Experimental Investigation of Frequency Domain Channel Extrapolation in Massive MIMO Systems for Zero-Feedback FDD
Experimental Investigation of Frequency Domain Channel Extrapolation in Massive MIMO Systems for Zero-Feedback FDD
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DOI：
10.1109/twc.2020.3028161
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发表时间：
2020-03
影响因子：
10.4
通讯作者：
Thomas Choi;François Rottenberg;Jorge Gómez-Ponce;Akshay Ramesh;Peng-Ju Luo;C. Zhang;A. Molisch
中科院分区：
文献类型：
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作者：
Thomas Choi;François Rottenberg;Jorge Gómez-Ponce;Akshay Ramesh;Peng-Ju Luo;C. Zhang;A. Molisch
在频分双工（FDD）大规模多输入多输出（MIMO）系统中，估计下行信道状态信息（CSI）通常需要下行导频和反馈开销。据此，本文研究了基于信道外推的零反馈FDD大规模MIMO系统的可行性。我们利用高分辨率参数估计（HRPE），特别是空间交替广义期望最大化（SAGE）算法，基于提取的上行信道多径分量参数外推DL CSI。我们将HRPE应用于两种不同的信道模型：矢量空间特征（VSS）模型和到达方向（DOA）模型。我们通过使用两种不同类型的信道测深器从信道测量活动中获得的真实信道数据来验证这些方法：a)基于交换阵列的，实时的，时域的，室外设置为3.5 GHz, b)基于虚拟阵列的，高精度的，频域的，室内设置为2.4和5-7 GHz。我们评估的外推信道的性能指标包括均方误差、波束形成效率和多用户MIMO场景下的频谱效率。结果表明，基于hrpe的信道外推在不需要阵列校准的简单VSS模型下表现最好，并且如果BS处于开放的室外环境中，并且与分隔良好的用户有视线（LOS）路径。
Estimating downlink (DL) channel state information (CSI) in frequency division duplex (FDD) massive multi-input multi-output (MIMO) systems generally requires downlink pilots and feedback overheads. Accordingly, this paper investigates the feasibility of zero-feedback FDD massive MIMO systems based on channel extrapolation. We use the high-resolution parameter estimation (HRPE), specifically the space-alternating generalized expectation-maximization (SAGE) algorithm, to extrapolate the DL CSI based on the extracted parameters of multipath components in the uplink channel. We apply the HRPE to two different channel models: the vector spatial signature (VSS) model and the direction of arrival (DOA) model. We verify these methods through real-world channel data acquired from channel measurement campaigns with two different types of channel sounders: a) a switched array-based, real-time, time-domain, outdoors setup at 3.5 GHz, and b) a virtual array-based, high-accuracy, frequency-domain, indoors setup at 2.4 and 5-7 GHz. The performance metrics of the extrapolated channels that we evaluate include the mean squared error, beamforming efficiency, and spectral efficiency in multiuser MIMO scenarios. The results show that the HRPE-based channel extrapolation performs best under the simple VSS model, which does not require array calibration, and if the BS is in an open outdoor environment having line-of-sight (LOS) paths to well-separated users.