We consider the design of a uniform circular array (UCA) system under array misalignment over line-of-sight (LoS) channels. UCAs have been considered as useful array structures since their LoS channels can be diagonalized without the channel state information at the transmitter (Tx). However, such a characteristic holds only when transceiver arrays are perfectly aligned. To overcome this difficulty, we propose an optimal design method and transceiver architectures for UCA systems under array misalignment that achieve channel capacity without knowledge of misalignment angles. To this end, we first verify that the singular values of the misaligned UCA system are independent of tilting and center-shift and small relative array rotation, but fluctuate with the Radii Product to Distance Ratio (RPDR). Using the result, we present an optimal design method for UCA systems that performs an one-dimensional search for the RPDR to maximize channel capacity, and we show that a simple zero-forcing (ZF) receiver can achieve the maximum channel capacity because of the channel characteristic at the optimal design criteria. Additionally, we propose a low-complexity precoding scheme for UCA systems in which the optimal design criteria cannot be fulfilled. The simulation results demonstrate the validity of the proposed design method and transceiver architectures.

中文翻译：

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具有均匀圆形阵列的 LoS-MIMO 系统的设计与分析

我们考虑了在视距 (LoS) 信道上阵列未对准情况下的均匀圆形阵列 (UCA) 系统的设计。UCA 被认为是有用的阵列结构，因为它们的 LoS 信道可以在没有发射机 (Tx) 的信道状态信息的情况下对角化。然而，只有当收发器阵列完全对齐时，这种特性才成立。为了克服这个困难，我们为阵列未对准下的 UCA 系统提出了一种最佳设计方法和收发器架构，可以在不知道未对准角度的情况下实现信道容量。为此，我们首先验证未对齐的 UCA 系统的奇异值是独立于倾斜和中心偏移和小的相对阵列旋转，但随着 半径积距离比 (RPDR)。使用该结果，我们提出了一种 UCA 系统的最佳设计方法，该方法对 RPDR 执行一维搜索以最大化信道容量，并且我们表明简单的迫零 (ZF) 接收器可以实现最大信道容量，因为最佳设计标准下的信道特性。此外，我们为无法满足最佳设计标准的 UCA 系统提出了一种低复杂度的预编码方案。仿真结果证明了所提出的设计方法和收发器架构的有效性。