This letter studies the pilot contamination (PC) problem for massive multiple-input multiple-output (MIMO) networks with coexisting terrestrial users and unmanned aerial vehicles (UAVs). Due to the strong line-of-sight (LoS) air-to-ground channels between UAVs and base stations (BSs), UAVs usually cause a more severe PC issue as compared to the traditional terrestrial users. To mitigate the PC caused by UAVs, we propose a low-complexity distributed scheme by exploiting the full-dimensional beamforming of massive MIMO BSs and the angle-dependent LoS channels between them and high-altitude UAVs. Numerical results show the effectiveness of the proposed pilot decontamination scheme and the significant signal-to-interference-plus-noise ratio (SINR) gains in both the uplink and downlink after pilot decontamination.

中文翻译：

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使用无人机的大规模 MIMO 网络的试点去污

这封信研究了地面用户和无人机 (UAV) 共存的大规模多输入多输出 (MIMO) 网络的导频污染 (PC) 问题。由于无人机和基站 (BS) 之间的强视距 (LoS) 空对地信道，与传统的地面用户相比，无人机通常会导致更严重的 PC 问题。为了减轻由无人机引起的 PC，我们通过利用大规模 MIMO BS 的全维波束成形以及它们与高空无人机之间的角度相关的 LoS 信道，提出了一种低复杂度的分布式方案。数值结果显示了所提出的导频去污方案的有效性以及导频去污后上行链路和下行链路中显着的信干噪比 (SINR) 增益。