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Closed-form evaluation of key performance indicators (KPIs) of telecommunication networks help perform mathematical analysis under several network configurations. This paper deals with a recent mathematical approach of indefinite quadratic forms to propose simple albeit exact closed-form expressions of the expectation of two significant logarithmic functions. These functions formulate KPIs which include the ergodic capacity and leakage rate of multi-user multiple-input multiple-output (MU-MIMO) systems in Rayleigh fading channels. Our closed-form expressions are generic in nature and they characterize several network configurations under statistical channel state information availability. As a demonstrative example of the proposed characterization, the derived expressions are used in the statistical transmit beamformer design in a broadcast MU-MIMO system to portray promising diversity gains using standalone or joint maximization techniques of the ergodic capacity and leakage rate. The results presented are validated by Monte Carlo simulations.
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http://dx.doi.org/10.3390/s21206792 | DOI Listing |
Phys Rev E
July 2025
Sam Houston State University, Hofstra University, Department of Physics, Hempstead, New York 11549, USA and Department of Physics, Huntsville, Texas 77341, USA.
It is known that the long-range quantum entanglement exhibited in free fermion systems is sufficient to "thermalize" a small subsystem in that the subsystem reduced density matrix computed from a typical excited eigenstate of the combined system is approximately thermal. Remarkably, fermions without any interactions are thus thought to satisfy the eigenstate thermalization hypothesis. We explore this hypothesis when the fermion subsystem is only minimally coupled to a quantum reservoir (in the form of another fermion system) through a quantum point contact (QPC).
View Article and Find Full Text PDFJ Chem Theory Comput
August 2025
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
The energy landscape of a model knotted ring polymer, consisting of 100 Lennard-Jones particles connected by harmonic springs, is extensively characterized for three topologies. Basin-hopping global optimization with unrestricted perturbation moves for the geometry can efficiently locate the global minimum of the topologically unconstrained energy landscape. We show that an isotropic radial potential to expand the structure provides a robust way to assign the crossing number and topology of each configuration.
View Article and Find Full Text PDFSci Rep
July 2025
Information and Navigation College, Air Force Engineering University, Xi'an, 710077, China.
Satellite-aerial-ground integrated network (SAGIN) confronts significant challenges from weather-induced impairments and transmission attenuation. To address this issue, this paper proposes a weather-dependent hybrid FSO/RF switching scheme for SAGIN, accounting for both weather effects and outdated channel state information (CSI). Specifically, three different working modes and two diversity schemes are designed to further mitigate the impact of adverse weather.
View Article and Find Full Text PDFSensors (Basel)
June 2025
School of Electronic Information and Artificial Intelligence, Shaanxi University of Science and Technology, Xi'an 710021, China.
In this paper, we investigate a simultaneous wireless information and power transfer (SWIPT) communication system enhanced by an intelligent reflecting surface (IRS). Our study takes into account the imperfections in the phase shift of the IRS and the presence of interfering signals reflected by the IRS at the destination terminal. Additionally, our analysis incorporates both the presence of a line-of-sight path between the source and destination and a non-linear energy-harvesting model.
View Article and Find Full Text PDFEntropy (Basel)
February 2025
Polytechnic School of Pernambuco, University of Pernambuco, Recife 50720-001, Brazil.
This paper analyzes for the first time how the Beckmann distribution can be used to characterize the random variable that represents the envelope of the effective channel gain experienced by the -th user equipment (UE) of a user-centric (UC) cell-free (CF) system in a scenario with noisy channel state information (CSI) estimation and line of sight (LoS). Additionally, it is shown how the Beckmann probability density function (PDF) can be used to derive the PDF and the cumulative density function (CDF) of the instantaneous signal-to-interference-plus-noise ratio (SINR) of the UC CF -th UE, followed by applications in the ergodic capacity (EC) and outage probability (OP) expression derivations. It is shown that, regardless of the type of distribution considered for the channel gain between each access point (AP) and UE links, the effective gain presents a Beckmann distribution.
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