Self-Interference Cancellation Circuits for Advanced Duplex Systems

The Advanced Duplex (AD) system is designed to enhance the flexibility and efficiency of duplex communication by optimizing the management of uplink (UL) and downlink (DL) signals on the same carrier frequency. Building upon traditional methods such as Time Division Duplex (TDD) and Frequency Division Duplex (FDD), it introduces innovative mechanisms to overcome their inherent limitations. The AD system utilizes a Full Duplex (FD) radio capable of simultaneously transmitting and receiving signals, which necessitates robust self-interference cancellation techniques in both the antenna/RF and digital domains. For example, Sub-Band Full Duplex (SBFD) currently under standardization enables simultaneous UL and DL transmissions on the same carrier by dividing the carrier into distinct frequency sub-bands, requiring FD radio capabilities on the gNodeB side. This presentation will explore the AD and FD systems with a focus on self-interference cancellation techniques and circuit designs, particularly in MIMO communication systems. Additionally, the self-interference signal will be analyzed to determine the optimal cancellation circuit with respect to hardware complexity.