Analog beamsteering for flexible hybrid beamforming design in mmwave communications
Analog beamsteering for flexible hybrid beamforming design in mmwave communications
复制标题
用于毫米波通信中灵活混合波束形成设计的模拟波束控制
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
G. Fettweis
中科院分区：
文献类型：
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作者：
Yaning Zou;W. Rave;G. Fettweis
在本文中，我们提出了一种模拟波束导向方法，用于实现灵活的混合波束形成设计，该设计可以在单用户情况下实现接近基于奇异值分解（SVD）的数字波束形成性能。作为起点，假设使用具有无限精度的码本，我们将天线阵列响应矩阵的转置作为BS和UE侧的模拟波束形成器。由此产生的有效信道矩阵，包括传播信道和模拟波束形成器，能够在低至中等信噪比下提供非常接近基于SVD的数字波束形成的最大可实现速率。其次，分析了有限尺寸码本对实际模拟波束形成器设计的影响。得到了将速率损耗映射到天线数、码本尺寸和接收信噪比的封闭形式推导。分析表明，为了获得与无限精度的模拟波束形成相当的性能，码本尺寸应至少大于所实现的天线数量。因此，所提出的模拟波束形成方法可以在不考虑数字波束形成的情况下独立设计。这种方法可以导致灵活的混合波束形成架构的发展，可以通过灵活的模拟波束选择来适应不断变化的传播环境，并通过适当的数字波束形成器设计来最大化空间复用增益。
In this paper, we propose an analog beamsteering approach for enabling flexible hybrid beamforming design that can achieve performance close to singular value decomposition (SVD) based digital beamforming with single user case. As a starting point, assuming the use of a codebook with infinite precision, we apply transposes of antenna array response matrices as analog beamformers at the BS and the UE sides. The resulting effective channel matrix including both propagation channel and analog beamformers is shown to be able to provide a maximal achievable rate very close to SVD based digital beamforming at low to medium SNR. Next, the impact of a finite size codebook is analyzed for practical analog beamformer design. A closed-form derivation is obtained for mapping rate loss to the number of antennas, code-book sizes and the received SNR. The analysis shows that in order to achieve performance comparable to analog beamforming with infinite precision, the codebook size should be at least larger than the number of implemented antennas. Therefore, the proposed analog beamforming approach can be designed independently without taking digital beamforming into account. Such an approach can lead to the development of flexible hybrid beamforming architectures that could adapt to a changing propagation environment via agile analog beam selection and maximize spatial multiplexing gain via proper digital beamformer design.