17 research outputs found
Self-Interference Cancellation with Nonlinear Distortion Suppression for Full-Duplex Systems
In full-duplex systems, due to the strong self-interference signal, system
nonlinearities become a significant limiting factor that bounds the possible
cancellable self-interference power. In this paper, a self-interference
cancellation scheme for full-duplex orthogonal frequency division multiplexing
systems is proposed. The proposed scheme increases the amount of cancellable
self-interference power by suppressing the distortion caused by the transmitter
and receiver nonlinearities. An iterative technique is used to jointly estimate
the self-interference channel and the nonlinearity coefficients required to
suppress the distortion signal. The performance is numerically investigated
showing that the proposed scheme achieves a performance that is less than 0.5dB
off the performance of a linear full-duplex system.Comment: To be presented in Asilomar Conference on Signals, Systems &
Computers (November 2013
Modeling and Efficient Cancellation of Nonlinear Self-Interference in MIMO Full-Duplex Transceivers
This paper addresses the modeling and digital cancellation of
self-interference in in-band full-duplex (FD) transceivers with multiple
transmit and receive antennas. The self-interference modeling and the proposed
nonlinear spatio-temporal digital canceller structure takes into account, by
design, the effects of I/Q modulator imbalances and power amplifier (PA)
nonlinearities with memory, in addition to the multipath self-interference
propagation channels and the analog RF cancellation stage. The proposed
solution is the first cancellation technique in the literature which can handle
such a self-interference scenario. It is shown by comprehensive simulations
with realistic RF component parameters and with two different PA models to
clearly outperform the current state-of-the-art digital self-interference
cancellers, and to clearly extend the usable transmit power range.Comment: 7 pages, 5 figures. To be presented in the 2014 International
Workshop on Emerging Technologies for 5G Wireless Cellular Network
Feasibility of In-band Full-Duplex Radio Transceivers with Imperfect RF Components: Analysis and Enhanced Cancellation Algorithms
In this paper we provide an overview regarding the feasibility of in-band
full-duplex transceivers under imperfect RF components. We utilize results and
findings from the recent research on full-duplex communications, while
introducing also transmitter-induced thermal noise into the analysis. This
means that the model of the RF impairments used in this paper is the most
comprehensive thus far. By assuming realistic parameter values for the
different transceiver components, it is shown that IQ imaging and
transmitter-induced nonlinearities are the most significant sources of
distortion in in-band full-duplex transceivers, in addition to linear
self-interference. Motivated by this, we propose a novel augmented nonlinear
digital self-interference canceller that is able to model and hence suppress
all the essential transmitter imperfections jointly. This is also verified and
demonstrated by extensive waveform simulations.Comment: 7 pages, presented in the CROWNCOM 2014 conferenc
Full-Duplex Systems Using Multi-Reconfigurable Antennas
Full-duplex systems are expected to achieve 100% rate improvement over
half-duplex systems if the self-interference signal can be significantly
mitigated. In this paper, we propose the first full-duplex system utilizing
Multi-Reconfigurable Antenna (MRA) with ?90% rate improvement compared to
half-duplex systems. MRA is a dynamically reconfigurable antenna structure,
that is capable of changing its properties according to certain input
configurations. A comprehensive experimental analysis is conducted to
characterize the system performance in typical indoor environments. The
experiments are performed using a fabricated MRA that has 4096 configurable
radiation patterns. The achieved MRA-based passive self-interference
suppression is investigated, with detailed analysis for the MRA training
overhead. In addition, a heuristic-based approach is proposed to reduce the MRA
training overhead. The results show that at 1% training overhead, a total of
95dB self-interference cancellation is achieved in typical indoor environments.
The 95dB self-interference cancellation is experimentally shown to be
sufficient for 90% full-duplex rate improvement compared to half-duplex
systems.Comment: Submitted to IEEE Transactions on Wireless Communication
On Phase Noise Suppression in Full-Duplex Systems
Oscillator phase noise has been shown to be one of the main performance
limiting factors in full-duplex systems. In this paper, we consider the problem
of self-interference cancellation with phase noise suppression in full-duplex
systems. The feasibility of performing phase noise suppression in full-duplex
systems in terms of both complexity and achieved gain is analytically and
experimentally investigated. First, the effect of phase noise on full-duplex
systems and the possibility of performing phase noise suppression are studied.
Two different phase noise suppression techniques with a detailed complexity
analysis are then proposed. For each suppression technique, both free-running
and phase locked loop based oscillators are considered. Due to the fact that
full-duplex system performance highly depends on hardware impairments,
experimental analysis is essential for reliable results. In this paper, the
performance of the proposed techniques is experimentally investigated in a
typical indoor environment. The experimental results are shown to confirm the
results obtained from numerical simulations on two different experimental
research platforms. At the end, the tradeoff between the required complexity
and the gain achieved using phase noise suppression is discussed.Comment: Published in IEEE transactions on wireless communications on
October-2014. Please refer to the IEEE version for the most updated documen
All-Digital Self-interference Cancellation Technique for Full-duplex Systems
Full-duplex systems are expected to double the spectral efficiency compared
to conventional half-duplex systems if the self-interference signal can be
significantly mitigated. Digital cancellation is one of the lowest complexity
self-interference cancellation techniques in full-duplex systems. However, its
mitigation capability is very limited, mainly due to transmitter and receiver
circuit's impairments. In this paper, we propose a novel digital
self-interference cancellation technique for full-duplex systems. The proposed
technique is shown to significantly mitigate the self-interference signal as
well as the associated transmitter and receiver impairments. In the proposed
technique, an auxiliary receiver chain is used to obtain a digital-domain copy
of the transmitted Radio Frequency (RF) self-interference signal. The
self-interference copy is then used in the digital-domain to cancel out both
the self-interference signal and the associated impairments. Furthermore, to
alleviate the receiver phase noise effect, a common oscillator is shared
between the auxiliary and ordinary receiver chains. A thorough analytical and
numerical analysis for the effect of the transmitter and receiver impairments
on the cancellation capability of the proposed technique is presented. Finally,
the overall performance is numerically investigated showing that using the
proposed technique, the self-interference signal could be mitigated to ~3dB
higher than the receiver noise floor, which results in up to 76% rate
improvement compared to conventional half-duplex systems at 20dBm transmit
power values.Comment: Submitted to IEEE Transactions on Wireless Communication