A Robust Emergency Communication System Assisted by Nyquist Folding Receiver

In order to enhance the robustness of emergency communication systems, a Nyquist folding receiver (NYFR) assisted transceiver is designed to achieve reliable communication while sensing wideband electromagnetic environments in real time. However, one of the key issues is canceling the self-interference of communication transmitters on NYFR. Firstly, the proposed transceiver structure is presented in this paper, which utilizes the baseband signal of the communication transmitter as a reference signal to complete the reconstruction and cancellation of self-interference after spectrum compression. Considering the frequency offset between the self-interference reconstructed signal and the received signal, the impact on interference cancellation performance is theoretically analyzed based on the non-uniform discrete Fourier transform (NUDFT), and a closed-form expression for the self-interference cancellation ratio in NYFR is provided. The analysis and simulation results show that when the normalized frequency offset exceeds <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3 \times 10^{-4}$</tex>, effective self-interference cancellation cannot be achieved.