812 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
Self-interference cancellation enabling high-throughput short-reach wireless full-duplex communication
In-band full-duplex (FD) wireless communication allows the simultaneous transmission and reception of data at the same frequency band, effectively doubling the spectral efficiency and data rate while reducing the latency. Previously published designs mostly target the self-interference (SI) cancellation in conventional wireless systems. In this paper, we focus on real-time SI cancellation for short-reach wireless FD systems. The superior signal quality of a point-to-point short-reach wireless system, allows the utilization of wideband communications to achieve a high throughput. Besides, in such wireless systems, the impacts of phase noise and nonlinear distortions are largely reduced, easing the SI cancellation. Moreover, the degradation of signal reception quality due to FD operation is experimentally evaluated in different environments. Experimental results of a prototype implementation show that a combination of antenna isolation and digital cancellation can already achieve an overall SI cancellation performance of 72.5 dB over a bandwidth of 123 MHz. This prototype can support a high-data-rate FD communication link of close to 1 Gbps up to 300 cm with an error vector magnitude lower than -26 dB in a typical indoor environment
Reference Receiver Based Digital Self-Interference Cancellation in MIMO Full-Duplex Transceivers
In this paper we propose and analyze a novel self-interference cancellation
structure for in-band MIMO full-duplex transceivers. The proposed structure
utilizes reference receiver chains to obtain reference signals for digital
self-interference cancellation, which means that all the transmitter-induced
nonidealities will be included in the digital cancellation signal. To the best
of our knowledge, this type of a structure has not been discussed before in the
context of full-duplex transceivers. First, we will analyze the overall
achievable performance of the proposed cancellation scheme, while also
providing some insight into the possible bottlenecks. We also provide a
detailed formulation of the actual cancellation procedure, and perform an
analysis into the effect of the received signal of interest on
self-interference coupling channel estimation. The achieved performance of the
proposed reference receiver based digital cancellation procedure is then
assessed and verified with full waveform simulations. The analysis and waveform
simulation results show that under practical transmitter RF/analog impairment
levels, the proposed reference receiver based cancellation architecture can
provide substantially better self-interference suppression than any existing
solution, despite deploying only low-complexity linear digital processing.Comment: 7 pages, 4 figures. To be presented in the 2014 IEEE Broadband
Wireless Access Worksho
Full-Duplex OFDM Radar With LTE and 5G NR Waveforms: Challenges, Solutions, and Measurements
This paper studies the processing principles, implementation challenges, and
performance of OFDM-based radars, with particular focus on the
fourth-generation Long-Term Evolution (LTE) and fifth-generation (5G) New Radio
(NR) mobile networks' base stations and their utilization for radar/sensing
purposes. First, we address the problem stemming from the unused subcarriers
within the LTE and NR transmit signal passbands, and their impact on
frequency-domain radar processing. Particularly, we formulate and adopt a
computationally efficient interpolation approach to mitigate the effects of
such empty subcarriers in the radar processing. We evaluate the target
detection and the corresponding range and velocity estimation performance
through computer simulations, and show that high-quality target detection as
well as high-precision range and velocity estimation can be achieved.
Especially 5G NR waveforms, through their impressive channel bandwidths and
configurable subcarrier spacing, are shown to provide very good radar/sensing
performance. Then, a fundamental implementation challenge of
transmitter-receiver (TX-RX) isolation in OFDM radars is addressed, with
specific emphasis on shared-antenna cases, where the TX-RX isolation challenges
are the largest. It is confirmed that from the OFDM radar processing
perspective, limited TX-RX isolation is primarily a concern in detection of
static targets while moving targets are inherently more robust to transmitter
self-interference. Properly tailored analog/RF and digital self-interference
cancellation solutions for OFDM radars are also described and implemented, and
shown through RF measurements to be key technical ingredients for practical
deployments, particularly from static and slowly moving targets' point of view.Comment: Paper accepted by IEEE Transactions on Microwave Theory and
Technique
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