Joint Transceiver Design for Full-Duplex Amplify-and-Forward Cooperative Systems with Frequency-Selective Fading Channels

To boost the spectral efficiency of cooperative communication systems, full duplex relays (FDRs) have been widely considered due to the concurrent signal transmission and reception at the relay. However, the self-interference (SI) is always a main problem that deteriorates the system performance. Most conventional FDR designs focus on narrowband transmission and treat SI as a harmful signal, consequently aiming to cancel SI as clear as possible. However, the relay transceiver can be inherently modeled as an infinite impulse response (IIR) filter by recognizing SI as a delayed desired signal. Based on this concept, we propose a novel design where the finite-length source, FDR filters, and the linear minimum mean-squared error (MMSE) equalizer are jointly optimized for frequency-selective fading channels. Simulations demonstrate the effectiveness of our design that preserving partial SI indeed enables further performance improvement.