Direction Estimation of the Attacked Signal in PBCH of 5G NR

This letter investigates the jamming attack in the physical broadcast channel (PBCH) of the fifth generation (5G) new radio (NR) that conveys critical information of the cell called master information block (MIB). Since smart attack on PBCH is simply possible using the information of synchronization signal block (SSB) that is unencrypted during the initial access, this channel is one of the most effective choices from a jammer's point of view. In this study, we propose a hypothesis test to detect the presence of a jamming attack in the PBCH block and, furthermore, we estimate the principal direction of the attacked PBCH demodulation reference signal (PBCH DMRS) that significantly deviates under that attack. These achievements are also presented in the form of semi-definite programming (SDP) relaxation. PBCH DMRS is located at 25% of the PBCH block and is vital for PBCH extraction to initiate a radio connection between user and an appropriate cell. Simulation results evaluate the proposed method in various aspects and prove its superiority over the recent competing methods.