  Single-antenna full-duplex communication technology has the potential to
substantially increase spectral efficiency. However, limited propagation domain
cancellation of single-antenna system results in a higher impact of receiver
chain nonlinearities on the residual self-interference (SI) signal. In this
paper, we offer a comprehensive SI model for single-antenna full-duplex systems
based on direct-conversion transceiver structure considering nonlinearities of
all the transceiver radio frequency (RF) components, in-phase/quadrature (IQ)
imbalances, phase noise effect, and receiver noise figure. To validate our
model, we also propose a more appropriate digital SI cancellation approach
considering receiver chain RF and baseband nonlinearities. The proposed
technique employs orthogonalization of the design matrix using QR decomposition
to alleviate the estimation and cancellation error. Finally, through
circuit-level waveform simulation, the performance of the digital cancellation
strategy is investigated, which achieves 20 dB more cancellation compared to
existing methods.
