Self-interference (SI) cancellation for full-duplex (FD) multiple input multiple output (MIMO) systems is challenging due to both hardware and signal processing complexity. In this paper, a beam-based adaptive filter structure with analog least mean square (ALMS) loops is proposed to significantly reduce the complexity of SI cancellation for FD MIMO systems. With this structure, the number of adaptive filters required for SI cancellation scales linearly with the number of transmit beams rather than quadratically with the number of antennas. Furthermore, to avoid additional transmit chains used to up-convert the beam signals to generate reference signals for the ALMS loops, a novel method is proposed to select the optimized reference signals from all transmitted signals. In addition, our stationary analysis shows that the proposed structure for FD MIMO systems outperforms the ALMS loop employed for an FD single input single output system. Simulations are conducted to confirm the theoretical analyses.

中文翻译：

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全双工 MIMO 系统中基于波束的模拟自干扰消除

由于硬件和信号处理的复杂性，全双工 (FD) 多输入多输出 (MIMO) 系统的自干扰 (SI) 消除具有挑战性。在本文中，提出了一种具有模拟最小均方 (ALMS) 环路的基于波束的自适应滤波器结构，以显着降低 FD MIMO 系统的 SI 消除复杂度。通过这种结构，SI 消除所需的自适应滤波器的数量与发射波束的数量成线性关系，而不是与天线数量成二次方关系。此外，为了避免用于对波束信号进行上变频以生成用于 ALMS 环路的参考信号的额外发射链，提出了一种从所有发射信号中选择优化参考信号的新方法。此外，我们的静态分析表明，所提出的 FD MIMO 系统结构优于用于 FD 单输入单输出系统的 ALMS 环路。进行模拟以确认理论分析。