Implementation of In-Band Full-Duplex Communication System with Self-Interference Cancellation Using Adaptive Filter.

For beyond 5G wireless communication systems, inband full-duplex (IBFD) is one of the important candidate technologies for realizing high capacity and low latency transmissions. However, in an IBFD system, the base station (BS) can perform uplink (UL) and downlink (DL) processes simultaneously, and hence there exists severe self-interference (SI) produced by the simultaneous UL and DL communications in the system. Therefore, to realize the IBFD system, it is necessary to deal with the SI problem. To cancel SI, adaptive filter is one of the possible candidates, which can be implemented with low cost and complexity. In our previous study, we proposed a digital SI cancellation method for IBFD system by using adaptive filter. To verify the performance of the method in our previous study, we implemented an IBFD system with 3-stage of SI cancellation: antenna, analog circuit, and digital cancellation. From the experiment results, it can be seen that our implemented system can finally offer significant SI cancellation performance, so that the demodulated output can reach $10^{-2}$ order bit error rate (BER).