably high number of signals, coming from each of the satellites that will constitute those constellations, will share the radio electric spectrum. Aeronautical Radio Navigation Systems (ARNS) share the E5 Galileo band. Examples of ARNS are Distance Measuring Equipment (DME) and Tactical Air Navigation system (TACAN). It should also be mentioned that electronic attacks (jamming or spoofing) have always been a latent threat for satellite services. All of this are important interference sources which can partially or completely disable a GNSS system. These interferences must be, and are currently being studied together with interference mitigation methods. The aim of the work presented in this thesis is to study the narrowband interference effects in Galileo E5 band and to assess three mitigation techniques against two types of narrowband interferences, Continuous Wave Interference (CWI) and DME signals. Cancellation techniques can be classified into two major groups: time-domain approaches and frequency-domain approaches. Methods that combine time and frequency together are also given in the literature (e.g. cyclostationarity-based methods) but their implementations are very costly with high sampling rates as those used for example in Galileo E5 signals. The mitigation techniques that are addressed in this thesis are zeroing, dynamic notch filtering and blanking pulse methods. All of them can be understood as filtering techniques that remove any signal above a certain threshold. This thesis shows that zeroing is more suitable for CWI and blanking is better against DME signals. These techniques have been developed within a Matlab-Simulink based simulator initiated in 2007 at Tampere University of Technology. The implemented simulator could be a great help tool for future research and development projects

NLOS mitigation techniques in GNSS receivers based on Level Crossing Rates (LCR) of correlation outputs

Global Navigation Satellite Systems (GNSS) provide navigation services with a highly precise estimation of the position. First military influenced, the use of satellite-based positioning has gained a lot of interest also in civilian tasks nowadays. Because the GNSS performance has been improved over the years, the state-of-the-art GNSS navigation does include indoor positioning and moving autonomously with help of GNSS. The accuracy, which essentially has to be high, can be disturbed by multipath (e.g. diffraction, reflection, refraction or scattering). A possibility to detect multipath, and possibly to avoid those signals in the position solution, is totally necessary. A non-direct signal, namely Non-Light-of-Sight (NLOS), can lead to low accuracy of the positioning. Therefore, this thesis is dealing with the NLOS detection by using the Level Crossing Rate (LCR), which has been used in electronic communication such as Wifi. The thesis is divided in two parts, including a literature review part, following by a simulation of the developed detection technique. All basic knowledge about this work can be extracted from the literature part. In the simulation section, several tests will be provided, done by Matlab simulations. To perform a realistic GNSS signal, a dynamic Galileo Composite Binary Offset Carrier (CBOC) signal was produced