Interference Measurement Methods in 5G NR: Principles and Performance

In this paper, we describe and analyze two different interference measurement (IM) methods for 5G New Radio (NR) networks, with particular emphasis on cell-edge users and thus interference limited scenarios. Specifically, the non-zero-power channel state information (CSI) reference signal (NZP CSI-RS) based method and the CSI interference measurement (CSI-IM) method are defined, studied and compared. In general, IMs are an essential ingredient in efficient link adaptation techniques, particularly in the form of channel quality indicator calculations which build on interference and channel response measurements at user equipment. Hence, we specifically study the impact of different IM methods on 5G NR link adaptation and throughput performance, incorporating both inner loop and outer loop link adaptation procedures. Different IM methods are defined, discussed and their basic operation principles are revised, including system overhead aspects, and detailed performance evaluation and comparison is provided. Our results show that NZP CSI-RS method allows to achieve more accurate IM than CSI-IM method, when measuring non-precoded interference and noting practical channel estimation and measurement errors. The CSI-IM method performs better than NZP CSI-RS method with practical channel estimation and measurements when the precoded interference is measured.