- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall) - Honolulu, HI, USA (2019.9.22-2019.9.25)] 2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall) - Performance of Free Space Optical Communication System under Jamming Attack and Its Mitigation over Non-Gaussian Noise Channel
摘要： In free space optical (FSO) communication, jamming can cause inaccuracy in the received information. In this paper, we investigate the impact of jamming over atmospheric turbulence (AT) fading channels. To describe the AT, negative exponential fading channel models are considered. The effect of jamming is studied over a single-input single-output (SISO) FSO link. We introduce a theoretical framework to acquire a closed-form expression of the average bit error rate (ABER) under jamming–leading to an additive non-Gaussian noise channel. It is observed by thorough analysis that a 2 × 1 FSO system performs better than SISO FSO system in presence of jamming signal. It is realized that under jamming the performance of FSO link is dependent on different AT conditions. Furthermore, increasing number of transmit apertures allows FSO system to significantly overcome the effect of jamming, in order to obtain an improved ABER.
关键词： Additive non-Gaussian noise,exponential fading,signal-to-jamming ratio (SJR),bit error rate (BER),free space optical (FSO) communication,jamming,Gamma-Gamma fading
更新于2025-09-12 10:27:22
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Fiber Optic and Atmospheric Optical Communication || Fading in Optical Communication Channels
摘要： As was mentioned in [1, 2], in most optical wired and wireless systems operated in the atmosphere [3, 4], there occur multiple diffraction, multiple reflection, and multiple scattering effects, due to artificial features inside fibers and dispersion of the inner material, or due to natural obstructions (aerosols, hydrometeors, such as rain, snow and clouds, etc.) filled in the atmosphere. All these effects, which cause not only addition losses (with respect to those obtained in line-of-sight [LOS] above-the-terrain conditions) but also addition fading of the signal strength observed at the detector, can be separated into two independent effects, the slow and the fast fading [5–10]. In real situations occurring in the atmospheric communication links, the various optical signals arriving at the moving or stationary detector via their respective paths have individual phases, which change continuously and randomly. Therefore, both the resultant signal envelope and its phase will also be random variables. Moreover, the Doppler effect can also be explained by random frequency modulation [11–14] due to different Doppler shifts of each of the received signals as multi-ray components. Therefore, to describe slow and fast signal fading, we need to introduce the corresponding mathematical description of the statistical effects that accompany real signal fading in multipath communication channels.
关键词： statistical description,optical communication,Doppler effect,multipath,fading
更新于2025-09-12 10:27:22
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Transmit laser selection for two hop decode and forward FSO communication with pointing errors
摘要： In this letter, two systems have been proposed for efficient unidirectional free space optical (FSO) cooperative communication-one with only transmit laser selection (TLS) and the other using optical spatial modulation (OSM) along with TLS. Performance analysis of such systems for Gamma-Gamma (G-G) fading channels both with and without Pointing errors have been carried out in terms of outage probability and average symbol error probability (ASEP). Our proposed TLS system over G-G channel (with pointing error) yields a signal to noise ratio (SNR) gain of at least 10 dBm over the conventional FSO system.
关键词： cooperative communication,Free space optical communication,transmit laser selection,pointing errors,Gamma-Gamma fading,optical spatial modulation
更新于2025-09-12 10:27:22
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Fine tunable PT-symmetric optoelectronic oscillator based on laser wavelength tuning
摘要： A fine tunable parity-time symmetric optoelectronic oscillator (PT-OEO) based on laser wavelength tuning is proposed and experimentally demonstrated. In the PT-OEO, an intensity modulator (IM) and a dispersion compensating fiber (DCF) are merged into the loop. Tuning the laser wavelength leads to a reconfigurable dispersion-induced power fading, serving as rough tunable oscillation mode selection. Meanwhile, to implement a fine-mode selection, parity-time symmetry breaking is introduced. Consequently, a fine tunable PT-OEO is achieved without using a high quality-factor (Q-factor) electrical filter. Experiment shows that the frequency of the generated signal can be tuned from 20.34 to 19.49 GHz with a step of 203 MHz, when the laser wavelength is manipulated from 1545 to 1565 nm. The phase noise is evaluated as -116.1 dBc/Hz @ 10-kHz offset frequency.
关键词： optoelectronic oscillator,Dispersion-induced power fading,parity-time symmetry
更新于2025-09-11 14:15:04
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Fiber Optic and Atmospheric Optical Communication || Transmission of Information Data in Optical Channels: Atmospheric and Fiber Optics
摘要： The chapter discusses the transmission of information data in optical channels, focusing on atmospheric and fiber optics. It highlights the challenges posed by atmospheric effects on wave propagation, including attenuation, optical signal amplitude, and phase scintillations caused by atmospheric turbulence. The chapter also explores the impact of these phenomena on the data stream parameters, such as bit error rate (BER) and signal-to-noise ratio (SNR), and proposes methods to mitigate these effects to achieve high performance in optical communication links.
关键词： atmospheric turbulence,bit error rate,optical communication,spectral efficiency,signal-to-noise ratio,scintillation,fading,Ricean K-factor,fiber optics,multipath channel
更新于2025-09-11 14:15:04
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Modeling the Random Orientation of Mobile Devices: Measurement, Analysis and LiFi Use Case
摘要： Light-fidelity (LiFi) is a networked optical wireless communication (OWC) solution for high-speed indoor connectivity for fixed and mobile optical communications. Unlike conventional radio frequency wireless systems, the OWC channel is not isotropic, meaning that the device orientation affects the channel gain significantly, particularly for mobile users. However, due to the lack of a proper model for device orientation, many studies have assumed that the receiver is vertically upward and fixed. In this paper, a novel model for device orientation based on experimental measurements of forty participants has been proposed. It is shown that the probability density function (PDF) of the polar angle can be modeled either based on a Laplace (for static users) or a Gaussian (for mobile users) distribution. In addition, a closed-form expression is obtained for the PDF of the cosine of the incidence angle based on which the line-of-sight (LOS) channel gain is described in OWC channels. An approximation of this PDF based on the truncated Laplace is proposed and the accuracy of this approximation is confirmed by the Kolmogorov-Smirnov distance (KSD). Moreover, the statistics of the LOS channel gain are calculated and the random orientation of a user equipment (UE) is modeled as a random process. The influence of random orientation on signal-to-noise-ratio (SNR) performance of OWC systems has been evaluated. Finally, an orientation-based random waypoint (ORWP) mobility model is proposed by considering the random orientation of the UE during the user’s movement. The performance of ORWP is assessed on the handover rate and it is shown that it is important to take the random orientation into account.
关键词： Laplace distribution,Optical wireless communications,light-fidelity (LiFi),receiver rotation,fading,device orientation,random waypoint
更新于2025-09-11 14:15:04
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Symbol Error Probability Analysis of DFrFT-based OFDM Systems with CFO and STO in Frequency Selective Rayleigh Fading Channels
摘要： In this article we derive exact symbol error probability (SEP) expressions for orthogonal frequency-division multiplexing (OFDM) based on discrete fractional Fourier transform (DFrFT) when symbol timing offset (STO) and carrier frequency offset (CFO) are present together. Closed form expressions are derived for binary phase shift keying, quadrature phase shift keying, and 16-ary quadrature amplitude modulation in the case of transmission over a frequency selective Rayleigh fading channel. As is well known, in OFDM the presence of CFO destroys the orthogonality between the sub-carriers, generating inter-carrier interference (ICI), while the presence of STO introduces intersymbol interference, between successive symbols, and phase rotations in frequency domain, within the same symbol. It is well recognized that an OFDM system based on DFrFT is more robust to ICI introduced by CFO than that based on discrete Fourier transform (DFT). Motivated by this, the combined effect of CFO and STO on the SEP of a DFrFT-based OFDM system is analyzed. Our results show that the DFrFT-based OFDM system outperforms that based on the DFT for different values of the DFrFT ‘angle parameter’. Monte Carlo simulations are used to demonstrate the correctness of the derived analytical expressions.
关键词： sampling-type FrFT,frequency selective fading,carrier frequency offset.,orthogonal frequency-division multiplexing (OFDM),Error rate analysis,symbol timing offset
更新于2025-09-10 09:29:36
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Performance analysis of physical layer security over α-η-κ-μ fading channels
摘要： In this paper, we consider the secure data transmission over α-η-κ-μ fading channels, which are recently proposed to encompass nearly all the well-known statistical models adopted in the literature. In particular, we address the secrecy performance in terms of the average secrecy capacity (ASC) and the secrecy outage probability (SOP), for which novel analytical expressions are derived. Simulation results verify the analysis and demonstrate the impact of the physical parameters on the secrecy performance of this new channel fading model.
关键词： secrecy outage probability,average secrecy capacity,α-η-κ-μ generalized fading channels,Physical layer security
更新于2025-09-10 09:29:36
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X-Ray Thermoluminescence Dosimetry Characterization of Commercially Available CVD Diamond
摘要： High quality commercially available CVD diamonds are being tested in novel clinical high energy photons, hadron therapy, and high energy physics applications. In the present work, the authors report on the thermoluminescence (TL) and dosimetry properties of commercial synthetic CVD diamond sample from Element6, exposed to X-ray irradiation at dose rates of 3.9–120 Gy min?1 from 0.13 to 90 Gy. The TL glow curves are composed of four peaks with maxima at about 104, 150, 210, and 280 °C and activation energies of 0.78, 0.79, 0.81, and 1.0 eV, respectively. The dose response of the area under TL glow curves is linear at doses lower than 0.6 Gy, supralinear between 0.6 and 6 Gy and sublinear at higher doses. The samples exhibited a strong TL fading of the low temperature 104 °C peaks that fades away around 120 min after irradiation, which is accompanied by increasing of the 210 and 280 °C peaks. The measured TL cycle reproducibility was very good, in spite of the fading exhibited by the lower temperature peak, with values of 0.1–3.0% at different dose rates and doses. It is concluded that CVD commercially single crystal electronic grade diamond may be securely used in clinical radiotherapy.
关键词： dosimetry,fading,thermoluminescence,diamond CVD crystal,X-ray irradiation
更新于2025-09-09 09:28:46
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[IEEE 2018 4th International Conference on Frontiers of Signal Processing (ICFSP) - Poitiers, France (2018.9.24-2018.9.27)] 2018 4th International Conference on Frontiers of Signal Processing (ICFSP) - Uplink Rate Based on Massive MIMO Channel Estimation Approach
摘要： Transmitted signal is degraded and problem remains reconstruction of symbols. In massive MIMO systems, channel estimation has been widely discussed. This paper investigated on the inaccuracy of the channel estimation and its effect on the uplink rate. Best solution is to have the most efficient channel estimation method that is not adversely affected by noise, interference and pilot contamination; hence choice of MMSE method compared to others. After channel estimation, the uplink rate is calculated at the receivers with the ZF and MMSE detectors by using training or pilot symbols. We noted that the two detectors converge towards an asymptotic solution which allows the knowledge of the channel. It is shown that the estimation error increases proportionally when the L cells significantly increases. And the higher the pilot power contamination increases respectively, the decrease in dB of the uplink rate is related proportionally to the increase of the channel attenuation.
关键词： massive multiple input multiple output,zero forcing,path loss,fading,minimum mean squared estimator
更新于2025-09-09 09:28:46