带内全双工系统的线性化光子辅助自干扰消除

A linearized self-interference cancellation scheme based on a dual-polarization dual-drive Mach-Zehnder modulator is proposed to cancel the self-interference and reduce the nonlinearity of the signal of interest for in-band full-duplex systems. The received signals consist of the signal of interest and self-interference. They are injected into the radio frequency ports of the upper arms of the two sub-dual-drive Mach-Zehnder modulators of the dual-polarization dual-drive Mach-Zehnder modulator, while the constructed reference signals are injected into the radio frequency ports of the lower arms. The two sub-dual-drive Mach-Zehnder modulators are respectively biased at the maximum transmission point and the quadrature transmission point. When the two optical signals from the two dual-drive Mach-Zehnder modulators are detected in two photodetectors, two electrical signals are generated. If the reference signals and the self-interference are the same, the two electrical signals from the photodetectors are self-interference free. The two self-interference-free electrical signals are sampled and further processed in the digital domain to obtain the signal of interest without self-interference and nonlinear components. In addition, an optimization algorithm to reduce the distortion caused by the power mismatch of the two electrical signals is proposed. The feasibility of this scheme is verified by simulations and experiments. The experimental results show that when the signal of interest is a 4-dBm two-tone signal with frequencies of 10 MHz and 12 MHz and the self-interference is a 4-Mbaud quadrature phase-shift keying signal with a center frequency of 11 MHz, a cancellation depth of around 25.6 dB for the self-interference and a cancellation depth of around 17.3 dB for the third-order intermodulation products can be achieved.