In-band full-duplex technology in VDES: a hardware implementation for high isolation in the analogue domain

Abstract In-band full-duplex technology can transmit and receive information in the same frequency band at the same time, which can greatly improve the throughput and spectrum utilization of the communication system. In this paper, the in-band full-duplex technology is applied to the VHF Data Exchange System (VDES) to eliminate the self-interference signal and improve the isolation between transceiver links in the 160 MHz frequency band. The time-domain reconstruction method is used to design the scheme for two narrow frequency bands of VDES. An RF cancellation board is designed to reconstruct the equal amplitude and inverse-phase signals of the self-interference signals by adjusting the amplitude and shifting the phase of the replica signals coupled from the transmitter link. It is then coupled into the receiving link to cancel the self-interference signals. The final physical test data shows that the isolation of approximately 62 dB is achieved in the frequency bands of 156.7~157.4 MHz and 161.8~162.1 MHz.