Adaptive Digital Self‐Interference Cancellation Using Software‐Defined Radio Technology

ABSTRACT One of the main benefits of the full‐duplex (FD) technique is to enhance the spectrum efficiency and throughput of the communication systems. This can be obtained by enabling simultaneous transmission and reception over the same frequency channel. Digital self‐interference (SI) cancellation becomes crucial for carrying out in‐band FD communication. In this paper, we use multicarrier signals in conjunction with three adaptive filters to cancel the SI signals. These filters include the least mean square (LMS), normalized LMS (NLMS), and QR decomposition‐based recursive least squares (QR‐RLS). The LabVIEW software is used to prepare the transmitted signal and the Universal Software Radio Peripheral (USRP) platform. At the same time, a software‐defined radio (SDR) technology is utilized to transmit and receive the signals. The experimental results demonstrate that the performance of using adaptive filters can achieve cancellation beyond the noise floor. In addition, SI signal reduction using the QR‐RLS algorithm is 31 dB, which exceeds the noise floor level (30 dB) by 1 dB and outperforms the LMS and NLMS algorithms. The QR‐RLS exhibits faster convergence and better stability in dynamic scenarios, making it a preferred choice for practical applications in real‐time systems.