Analog beamforming greatly reduces the implementation cost of massive antenna transceivers by using only one up/down-conversion chain. However, it incurs a large pilot overhead when used with conventional channel estimation (CE) techniques. This is because these CE techniques involve digital processing, requiring the up/down-conversion chain to be time-multiplexed across the antenna dimensions. This paper introduces a novel CE technique, called continuous analog channel estimation (CACE), that avoids digital processing, enables analog beamforming at the receiver and additionally provides resilience against oscillator phase-noise. By avoiding time-multiplexing of up/down-conversion chains, the CE overhead is reduced significantly and furthermore becomes independent of the number of antenna elements. In CACE, a reference tone is transmitted continuously with the data signals, and the receiver uses the received reference signal as a matched filter for combining the data signals, albeit via analog processing. We propose a receiver architecture for CACE, analyze its performance in the presence of oscillator phase-noise, and derive near-optimal system parameters and power allocation. Transmit beamforming and initial access procedure with CACE are also discussed. Simulations confirm that, in comparison to conventional CE, CACE provides phase-noise resilience and a significant reduction in the CE overhead, while suffering only a small loss in signal-to-interference-plus-noise-ratio.

中文翻译：

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用于大规模 MIMO 系统的连续模拟信道估计辅助波束成形

模拟波束成形仅使用一个上/下变频链，大大降低了海量天线收发器的实现成本。然而，当与传统的信道估计 (CE) 技术一起使用时，它会产生大量的导频开销。这是因为这些 CE 技术涉及数字处理，需要在天线维度上时分复用上/下变频链。本文介绍了一种称为连续模拟信道估计 (CACE) 的新型 CE 技术，该技术避免了数字处理，在接收器实现模拟波束成形，另外还提供了对振荡器相位噪声的恢复能力。通过避免上/下变频链的时分复用，CE 开销显着降低，而且与天线单元的数量无关。在 CACE 中，参考音与数据信号一起连续传输，接收器使用接收到的参考信号作为匹配滤波器来组合数据信号，尽管是通过模拟处理。我们为 CACE 提出了一种接收器架构，在存在振荡器相位噪声的情况下分析其性能，并推导出接近最优的系统参数和功率分配。还讨论了使用 CACE 的传输波束成形和初始接入过程。仿真证实，与传统 CE 相比，CACE 提供了相位噪声恢复能力和 CE 开销的显着降低，同时信号干扰加噪声比的损失很小。我们为 CACE 提出了一种接收器架构，在存在振荡器相位噪声的情况下分析其性能，并推导出接近最优的系统参数和功率分配。还讨论了使用 CACE 的传输波束成形和初始接入过程。仿真证实，与传统 CE 相比，CACE 提供了相位噪声恢复能力和 CE 开销的显着降低，同时信号干扰加噪声比的损失很小。我们为 CACE 提出了一种接收器架构，在存在振荡器相位噪声的情况下分析其性能，并推导出接近最优的系统参数和功率分配。还讨论了使用 CACE 的传输波束成形和初始接入过程。仿真证实，与传统 CE 相比，CACE 提供了相位噪声恢复能力和 CE 开销的显着降低，同时信号干扰加噪声比的损失很小。