5G NTN Primary Synchronization Signal: An Improved Detector for Handheld Devices

We consider a Low Earth Orbit (LEO) satellite hosting a 5G base station transmitting to a handheld device in L-band or S-band. This link is critical because it is characterized by a very low Signal-to-Noise Ratio and significant Residual Frequency Offset (RFO) due to imperfect Doppler compensation. Usual methods adopted to detect the Primary Synchronization Signal (PSS) during Cell Search of terrestrial networks may fail in these conditions. In this paper we present an improved method for PSS detection, working in the frequency domain and exploiting the peculiar structure of the 5G PSS. We derive the exact analytical model, taking into account the Orthogonal Frequency Division Multiplexing (OFDM) InterCarrier Interference (ICI) and we obtain the corresponding optimal statistical test. We present a number of results showing that the new detector achieves significant performance improvements for realistic 5G Non-Terrestrial Network (NTN) scenarios.