In-band full duplex (IBFD) radio represents one of the key technologies for future wireless communication and radar applications. A major challenge of this technology is to mitigate the strong self-interfer-ence (SI) so that the residual SI level falls below the receiver's noise floor. Radio frequency (RF) self-inter-ference cancellation (SIC) is essential for preventing an IBFD receiver from becoming saturated by the SI. We commence with an in-depth review of the promising analog least mean square (ALMS) adaptive filtering architecture, conceived for RF SIC in the IBFD radio RF front-end. The cancellation circuits employing this architecture can be implemented purely by analog components without any involvement of more power-thirsty digital signal processing. The behaviors, performance, and implementation of the ALMS loop are presented. Finally, their applications in various IBFD radios are discussed, and future research directions are provided.

中文翻译：

---

全双工无线电中自干扰消除的模拟最小二乘自适应滤波

带内全双工（IBFD）无线电代表了未来无线通信和雷达应用的关键技术之一。这项技术的主要挑战是减轻强烈的自干扰（SI），以使残留的SI电平降到接收机的本底噪声以下。射频（RF）自干扰消除（SIC）对于防止IBFD接收器被SI饱和至关重要。我们首先深入探讨有前途的模拟最小均方（ALMS）自适应滤波架构，该架构是为IBFD射频RF前端中的RF SIC设计的。采用这种架构的抵消电路可以完全由模拟组件来实现，而无需进行更多耗电的数字信号处理。介绍了ALMS循环的行为，性能和实现。