论文标题

无瞬时CSI反馈的混合波束形成的深度学习框架

A Deep Learning Framework for Hybrid Beamforming Without Instantaneous CSI Feedback

论文作者

Elbir, Ahmet M.

论文摘要

混合波束形式的设计在下一代毫米波(mm波)大量MIMO(多输入多输出)系统中起着非常关键的作用。先前的工作假设了完美的频道状态信息(CSI),从而导致大量反馈开销。为了降低复杂性,可以利用频道统计信息,以便仅需要很少更新频道信息。为了降低复杂性并提供鲁棒性,在这项工作中,我们提出了一个深度学习(DL)框架,以处理混合光束成形和频道估计。为此,我们介绍了三个深度卷积神经网络(CNN)架构。我们假设基站(BS)仅具有通道统计数据,并将通道协方差矩阵馈入CNN以获得混合预言器。在接收器,使用了两个CNN。第一个用于通道估计目的,另一种用于设计混合组合。提出的DL框架不需要BS的CSI瞬时反馈。我们已经表明,与常规技术相比,所提出的方法具有更高的光谱效率。由于传播环境的变化,例如接收路径的偏差和接收的路径角度的波动最高为4度,因此不需要重新训练经过训练的CNN结构。同样,与常规优化方法相比,提出的DL框架的计算复杂性至少降低了10倍。

Hybrid beamformer design plays very crucial role in the next generation millimeter-wave (mm-Wave) massive MIMO (multiple-input multiple-output) systems. Previous works assume the perfect channel state information (CSI) which results heavy feedback overhead. To lower complexity, channel statistics can be utilized such that only infrequent update of the channel information is needed. To reduce the complexity and provide robustness, in this work, we propose a deep learning (DL) framework to deal with both hybrid beamforming and channel estimation. For this purpose, we introduce three deep convolutional neural network (CNN) architectures. We assume that the base station (BS) has the channel statistics only and feeds the channel covariance matrix into a CNN to obtain the hybrid precoders. At the receiver, two CNNs are employed. The first one is used for channel estimation purposes and the another is employed to design the hybrid combiners. The proposed DL framework does not require the instantaneous feedback of the CSI at the BS. We have shown that the proposed approach has higher spectral efficiency with comparison to the conventional techniques. The trained CNN structures do not need to be re-trained due to the changes in the propagation environment such as the deviations in the number of received paths and the fluctuations in the received path angles up to 4 degrees. Also, the proposed DL framework exhibits at least 10 times lower computational complexity as compared to the conventional optimization-based approaches.

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