Cancellation of power amplifier induced nonlinear self-interference in full-duplex transceivers

Abstract

Abstract-Recently, full-duplex (FD) communications with simultaneous transmission and reception on the same channel has been proposed. The FD receiver, however, suffers from inevitable self-interference (SI) from the much more powerful transmit signal. Analogue radio-frequency (RF) and baseband, as well as digital baseband, cancellation techniques have been proposed for suppressing the SI, but so far most of the studies have failed to take into account the inherent nonlinearities of the transmitter and receiver front-ends. To fill this gap, this article proposes a novel digital nonlinear interference cancellation technique to mitigate the power amplifier (PA) induced nonlinear SI in a FD transceiver. The technique is based on modeling the nonlinear SI channel, which is comprised of the nonlinear PA, the linear multipath SI channel, and the RF SI canceller, with a parallel Hammerstein nonlinearity. Stemming from the modeling, and appropriate parameter estimation, the known transmit data is then processed with the developed nonlinear parallel Hammerstein structure and suppressed from the receiver path at digital baseband. The results illustrate that with a given IIP3 figure for the PA, the proposed technique enables higher transmit power to be used compared to existing linear SI cancellation methods. Alternatively, for a given maximum transmit power level, a lower-quality PA (i.e., lower IIP3) can be used.

Digitally Assisted RF-Analog Self Interference Cancellation for Wideband Full-Duplex Radios

“…Previous works have also used digital cancellation to compensate for nonidealities in the TX and RX chains from active components, and phase noise [4,[20][21][22][23][24][25]. Here, the linear and nonlinear distortions can be estimate using complex models to account for the dynamic TX signal through the components.…”

“…Another source of nonlinearity in the system stems from the transmitter itself [35]. The transmitter is operating at a high power and it is not uncommon for the components to have small nonlinearities associated with them or in the case of the PA, fully operate in the nonlinear region to improve efficiency.…”

“…Noise from the transmitter will also be high enough to desensitize the received signal and estimation of the exact noise signal is not possible [21,36]. This becomes particularly relevant as the specification for transmitter noise is not very strict and can be much larger than the carefully specified noise floor of the receiver.…”

Novel self-interference suppression schemes based on Dempster-Shafer theory with network coding in two-way full-duplex MIMO relay

“…After analog RF cancellation, the received signal at the relay becomes (41) where H RSI = H SI − H RF denotes the n R × n T residual self-interference (RSI) channel after RF analog cancellation. For simplicity, we assume that H SI and H RF can be estimated at the RF receiver front end with several methods [42] and H RSI is a Gaussian matrix whose elements are zero mean and variance λ random variables. The variance λ reflects the quality of RF analog cancellation.…”

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

“…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]. A widely linear I/Q imbalance and SI cancellation concept is proposed in [14] for a generic FD transceiver and in [23] for an AF FD relay.…”