Average Spectral Efficiency for TDD-based non-Stationary XL-MIMO with VR Estimation

Extra large scale massive multiple-input multiple-output (XL-MIMO) has become a key technology for the next generation wireless communications. This paper considers a multi-user XL-MIMO system in non-stationary scenarios, where the impact of spatial non-stationarity is characterized by visibility region (VR). We first estimate VR of users by using the received training signal with the pilot sequences since VR information is unknown. Then, we estimate the channel from users to the BS antennas within their corresponding VR estimation. By using the VR and channel estimations, we derive an approximation of the average spectral efficiency and design the optimal VR detection threshold to maximize the average spectral efficiency. Finally, we confirm the correctness of our analysis and the effectiveness of the proposed method by simulation and numerical analysis.