163 research outputs found
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
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
Joint Design of Multi-Tap Analog Cancellation and Digital Beamforming for Reduced Complexity Full Duplex MIMO Systems
Incorporating full duplex operation in Multiple Input Multiple Output (MIMO)
systems provides the potential of boosting throughput performance. However, the
hardware complexity of the analog self-interference canceller scales with the
number of transmit and receive antennas, thus exploiting the benefits of analog
cancellation becomes impractical for full duplex MIMO transceivers. In this
paper, we present a novel architecture for the analog canceller comprising of
reduced number of taps (tap refers to a line of fixed delay and variable phase
shifter and attenuator) and simple multiplexers for efficient signal routing
among the transmit and receive radio frequency chains. In contrast to the
available analog cancellation architectures, the values for each tap and the
configuration of the multiplexers are jointly designed with the digital
beamforming filters according to certain performance objectives. Focusing on a
narrowband flat fading channel model as an example, we present a general
optimization framework for the joint design of analog cancellation and digital
beamforming. We also detail a particular optimization objective together with
its derived solution for the latter architectural components. Representative
computer simulation results demonstrate the superiority of the proposed low
complexity full duplex MIMO system over lately available ones.Comment: 8 pages, 4 figures, IEEE ICC 201
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