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Moment-based Approach for Statistical and Simulative Analysis of Turbulent Atmospheric Channels in FSO Communication
摘要： Free Space Optical (FSO) or wireless optical communication networks involve atmosphere as the channel, which at times can be turbulent in nature, thus degrading the system performance. These turbulent channels can be analysed by introducing various channel models and modulation techniques. Various researchers have analysed the performance by presenting different approaches for each type of channel model. In this paper, we present a uni?ed approach for the performance analysis of Log-normal, Nakagami-n (Rician) and Rayleigh statistical models by deriving the exact closed form expressions for average bit error probability and the outage probability of each model. It is achieved by using alternative form of Q-function and Gauss-Hermite Quadrature approximation to the moment-generating function of the output Signal-to-Noise Ratio (SNR). Further, de?nite expressions for each type of modulation technique are also derived to describe the channel fading in FSO communication system. The system of interest includes M-ary Phase Shift Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) techniques. Moreover, the average output SNR, average received irradiance and the amount of fading (fading strength) are also expressed in simple closed forms for above mentioned turbulent channels. In addition to this, the performance of FSO system in presence of atmospheric turbulence and pointing errors is also investigated. The statistical model is examined for zero and nonzero boresight point errors modelled by Rayleigh and Rician distributions in Log-normal fading channel. The composite Log-normal PDFs along with asymptotic error rate and outage probability are also presented for such system. The effect of Tikhonov distributed phase noise arised due to BPSK modulation on BER performance is evaluated on three turbulent channels by deriving its closed-form expression using moment based approach.The mathematical analysis is veri?ed by comparing numerical results with Monte-Carlo Simulated values and graphs.
关键词： Rayleigh,SNR,BER,phase noise,Log-normal,Nakagami-n,path loss,outage probability,pointing errors
更新于2025-09-19 17:15:36
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[IEEE 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) - Sydney, Australia (2018.11.21-2018.11.23)] 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) - Analysis of the effects of multiple reflection paths on high speed VLC system performance
摘要： In the recent past, research in visible light communication (VLC) has gained a lot interest due to its distinct characteristics in supporting high-speed data transmission and illumination simultaneously. To implement a reliable VLC system, few parameters have to be considered for communication channels such as distance between transmitter and receiver, data rate, line of sight (LOS) and non-line of sight (NLOS) communication paths, signal power and delay of the channel. In this paper, we designed and simulated a LOS and NLOS multipath VLC model using single and multiple LEDs. Basic on-off keying (OOK) modulation scheme and available conventional LED configuration have been considered to analyze the effects of field of view (FOV) and the reflection of the light signal on received power level. Moreover, BER and quality of transmission were measured for single and multipath transmissions considering distance, incident and irradiance angles.
关键词： BER,LED refraction,Visible Light Communication,multi-channel,FOV,irradiance and incident angle
更新于2025-09-19 17:15:36
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Secure Spatial Modulation Based on Dynamic Multi-Parameter WFRFT
摘要： A novel secure spatial modulation (SM) scheme based on dynamic multi-parameter weighted-type fractional Fourier transform (WFRFT), abbreviated as SMW, is proposed. Each legitimate transmitter runs WFRFT on the spatially modulated super symbols before transmit antennas, the parameters of which are dynamically updated using the transmitting bits. Each legitimate receiver runs inverse WFRFT to demodulate the received signals, the parameters of which are also dynamically generated using the recovered bits with the same updating strategies as the transmitter. The dynamic update strategies of WFRFT parameters are designed. As a passive eavesdropper is ignorant of the initial WFRFT parameters and the dynamic update strategies, which are indicated by the transmitted bits, it cannot recover the original information, thereby guaranteeing the communication security between legitimate transmitter and receiver. Besides, we formulate the maximum likelihood (ML) detector and analyze the secrecy capacity and the upper bound of BER. Simulations demonstrate that the proposed SMW scheme can achieve a high level of secrecy capacity and maintain legitimate receiver’s low BER performance while deteriorating the eavesdropper’s BER.
关键词： spatial modulation (SM),ML detector,BER upper bound,physical layer security,WFRFT,secrecy capacity
更新于2025-09-19 17:15:36
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Smart Biosensors in Medical Care || BER performance comparison of EEG healthcare system using 8-pixel, 16-pixel OLED screen, and DSLR camera
摘要： This chapter demonstrated the BER performance of the VL-OCC EEG healthcare system; the transmitter was OLED screen with varying pixel sizes 8 and 16, the DSLR camera being the receiver. The use of camera at receiver section does not need hardware modification due to inbuilt filters and focusing properties in context to conventional VLC systems. Furthermore, the proposed VL-OCC system is best suited in healthcare as free from harmful radiations such as EMI in comparison to RF protocols used in healthcare, which suffers from EMI and has adverse effect on patient’s health in RF restricted areas. The BER performance comparison among 8-pixel and 16-pixel transmitter shows that there is a trade-off between the pixel size and the number of bits transmitted. Though more data bits can be transmitted through the 8-pixel OLED screen, the BER increases significantly after 1.75 m or 175 cm in comparison to 16-pixel OLED screen where the error-free transmission was achieved until 2.25 m or 225 cm. Furthermore, due to system on chip prototype, low cost, low power consumption, and EMI free, the proposed could be used for wireless remote monitoring in both hospitals and BCI in context to EEG applications.
关键词： VL-OCC,OLED screen,EEG healthcare system,BER performance,DSLR camera
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - An Optimization Scheme based on Transmitters Selection for MIMO VLC Systems
摘要： Multi-input and multi-output (MIMO) visible light communication (VLC) is one of the promising solutions for future network environment. Considering in most cases, the transmitters and the receivers cannot meet the requirements of the ideal layout. This paper presents an in-depth study on the channel matrix of the MIMO visible light communication system. The singular value decomposition (SVD) is used to select the transmitters which have good performance for transmission, and the corresponding power is allocated according to the principle of equal bit error rate (BER) of the receivers. Simulation results show that this method can effectively improve the channel capacity of MIMO VLC system, and can achieve good BER performance for each receiver.
关键词： BER,MIMO system,visible light communication,channel correlation
更新于2025-09-16 10:30:52
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[IEEE 2019 10th International Conference on Computing, Communication and Networking Technologies (ICCCNT) - Kanpur, India (2019.7.6-2019.7.8)] 2019 10th International Conference on Computing, Communication and Networking Technologies (ICCCNT) - Performance Analysis of Free Space Optical Communication Systems for High-Speed Trains
摘要： Free space optics(FSO) can be used as an alternative the currently used wireless Radio communication systems to meet the increasing demands for the uninterrupted internet connection in High-Speed Trains(HSTs). FSO is less prone to interference, license-free and more secure as compared to Radio Frequency (RF) technology. The performance of the FSO system can be measured in terms of the average bit error rate(BER) and quality factor (Q-factor). In this paper, we have compared the NRZ and RZ modulation formats using a dual wavelength model at a bit rate of 10 Gbps to see which modulation format gives better Q-factor. The RZ modulation format is studied for a duty cycle of 33% and 67% and the comparison is made in terms of Q-factor. The system is also studied under different weather conditions in terms of Q-factor.
关键词： HSTs(high speed trains),Q-factor,RZ,FSO,BER,NRZ
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Advanced Information Technologies (ICAIT) - Yangon, Myanmar (2019.11.6-2019.11.7)] 2019 International Conference on Advanced Information Technologies (ICAIT) - Minimization of Four Wave Mixing Effect in Long-Haul DWDM Optical Fiber Communication System
摘要： Four Wave Mixing (FWM) of nonlinear effect is a major damage and degradation of the signal quality in the DWDM system. In this research paper, the proposed DWDM system is 70 km fiber length at 10 Gbps bit rate with 3 channels and channel spacing is 100 GHz. By using increasing dispersion coefficient techniques and dispersion compensated fiber mitigate the impact of FWM. The performance of the system evaluated on Bit Error Rate (BER) and Quality factor (Q-factor) which are simulated on commercial Optisystem (version-16) software. The results showed the decreasing of BER value, which got the superior performances and enhanced signal quality with more bandwidth in long-haul optical fiber communication.
关键词： DWDM,Long-haul,Q-factor,BER,FWM
更新于2025-09-12 10:27:22
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Enhancement of Signals Characteristics with Least Effect of Optical Communication Losses for Dense Optical Communication Systems
摘要： In this paper, the major aim is to enhance the bandwidth and therefore increase the capacity of the optical fibre communication system by reducing the dispersion in the fibre. Dispersion compensation is necessary to reduce losses and cost of the system. In this paper, we are basically focusing on reducing or decreasing chromatic dispersion. Chromatic dispersion is a type of dispersion in which pulse broadening occurs due to delay in different spectral components. We here make use of dispersion compensated fibre (DCF) for reducing the dispersion in the WDM system. Here, we basically use three dispersion compensated techniques (pre-compensation, post-compensation and mix compensation). The comparison in the three models of dispersion compensated technique is made in terms of transmission power vs. Q factor and also transmission power vs. Bit Error Rate.
关键词： DCF,MMF,WDM,SMF,quality factor,BER,optical amplifier
更新于2025-09-12 10:27:22
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Physical implementation of underwater optical wireless system using spatial mode laser sources with optimization of spatial matching components
摘要： This article numerically investigates the e?ect of absorption and scattering loss in the presence of underwater. Presenting optical wireless channel, system is considered for fundamental mode (LP01) and its higher order modes (LP11, LP21 & LP31). The system performance is examined in terms of bit error rate (BER) with the function of wavelength, distance, attenuation and beam divergence. This implementation also shows the optimized results with respect to spatial mode matching component using spatial aperture and collimating lens as well. The graded results producing the new sight and will have greater attention among the optical wireless technology. The overall analysis of system design promises for better performance even at the treaty of high attenuation loss 49.34 dB/m on the propagation of all spatial modes. Each results obtained in this paper reaches the stability at the greater attenuation with the wavelength range from 1000 nm to 1600 nm.
关键词： Absorption,Attenuation,Underwater,BER,Scattering loss
更新于2025-09-12 10:27:22
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Experimental study of the effects of thermally induced optical turbulence on underwater wireless optical communication link parameters
摘要： In this experimental research, the effects of refractive index fluctuations resulting from temperature fluctuations on some of the most important underwater communication link parameters such as the average received power, Signal to Noise Ratio (SNR) and normalized power variance (aperture averaged scintillation) has been experimentally investigated. Moreover, by introducing a new probability density function which is fitted more appropriately to the experimental data obtained from our simulator tank, the Bit Error Rate (BER) behavior of an Underwater Wireless Optical Communication (UWOC) link is also studied. These investigations are essential due to the optical turbulence limiting effects on the performance of UWOC systems. The experimental results indicate that reduction of the aperture averaged scintillation effects by using of optical components in the transmitter and receiver of UWOC links can enhance their performance. In general, increasing the strength of the optical turbulence (by increasing the temperature gradient induced by the rod heater) or the distance of the localized turbulence screen generated by temperature gradient from the transmitter plane, the aperture averaged scintillation decreases and consequently the SNR raises whilst the BER declines. Also, expanding the aperture diameter of the receiver optics reduces the normalized power variance which leads to decrease and increase in the BER and the SNR amounts respectively. The results are presented as experimental simulation graphs.
关键词： Laser beam propagation through turbulence,aperture averaged scintillation,Probability density function,BER,SNR,Underwater optical communication link
更新于2025-09-12 10:27:22