Abstract:

Recent research shows that it is possible to achieve the full-duplex system by cancelling strong self-interference signals, which can be divided into three classes respectively, i.e., passive cancellation, active cancellation and digital cancellation. This paper tries to achieve the full-duplex system without using active cancellation, thus a full-duplex system using a joint mechanism based on a novel passive cancellation method and a novel digital cancellation method is proposed. Therein, a good antenna placement guided by the theory of the antenna electromagnetic field for the passive cancellation is presented. For the proposed digital cancellation method, unlike previous separate mechanisms, it is designed by using the recursive least square (RLS) algorithm jointly with passive cancellation. The self-interference channel state information (CSI) is transferred as the input of digital cancellation to balance the performance and the complexity. Experimental results show that the proposed self-interference cancellation mechanism can achieve about 85 dB which is better than the previous research. Meanwhile, this design provides a better performance compared with half-duplex with both line-of-sight channel and nonline-of-sight channel.