Codes Cross-Correlation Impact on the Interference Vulnerability of Galileo E1 OS and GPS L1C Signals

This paper presents an assessment study of the impact of the spreading code properties in the reception of Galileo E1 Open Service (OS) and GPS L1C Multiplexed Binary Offset Carrier (MBOC) signals. The distortion of the discrimination function due to codes cross-correlations properties is analyzed, considering the features of the modulation schemes and investigating also different code families. Simulation results demonstrate that the S-curve of the code synchronization loop can be affected by an asymmetry and a bias in the lock point. Such a distortion can be noticed only in case of receiving a single channel (e.g. the pilot channel), whereas it is not present if the received signal is correlated with a coherent local replica including both data and pilot channels. This effect depends on the code cross-correlation properties and on the receiver setup (reception of data/pilot channels, variable correlators spacing). As a demonstration of its impact on a real single channel receiver, it is also shown that in presence of an interfering signal such a distortion can be magnified and lead to relevant performance degradation.