Challenges and approaches to software defined duplexing radio

Recent advances in reconfigurable RF front end circuits, such as passive mixer first receivers have opened the door to the possibility of building radios that can be programmed to both transmit and receive across octaves of frequency while maintaining reasonable performance and extremely high levels of integration. One of the remaining challenges in software defined radio hardware is the construction of a flexible RF system capable of duplex operation. Specifically, transmitting and receiving on the same antenna across a wide band of frequencies presents a significant challenge. This paper presents some of the primary challenges that arise in this space, as well as some interesting published and potential solutions.