Cell densification is a key driver to increase area spectral efficiencies in multi-antenna cellular systems. As increasing the densities of base stations (BSs) and users that share the same spectrum, however, both inter-user-interference (IUI) and inter-cell interference (ICI) problems give rise to a significant loss in spectral efficiencies in such systems. To resolve this problem under the constraint of local channel state information per BS, in this paper, we present a novel noncooperative multi-user multiple-input multiple-output (MIMO) precoding technique, called signal-to-interference-pulse-leakage-pulse-noise-ratio (SILNR) maximization precoding. The key innovation of our distributed precoding method is to maximize the product of SILNRs of users per cell using local channel state information at the transmitter (CSIT). We show that our precoding technique only using local CSIT can asymptotically achieve the multi-cell cooperative bound attained by cooperative precoding using global CSIT in some cases. We also present a precoding algorithm that is robust to CSIT errors in multi-cell scenarios. By multi-cell system-level simulations, we demonstrate that our distributed precoding technique outperforms all existing noncooperative precoding methods considerably and can also achieve the multi-cell bound very tightly even with not-so-many antennas at BSs.

中文翻译：

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用于 MU-MIMO 异构蜂窝网络的使用本地 CSIT 的分布式预编码

小区密集化是提高多天线蜂窝系统中区域频谱效率的关键驱动因素。然而，随着共享同一频谱的基站 (BS) 和用户密度的增加，用户间干扰 (IUI) 和小区间干扰 (ICI) 问题都会导致此类系统中频谱效率的显着损失. 为了在每个 BS 的本地信道状态信息的约束下解决这个问题，在本文中，我们提出了一种新的非合作多用户多输入多输出 (MIMO) 预编码技术，称为信号干扰脉冲泄漏-脉冲噪声比 (SILNR) 最大化预编码。我们的分布式预编码方法的关键创新是使用发射机的本地信道状态信息 (CSIT) 来最大化每个小区用户的 SILNR 乘积。我们表明，在某些情况下，仅使用局部 CSIT 的预编码技术可以渐近地实现通过使用全局 CSIT 的协同预编码获得的多小区协同边界。我们还提出了一种对多小区场景中的 CSIT 错误具有鲁棒性的预编码算法。通过多小区系统级模拟，我们证明了我们的分布式预编码技术明显优于所有现有的非合作预编码方法，并且即使在基站的天线数量不多的情况下，也可以非常紧密地实现多小区绑定。