# Study and Analysis of Interference Signals of the LTE System of the GNSS Receiver
## 5 Summary and Conclusions
In contrast, when an interference signal is introduced from an LTE system, BER depends on which part of the signal is dominant in demodulation. So, to effectively decode the GNSS signal, it should not be too large to dominate the demodulation. Simulations were performed for dynamic situations in realistic urban environments. Four types of GNSS measurements were considered during the simulations, including the LOS, LTE system interference signal, diffraction, and multipath, which covers most of the interference found in an urban area (Figure 7). From the point of view of each measurement, both the one-hour static experiment and the dynamic experiment with vehicles confirm that the measurement from the proposed simulator has a consistent and reasonable behavior in the error range compared to the real measurement. Furthermore, it should be added that the proposed algorithm effectively eliminated some of the noise from the correlator of the GNSS system receiver. In the next stage, the simulated measurements were applied together with advanced positioning algorithms, which verifies that the proposed simulator can adequately reflect the current difficulties in both precise positioning and in the scope of the so-called \"bottle-neck\" of different positioning algorithms. Therefore, the proposed simulator can provide realistic GNSS system measurements for multiple intermediaries (agents) to investigate and improve state-of-the-art GNSS system positioning algorithms in an urban area. It should be noted that in addition to the well-known \"noise\" caused by the interference signal of the LTE system occurring in the navigation tracking loop, the effect resulting from the initial detection process (or correlation process) and the use of the developed method significantly contributes to reducing the systematic error resulting from the fading of the navigation signals of the PLL loop of the GNSS system receiver. Another result of the analysis and simulation is the phenomenon referred to as the so-called dynamic short-range effect. This effect is an error induced in the tracking loops when the receiver moves relatively close to the signal transmitter of the LTE system. In this case, the higher derivatives of the line of sight can reach large values, even if the receiver is moving at a constant speed. This causes range errors in the tracking loops due to their indeterminate response. Additionally, in some cases, this can even cause the receiver to lose lock, whereby when the signal comes from a satellite, this effect should not be significant. However, in the case of pseudolites, it can be significant. The most significant errors are mainly generated in situations where the direct line of sight of navigation signals by the GNSS receiver is blocked and the receiver is able to track an indirect signal. In theoretical considerations, this can result in a range of errors of virtually any magnitude. In all simulations involving complete constellations, it has been clearly demonstrated that in difficult conditions (urban canyons and mountainous areas), the combined use of GPS and Galileo can significantly increase the availability and quality of service. Therefore, interoperability between these systems (GPS and Galileo) is very important (Figures 8-15). Thus, in general, it can be said that as signal structures become more sophisticated and efficient, it is more important to reduce other sources of error in the GNSS system. For example, it would be appropriate and reasonable for the Galileo to provide more accurate orbit and clock parameters than the GPS system in order to improve the overall positioning accuracy. Conceptualization, L.S. and R.K.; methodology, L.S. and R.K.; software, R.K.; validation, L.S. ; formal analysis, L.S. and R.K.; investigation, L.S. and R.K.; resources, L.S. and R.K.; data curation, L.S. and R.K.; writing--original draft preparation, L.S. and R.K.; writing--review and editing, L.S. and R.K.; visualization, L.S. and R.K.; supervision, L.S. and R.K.; project administration, L.S. and R.K.; funding acquisition, L.S.