# Study and Analysis of Interference Signals of the LTE System of the GNSS Receiver
## 5 Summary and Conclusions  
The effect of the signal from the LTE system is realized and tested to determine how this might affect the GNSS system. The main purpose of the article was to answer the question of how it will affect symbol synchronization in the PRN code or time acquisition. All phenomena were analyzed in the GNSS receiver correlator. The method of implementation of the filter system adopted in this paper enables strong suppression of interference signals of the LTE system arriving from one direction, which is defined by the values of phase delays of carrier waves (Figure 2). Figure 15: Signal processing in the Galileo receiver operating on the L1 frequency; on the left side, the signal waveform in color without the noise suppression system applied; on the right side, the working system operating in the LTE system signal elimination for the reception of signals from six satellites. When a signal reaches the receiver via multiple paths, only the reception of the strongest component and possibly other signals coming from the same direction are blocked. If at least one of the other spatial components of the received signal is relatively strong, the reception of GNSS satellite signals may be hindered. The simultaneous elimination of signals coming from different directions is possible using such a form of the spatial filtration weights vector, in which the receiving characteristic has many zeros. If the antenna array is built of \(n\) elements, it is possible to suppress signals from up to \(n-1\) directions (Figure 4). In this case, it is necessary to determine the phase delay sets independently for each component of the antenna array in such a way that such zeros are more spatially dispersed; therefore, real signals coming from other directions than those of the LTE system may also be attenuated. For example, Figure 7 presents a comparison of averaged values of the \(C/N_{0}\) signal GNSS system and GNSS system with simultaneous reception of the LTE system signal; also plotted is a case of intentional jamming of the GNSS signal, when the signal arrives from the direction of azimuth \(\Psi\) and elevation \(\Theta\). Each of the determined values of transmission quality is an average value of 1000 results calculated for different realizations of phase delay estimation error, occurring in the GNSS receiver. It should be noted here that the scatter of this error in transmission quality depends on the \(C/N_{0}\) ratio. When GNSS signals are received with low-quality LTE signals, they are attenuated on average by several dBHz. The use of a filtering module in this situation allows achieving an improvement in \(C/N_{0}\) attenuation of unwanted signals in the range of 2 to 3 dBHz. Thus, with a high \(C/N_{0}\) ratio, the total attenuation reaches 50 dBHz, which, as mentioned earlier, is the maximum attenuation value possible in this array configuration for the assumed signal arrival direction. The simulations performed prove that the LTE system signal may cause disturbances in the carrier wave signal and in the PRN code transmitted by the satellite. The computed position may deviate slightly from that determined in the absence of an LTE signal when the GNSS receiver selects different satellites in the computation performed by the radio part of the navigation receiver. In the case when the signal power of the LTE system is high enough, it can \"jam\" the GPS receiver in such a way that the receiver was not able to acquire enough signals from the satellites and estimate the noise value currently in the receiver, which could reduce the measured distance. In turn, due to the fact that the GNSS system signal uses direct carrier modulation using the DSSS (Direct Sequence Spread Spectrum) code sequence, after conversion to navigation message data bits, the error rate (number of bits incorrectly received) BER will be much lower, because \(20\times 1023\) corresponds to one bit of navigation data.