This paper addresses the mobility problem in extremely large antenna array (ELAA) communication systems. In order to account for the performance loss caused by the spherical wavefront of ELAA in the mobility scenario, we propose a wavefront transformation-based matrix pencil (WTMP) channel prediction method. In particular, we design a matrix to transform the spherical wavefront into a new wavefront, which is closer to the plane wave. We also design a time-frequency projection matrix to capture the time-varying path delay. Furthermore, we adopt the matrix pencil (MP) method to estimate channel parameters. Our proposed WTMP method can mitigate the effect of near-field radiation when predicting future channels. Theoretical analysis shows that the designed matrix is asymptotically determined by the angles and distance between the base station (BS) antenna array and the scatterers or the user when the number of BS antennas is large enough. For an ELAA communication system in the mobility scenario, we prove that the prediction error converges to zero with the increasing number of BS antennas. Simulation results demonstrate that our designed transform matrix efficiently mitigates the near-field effect, and that our proposed WTMP method can overcome the ELAA mobility challenge and approach the performance in stationary setting.

翻译：本文针对超大规模天线阵列（ELAA）通信系统中的移动性问题展开研究。为应对移动场景下ELAA球面波前引起的性能损失，我们提出一种基于波前变换的矩阵束（WTMP）信道预测方法。具体而言，我们设计了一个变换矩阵，将球面波前转化为更接近平面波的新波前。同时设计了时频投影矩阵以捕捉时变路径延迟。此外，我们采用矩阵束（MP）方法进行信道参数估计。所提出的WTMP方法能够在预测未来信道时抑制近场辐射效应。理论分析表明，当基站天线数量足够大时，所设计变换矩阵渐近地由基站天线阵列与散射体或用户之间的角度和距离决定。针对移动场景下的ELAA通信系统，我们证明预测误差随基站天线数量增加而收敛至零。仿真结果表明，所设计的变换矩阵能有效抑制近场效应，且提出的WTMP方法能够克服ELAA移动性挑战，逼近静态场景下的性能表现。