This paper considers the problem of radar sensing by using a large number of antennas. We use the orthogonal frequency division multiplexing (OFDM) waveform, and show that the large arrays used in massive multiple-input multiple-output (MIMO) communications enable accurate localization in the array near-field, even at the narrow bandwidths typically encountered at low carrier frequencies. We validate our findings experimentally with a massive MIMO testbed operating at 3.5 GHz carrier frequency and 18 MHz OFDM bandwidth in an indoor environment. We consider a single moving cylinder, and demonstrate a median accuracy of (3.4, 5.6) cm in ( xx , yy ) in the near-field. We show that the accuracy is maintained with only a single subcarrier, and that the resolution increases with an order of magnitude when combining all antennas, effectively surpassing the 16.67 m bistatic range resolution set by the OFDM waveform. We use a radar symbol duration of 71.88 μ71.88~\mu s at an effective transmission period of 2.5 ms, which indicates that the radar and communication systems can be implemented in time-division with a capacity loss of only 2.9%. Our results suggest that near-field radar sensing can be integrated into future massive MIMO systems operating at low carrier frequencies and narrow bandwidths.

中文翻译：

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使用大规模 MIMO 通信测试台进行近场相干雷达传感


本文考虑使用大量天线的雷达传感问题。我们使用正交频分复用 (OFDM) 波形，并表明大规模多输入多输出 (MIMO) 通信中使用的大型阵列能够在阵列近场中实现精确定位，即使在低带宽下通常遇到的窄带宽下也是如此。载波频率。我们通过在室内环境中以 3.5 GHz 载波频率和 18 MHz OFDM 带宽运行的大规模 MIMO 测试台通过实验验证了我们的发现。我们考虑单个移动圆柱体，并证明近场 ( xx , yy ) 的中值精度为 (3.4, 5.6) 厘米。我们证明，仅使用单个子载波即可保持精度，并且当组合所有天线时，分辨率提高了一个数量级，有效超过了 OFDM 波形设置的 16.67 m 双基地距离分辨率。我们使用的雷达符号持续时间为71.88 μ71.88~μ s，有效传输周期为2.5 ms，这表明雷达和通信系统可以分时实现，容量损失仅为2.9%。我们的结果表明，近场雷达传感可以集成到未来在低载波频率和窄带宽下运行的大规模 MIMO 系统中。