Simultaneous transmit and receive system architecture with four stages of cancellation

Simultaneous transmit and receive systems (STAR) are proposed to double the spectral efficiency and enhance spectrum utilization in the traditional microwave band. A major problem is high power self-interference (SI) due to the proximity of the transmit and receive antennas. In this paper, we propose to significantly improve system-level performance using a novel high isolation RF front-end based on collocated Tx/Rx antenna pair(s). Among our improvements, we propose a novel architecture for a STAR system incorporating four stages of self-interference cancellation across the propagation, analog, and digital domains. We aim to attain at least 120dB of total SI cancellation over a >100MHz bandwidth.