Noise Variance Estimation in 5G NR Receivers: Bias Analysis and Compensation

This paper investigates the problem of noise variance estimation in orthogonal frequency domain multiplexing (OFDM)-based systems such as SG New Radio (NR). Accurate estimation of the noise variance is critical for the receiver performance, especially when applied with linear minimum mean square error (LMMSE) channel estimation (CE). A commonly used method estimates the noise variance from the power of the residual signal at the CE output. In this paper, we prove that such conventional estimator is biased, resulting in underestimation of the noise variance; then, we derive a bias correction method. Simulation results show that the proposed bias correction can significantly improve LMMSE CE performance, achieving up to 1dB gain in terms of block error rate (BLER).