In this letter, we propose a novel way to mitigate the notorious pilot contamination in massive multiple-input multiple-output (MIMO) systems by exploiting the intelligent reflecting surfaces (IRSs). Particularly, we intentionally break the uplink (UL) and downlink (DL) channel reciprocity in time-division duplexing (TDD) systems by configuring the phases of the IRSs differently during the UL training phase and the DL data transmission phase. In this way, we show that the pilot contamination is mitigated and can be eliminated in some cases. Meanwhile, we analyze the signal-to-interference-plus-noise ratio (SINR) performance due to the non-reciprocal UL and DL channels. We further show the asymptotic optimality of our proposed decontamination scheme. The analytical results are also corroborated by numerical simulations.

中文翻译：

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基于 IRS 的 TDD 互易破坏用于大规模 MIMO 中的导频去污

在这封信中，我们提出了一种通过利用智能反射面 (IRS) 来减轻大规模多输入多输出 (MIMO) 系统中臭名昭著的导频污染的新方法。特别地，我们通过在 UL 训练阶段和 DL 数据传输阶段不同地配置 IRS 的相位，有意打破了时分双工 (TDD) 系统中的上行链路 (UL) 和下行链路 (DL) 信道互易性。通过这种方式，我们表明试点污染得到缓解，并且在某些情况下可以消除。同时，我们分析了由于 UL 和 DL 信道不互易导致的信号干扰加噪声比 (SINR) 性能。我们进一步展示了我们提出的净化方案的渐近最优性。数值模拟也证实了分析结果。