Monostatic Antenna In-Band Full Duplex Radio: Performance Limits and Characterization

This paper presents an in-band full duplex (IBFD) architecture, comprised of a monostatic antenna and software defined radio (SDR) implementing digital self-interference cancellation (DSIC). For this architecture, three alternative monostatic antennas with high passive suppression are integrated with a least squares linear DSIC algorithm implemented on the WARP v3 orthogonal frequency-division multiplexing based IEEE 802.11 SDR. Via detailed laboratory tests, the performance of the proposed IBFD radio architecture is investigated, considering various indoor positions and orientations for each antenna. The measurement results have been utilized to devise an analytical model for characterizing the power of the residual self-interference in the monostatic antenna IBFD radio as a function of transmit power levels. It is shown that the monostatic IBFD architecture can achieve up to almost 99 dB total cancellation, enabling medium range full duplex communication with moderate transmit power levels. Bidirectional communication is demonstrated between the two IBFD nodes with the proposed architecture, and error vector magnitude is observed as a function of increasing transmit power, i.e., SI. The throughput gain of full-duplex communication over half-duplex communication is also calculated as a function of payload size and the gain is found to be close to two for the settings used in the experiments.