Current Issue : April - June Volume : 2019 Issue Number : 2 Articles : 5 Articles
OFDM modulated millimeter wave (mm-wave) at 60GHz. In order to improve transmission of this system, the discrete Fourier\ntransform spread (DFT-Spread) technology and the averaging of the channel frequency response (H-averaging) technology are\napplied. The DFT-Spread technology helps to reduce the peak-to-average power ratio (PAPR) of the OFDM signal, and the Haveraging\ntechnology helps to optimize channel estimation.This is the first time that the two kinds of technologywere used together\nin this reverse modulation system. According to the simulation, the 22Gbit/s 16QAM-OFDM at 60GHz can be generated and\ntransmitted for 90km fiber transmission under the soft decision forward error correction (SD-FEC) threshold 3.8Ã?10-3.The results\nshow that the two jointed DSP algorithms can improve the reverse modulation system transmission performance obviously...
An Optical Frequency Domain Reflectometry (OFDR) based fiber optic sensor scheme\nâ??embeddedâ? in concrete for the purpose of structural health monitoring (SHM) of carbon concrete\ncomposites (C3) is presented. The design, while strengthening the concrete structure, also aims to\nmonitor common SHM parameters such as strain and cracks. This was achieved by weaving the\ncarbon fiber together with optical fiber, based on a specialized technique that uses an embroidery\nsetup where both the carbon and optical fiber are woven on a water dissolvable polymer substrate.\nThe performance of the sensing scheme was characterized in-situ utilizing the OFDR based technique\nand the results presented. The sensors embedded on a custom made concrete block were subjected to\nvarying strain via a three point bending test to destruction and the results discussed. The intended\ndual-achievement of the scheme thus proposed in SHM and strengthening the C3 is demonstrated.\nThe suitability of the OFDR scheme for C3 is combined with a fibre Bragg grating (FBG)-based\napproach, and discussed in detail....
Limitations imposed by Four-Wave Mixing (FWM), Amplified Spontaneous\nEmission (ASE), dispersion and Stimulated Raman Scattering (SRS) on a\nmulti-spam DWDM system are theoretically studied. In this work, expression\nfor the linear dispersion parameter D has been defined as a function of number\nof channels in order to separate FWM and SRS effects and calculates both\nmaximum fibre length and optimum power. Additionally, our simulation results\nconsider the effect of ASE noise from Erbium Doped Fibre Amplifiers\n(EDFAs). This theoretical analysis yields a set of design criteria from optimized\nmulti-span DWDM systems....
The amount of computation for detecting moving objects by the optical flow\nalgorithm is large. The optical flow information in the smooth region cannot\nbe detected by the optical flow algorithm, and it is susceptible to noise in a\ncomplicated environment. In this study, an optimized Horn-Schunck (HS)\noptical flow algorithm based on motion estimation is proposed. To detect\nHarris corner in the image, the proposed algorithm is used in combination\nwith the motion estimation algorithm based on macroblock to determine the\nregion of interest (ROI) [1]. The ROI is then used as the initial motion vector\nfor HS calculation to obtain the optical flow information. Filtering is conducted\nto eliminate the background noise. Experimental result shows that the\napplication of the proposed algorithm improves the computational speed,\navoids the interference of background noise, and enhances the robustness of\nHS. Moreover, the algorithm solves the problem rooted in the inability of the\nHS algorithm to detect the smooth part of optical flow information [2]....
The optical access network is currently driving studies on transmissions beyond 10 Gbit/s.\nThis paper reports an analysis of Pulse Amplitude Modulation (PAM), seen as a promising\ncandidate for future Passive Optical Networks (PON). Previous 25 Gbit/s real-time PAM4 results are\nextrapolated here with simulations to higher bit rates and a higher number of PAM levels. Our main\ngoal is to evaluate the compliancy of PAM with the existing standards and legacy networks as far\nas fiber length, optical budget class, and wavelength plan are concerned. The simulations enlighten\nus as to the challenges of multilevel modulation formats, such as noise and jitter, compared to the\ncurrently adopted Non-Return-to-Zero (NRZ)....
Loading....