A review of methods of measuring system parameters in time-variant space communication channels

This paper investigates the distributed filtering for discrete-time-invariant systems in sensor networks where each sensor’s measuring system may not be observable, and each sensor can just obtain partial system parameters with unknown coefficients which are modeled by Gaussian white noises. A fully distributed robust Kalman filtering algorithm consisting of two parts is proposed. One is a consensus Kalman filter to estimate the system parameters. It is proved that the mean square estimation errors for the system parameters converge to zero if and only if, for any one system parameter, its accessible node subset is globally reachable. The other is a consensus robust Kalman filter to estimate the system state based on the system matrix estimations and covariances. It is proved that the mean square estimation error of each sensor is upper-bounded by the trace of its covariance. An explicit sufficient stability condition of the algorithm is further provided. A numerical simulation is given to illustrate the results.

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Preserving Nonclassicality in Noisy Communication Channels

Proceedings ◽

10.3390/proceedings2019012003 ◽

2019 ◽

Vol 12 (1) ◽

pp. 3 ◽

Cited By ~ 1

Author(s):

Alessia Allevi ◽

Maria Bondani

Keyword(s):

Quantum Information ◽

Photon Number ◽

Communication Channels ◽

Global Scale ◽

Noisy Channels ◽

Space Communication ◽

Main Obstacle ◽

Cryptographic Keys ◽

Light Signals ◽

Twin Beam

Nowadays, the transmission of quantum information, especially for the distribution of cryptographic keys, is required on a global scale. The main obstacle to overcome in free-space communication is the presence of turbulence, which causes both spatial and temporal deformations of the light signals that code information. Here we investigate the extent at which the transmission of mesoscopic twin-beam states through asymmetric noisy channels degrades the nonclassical nature of the photon-number correlations between signal and idler. We consider three nonclassicality criteria, all written in terms of measurable quantities, and demonstrate, both theoretically and experimentally, that the asymmetry introduced by losses affects the three criteria in different ways.

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Blind Adaptive Equalization for Aerospace Communication Channels

Journal of Karary University for Engineering and Science ◽

10.54388/jkues.v1i2.137 ◽

2021 ◽

Author(s):

Elessaid S. Saad

Keyword(s):

Communication Systems ◽

Blind Equalization ◽

Communication Channels ◽

Training Sequence ◽

Adaptive Equalization ◽

Space Communication ◽

The Past ◽

Blind Adaptive ◽

Transmitted Sequence ◽

Selective Channel

In some communication systems, it is desirable for the receiver to synchronize to the received signal and to adjust the equalizer without having knowledge of a training sequence. Blind equalization uses the initial adjustment of the coefficients without making use of a training sequence. Different adaptive blind equalization algorithms have been developed over the past four decades. In this paper, we investigate the effect of blind equalization on space communication channels. The space channel under investigation is considered to be a multipath frequency selective channel having four paths. The channel is subjected to the phenomenon of InterSymbol Interference (ISI) which severely degrades the performance of the space communication system. Two blind algorithms are used in equalizer adjustment. The impulse responses of the space channel, the blind equalizer and the combination of channel and equalizer for QPSK and 16-QAM transmission are shown. The scatter diagrams for the transmitted sequence, received sequence, and the output of the equalizer using two of the blind algorithms are shown.

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THE MONITORING SYSTEM OF THE WATER ENVIRONMENT HYDROPHYSICAL FIELDS

Fundamental and Applied Problems of Engineering and Technology ◽

10.33979/2073-7408-2020-343-5-153-164 ◽

2020 ◽

Vol 5 ◽

pp. 153-164

Author(s):

E.O. SAVKOVA ◽

O.V. CHENGAR ◽

V.I. SHEVCHENKO

Keyword(s):

Fine Structure ◽

Detailed Analysis ◽

Monitoring System ◽

Measurement Accuracy ◽

Water Environment ◽

Measuring System ◽

Information Flows ◽

System Parameters ◽

The Cost ◽

Selected Functions

The article considers the functions performed by the system for monitoring the fine structure of the water environment hydrophysical fields, starting from initialization the system parameters to visualization the received information. As a result of a detailed analysis the selected functions, which consists in determining the input information flows, their representation and transformation, a functional diagram of the measuring system for monitoring the fine structure of the water environment hydrophysical fields was developed, which allows reducing the cost of conducting sounding and ensuring the necessary measurement accuracy, thanks to the chosen sensing strategy and the use of a database of simulated parameters of turbulated layers .

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