The in-band full-duplex (IBFD) systems can send and receive data simultaneously in the same frequency band. Although the electromagnetic interference among RF channels can be released using radio over fiber (RoF) links, the receiving antenna is susceptible to the signal leakage from adjacent transmitting antennas. Due to the electronic bottlenecks, traditional RF self-interference cancellation (SIC) systems have some problems, such as low operating frequency, narrow transmission bandwidth, and electromagnetic interference, which seriously reduces the communication performance. In this paper, a photonic RF SIC system based on dual-phase modulation in a Sagnac loop is proposed to further increase the resistance to electromagnetic interference of the IBFD systems. Based on the principle of polarization multiplexing, the damaged received signal and local interference signal are modulated on two beams of a light wave with orthogonal polarization states. The received interference signal can be canceled by polarization adjustment. In the experiment, a single- frequency interference cancelation depth of 45 dB is achieved in the proposed photonic SIC system over the operating frequency range of 5–20 GHz. Also, a demonstration of cancellation for modulated interference with a center frequency of 10 GHz and bandwidths of 20, 30, and 50 MHz is carried out.

中文翻译：

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Sagnac环路中基于双相调制的无线光纤链路射频自干扰消除

带内全双工（IBFD）系统可以在同一频带中同时发送和接收数据。尽管可以使用光纤无线电（RoF）链路释放RF通道之间的电磁干扰，但是接收天线容易受到相邻发射天线的信号泄漏的影响。由于电子瓶颈，传统的射频自干扰消除（SIC）系统存在工作频率低，传输带宽窄和电磁干扰等问题，严重降低了通信性能。本文提出了一种基于Sagnac环路中双相调制的光子RF SIC系统，以进一步提高IBFD系统的抗电磁干扰能力。基于偏振复用的原理，受损的接收信号和本地干扰信号被调制在具有正交偏振态的两束光波上。接收到的干扰信号可以通过极化调整来消除。在实验中，在5-20 GHz的工作频率范围内，所提出的光子SIC系统实现了45 dB的单频干扰消除深度。此外，还演示了消除中心频率为10 GHz且带宽为20、30和50 MHz的调制干扰的方法。在建议的光子SIC系统中，在5–20 GHz的工作频率范围内，实现了45 dB的单频干扰消除深度。此外，还演示了消除中心频率为10 GHz且带宽为20、30和50 MHz的调制干扰的方法。在建议的光子SIC系统中，在5–20 GHz的工作频率范围内，实现了45 dB的单频干扰消除深度。此外，还演示了消除中心频率为10 GHz且带宽为20、30和50 MHz的调制干扰的方法。