- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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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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Quasi blind carrier phase estimation scheme for special-shaped circular (7,1) modulation in high-speed visible light communication
摘要： A novel digital signal processing (DSP) scheme for special-shaped circular (7,1) modulated signals based on quasi blind carrier phase estimation (QBCPE) is proposed. The results show that applying 0.33‰ overhead QBCPE provides similar performance as 3% training sequence data-aided equalization of least mean square (LMS) algorithm.
关键词： Constant Modulus Algorithm (CMA),visible light communication (VLC),least mean square (LMS),circular (7,1) modulation,quasi blind carrier phase estimation (QBCPE)
更新于2025-09-23 15:21:01
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Plasmonic Nano-antenna Optimization Using Characteristic Mode Analysis
摘要： Plasmonic nano-antennas are typically designed with RF-inspired rigorous parametric optimization processes that lack proper physical insights. In this study, we demonstrate a systematic optimization approach for nano-antennas based on characteristic mode analysis (CMA). A complex geometry, designated as split-ring two-wire antenna (SRA), is selected and optimized using the CMA technique. CMA identifies the dominant modes of the structure at the frequency of interest as well as explains the dependency of the modes on the structure’s shape, size and material properties. These insights from CMA have been used in the present study to efficiently optimize SRA shape, size, and material which yield more than 700 % near-field intensity enhancement (NFIE) at the desired operating frequency. This proposed CMA based optimization method can be adapted easily for many other nano-antenna applications, facilitating the development of improved nano-structures.
关键词： Split-ring Two-wire Antenna (SRA),Method of Moments (MOM),Plasmonic,Nano-structures / Nano-antennas,Near Field Intensity Enhancement (NFIE),Surface Integral Equation (SIE),Characteristic Mode Analysis (CMA)
更新于2025-09-11 14:15:04
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ALMA observations of TiO <sub/>2</sub> around VY CMa
摘要： Titanium dioxide, TiO2, is a refractory species that could play a crucial role in the dust-condensation sequence around oxygen-rich evolved stars. We present and discuss the detections of 15 emission lines of TiO2 with ALMA in the complex environment of the red supergiant VY CMa. The observations reveal a highly clumpy, anisotropic out?ow in which the TiO2 emission likely traces gas exposed to the stellar radiation ?eld. We ?nd evidence for a roughly east-west oriented, accelerating bipolar-like structure, of which the blue component runs into and breaks up around a solid continuum component. We see a distinct tail to the south-west for some transitions, consistent with features seen in the optical and near-infrared. We ?nd that a signi?cant fraction of TiO2 remains in the gas phase outside the dust-formation zone and suggest that this species might play only a minor role in the dust-condensation process around extreme oxygen-rich evolved stars like VY CMa.
关键词： oxygen-rich evolved stars,ALMA,dust-condensation,TiO2,VY CMa
更新于2025-09-09 09:28:46