A Low Complexity PMI Selection Scheme for 3GPP 5G NR FDD Systems

In the 3rd generation partnership project (3GPP) new radio (NR) system, two types of codebooks, namely type I and type II, have been designed. Both types are utilized in the frequency division duplexed (FDD) codebook-based system. In the FDD codebook based system, the mobile station (MS) estimates channel state information (CSI) which includes the rank indicator (RI), the precoding matrix indicator (PMI), and the channel quality indicator (CQI), and feedbacks the CSI to the base station (BS). Although the type II CSI feedback promises more significant performance gain than the type I CSI feedback, the computational burden to estimate CSI is increased due to the high resolution of the type II codebook. This paper proposes a low complexity PMI selection scheme of type II codebook for 3GPP 5G NR FDD systems. The proposed scheme achieves similar performance to the conventional search scheme with a full search while the computational complexity is significantly reduced.