In this paper, we present a novel nonlinear digital self-interference canceller algorithm, its implementation details on a software-defined radio (SDR) platform, and performance results of real-time full-duplex experiments on both device and link level. The canceller algorithm is based on an augmented Hammerstein model, with a nonlinear part modeling the transmitter non-idealities followed by a linear filter to model the self-interference (SI) channel. The nonlinear part includes a spline-based model for the nonlinear power amplifier, a polynomial model for baseband nonlinearities, as well as models for I/Q mismatch and LO leakage. The canceller is implemented on an FPGA as a part of an OFDM transceiver testbed for real-time measurements. Extensive real-time measurements show excellent performance: (1) the digital canceller, together with an RF isolator, can suppress the SI to within 1–2 dB’s of the receiver noise floor, with total SI suppression of up to 103 dB; (2) digital cancellation of up to 46 dB is evidenced, which is among the highest real-time cancellations in literature; (3) system-level measurements with OFDM signals demonstrate the benefit of utilizing the proposed canceller in a two-way communication scenario, showing up to 90 % increase in sum-rate compared to half-duplex communication.

中文翻译：

---

使用SDR器件进行全双工：算法，FPGA实现和实时结果

在本文中，我们提出了一种新颖的非线性数字自干扰消除器算法，其在软件定义无线电（SDR）平台上的实现细节以及在设备和链路级别的实时全双工实验的性能结果。抵消器算法基于增强的Hammerstein模型，其中非线性部分对发射机的非理想性进行建模，然后使用线性滤波器对自干扰（SI）信道进行建模。非线性部分包括用于非线性功率放大器的基于样条的模型，用于基带非线性的多项式模型，以及用于I / Q失配和LO泄漏的模型。抵消器在FPGA上实现，作为用于实时测量的OFDM收发器测试平台的一部分。广泛的实时测量显示出出色的性能：（1）数字消除器，与RF隔离器一起，可以将SI抑制在接收机本底噪声的1-2 dB范围内，总SI抑制高达103 dB；（2）证明了高达46 dB的数字消除，这在文献中是最高的实时消除之一；（3）使用OFDM信号的系统级测量证明了在双向通信场景中利用建议的抵消器的好处，与半双工通信相比，总和率提高了90％。