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Deep clipping noise mitigation using ISTA with the specified observations for LED-based DCO-OFDM system
摘要： Deep clipping is beneficial for the optical orthogonal frequency division multiplexing (O-OFDM) system, since it can lower the peak-to-average power ratio, reduce the direct current requirement in light emitting diodes (LEDs), and relax the bit-resolution requirement in digital-to-analogue converters (DACs). However, it is accompanied by more signal distortions. In this study, a deep clipping noise mitigation scheme using iterative shrinkage/thresholding algorithm (ISTA) with three steps is proposed to improve bit error rate (BER) performance of the LED-based DCO-OFDM systems. In the first step, the estimated observation interference is eliminated from the received symbols to minimise the negative effect of channel noise. In the second step, two strategies are presented to generate the specified observations thus reduce the component of measurement noise in the whole observation vector. In the last step, combining the generalised cross validation and the estimation of observation interference, the appropriate regularisation parameter are calculated for ISTA to improve the robustness of the sparse recovery performance. They use simulations to show that the proposed scheme can correct the deep clipping noise with favourable reconstruction quality, which significantly improves the BER performance and therefore assist the LED non-linearity mitigation.
关键词： clipping noise mitigation,ISTA,BER performance,LED-based DCO-OFDM system,Deep clipping
更新于2025-09-23 15:21:01
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Random distributed feedback fiber lasers: Impact of third-order dispersion
摘要： In this paper, one of the most modern random lasers known as random distributed feedback ˉber laser is investigated when the third-order dispersion (TOD) is taken into account. The laser characteristics are simulated based on the nonlinear Schr€odinger equations (NLSEs) where the power evolution of three interacting waves: the pump, the forward and the backward Stokes waves, are investigated as they propagate down the ˉber. The results show that due to TOD, the output characteristics of the laser are changed and particularly, the output power becomes asymmetrical. Moreover, the impacts of ˉber nonlinear coe±cient and input power on the output power and the output spectrum are studied.
关键词： nonlinear Schr€odinger equations (NLSEs),third-order dispersion,Random distributed feedback ˉber laser
更新于2025-09-23 15:21:01
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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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Effect of LED Radiation Pattern on BER Performance in Indoor Multipath MIMO-VLC System
摘要： The present paper investigates the impact of three radiation patterns of LED namely Lambertian, Batwing, Elliptical on the BER performance of 4 × 4 indoor multiple-input multiple-output (MIMO) visible light communication (VLC) system. The BER simulation has been done using LOS and LOS plus first reflection (L-R1) signals for ceiling-mounted and wall-mounted LEDs. For the case of ceiling-mounted LEDs, impulse response and BER have been computed using those radiation patterns at the centre and corner of a room (5 m × 5 m × 3 m). It has been found that LED having Elliptical radiation profile is more suitable for LOS signal when receiver is placed at the centre position whereas, Batwing radiation is suitable for L-R1 signal, both at the centre and corner positions. In the case of wall-mounted LEDs, impulse response and BER have been determined at the centre of the room using LOS and L-R1 signals. The results show that Batwing has least BER using LOS signal due to its wide radiation beam, but for L-R1 signal, the Elliptical profile having its narrow radiation beam has provided better BER performance. The present study shows that the BER in MIMO-VLC system not only depends on the transmitter and receiver position but also on the radiation patterns of LED and higher order reflection signals.
关键词： BER,MIMO,LED radiation pattern,VLC,Impulse response
更新于2025-09-23 15:21:01
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High Speed Passive Optical Network Based Elastic Optical Communication System
摘要： For addressing needs of modern day communication needs, new type of networks are required to be evolved to cater the demand of high data rates. Use of survivable elastic-optical-network (EON) with existing passive-optical-networks (PON) may provide the solution for this. The present work focus on employing EON–PON based wave-length-division multiplexing enabled communication system comprises of 2 × 5 Gbps for downlink and 2 × 1 Gbps for uplink over a single-mode-fibre of length 100 km. The results are the evaluated via bit-error-rate analyser, q factor and eye diagrams.
关键词： division multiplexing (WDM),rate (BER),bit,elastic,network (EON),networks (PON),length,wave,optical,error,passive
更新于2025-09-23 15:19:57
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Performance studies of MIMO based DCO-OFDM in underwater wireless optical communication systems
摘要： The research in underwater communication system is focused towards wireless networks in view of recent developments in wireless technology and increasing need for deep sea data mining. The underwater wireless optical communication (UWOC) have more advantages for short-range wireless links due to very high bandwidth and data rate than acoustic communication. Although UWOC offers high capacity links at low latencies, they suffer from limited communication range due to various distinctive characteristics of underwater channel. A major degrading effect associated with the underwater channel is turbulence-induced fading. To mitigate this fading and to extend the viable communication range, spatial multipath diversity techniques can be adopted over UWOC links. The proposed work evaluates the performance of a multicarrier modulation scheme, i.e., MIMO based DC biased Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) for underwater wireless optical channel. The simulation of MIMO-DC biased optical OFDM technique employing spatial diversity in underwater optical communication is a novel approach towards the determination of an optimal modulation technique for underwater optical wireless channels. The performance is evaluated based on the various parameters such as Signal to Interference plus Noise Ratio (SINR), Throughput and Bit Error Rate (BER). A simple experiment is conducted to demonstrate the BER performance assessment for different link distance of 0.45 m and 1.5 m with different transmitter and receiver configurations (SIMO and MIMO) for both clear water and coastal water using MIMO DCO OFDM technique.
关键词： SNR,BER,MIMO,DCO-OFDM,QAM,Underwater wireless optical communication
更新于2025-09-23 15:19:57
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Investigation and Analysis of Data Rate for Free Space Optical Communications System Under Dust Conditions
摘要： In this study, the performance of free-space optics (FSO) communication link under dust conditions was analysed. The data were modulated by the non-return-to-zero technique. The optical link was investigated with varying data rates under the effect of dust conditions. The performance of the FSO system was tested in terms of the bit error rate (BER), Q-factor and received power at the maximum link. Simulation results were obtained to compare between two transmit data rates (0.3 and 0.7 Gbps). The system has a high BER at a high data rate. In the meantime, it has a high Q-factor at a low data rate.
关键词： OptiSystem 7.0,Atmospheric transmittance,FSO,BER,Dust concentration,Attenuation,Q-factor,Propagation,WDM
更新于2025-09-23 15:19:57
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Evaluation of Chirped Fiber Bragg Grating with APD on Designed Optical Fiber Communication Link
摘要： Application of fiber Bragg grating (FBG) in optical communication is an evolving field. In this research paper, various types of chirped FBG’s (CFBG) have been used with avalanche photodiode (APD) on the designed optical fiber communication (OFC) link. Data rate of 20 Gbps and return-to-zero modulation format has been kept as fixed parameters. The designed link has been evaluated for varying fiber lengths (100, 200, 300, 400 and 500 km), various type of CFBG’s (linear, quadratic, square root and cubic root) with Gaussian apodization function, varying grating lengths (10, 20, 30, 40 and 50 mm) and operating temperatures (5°C, 10°C, 15°C, 20°C, 25°C, 30°C). The designed OFC link has also been evaluated for APD with and without CFBG. The performance evaluation matrix parameters selected are Q-factor, bit error rate and eye diagram. The OFC link employing CFBG with APD has been found to be superior. In compensating chromatic dispersion, optimum results have been observed for linear CFBG with Gaussian apodization function in comparison to other types of CFBG with 50 mm grating length for the maximum transmission distance.
关键词： bit error rate (BER),Optical fiber communication (OFC),eye diagram,chirped fiber Bragg grating (CFBG),vertical cavity surface emitting laser (VCSEL),avalanche photodiode (APD),Q-factor
更新于2025-09-23 15:19:57
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Q-switched all-fiber laser based on MoSe <sub/>2</sub> films with chemical vapor deposition method
摘要： In this work, MoSe2 ˉlm is synthesized by the chemical vapor deposition method. Saturable absorber (SA) is assembled with the tapered ˉber and MoSe2 ˉlms. Q-switched operation is achieved with the MoSe2-based SA. The experimental result reveals that the MoSe2-based SA has excellent saturable absorption characteristic with 23.41% modulation depth. When the pump power is greater than 289.2 mW, Q-switched all-ˉber lasing action is demonstrated. The repetition rate of the Q-switched pulses varies from 185.6 to 252.8 kHz. The shortest pulse duration is 801.9 ns, and the largest output energy is 69.3 nJ. Results indicate that MoSe2 ˉlms can provide new opportunities for large-modulation-depth optical modulators in ultrafast photonics.
关键词： Q-switched,saturable absorbers,ˉber laser,Nonlinear optical materials
更新于2025-09-23 15:19:57
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Evaluation of the Impact of MZM Frequency Response on BER Performance of PAM-4 Modulated WDM-PON
摘要： Continuous growth of data tra?c in optical access networks is driving the increase of utilized data rates even up to 25 Gbit/s per wavelength. While due to utilization of signals with large electrical bandwidth, requirements on the bandwidth of electrical and electro-optical components increase signi?cantly. Addressing that, the feasibility of application of the minimal transmitter and receiver bandwidth has received considerable attention. In this research, via numerical simulation in VPI Photonics Design Suite software we evaluate the impact of the shape of MZM frequency response based on amplitude frequency response (S21) from commercial MZM speci?cation. Moreover, addressing the requirements on numerical simulation models that ensure simulation of MZM frequency response curve for prediction of the overall system performance, we have also evaluated several analytical frequency responses (corresponding to the responses of 1 and 4-pole, Bessel and Gaussian ?lters) with di?erent 3-dB bandwidth values. Based on the obtained results, we propose the approach for the simulation of MZM frequency response that is the most relevant for our utilized PAM-4 modulated WDM-PON system with 25 Gbit/s bitrate per channel.
关键词： MZM frequency response,PAM-4 modulated WDM-PON,numerical simulation,VPI Photonics Design Suite,BER performance
更新于2025-09-23 15:19:57