We consider the downlink of a multi-cell massive MIMO system suffering from asymptotic rate saturation due to pilot contamination. As opposed to treating pilot contamination interference as noise (TIN), we study the performance of decoding the pilot contamination interference. We model pilot-sharing users as an interference channel (IC) and study the performance of schemes that decode this interference partially based on rate-splitting (RS), and compare the performance to schemes that decode the interference in its entirety based on simultaneous unique decoding (SD) or non-unique decoding (SND). For RS, we non-uniquely decode each layer of the pilot contamination interference and use one common power splitting coefficient per IC. Additionally, we establish an achievable region for this RS scheme. Solving a maximum symmetric rate allocation problem based on linear programming (LP), we show that for zero-forcing (ZF) with spatially correlated/uncorrelated channels and with a practical number of BS antennas, RS achieves significantly higher spectral efficiencies than TIN, SD and SND. Furthermore, we numerically examine the impact of increasing the correlation of the channel across antennas, the number of users as well as the degree of shadow fading. In all cases, we show that RS maintains significant gain over TIN, SD and SND.

中文翻译：

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多小区大规模 MIMO 系统中非唯一解码的速率分割


我们考虑多小区大规模 MIMO 系统的下行链路由于导频污染而遭受渐近速率饱和的影响。与将导频污染干扰视为噪声（TIN）相反，我们研究了对导频污染干扰进行解码的性能。我们将导频共享用户建模为干扰信道（IC），并研究部分基于速率分割（RS）解码该干扰的方案的性能，并将性能与基于同时唯一码解码整体干扰的方案进行比较。解码（SD）或非唯一解码（SND）。对于 RS，我们对每一层导频污染干扰进行非唯一解码，并为每个 IC 使用一个公共功率分配系数。此外，我们为该 RS 方案建立了一个可实现的区域。解决基于线性规划 (LP) 的最大对称速率分配问题，我们表明，对于空间相关/不相关信道和实际数量的 BS 天线的迫零 (ZF)，RS 实现了比 TIN、SD 显着更高的频谱效率和 SND。此外，我们还以数字方式研究了增加天线间信道相关性、用户数量以及阴影衰落程度的影响。在所有情况下，我们都表明 RS 相对于 TIN、SD 和 SND 保持了显着的增益。