Interference Reduction Characteristics by Circular Array Based Massive MIMO in a Real Microcell Environment
Interference Reduction Characteristics by Circular Array Based Massive MIMO in a Real Microcell Environment
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DOI：
10.1587/transcom.e98.b.1447
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发表时间：
2015-08-01
影响因子：
0.7
通讯作者：
Makino, Hideo
中科院分区：
文献类型：
--
作者：
Kataoka, Ryochi;Nishimori, Kentaro;Makino, Hideo
最近提出了大规模多输入多输出（MIMO）的概念。据报道，使用线性或平面阵列来实现大规模MIMO产生窄波束，即使不采用诸如迫零（ZF）的干扰消除技术，也可以减轻干扰信号。在这项工作中，我们研究了在真实的微小区环境中，圆形阵列实现的大规模MIMO的干扰抑制性能。在城市地区的2-GHz频带内，使用具有圆柱形96单元阵列的宽带信道探测器获得信道状态信息（CSI）。圆阵具有比线阵大得多的波束宽度和旁瓣电平。本文在考虑圆柱阵的情况下，比较了当微小区内存在一个期望用户，而干扰用户在相邻小区内移动时，ZF和最大比合并的干扰抑制性能。我们表明，ZF是必不可少的，以减少来自相邻小区的干扰，在基于圆形阵列的大规模MIMO。为了简化ZF算法在大规模MIMO中的信号处理负担，评估了用于干扰减少的垂直和水平平面中所需的天线数量。由于考虑圆柱形96元阵列时存在低信噪比的阵元，因此当天线数目减少时，信号噪声干扰功率比（SINR）的下降小于线性阵理想天线增益降低时的下降。此外，我们表明，适当的天线时，应选择有限数量的天线被假定，因为主导波到达某些特定的方向。
The concept of massive multiple input multiple output (MIMO) has recently been proposed. It has been reported that using linear or planar arrays to implement massive MIMO yields narrow beams that can mitigate the interference signal even if interference cancellation techniques such as zero forcing (ZF) are not employed. In this work, we investigate the interference reduction performance achieved by circular array implemented massive MIMO in a real micro cell environment. The channel state information (CSI) is obtained by using a wideband channel sounder with cylindrical 96-element array in the 2-GHz band in an urban area. Circular arrays have much larger beamwidth and sidelobe level than linear arrays. In this paper, when considering the cylindrical array, the interference reduction performance between ZF and maximum ratio combining is compared when one desired user exists in the micro cell while the interference user moves around the adjacent cell. We show that ZF is essential for reducing the interference from the adjacent cell in the circular array based massive MIMO. The required number of antennas in the vertical and horizontal planes for the interference reduction is evaluated, in order to simplify the burden of signal processing for the ZF algorithm in massive MIMO. Because there are elements with low signal to noise power ratio (SNR) when considering cylindrical 96-element array, it is shown that the degradation of the signal to noise plus interference power ratio (SINR) when the number of antennas is reduced is smaller than that by ideal antenna gain reduction with a linear array. Moreover, we show that the appropriate antennas should be selected when a limited number of antennas is assumed, because the dominant waves arrive from certain specific directions.