We analyze the influence of an reconfigurable intelligent surface (RIS) on the channel eigenvalues within a high signal-to-noise ratio (SNR) scenario. This allows to connect specific channel properties with the rank improvement capabilities of the RIS. In particular, fundamental limits due to a possible line of sight (LOS) setup between the base station (BS) and the RIS are derived. Furthermore, dirty paper coding (DPC) based schemes are compared to linear precoding in such a scenario and it is shown that under certain channel conditions, the performance gap between DPC and linear precoding can be made arbitrarily small by the RIS.

翻译：我们分析了在高信号对噪音比情况下可重新配置的智能表面对频道电子值的影响,这样可以将特定的频道特性与RIS的等级改进能力联系起来,特别是,由于在基地站和RIS之间建立了可能的视线(LOS),因此产生了基本限制,此外,基于肮脏的纸质编码(DPC)办法与这种情况下的线性预编码比较,并表明在某些频道条件下,IRS可以任意缩小DPC和线性预编码之间的性能差距。