Pilot-Free Channel Change Detection for mmWave Massive MIMO System

Millimeter wave (mmWave) communication is a promising technology for future outdoor cellular systems. However, the abrupt channel change is more prone to occur over mmWave band compared to conventional frequencies, which will degrade the system performance. Hence, it is important to detect the channel change accurately for preparation of re- estimating the channel state information (CSI). In this paper, we attempt to solve the channel change problem from the perspective of change-point detection. By exploiting the low-rank characteristic of mmWave massive multiple-input multiple-output (MIMO) channel, the received signals can be viewed as data points in a subspace superimposed with noises. Then a cumulative sum (CUSUM)-based subspace change-point detection algorithm is designed to detect the mmWave channel change. The method can work without the aid of pilot signals and is of low computational complexity and memory requirement. Results are provided to validate the satisfactory of the proposed method.