1,705 research outputs found
Achievable Sum Rates of Half- and Full-Duplex Bidirectional OFDM Communication Links
While full-duplex (FD) transmission has the potential to double the system
capacity, its substantial benefit can be offset by the self-interference (SI)
and non-ideality of practical transceivers. In this paper, we investigate the
achievable sum rates (ASRs) of half-duplex (HD) and FD transmissions with
orthogonal frequency division multiplexing (OFDM), where the non-ideality is
taken into consideration. Four transmission strategies are considered, namely
HD with uniform power allocation (UPA), HD with non-UPA (NUPA), FD with UPA,
and FD with NUPA. For each of the four transmission strategies, an optimization
problem is formulated to maximize its ASR, and a (suboptimal/optimal) solution
with low complexity is accordingly derived. Performance evaluations and
comparisons are conducted for three typical channels, namely symmetric
frequency-flat/selective and asymmetric frequency-selective channels. Results
show that the proposed solutions for both HD and FD transmissions can achieve
near optimal performances. For FD transmissions, the optimal solution can be
obtained under typical conditions. In addition, several observations are made
on the ASR performances of HD and FD transmissions.Comment: To appear in IEEE TVT. This paper solves the problem of sum
achievable rate optimization of bidirectional FD OFDM link, where joint time
and power allocation is involve
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
Hardware Impairments Aware Transceiver Design for Bidirectional Full-Duplex MIMO OFDM Systems
In this paper we address the linear precoding and decoding design problem for
a bidirectional orthogonal frequencydivision multiplexing (OFDM) communication
system, between two multiple-input multiple-output (MIMO) full-duplex (FD)
nodes. The effects of hardware distortion as well as the channel state
information error are taken into account. In the first step, we transform the
available time-domain characterization of the hardware distortions for FD MIMO
transceivers to the frequency domain, via a linear Fourier transformation. As a
result, the explicit impact of hardware inaccuracies on the residual
selfinterference (RSI) and inter-carrier leakage (ICL) is formulated in
relation to the intended transmit/received signals. Afterwards, linear
precoding and decoding designs are proposed to enhance the system performance
following the minimum-mean-squarederror (MMSE) and sum rate maximization
strategies, assuming the availability of perfect or erroneous CSI. The proposed
designs are based on the application of alternating optimization over the
system parameters, leading to a necessary convergence. Numerical results
indicate that the application of a distortionaware design is essential for a
system with a high hardware distortion, or for a system with a low thermal
noise variance.Comment: Submitted to IEEE for publicatio
- …