852 research outputs found
Existence of Periodic Solutions of Linear Hamiltonian Systems with Sublinear Perturbation
We investigate the existence of periodic solutions of linear Hamiltonian systems with a nonlinear perturbation. Under generalized Ahmad-Lazer-Paul type coercive conditions for the nonlinearity on the kernel of the linear part, existence of periodic solutions is obtained by saddle point theorems. A note on a result of Rabinowitz is also given
Fast Neighbor Discovery for Wireless Ad Hoc Network with Successive Interference Cancellation
Neighbor discovery (ND) is a key step in wireless ad hoc network, which
directly affects the efficiency of wireless networking. Improving the speed of
ND has always been the goal of ND algorithms. The classical ND algorithms lose
packets due to the collision of multiple packets, which greatly affects the
speed of the ND algorithms. Traditional methods detect packet collision and
implement retransmission when encountering packet loss. However, they does not
solve the packet collision problem and the performance improvement of ND
algorithms is limited. In this paper, the successive interference cancellation
(SIC) technology is introduced into the ND algorithms to unpack multiple
collision packets by distinguishing multiple packets in the power domain.
Besides, the multi-packet reception (MPR) is further applied to reduce the
probability of packet collision by distinguishing multiple received packets,
thus further improving the speed of ND algorithms. Six ND algorithms, namely
completely random algorithm (CRA), CRA based on SIC (CRA-SIC), CRA based on SIC
and MPR (CRA-SIC-MPR), scan-based algorithm (SBA), SBA based on SIC (SBA-SIC),
and SBA based on SIC and MPR (SBA-SIC-MPR), are theoretically analyzed and
verified by simulation. The simulation results show that SIC and MPR reduce the
ND time of SBA by 69.02% and CRA by 66.03% averagely.Comment: 16 pages, 16 figure
Iterative Signal Processing for Integrated Sensing and Communication Systems
Integrated sensing and communication (ISAC), with sensing and communication
sharing the same wireless resources and hardware, has the advantages of high
spectrum efficiency and low hardware cost, which is regarded as one of the key
technologies of the fifth generation advanced (5G-A) and sixth generation (6G)
mobile communication systems. ISAC has the potential to be applied in the
intelligent applications requiring both communication and high accurate sensing
capabilities. The fundamental challenges of ISAC system are the ISAC signal
design and ISAC signal processing. However, the existing ISAC signal has low
anti-noise capability. And the existing ISAC signal processing algorithms have
the disadvantages of quantization errors and high complexity, resulting in
large energy consumption. In this paper, phase coding is applied in ISAC signal
design to improve the anti-noise performance of ISAC signal. Then, the effect
of phase coding method on improving the sensing accuracy is analyzed. In order
to improve the sensing accuracy with low-complexity algorithm, the iterative
ISAC signal processing methods are proposed. The proposed methods improve the
sensing accuracy with low computational complexity, realizing energy efficient
ISAC signal processing. Taking the scenarios of short distance and long
distance sensing into account, the iterative two-dimensional (2D) fast Fourier
transform (FFT) and iterative cyclic cross-correlation (CC) methods are
proposed, respectively, realizing high sensing accuracy and low computational
complexity. Finally, the feasibility of the proposed ISAC signal processing
methods are verified by simulation results
Interplay between multiple charge-density waves and the relationship with superconductivity in PdHoTe
HoTe, a member of the rare-earth tritelluride (Te) family, and
its Pd-intercalated compounds, PdHoTe, where superconductivity (SC)
sets in as the charge-density wave (CDW) transition is suppressed by the
intercalation of a small amount of Pd, are investigated using angle-resolved
photoemission spectroscopy (ARPES) and electrical resistivity. Two
incommensurate CDWs with perpendicular nesting vectors are observed in
HoTe at low temperatures. With a slight Pd intercalation ( = 0.01),
the large CDW gap decreases and the small one increases. The momentum
dependence of the gaps along the inner Fermi surface (FS) evolves from
orthorhombicity to near tetragonality, manifesting the competition between two
CDW orders. At = 0.02, both CDW gaps decreases with the emergence of SC.
Further increasing the content of Pd for = 0.04 will completely suppress
the CDW instabilities and give rise to the maximal SC order. The evolution of
the electronic structures and electron-phonon couplings (EPCs) of the multiple
CDWs upon Pd intercalation are carefully scrutinized. We discuss the interplay
between multiple CDW orders, and the competition between CDW and SC in detail.Comment: 6 pages, 5 figure
A 5G DMRS-based Signal for Integrated Sensing and Communication System
Integrated sensing and communication (ISAC) is considered as the potential
key technology of the future mobile communication systems. The signal design is
fundamental for the ISAC system. The reference signals in mobile communication
systems have good detection performance, which is worth further research.
Existing studies applied the single reference signal to radar sensing. In this
paper, a multiple reference signals collaborative sensing scheme is designed.
Specifically, we jointly apply channel state information reference signal
(CSI-RS), positioning reference signal (PRS) and demodulation reference signal
(DMRS) in radar sensing, which improve the performance of radar sensing via
obtaining continuous time-frequency resource mapping. Cr\'amer-Rao lower bound
(CRLB) of the joint reference signal for distance and velocity estimation is
derived. The impacts of carrier frequency and subcarrier spacing on the
performance of distance and velocity estimation are revealed. The results of
simulation experiments show that compared with the single reference signal
sensing scheme, the multiple reference signals collaborative sensing scheme
effectively improves the sensing accuracy. Moreover, because of the
discontinuous OFDM symbols, the accuracy of velocity estimation could be
further improved via compressed sensing (CS). This paper has verified that
multiple reference signals, instead of single reference signal, have much more
superior performance on radar sensing, which is a practical and efficient
approach in designing ISAC signal
Integrated Sensing and Communication Signals Toward 5G-A and 6G: A Survey
Integrated sensing and communication (ISAC) has the advantages of efficient
spectrum utilization and low hardware cost. It is promising to be implemented
in the fifth-generation-advanced (5G-A) and sixth-generation (6G) mobile
communication systems, having the potential to be applied in intelligent
applications requiring both communication and high-accurate sensing
capabilities. As the fundamental technology of ISAC, ISAC signal directly
impacts the performance of sensing and communication. This article
systematically reviews the literature on ISAC signals from the perspective of
mobile communication systems, including ISAC signal design, ISAC signal
processing algorithms and ISAC signal optimization. We first review the ISAC
signal design based on 5G, 5G-A and 6G mobile communication systems. Then,
radar signal processing methods are reviewed for ISAC signals, mainly including
the channel information matrix method, spectrum lines estimator method and
super resolution method. In terms of signal optimization, we summarize
peak-to-average power ratio (PAPR) optimization, interference management, and
adaptive signal optimization for ISAC signals. This article may provide the
guidelines for the research of ISAC signals in 5G-A and 6G mobile communication
systems.Comment: 25 pages, 13 figures, 8 tables. IEEE Internet of Things Journal, 202
Research on energy sharing between distribution network and multiple systems based on the mixed game strategy and water-electric-gas integrated energy complementation
Introduction: It is significant for energy sharing to study the complementary utilization of multiple energy sources, such as water, electricity and gas, and the interaction among multiple stakeholders.Methods: We propose a research on energy sharing between distribution network and multiple systems based on the mixed game strategy and water-electric-gas integrated energy complementation. Firstly, this paper describes the relationship and functions of all stakeholders under the research framework, and establishes the mathematical model of each unit in the water-electric-gas complementary IES. Secondly, the internal roles are layered based on the relationship between stakeholders in the system. Then a non-cooperative game model for the distribution network operator and multiple subsystems is established according to the theory of Stackelberg game, and a cooperative game model for multiple subsystems is further established based on the theory of Nash bargaining. In the next step, the complexity of the problem is analyzed, followed by the description of the specific algorithm and process of solving the model.Results: Finally, the results of example analysis show that the model proposed in this paper not only balances the interests of stakeholders at the upper and lower layers of the system, but also allocates the interests of multiple subsystems at the lower layer.Discussion: Thus effectively improving the energy utilization of the system
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