- 标题
- 摘要
- 关键词
- 实验方案
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Channel modeling and analysis of OWC-massive MIMO systems
摘要： In this paper, we study the difference between the uplink and downlink channels of short-range slant free-space optical wireless between Ground - alpine base stations using massive MIMO linear arrays at both ends. The uplink and downlink atmospheric loss, scintillation, beam spreading and pointing error model of linear array slant range are constructed. The uplink and downlink atmospheric loss, spatial coherence length, receiver beamwidth, pointing error variance, relative mean square error (RMSE) and bit error rate (BER) are compared and analyzed under different distances of different wavelengths of light waves. After simulation analysis, it is concluded that the uplink and downlink atmospheric losses are the same, the uplink receiver beamwidth is larger than the downlink, and the downlink coherence length and the pointing error variance are larger than the uplink, and both monotonously change with the wavelength of the light wave and the propagation distance.
关键词： Optical wireless communication,MSE,Wavelength,Channel modeling,Massive MIMO
更新于2025-09-23 15:23:52
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Blind Joint Polarization Demultiplexing and IQ Imbalance Compensation for M-QAM Coherent Optical Communications
摘要： A novel joint polarization demultiplexing and IQ imbalance compensation scheme for coherent optical communications that uses global update is proposed and analyzed through numerical simulations. We describe the system model and derive its related equations. Next, we formulate our blind M -QAM arbitrary approach based on EASI algorithm and using the second order statistics of the observed signals. A comparison of the proposed joint method with the traditional CMA for polarization demultiplexing followed by BASS for IQ imbalance compensation is also reported. Evaluated metrics (EVM, MSE, BER) demonstrate its effectiveness compared with CMA cascaded with BASS algorithm.
关键词： CMA,Joint algorithm,BER,IQ imbalance compensation,MSE,EVM,Optical communications,Polarization demultiplexing
更新于2025-09-23 15:21:01
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Secure medical image steganography through optimal pixel selection by EH-MB pipelined optimization technique
摘要： In today’s world, transmission of information over the channel is not secure for example patient records and other sensitive information. In order to protect this sensitive information, it is coded within the image, audio or text files which is decodable only with the help of a particular key. To enable security to the covert communication and safeguarding the information for securing medical data to avoid medical related cybercrimes, we have proposed a method for medical image steganography using Elephant Herding-Monarch Butterfly (EH-MB) Optimization algorithm for effective selection of pixels for embedding the secret message (i.e. image/text medical report data) in the cover image. Initially, the cover is converted to frequency domain using multilevel DWT, where, the pixel selection is done optimally in the high frequency components using EH-MB algorithm. EH-MB based pixel selection procedure uses a fitness function that depends on the cost function, which calculates the edge, entropy, and intensity of the pixel for evaluating fitness. Simulation was done in the working platform of MATLAB and comparison of the proposed steganography approach was done with the other existing methods in terms of Peak-Signal-to Noise-Ratio and Mean Square Error to prove the effectiveness of the proposed approach.
关键词： Intensity,Elephant herding,Steganography,Object,MSE,PSNR,Entropy,Covert,Segmentation,Edge,Monarch butterfly
更新于2025-09-19 17:15:36
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Open Innovation Using Satellite Imagery for Initial Site Assessment of Solar Photovoltaic Projects
摘要： Two novel blind equalization techniques for odd bit rectangular quadrature amplitude modulation (RQAM) signaling are proposed in this paper, namely, rectangular contour algorithm (RRECT CA) and improved rectangular contour algorithm (IRCA). The proposed RRECT CA algorithm minimizes the dispersion of constant with respect to a rectangular-shaped zero error contour. The algorithm exploits the geometry of the RQAM to correct phase error within 180?, thus enhancing the convergence rate while minimizing the equalizer mis-adjustments. On the other hand, the proposed IRCA algorithm employs the estimated output from the decision device into the cost function, thus guiding the equalizer output to reside on multiple zero error rectangular shaped moduli. This method of feeding back the slicer output further reduces the mis-adjustment between the transmitted constellation and the new cost function in an ef?cient manner, which leads to faster convergence and better intersymbol interference suppression. The proposed algorithms can also work for the square QAM by mere change of only two constellation dependent constants, thus facilitating the implementation in hardware to enable transmission of both even and odd number of bits per symbol based constellations. Steady-state error analysis, MSE, and residual ISI comparison through the simulation results con?rm the good performance of the proposed algorithms. Furthermore, the convergence characteristics of the proposed IRCA scheme establish the supremacy of IRCA over RRECTCA, which is its parent algorithm.
关键词： rectangular QAM,quadrature amplitude modulation (QAM),Blind equalization,cross QAM,inter symbol interference (ISI),mean square error (MSE)
更新于2025-09-19 17:13:59
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Debye Frequency-extended Waveguide Permittivity Extraction for High Complex Permittivity Materials. Concrete Setting Process Characterization
摘要： A waveguide with central frequency 868 MHz is used in transmission/re?ection operation regime to accurately measure the behaviour of the complex permittivity of high complex permittivity granular materials and it has been frequency-extended up to 3 GHz using the Debye ?tted relaxation model. It is shown that for highly granular high permittivity materials a waveguide based transmission/re?ection technique is necessary to reduce the uncertainty of the extracted permittivity values. The technique is ?rst described and validated with isopropyl alcohol and then applied to the characterization of cement based materials. This paper provides accurate data on the evolution of the complex permittivity of concrete and mortar from the moment of pouring until air dried condition is achieved.
关键词： loss tangent,Debye,RFID,MSE,loss factor,waveguide,concrete setting process,relative permittivity
更新于2025-09-12 10:27:22
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Measurement of IPTV Services on a Hybrid Access Network
摘要： Future telecommunication networks will be formed by means of different types of telecommunication systems that were used in the past. Considering expanding options of today’s smart mobile phones there is increasing pressure on telecommunication operators, who face a challenge how to cooperate across different telecommunication systems within their networks. The work focuses on the expansion of IPTV data flow on a hybrid network that is formed by the EPON and ADSL technologies. Along with the hybrid topology we focus on comparing multicast and unicast expansion of IPTV data traffic within this work.
关键词： EPON,MSE,ADSL,hybrid network,PSNR,SSIM,IPTV
更新于2025-09-10 09:29:36
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Research on Beam Emission Spectroscopy Combined HL-2A Tokamak Real Experimental Data With Spectra Simulation Code
摘要： A beam emission spectroscopy (BES) diagnostic system has been developed on HL-2A tokomak. Combined with motional Stark effect (MSE) diagnostics, the BES could assess the radial electric ?eld Er and the safety factor q, which play an important role in plasma control and impurity transport processes. A simulation of spectra (SOS) code has been developed for spectra simulations based on various tokamak devices’ real situations. It can be used for designing visible spectral diagnostics systems and predicting their performance. In this paper, based on the HL-2A real experimental running parameters, we used the SOS code to simulate BES and MSE spectra. These spectra were consistent with experimental data ?tting results. The SOS code was also able to get the safety factor q and other parameters. The results reveal that the SOS code could be used to design similar diagnostic systems for ITER in the future.
关键词： neutral beam injection (NBI) diagnostics,motional Stark effect (MSE),simulation of spectra (SOS),Beam emission spectroscopy (BES)
更新于2025-09-04 15:30:14