Performance evaluation of parallel hammerstein canceller in in-band full-duplex experimental system with shared LO and low-IF architecture at 5.8 GHz

In-band full-duplex communication has the potential to theoretically double spectral efficiency and is a promising next-generation communication technology. However, to address the severe self-interference arising from simultaneous transmission and reception over the same frequency band, the application of self-interference cancellation (SIC) techniques is essential. In this study, a digital-domain SIC approach is evaluated, considering practical imperfections in radio frequency (RF) circuits, including nonlinear distortion from power amplifiers, in-phase/quadrature imbalance, and direct-current offsets. An in-band full-duplex communication terminal was constructed using a software-defined radio and RF circuits, adopting a shared local oscillator architecture to reduce phase noise effects. A parallel Hammerstein canceller based on alow-intermediate-frequency architecture and a parallel Hammerstein model was implemented to mitigate nonlinear self-interference components. SIC performance was evaluated using orthogonal frequency-division multiplexing (OFDM)-modulated signals. A digital-domain SIC ratio exceeding 50 dB was achieved. These results demonstrate the effectiveness of the parallel Hammerstein canceller in a practical in-band full-duplex communication system employing OFDM signals.