An In-Band Full-Duplex Transceiver for Simultaneous Communication and Environmental Sensing

To obtain Tx-Rx isolation in an in-band full-duplex (IBFD) transceiver, the electrical-balance duplexer (EBD) can be utilized to suppress the self-interference (SI). Although the EBD can provide more than 50 dB cancellation of the SI directly at RF, it cannot fully overcome strong signals reflecting off of nearby objects. As a result, the environmental reflections could still limit the performance of IBFD communication and have to be attenuated in an extra cancellation step, e.g., in digital baseband using a digital SI canceler. While mitigating the reflections is a challenging dimension of this technology, it opens a new opportunity to perform environmental sensing. In this paper, an IBFD transceiver architecture is introduced to enable such context-aware communication functionality. We investigate how the EBD's SI rejection property influences the performance of the proposed communication device which also functions as a Doppler radar. The simulation result demonstrates that the proposed architecture can produce high-resolution Doppler when the EBD provides > 20 dB Tx-Rx isolation. Concerning the constraints dictated by the application, this paper finally suggests a radar-communication trade-off.