Rotationally-symmetrical array for self-interference reduction in full-duplex MIMO

Abstract

In order to realize a full-duplex wireless communication, the authors have proposed a spatial self-interference reduction technique with an end-fire array (EFA) which consumes only one degree of the multiple-input multiple-output (MIMO) freedom. However, this technique has a limited interference reduction performance due to an insufficient rank-degenerated interference channel because amplitude differences of the paths increase the rank of the channel in the EFA. In this letter, the authors propose a rotationally-symmetrical array (RSA) suitable for our conventionally proposing scenario to reduce the self-interference, where geometrical symmetry of the MIMO paths achieves a perfectly one-ranked channel and suppresses all of the self-interference in theory. Performance evaluation on the interference reduction level P BF clarifies that the RSA reduces more interference than the EFA: P BF = 47.3 dB (RSA), 23.0 dB (EFA) while array length of the transmitter (Tx), element spacing of the receiver (Rx), and distance between the Tx and Rx are 3.5 wavelengths, 0.5 wavelengths, and 5 wavelengths, respectively. Keywords: MIMO, full-duplex, interference reduction, rotationally-symmetrical array, eigen-beamforming Classification: Antennas and Propagation References[1] A. Sabharwal, P. Schniter, D. Guo, D. W. Bliss, S. Rangarajan, and R. Wichman, "In-band full-duplex wireless: challenges and opportunities," IEEE J. Sel. Areas

Numerical study on a rotationally-symmetrical dipole array antenna position for a MIMO full-duplex system

“…Previously, an array antenna arrangement such as rotationally-symmetrical array (RSA) has been proposed to increase the spatial correlation and improve the performance of the NBF method [6]. In RSA, the NBF method can considerably suppress the self-interference if all antennas are point wave sources.…”