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 selfinterference, 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 PBF clarifies that the RSA reduces more interference than the EFA: PBF = 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.
[1]
Sampath Rangarajan,et al.
MIDU: enabling MIMO full duplex
,
2012,
Mobicom '12.
[2]
Risto Wichman,et al.
In-Band Full-Duplex Wireless: Challenges and Opportunities
,
2013,
IEEE Journal on Selected Areas in Communications.
[3]
Philip Levis,et al.
Applications of self-interference cancellation in 5G and beyond
,
2014,
IEEE Communications Magazine.
[4]
Ashutosh Sabharwal,et al.
Passive Self-Interference Suppression for Full-Duplex Infrastructure Nodes
,
2013,
IEEE Transactions on Wireless Communications.
[5]
Kentaro Murata,et al.
Interference reduction between SDD linear array antennas using end-fire arrangement
,
2015,
2015 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting.