Automatic Convergence Detection for In-Band Full-Duplex System with Digital Self-Interference Cancellation Using Adaptive Filter

For beyond 5G wireless communication systems, in-band full-duplex (IBFD) is one of the important candidate technologies due to its capacity and low latency transmissions. However, for IBFD systems, the base station performs uplink (UL) and downlink (DL) processes simultaneously, and hence the system suffers from severe self-interference (SI) because of the simultaneous UL and DL communications. Therefore, to realize the IBFD system, it is necessary to suppress the SI problem. For suppressing SI, adaptive filter could be considered as one of the candidate digital interference cancellation technology. However, using adaptive filter needs to make sure that the adaptive filter is working in convergence status. Therefore, in this paper we propose a novel method to automatically detect if the adaptive filter enters convergence status so that it can make sure that the SI is always optimally suppressed in the system by the adaptive filter. By conducting computer simulations, it can be seen that the proposed method can effectively detect the convergence point of the adaptive filter and provide output with optimally suppressed SI, so that the resultant BER performance of the IBFD system can very closely approach the optimal case without SI, which validates the effectiveness of the proposed method.