A novel OFDM technique based on IIR signal model for full-duplex UAV relay communications

Residual loop-interference (LI) poses a significant challenge for the full-duplex (FD) unmanned aerial vehicle (UAV). To address the issue of residual LI, this paper proposes an amplify-and-forward (AaF) FD-UAV relay system based on a novel orthogonal frequency division multiplexing (OFDM) technique, in which a signal model of infinite impulse response (IIR) is established, instead of the classical finite impulse response (FIR). In the proposed scheme, the residual LI is considered a useful signal and can be combined with the novel OFDM to establish the IIR signal model. Meanwhile, the guard interval (GI) is designed to maintain the circular convolution structure, which differs from the cyclic prefix (CP) applied by the classical OFDM. At the receiver, the IIR signals are influenced only by Gaussian white noise. The proposed FD-UAV relay system can maintain a satisfactory bit error rate (BER) even in the presence of significant residual LI, compared to conventional solutions for suppressing LI on FD-UAV relay. Numerical simulations validate that our proposed scheme offers a fresh solution to the residual LI problem in FD-UAV communication.