Wideband Co-site Interference Cancellation Based on Single-Tap Structure

In simultaneous transmit and receive (STAR) systems, receivers always suffer from strong co-site radio frequency (RF) interference from transmitters in the same platform due to the limited antenna isolation, which can saturate the receivers RF front-end. This paper presents an analog interference cancellation scheme based on orthogonal combination with single tap delay to suppress wideband co-site interference in RF domain. The reference signal coupled from the transmitter RF output is divided into two orthogonal components, both of which are attenuated independently by the variable attenuators and subsequently combined to generate a cancelling signal to mitigate the co-site interference. In this paper, the optimal weights of cancellation system and the corresponding interference suppression performance are analyzed. And the analog least mean square (ALMS) algorithm is adopted to adjust the weights adaptively. Finally several simulations are performed to verify the effectiveness of the presented cancellation scheme and its performance.