In this article, the bit error rate (BER) performance of a tightly packed reconfigurable intelligent surface (RIS) assisted communication system is analyzed in terms of the level of spatial correlation. In conventional models, channels are assumed to be independent and identically distributed and continuous phase shifts are available for phase compensation. However, in practice, as RIS reflecting units are arranged in more compact form (less than 0.5) due to space constraints, correlation effects among the reflecting elements are to be considered. Further, discrete phase shifters are widely used to meet practical deployment limitations. These practical constraints severely affect the error performance of the system. It necessitates that the impact of spatial correlation and discrete phase shifts on the BER performance of the system is to be analyzed. The instantaneous signal to noise ratio is the square of the sum of correlated random variables. In order to analyze the BER performance accurately, the exact statistical distribution for the sum of spatially correlated random variables is to be chosen. In this work, appropriate distribution fitting is chosen based on the level of spatial correlation. Numerical BER expressions are derived with the chosen statistical distributions. The analysis on the impact of spatial correlation and discrete phase shifter on BER performance would be more beneficial for design and practicing engineers in the field of 6G wireless communications.

中文翻译：

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使用空间相关级别和离散移相器的紧密封装平面 RIS 系统的 BER 分析

在本文中，从空间相关性的角度分析了紧密封装的可重构智能表面（RIS）辅助通信系统的误码率（BER）性能。在传统模型中，假设通道是独立的，并且均匀分布，并且连续相移可用于相位补偿。然而，在实践中，由于 RIS 反射单元以更紧凑的形式排列（小于 0.5) 由于空间限制，要考虑反射元件之间的相关效应。此外，离散移相器被广泛用于满足实际部署限制。这些实际限制严重影响了系统的错误性能。需要分析空间相关性和离散相移对系统 BER 性能的影响。瞬时信噪比是相关随机变量之和的平方。为了准确分析 BER 性能，需要选择空间相关随机变量之和的准确统计分布。在这项工作中，根据空间相关性水平选择适当的分布拟合。数字 BER 表达式是根据所选的统计分布得出的。