An Adaptive Feedback Canceller for Full-Duplex Relays Based on Spectrum Shaping

Abstract

Although full-duplex relaying schemes are appealing in order to improve spectral efficiency, simultaneous reception and transmission in the same frequency results in selfinterference, distorting the retransmitted signal and making the relay prone to oscillation. Current feedback cancellation techniques by means of adaptive filters are hampered by the fact that the useful and interference signals are highly correlated. We present a new adaptive algorithm which effectively and blindly restores the spectral shape of the desired signal. In contrast with previous schemes, the novel adaptive feedback canceller has low complexity, does not introduce additional delay in the relay station, and partly compensates for multipath propagation.

Full-Duplex Wireless Communications: Challenges, Solutions, and Future Research Directions

“…High The SI leakage-channels are assumed to remain time-invariant during each symbol period. 2012 Lopez et al [73] Implements the active feedback cancellation for an FD relay with multiple receive and one TA.…”

Wideband full-duplex MIMO relays with blind adaptive self-interference cancellation

“…In view of (33) [31]. To ease filtering requirements at the analog-to-digital and digital-to-analog conversion stages, the sampling rate at the relay is likely to exceed the Nyquist rate, which results in signals having correlated samples or non-flat PSDs.…”

“…Even though the minimization of (31) with respect to A does not directly lead to proper SI mitigation, we can still develop a recursive least-squares based algorithm by introducing a bias-correcting term that results in the desired interference cancellation properties [31]. For the sake of clarity, let first consider a bias-corrected minimization of (31), which was introduced in [33].…”

Full-duplex amplify-and-forward relays with optimized transmission power under imperfect transceiver electronics

“…In compact transceivers, the interference level is usually high compared to the signal of interest [8], depending on the transmitted signal power, the isolation between transmitter and receiver antennas, and the surrounding environmental reflectors. Self-interference is mitigated by a combination of passive and active antenna cancellation [9,10] and RF cancelers [11,12], both in the analog domain; and a digital cancellation [13][14][15][16]. Antenna cancellation techniques aim to reduce the physical coupling between the transmitter and the receiver antennas.…”

“…Many cancelers have been proposed in the literature [1,9,15,16], but their performance is greatly affected by hardware imperfections. In particular, the effect of power amplifier (PA) non-linearity for FD transceivers is considered in [3,[18][19][20][21], while the HD relay case is treated in [22].…”