- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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-Distribution Dual-Hop RF/FSO Systems
摘要： In this correspondence, we investigate the physical-layer security of a mixed radio frequency/free space optical (RF/FSO) dual-hop communication system for both fixed- and variable-gain relaying schemes. More specifically, we only assume that the eavesdropping happens at the RF link because the optical link has high security. We assume that all RF channels suffer from η–μ fading, while the FSO link experiences M-distributed fading. Then, we derive some analytical results for the average secrecy rate and the secrecy outage probability.
关键词： secrecy outage probability,Average secrecy rate,radio frequency-free space optical,M-distributed fading,η-μ fading,physical-layer security
更新于2025-09-23 15:22:29
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Precise Performance Analysis of Dual-Hop Mixed RF/Unified-FSO DF Relaying with Heterodyne Detection and Two IM-DD Channel Models
摘要： This paper provides precise performance analysis of the dual-hop mixed radio frequency (RF)/unified free space optical (FSO) decode-and-forward (DF) relaying system, in which the heterodyne detection (HD) and the intensity modulation-direct detection (IM-DD) are taken into account for FSO detection. To this end, we derive closed-form expressions for the outage probability, average bit error rate (BER), and the ergodic channel capacity of this system. In this analysis, we utilize, for the first time as per our knowledge, a precise channel capacity result for the IM-DD channel. Moreover, this is the first time that not only the (IM-DD input-independent) but also the (IM-DD cost-dependent) AWGN channel is considered in such system analyses. Additionally in this study, we assume that the first hop (RF link) follows Nakagami-m fading, and the second hop (FSO link) follows Málaga (M) turbulence with pointing errors. These fading and turbulence models contain other models (such as Rayleigh and Gamma-Gamma) as special cases, thus our analyses can be seen as a generalized one from the RF and FSO fading models point of view. Also, in BER derivation, we assume that the modulation schemes in the two hops can be different, since not all modulation schemes are suitable for IM-DD FSO links. In addition, the system performance is investigated asymptotically at high signal to noise ratios (SNRs). This investigation leads to new non-reported coding gain and diversity order analyses of such system. Interestingly, we find that in the FSO hop, at high transmitted powers, all the considered FSO detectors result in the same diversity order. Furthermore, we provide simulation results that verify the accuracy of the obtained analytical and asymptotic expressions.
关键词： Nakagami-m fading,Málaga (M) fading,HD,DF,heterodyne detection,Mixed RF/FSO relay network,IM-DD,decode-and-forward,intensity modulation-direct detection
更新于2025-09-23 15:22:29
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Thermoluminescence properties of strontium doped magnesium tetraborate
摘要： It is worth to continuous and systematic investigations related with magnesium tetraborate (MBO) due to its attractive candidate for dosimetric application. The study was done to develop new phosphor with adding strontium (Sr) into MBO which was prepared by the simple high temperature solid state method. Its main dosimetric properties, like glow curve structure, dose response, trapping parameters and fading, were investigated for the first time in the literature. The experimental results indicated that Sr doped MBO ensured essential characteristics for applicability in medical dosimetry, except for the fading (45 % lost in 7 days) feature. It had main glow peak with highest intensity at nearly 200 °C with good linearity of the dose–response up to 1150 Gy. This study suggests that Sr-doped MBO is a promising material for dosimetric application, just need to solve the fading problem with addition of another activators as a co-dopant.
关键词： thermoluminesence,strontium,Magnesium tetraborate,fading problem
更新于2025-09-23 15:22:29
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Measurements of Beamswitching Gains and Fade Dynamics for 28 GHz Indoor Static Links in the Presence of Pedestrian Traffic
摘要： We measured channel dynamics for fixed wireless indoor channels at 28 GHz. We characterize pedestrian-induced fades in open indoor spaces and the effectiveness of beamswitching to mitigate them. We find that fades of the dominant propagation path may be as deep as 9 dB at the 90th percentile and that alternative signal paths are typically not strong enough to provide significant beamswitching gains.
关键词： Millimeter wave propagation,Rician channels,Channel models,Multipath channels,Fading channels
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Jeju (2018.10.17-2018.10.19)] 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Performance of SIM/S-QAM FSO Systems with Phase Errors in Gamma-Gamma Turbulence Channels
摘要： In this paper, we study the performance of subcarrier intensity modulation (SIM) squared quadrature-amplitude modulation (S-QAM) free-space optical (FSO) communication systems considering the atmospheric turbulence-induced phase error in fading channel. The atmospheric fading channel is modeled by Gamma-Gamma distribution while the Tikhonov model is used for the turbulence-induced phase error. The numerical results quantitatively show the impact of atmospheric turbulence parameters to the performance of FSO systems in terms of average symbol-error probability (ASEP) and the power penalty. Besides, the theoretical results are validated through Monte Carlo simulation to confirm our analysis.
关键词： Free-space optics (FSO),Phase error.,Atmospheric Turbulence,Fading Channel,Squared quadrature-amplitude modulation (QAM)
更新于2025-09-23 15:22:29
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Laser Doppler Vibrometry Measurements of Conversion of Surface Guided Waves to Optical Fiber Modes
摘要： This paper investigates a multi-pair two-way massive MIMO amplify-and-forward full-duplex relay (FDR) system over Ricean fading channels, where multiple pairs of full-duplex users exchange information within pair through a full-duplex relay with a very large number of antennas (M for transmission and M for reception). First, the zero-forcing reception/zero-forcing transmission and maximum-ratio combining/maximum-ratio transmission processing matrices with imperfect channel state information at the relay are presented. Then, the corresponding asymptotic expressions (in M ) of the end-to-end signal-to-interference-plus-noise ratio are derived. Finally, the asymptotic spectral ef?ciency (SE) and energy ef?ciency (EE) at the general power scaling schemes when the number of the relay antennas tends to in?nity is analyzed. Theoretical analyses and simulation results show that, when M → ∞, the effects of channel estimation error, the self-loop of each user as well as the relay, inter-user interferences, the noise at users and the relay can be eliminated, respectively, if the power scaling scheme is properly selected. Besides, the considered multi-pair two-way FDR outperforms the multi-pair two-way half-duplex relaying on SE and EE performances when M is large. Moreover, a low complexity power control scheme is proposed to optimize the SE and we analyze the impact of the number of user pairs on the SE.
关键词： imperfect CSI,power control,full-duplex,Massive MIMO,Ricean fading channels
更新于2025-09-23 15:21:01
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High Charge Carrier Storage Capacity in Lithium Lutetium Silicate Doped with Cerium and Thulium
摘要： It is demonstrated that LiLuSiO4:Ce,Tm has excellent charge carrier storage properties. Comparative studies are performed with the state-of-the art X-ray storage phosphor BaFBr(I):Eu. The thermoluminescence (TL) intensity of the optimized LiLuSiO4:Ce,Tm is four times higher than the TL of BaFBr(I):Eu. After 3 h of storage at room temperature (RT) there is still 94% of initial thermoluminescence and only 48% for BaFBr(I):Eu which demonstrates insignificant thermal fading. The signal can be read out by a blue LED and less efficiently by a red laser. It does require higher stimulation energy than in the case of BaFBr(I):Eu. The self-irradiation with a dose rate of 13 mGy h due to 176Lu isotopes is not a serious drawback for application.
关键词： storage phosphors,thulium,cerium,traps,thermoluminescence,fading,self-irradiation
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Assessing the impact of back-contact recombination on CIGS solar cells with improved crystal quality
摘要： We propose and prove a theorem that allows the calculation of a class of functionals on Poisson point processes that have the form of expected values of sum–products of functions. In proving the theorem, we present a variant of the Campbell–Mecke theorem from stochastic geometry. We proceed to apply our result in the calculation of expected values involving interference in wireless Poisson networks. Based on this, we derive outage probabilities for transmissions in a Poisson network with Nakagami fading. Our results extend the stochastic geometry toolbox used for the mathematical analysis of interference-limited wireless networks.
关键词： interference,Wireless networks,time diversity,correlation,Poisson point process,Nakagami fading,stochastic geometry,Rayleigh fading
更新于2025-09-23 15:19:57
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[IEEE 2020 IEEE Texas Power and Energy Conference (TPEC) - College Station, TX, USA (2020.2.6-2020.2.7)] 2020 IEEE Texas Power and Energy Conference (TPEC) - Performance Evaluation of Photovoltaic Grid-connected Microgrid with Hybrid Energy Storage using Predictive Current Control
摘要： We propose and prove a theorem that allows the calculation of a class of functionals on Poisson point processes that have the form of expected values of sum–products of functions. In proving the theorem, we present a variant of the Campbell–Mecke theorem from stochastic geometry. We proceed to apply our result in the calculation of expected values involving interference in wireless Poisson networks. Based on this, we derive outage probabilities for transmissions in a Poisson network with Nakagami fading. Our results extend the stochastic geometry toolbox used for the mathematical analysis of interference-limited wireless networks.
关键词： interference,Wireless networks,time diversity,correlation,Poisson point process,Nakagami fading,stochastic geometry,Rayleigh fading
更新于2025-09-23 15:19:57
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Asymptotic Performance of Generalized Transmit Laser Selection Over Lognormal Turbulence Channels
摘要： In free space optical communication systems, transmit laser selection (TLS) has been proposed as an efficient fading-mitigation technique over turbulence channels. In TLS, the transmitter is equipped with a number of laser sources and the best laser source is selected for transmission. In practice, feedback error or outdated selection due to temporal changes in the channel may result in selecting another source rather than the best one. In this paper, we consider a FSOC system with generalized TLS (GTLS) where the nth best laser is selected among the available N lasers. Under the assumption of lognormal turbulence channels in addition to pointing errors, we derive a closed-form expression for asymptotic bit error rate. We use our derived closed-form expression to determine the diversity gains. We finally present simulation results to corroborate our analytical findings.
关键词： Free space optical communication,diversity order,lognormal fading,generalized transmit laser selection
更新于2025-09-23 15:19:57