184 research outputs found
Time-Frequency-Space Transmit Design and Signal Processing with Dynamic Subarray for Terahertz Integrated Sensing and Communication
Terahertz (THz) integrated sensing and communication (ISAC) enables
simultaneous data transmission with Terabit-per-second (Tbps) rate and
millimeter-level accurate sensing. To realize such a blueprint, ultra-massive
antenna arrays with directional beamforming are used to compensate for severe
path loss in the THz band. In this paper, the time-frequency-space transmit
design is investigated for THz ISAC to generate time-varying scanning sensing
beams and stable communication beams. Specifically, with the dynamic
array-of-subarray (DAoSA) hybrid beamforming architecture and multi-carrier
modulation, two ISAC hybrid precoding algorithms are proposed, namely, a
vectorization (VEC) based algorithm that outperforms existing ISAC hybrid
precoding methods and a low-complexity sensing codebook assisted (SCA)
approach. Meanwhile, coupled with the transmit design, parameter estimation
algorithms are proposed to realize high-accuracy sensing, including a wideband
DAoSA MUSIC (W-DAoSA-MUSIC) method for angle estimation and a sum-DFT-GSS
(S-DFT-GSS) approach for range and velocity estimation. Numerical results
indicate that the proposed algorithms can realize centi-degree-level angle
estimation accuracy and millimeter-level range estimation accuracy, which are
one or two orders of magnitudes better than the methods in the millimeter-wave
band. In addition, to overcome the cyclic prefix limitation and Doppler effects
in the THz band, an inter-symbol interference- and inter-carrier
interference-tackled sensing algorithm is developed to refine sensing
capabilities for THz ISAC
Electrospun Metal Oxides and Carbon Nanofiber-Based Materials in the Application of Rechargeable Lithium Battery
Ph.DDOCTOR OF PHILOSOPH
Sensing Integrated DFT-Spread OFDM Waveform and Deep Learning-powered Receiver Design for Terahertz Integrated Sensing and Communication Systems
Terahertz (THz) communications are envisioned as a key technology of
next-generation wireless systems due to its ultra-broad bandwidth. One step
forward, THz integrated sensing and communication (ISAC) system can realize
both unprecedented data rates and millimeter-level accurate sensing. However,
THz ISAC meets stringent challenges on waveform and receiver design to fully
exploit the peculiarities of THz channel and transceivers. In this work, a
sensing integrated discrete Fourier transform spread orthogonal frequency
division multiplexing (SI-DFT-s-OFDM) system is proposed for THz ISAC, which
can provide lower peak-to-average power ratio than OFDM and is adaptive to
flexible delay spread of the THz channel. Without compromising communication
capabilities, the proposed SI-DFT-s-OFDM realizes millimeter-level range
estimation and decimeter-per-second-level velocity estimation accuracy. In
addition, the bit error rate (BER) performance is improved by 5 dB gain at the
BER level compared with OFDM. At the receiver, a deep learning based
ISAC receiver with two neural networks is developed to recover transmitted data
and estimate target range and velocity, while mitigating the imperfections and
non-linearities of THz systems. Extensive simulation results demonstrate that
the proposed deep learning methods can realize mutually enhanced performance
for communication and sensing, and is robust against Doppler effects, phase
noise, and multi-target estimation
Boundary stabilization of quasilinear hyperbolic systems of balance laws: Exponential decay for small source terms
We investigate the long-time behavior of solutions of quasilinear hyperbolic
systems with transparent boundary conditions when small source terms are
incorporated in the system. Even if the finite-time stability of the system is
not preserved, it is shown here that an exponential convergence towards the
steady state still holds with a decay rate which is proportional to the
logarithm of the amplitude of the source term. The result is stated for a
system with dynamical boundary conditions in order to deal with initial data
that are free of any compatibility condition
THz ISAC: A Physical-Layer Perspective of Terahertz Integrated Sensing and Communication
The Terahertz (0.1-10 THz) band holds enormous potential for supporting
unprecedented data rates and millimeter-level accurate sensing thanks to its
ultra-broad bandwidth. Terahertz integrated sensing and communication (ISAC) is
viewed as a game-changing technology to realize connected intelligence in 6G
and beyond systems. In this article, challenges from THz channel and
transceiver perspectives, as well as difficulties of ISAC are elaborated.
Motivated by these challenges, THz ISAC channels are studied in terms of
channel types, measurement and models. Moreover, four key signal processing
techniques to unleash the full potential of THz ISAC are investigated, namely,
waveform design, receiver processing, narrowbeam management, and localization.
Quantitative studies demonstrate the benefits and performance of the
state-of-the-art signal processing methods. Finally, open problems and
potential solutions are discussed
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