Millimeter-Wave Full-Duplex Phased Array RF Self-Interference Cancellation Technology

In the integrated access and backhaul (IAB) base stations, a model of large-scale antenna arrays is established to address the problem of radio frequency self-interference cancellation (RFSIC) in millimeter-wave (mmW) full-duplex (FD) systems. The characteristics of the SI under the condition of separating the receiving and transmitting antenna arrays are analyzed. This paper simplifies the RFSIC model using the equivalent delay method, while an RFSIC model applicable to the received beamforming synthesis is proposed. The RFSIC performance under different tap numbers is also compared by simulation experiments. The simulation results show that the RFSIC ability of the 16 taps is greater than 50 dB for the SI with a carrier frequency of 26.5 GHz and a bandwidth of 200 MHz. Furthermore, the proposed method is tested and verified in a real scenario, and the test results show that the RFSIC ability is greater than 35 dB when 16 taps are used for SI reconstruction. Combined with digital self-interference cancellation (DSIC), the error vector magnitude (EVM) can be effectively increased by 30.8 dB, while the phased array system can realize FD communication.