Multi-Cell Massive MIMO Systems With Hardware Impairments: Uplink-Downlink Duality and Downlink Precoding
Multi-Cell Massive MIMO Systems With Hardware Impairments: Uplink-Downlink Duality and Downlink Precoding
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DOI：
10.1109/twc.2017.2705709
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发表时间：
2017-05
影响因子：
10.4
通讯作者：
S. Zarei;W. Gerstacker;J. Aulin;R. Schober
中科院分区：
文献类型：
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作者：
S. Zarei;W. Gerstacker;J. Aulin;R. Schober
在本文中，我们提出了一个新的框架，在多小区多用户多输入多输出系统的上行链路和下行链路的对偶遭受残留的硬件损伤（HWI）在基站和用户终端。我们应用所提出的上行链路-下行链路的对偶框架，推导出多小区干扰和HWI感知的最小均方误差（MCHA-MMSE）预编码器，该预编码器还考虑到信道状态信息估计误差。我们使用随机矩阵理论的结果，推导出一个解析表达式的下行链路功率分配的建议MCHA-MMSE预编码器在大系统的限制，这只取决于信道的二阶统计。与传统的MMSE预编码器相比，所提出的MCHA-MMSE预编码器考虑了小区间干扰、导频污染和残留HWI，因此实现了显著更高的和速率。所提出的MCHA-MMSE预编码器利用统计信道知识，但不需要经由回程链路在基站之间进行数据交换。为了降低计算复杂度，MCHA-MMSE预编码器的计算所需的矩阵求逆近似的矩阵多项式，导致一个新的多项式扩展MCHA-MMSE预编码器。使用随机矩阵理论的结果，我们推导出封闭形式的表达式的渐近最优系数的矩阵多项式，这只取决于信道的二阶统计。
In this paper, we propose a new framework for uplink–downlink duality in multi-cell multi-user multiple-input multiple-output systems suffering from residual hardware impairments (HWIs) at the base stations and the user terminals. We apply the proposed uplink–downlink duality framework to derive a multi-cell interference and HWI aware minimum mean square error (MCHA-MMSE) precoder which also takes channel state information estimation errors into account. We use results from random matrix theory to derive an analytical expression for the downlink power allocation for the proposed MCHA-MMSE precoder in the large system limit, which only depends on the channel’s second order statistics. In contrast to the conventional MMSE precoder, the proposed MCHA-MMSE precoder takes inter-cell interference, pilot contamination, and residual HWIs into account and therefore achieves substantially higher sum rates. The proposed MCHA-MMSE precoder exploits statistical channel knowledge, but does not require data exchange between base stations via backhaul links. In order to reduce the computational complexity, the matrix inversion required for the computation of the MCHA-MMSE precoder is approximated by a matrix polynomial leading to a new polynomial-expansion MCHA-MMSE precoder. Using results from the random matrix theory, we derive closed-form expressions for the asymptotically optimal coefficients of the matrix polynomial, which only depend on the channel’s second order statistics.