A Novel Scheme to Mitigate the RNTI-FA in Blind Detection of 5G Polar Codes

Polar codes have been selected as the channel coding scheme for 5G new radio physical downlink control channel (NR PDCCH). In 5G NR PDCCH, blind detection is performed by user equipment (UE) to obtain its intended information. During blind detection, false alarm (FA) may happen which means that the UE can decode successfully even there is no intended information. FA can be caused by many factors. In this paper, we focus on the FA caused by radio network temporary identifier (RNTI), we call it RNTI-FA. RNTI-FA may happen even in high SNR range and results in abnormal network status. We firstly investigate the causes of RNTI-FA. Then a novel RNTIFA mitigate scheme, based on the Hamming distance metric, is proposed to reduce the RNTI-FA. The simulation results show that the RNTI-FA rate can be reduced from $10^{-1}$ to $10^{-5}$ or lower with negligible performance loss in the medium-to-high SNR range.