This paper aims to point out the nonlinear phenomenon occurring in coarse/dense wavelength division multiplex (C/D-WDM) systems. This phenomenon has to betaken into account during the design of the optical network itself, as wavelengthsin the optical fiber are constantly densified. The paper points out the emergence of the non-linear four-wave mixing (FWM) phenomenonand how it relates to the dispersion in the optical fiber together with the transmit power. The output of the paper is a proposed design of the system that points to the improvement of the bit error rate (BER) with a suitable choice of dispersion and suitable transmission power.
Single Mode Optical Fiber in Rof System Using DWDMIJERA Editor
Performance analysis was carried out to find the effect of crosstalk in a WDM system. Firstly, analysis of BER
was carried out without crosstalk. Then analysis of BER with crosstalk was done. Using equation for crosstalk,
number of channels was plotted using matlab. System parameters were optimized for a particular crosstalk.
Objective of the thesis work
Performance Analysis is carried out to find the effect of crosstalk due to optical cross connect in a DWDM
system considering a WDM based optical cross connect (OXC). An analysis is carried out to find the amount of
crosstalk due to OXC. The bit error rate performance degradation due to crosstalk is evaluated for OXC
parameter and number of wavelengths per fiber. The optimum parameters such as optimum number of channels
and hops are determined.
Performance Analysis of OFDM in Combating Multipath FadingIOSR Journals
Mobile Communication system has been on high rampage for high data transmission over wireless
medium with various challenges caused by the transmission Channel. OFDM is been discovered in recent years
to deal with this problems because of its ability to elegantly cope with multipath interference. This paper
investigates the performance of different modulation schemes using M-ary Phase Shift Keying (M-PSK) and Mary
Quadrature Amplitude Modulation (M-QAM) in information transmission with OFDM technique over Ideal
channel AWGN and worst channel Rayleigh Fading channel in terms of Bits Error Rate (BER). Analysis was
made for different types of modulation schemes BPSK, QPSK, 4-QAM and 16-QAM gray coded bit mapping.
Also, a feasibility of OFDM been used to combat multipath fading was analyzed with comparison between a
single carrier technique and OFDM multicarrier technique. Variation between SNR results with respect to BER
is plotted to show the trade off differences between the modulation schemes with the result showing that OFDM
allows data transmission with minimal error over fading channel than a Single Carrier
A mitigation of channel crosstalk effect in dispersion shifted fiber based on...IJECEIAES
In fiber optics the Four Wave Mixing (FWM) has the harmful effect of an optical transmission system that can severely limit Wavelength Division Multiplexing (WDM) and reduce the transmission aptness. This work preset the durability of the different modulation format was tested to FWM by using Dispersion Shifted Fiber (DSF). Moreover, the performance of the proposed system is surveyed by changing the fiber length and applying an information rate of 200 Gb/s. The experimental results show that the FWM capacity has decreased significantly by more than 14 dB when applying Return to Zero (RZ) modulation form. In addition, in terms of the propsed system performance in the first channel and with 700 km distance, it was observed that the lower Bit Error Rate (BER) in the normal RZ modulation is equal to 1.3×10 -13 . As well as it is noticeable when applied the Non Return to Zero (NRZ), the Modified Duobinary Return to Zero (MDRZ) and Gaussian modulation, the system performance will be quickly changed and getting worse, where the BERs increased to 1.3×10 consecutively at same channel and for the same parameters. -4 , 1.3×10 -6 and 1.3×10 -2
Wavelet Packet based Multicarrier Modulation for Cognitive UWB SystemsCSCJournals
Orthogonal frequency division multiplexing (OFDM) is a multi-carrier modulation (MCM) scheme where the sub carriers are orthogonal waves. The main advantages of OFDM are robustness against multi-path fading, frequency selective fading, narrowband interference, and efficient use of spectrum. Recently it is proved that MCM system optimization can be achieved by applying wavelet bases instead of conventional fourier bases. Wavelet packet based MCM (WPMCM) systems have overall the same capabilities as OFDM systems with some improved features. In this research the literature and analytic schemes of WPMCM system is addressed, a wavelet packet based cognitive ultra wideband (UWB) transceiver is proposed, and performance analysis of WPMCM in different wireless multipath channels is investigated. Simulation results show a significant enhancement in terms of BER, spectral efficiency and side-lobes suppression comparing to conventional OFDM.
Single Mode Optical Fiber in Rof System Using DWDMIJERA Editor
Performance analysis was carried out to find the effect of crosstalk in a WDM system. Firstly, analysis of BER
was carried out without crosstalk. Then analysis of BER with crosstalk was done. Using equation for crosstalk,
number of channels was plotted using matlab. System parameters were optimized for a particular crosstalk.
Objective of the thesis work
Performance Analysis is carried out to find the effect of crosstalk due to optical cross connect in a DWDM
system considering a WDM based optical cross connect (OXC). An analysis is carried out to find the amount of
crosstalk due to OXC. The bit error rate performance degradation due to crosstalk is evaluated for OXC
parameter and number of wavelengths per fiber. The optimum parameters such as optimum number of channels
and hops are determined.
Performance Analysis of OFDM in Combating Multipath FadingIOSR Journals
Mobile Communication system has been on high rampage for high data transmission over wireless
medium with various challenges caused by the transmission Channel. OFDM is been discovered in recent years
to deal with this problems because of its ability to elegantly cope with multipath interference. This paper
investigates the performance of different modulation schemes using M-ary Phase Shift Keying (M-PSK) and Mary
Quadrature Amplitude Modulation (M-QAM) in information transmission with OFDM technique over Ideal
channel AWGN and worst channel Rayleigh Fading channel in terms of Bits Error Rate (BER). Analysis was
made for different types of modulation schemes BPSK, QPSK, 4-QAM and 16-QAM gray coded bit mapping.
Also, a feasibility of OFDM been used to combat multipath fading was analyzed with comparison between a
single carrier technique and OFDM multicarrier technique. Variation between SNR results with respect to BER
is plotted to show the trade off differences between the modulation schemes with the result showing that OFDM
allows data transmission with minimal error over fading channel than a Single Carrier
A mitigation of channel crosstalk effect in dispersion shifted fiber based on...IJECEIAES
In fiber optics the Four Wave Mixing (FWM) has the harmful effect of an optical transmission system that can severely limit Wavelength Division Multiplexing (WDM) and reduce the transmission aptness. This work preset the durability of the different modulation format was tested to FWM by using Dispersion Shifted Fiber (DSF). Moreover, the performance of the proposed system is surveyed by changing the fiber length and applying an information rate of 200 Gb/s. The experimental results show that the FWM capacity has decreased significantly by more than 14 dB when applying Return to Zero (RZ) modulation form. In addition, in terms of the propsed system performance in the first channel and with 700 km distance, it was observed that the lower Bit Error Rate (BER) in the normal RZ modulation is equal to 1.3×10 -13 . As well as it is noticeable when applied the Non Return to Zero (NRZ), the Modified Duobinary Return to Zero (MDRZ) and Gaussian modulation, the system performance will be quickly changed and getting worse, where the BERs increased to 1.3×10 consecutively at same channel and for the same parameters. -4 , 1.3×10 -6 and 1.3×10 -2
Wavelet Packet based Multicarrier Modulation for Cognitive UWB SystemsCSCJournals
Orthogonal frequency division multiplexing (OFDM) is a multi-carrier modulation (MCM) scheme where the sub carriers are orthogonal waves. The main advantages of OFDM are robustness against multi-path fading, frequency selective fading, narrowband interference, and efficient use of spectrum. Recently it is proved that MCM system optimization can be achieved by applying wavelet bases instead of conventional fourier bases. Wavelet packet based MCM (WPMCM) systems have overall the same capabilities as OFDM systems with some improved features. In this research the literature and analytic schemes of WPMCM system is addressed, a wavelet packet based cognitive ultra wideband (UWB) transceiver is proposed, and performance analysis of WPMCM in different wireless multipath channels is investigated. Simulation results show a significant enhancement in terms of BER, spectral efficiency and side-lobes suppression comparing to conventional OFDM.
DISCRETE COSINETRANSFORM-II FOR REDUCTION IN PEAK TO AVERAGE POWER RATIO OF O...ijwmn
Orthogonal frequency Division multiplexing (OFDM) is the most familiar word in telecommunication
and wireless communication systems as it provides enhanced spectral efficiency than Frequency division
multiplexing (FDM).Although it is sustaining an orthogonal relation betweencarriers but high peak to
average power ratio (PAPR) is one of the main disadvantages of OFDM system.Various PAPR reduction
techniques have been used, including techniques based on companding. Incompanding, -Law
companding has potential to reduce the PAPR of OFDMsignals. -Law Companding technique
preserves the dynamic range of samples at low amplitudes.A new method named as precoding which is
having less complexity compared to the other power reduction techniques is proposed to reduce PAPR.
This paper put forward combination of two existing techniques namely -Law Companding Transform
and Discrete Cosine Transform-II precoding technique. The simulation results show that, the proposed
combinedscheme gives better result for PAPR Reduction and results in no distortion.
It is prepared for simple presentation. Focused on basic optical fiber communication. And contains some important information about Space Division Multiplexing Technique.
Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in...CrimsonPublishersRDMS
Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in Next Generation Wireless Systems by Himanshu Monga* in Crimson Publishers: Peer Reviewed Material Science Journals
What does WDM (Wavelength Division Multiplexing )stand for?HYC Co., Ltd
This article will include these subject.
What does WDM stand for?
The basic structure of WDM system
Advantages of WDM technology
What does Mux and Demux stand for?
The difference between WDM and optical splitter
The indicators that affect the WDM devices
How to understand the O, E, S, C, L, U band
What does CWDM stand for vs. DWDM, FWDM, LWDM, MWDM?
HYC can provide customers with a one-stop optical network device and low-cost optical communication products, supplying a range of WDM products. HYC Co.,Ltd(HYC)is a national Hi-tech optoelectronics company engaged in R&D, manufacture and marketing of fiber optical products. Providing professional product and service for fiber connectivity,WDM, PLC splitter and high density datacom cabling. HYC products and solutions widely applied in 4G/5G, Data Center and Cloud Computing industry etc.
SPACE DIVISION MULTIPLE ACCESS (SDMA) SATELLITE COMMUNICATION Soumen Santra
SPACE DIVISION MULTIPLE ACCESS (SDMA)
Definition : The communication channel encountered by this array of antennas.
advanced antenna technology.
Smart Antenna
Uplink Transmission
Downlink Transmission
Block Diagram
Features
Beam Frequency Reuse
Advantages
Disadvantages
COMPARISON OF BER AND NUMBER OF ERRORS WITH DIFFERENT MODULATION TECHNIQUES I...Sukhvinder Singh Malik
This paper provides analysis of BER and Number of Errors for MIMO-OFDM wireless communication system by using different modulation techniques. Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks, and link reliability. So the performances of the wireless communication systems can be enhanced by using multiple transmit and receive antennas, which is generally referred to as the MIMO technique. Here analysis will be carried out for an OFDM wireless communication system using different modulation techniques and considering the effect and the wireless channel like AWGN, fading. Performance results will be evaluated numerically and graphically using the plots of BER versus SNR and plots of number of errors versus SNR.
Performance Analsis of Clipping Technique for Papr Reduction of MB-OFDM UWB S...ijcisjournal
Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) is used as efficacious procedure for
ultra-wideband (UWB) wireless communication applications, which divides the spectrum into various subbands,
whose bandwidth is approximately 500MHz. Major arduousness in multiband-OFDM is ,it have
very large peak to average power ratio value which causes the signal to enter into dynamic region that
consequence in the loss of orthogonal properties and results in the interference of the carrier signals which
crops the amplifier saturation and finally limits the capacity of the system. Many PAPR amortize
algorithms have reported in the survey and pre-coding is PAPR reduction which is inserted after
modulation in the OFDM system. The Existing work presents the reduction of that value by different
clipping techniques namely Classical-Clipping (CC), Heavy side-Clipping (HC), Deep-Clipping (DC) and
Smooth-Clipping (SC) and their comparison analysis is done. Every clipping method is best at its own
level .The proficiency of these strategies are evaluated in locutions of average power disparity, complete
system decadence and PAPR reduction. Finally results show the MB OFDM yields better performance to
reduce PAPR in effective way.
The Effect of PMD (Polarization Mode Dispersion) the Fibers of New and Old In...inventionjournals
This is a study conducted in a laboratory at the university as a simulation to see the effect of new fiber PMD for different distances. This is done to compare the performance of the digital system with optical fiber WDM. In this simulation are not included remission, chromatic dispersion and nonlinear effects. In this way all of the signal distortions caused only by different combinations of PDM. Polarization effects are very important in communications systems with optical fiber. Optical fiber that is used mainly during the simulation is a standard single mode fiber (SSMF).
DISCRETE COSINETRANSFORM-II FOR REDUCTION IN PEAK TO AVERAGE POWER RATIO OF O...ijwmn
Orthogonal frequency Division multiplexing (OFDM) is the most familiar word in telecommunication
and wireless communication systems as it provides enhanced spectral efficiency than Frequency division
multiplexing (FDM).Although it is sustaining an orthogonal relation betweencarriers but high peak to
average power ratio (PAPR) is one of the main disadvantages of OFDM system.Various PAPR reduction
techniques have been used, including techniques based on companding. Incompanding, -Law
companding has potential to reduce the PAPR of OFDMsignals. -Law Companding technique
preserves the dynamic range of samples at low amplitudes.A new method named as precoding which is
having less complexity compared to the other power reduction techniques is proposed to reduce PAPR.
This paper put forward combination of two existing techniques namely -Law Companding Transform
and Discrete Cosine Transform-II precoding technique. The simulation results show that, the proposed
combinedscheme gives better result for PAPR Reduction and results in no distortion.
It is prepared for simple presentation. Focused on basic optical fiber communication. And contains some important information about Space Division Multiplexing Technique.
Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in...CrimsonPublishersRDMS
Hybrid PAPR Reduction Scheme for Universal Filter Multi-Carrier Modulation in Next Generation Wireless Systems by Himanshu Monga* in Crimson Publishers: Peer Reviewed Material Science Journals
What does WDM (Wavelength Division Multiplexing )stand for?HYC Co., Ltd
This article will include these subject.
What does WDM stand for?
The basic structure of WDM system
Advantages of WDM technology
What does Mux and Demux stand for?
The difference between WDM and optical splitter
The indicators that affect the WDM devices
How to understand the O, E, S, C, L, U band
What does CWDM stand for vs. DWDM, FWDM, LWDM, MWDM?
HYC can provide customers with a one-stop optical network device and low-cost optical communication products, supplying a range of WDM products. HYC Co.,Ltd(HYC)is a national Hi-tech optoelectronics company engaged in R&D, manufacture and marketing of fiber optical products. Providing professional product and service for fiber connectivity,WDM, PLC splitter and high density datacom cabling. HYC products and solutions widely applied in 4G/5G, Data Center and Cloud Computing industry etc.
SPACE DIVISION MULTIPLE ACCESS (SDMA) SATELLITE COMMUNICATION Soumen Santra
SPACE DIVISION MULTIPLE ACCESS (SDMA)
Definition : The communication channel encountered by this array of antennas.
advanced antenna technology.
Smart Antenna
Uplink Transmission
Downlink Transmission
Block Diagram
Features
Beam Frequency Reuse
Advantages
Disadvantages
COMPARISON OF BER AND NUMBER OF ERRORS WITH DIFFERENT MODULATION TECHNIQUES I...Sukhvinder Singh Malik
This paper provides analysis of BER and Number of Errors for MIMO-OFDM wireless communication system by using different modulation techniques. Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks, and link reliability. So the performances of the wireless communication systems can be enhanced by using multiple transmit and receive antennas, which is generally referred to as the MIMO technique. Here analysis will be carried out for an OFDM wireless communication system using different modulation techniques and considering the effect and the wireless channel like AWGN, fading. Performance results will be evaluated numerically and graphically using the plots of BER versus SNR and plots of number of errors versus SNR.
Performance Analsis of Clipping Technique for Papr Reduction of MB-OFDM UWB S...ijcisjournal
Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) is used as efficacious procedure for
ultra-wideband (UWB) wireless communication applications, which divides the spectrum into various subbands,
whose bandwidth is approximately 500MHz. Major arduousness in multiband-OFDM is ,it have
very large peak to average power ratio value which causes the signal to enter into dynamic region that
consequence in the loss of orthogonal properties and results in the interference of the carrier signals which
crops the amplifier saturation and finally limits the capacity of the system. Many PAPR amortize
algorithms have reported in the survey and pre-coding is PAPR reduction which is inserted after
modulation in the OFDM system. The Existing work presents the reduction of that value by different
clipping techniques namely Classical-Clipping (CC), Heavy side-Clipping (HC), Deep-Clipping (DC) and
Smooth-Clipping (SC) and their comparison analysis is done. Every clipping method is best at its own
level .The proficiency of these strategies are evaluated in locutions of average power disparity, complete
system decadence and PAPR reduction. Finally results show the MB OFDM yields better performance to
reduce PAPR in effective way.
The Effect of PMD (Polarization Mode Dispersion) the Fibers of New and Old In...inventionjournals
This is a study conducted in a laboratory at the university as a simulation to see the effect of new fiber PMD for different distances. This is done to compare the performance of the digital system with optical fiber WDM. In this simulation are not included remission, chromatic dispersion and nonlinear effects. In this way all of the signal distortions caused only by different combinations of PDM. Polarization effects are very important in communications systems with optical fiber. Optical fiber that is used mainly during the simulation is a standard single mode fiber (SSMF).
Reduction of Four-Wave Mixing in DWDM System using Electro-Optic Phase Modula...IJECEIAES
In this paper, electro-optic phase modulator (EOPM) is used to reduce the effect of four-wave mixing (FWM), which is placed after 64 DWDMchannels multiplexer. It was found that the FWM is very sensitive to the phase deviation of the EOPM, and it can be reduced by introducing a phase shift between pulses. The simulation results confirmed the ability of the EOPM in improving the system performanceas indicated by the bit error rates. In term of comparison, the system of 64 channels based intensity modulated/ direct detection (IM/DD) transmission achieved bit error rate of 10 over 30 km and 70km without and with EOPM, respectively. -26
About Quality of Optical Channels in Wavelength Division Multiplexing Systems...TELKOMNIKA JOURNAL
Researches and the analysis of factors of the systems influencing quality with division according to radiation wavelength are given in article. Especially the communication quality in systems with wave division of channels is influenced by hindrances from Four Wave Mixing. In this regard the technique of definition of number of products of nonlinear effect of Four Wave Mixing getting to ranges of working channels, results of calculation of combinational products for the different number of channels in systems with division according to radiation wavelength is given. Power of a hindrance of Four Wave Mixing in systems with wave division of channels is calculated. Methods of reduction of influences of these nonlinear effects are considered. Conclusions and recommendations on ensuring quality of optical channels are provided in systems with wave division.
Integrated DWDM and MIMO-OFDM System for 4G High Capacity Mobile Communicatio...CSCJournals
Dense wavelength-division multiplexing (DWDM) technique is a very promising data transmission technology for utilizing the capacity of the fiber. By DWDM, multiple signals (video, audio, data etc) staggered in wavelength domain can be multiplexed and transmitted down the same fiber. The Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency division multiplexing (MIMO-OFDM) is an attractive air-interface solution for next-generation wireless local area networks (WLANs) and fourth-generation mobile cellular wireless systems. This article provides an overview of the integrated DWDM MIMO-OFDM technology and focuses on DWDM transmitter design with adequate dispersion compensation for high data rate of 10Gbps ,MIMO-OFDM system design, space-time coded signaling, receiver design and performance analysis in terms of bit error rate for Integrated system. The simulation is carried out using powerful software tools Optisystem and MATLAB . In this paper a 64 channel DWDM system is simulated for transmission of baseband NRZ signal over fiber. Each of the transmission is at bit rate of 10 Gbps leading to high data rate transmission of 640 Gbps.The resultant Bit Error Rate(BER) is in the range 10-12 for DWDM system which is given as input to MIMO-OFDM system..This system performance is analyzed in terms of BER with SNR for Rayleigh, and AWGN channels and BER of 10-4 is achieved at SNR of 10dbs
Simulation Study and Performance Comparison of OFDM System with QPSK and BPSKpaperpublications3
Abstract: FDMA, TDMA and CDMA are the well-known multiplexing techniques used in wireless communication systems. While working with the wireless systems using these techniques various problems are encountered especially when a typical transmitted signal arrives at the receiver using various paths of different lengths. Since multiple versions of the signal interfere with each other, it becomes difficult to extract the original information. The use of orthogonal frequency division multiplexing (OFDM) technique provides better solution for the above mentioned problem. OFDM technique distributes the data over a large number of carriers that are spaced apart at precise frequencies. This spacing provides the "orthogonality", which prevents the demodulator from seeing frequencies other than their own. The benefits of OFDM are high spectral efficiency, resiliency of RF interference, and lower multi-path distortion. OFDM is a powerful modulation technique that is capable of high data rate and is able to eliminate ISI. Using MATLAB, simulation of OFDM was done with different modulation techniques using different transform techniques. The digital modulation schemes such as BPSK and QPSK were selected to assess the performance of the designed OFDM system.
Empirical analysis of polarization division multiplexing-dense wavelength di...IJECEIAES
This paper exemplifies dense wavelength division multiplexing combined with polarization division multiplexing with C-band frequency range-based single-mode fiber. In the proposed link, 32 independent channels with 16 individual wavelengths are multiplexed with two different angles of polarization. Each carrying 130 Gbps dual-polarization data with 200 GHz channel spacing claiming a net transmission rate of 4.16 Tbits/s with spectral efficiency of 69% with 20% side-mode-suppression-ratio (SMSR) and optical signal to noise ratio (OSNR) 40.7. The performance of the proposed techniques has been analyzed using optimized system parameters securing a minimum bit error rate (BER) 10-9 at a transmission distance up to 50 km.
Performance Analysis of OFDM in Combating Multipath FadingIOSR Journals
Abstract: Mobile Communication system has been on high rampage for high data transmission over wireless medium with various challenges caused by the transmission Channel. OFDM is been discovered in recent years to deal with this problems because of its ability to elegantly cope with multipath interference. This paper investigates the performance of different modulation schemes using M-ary Phase Shift Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) in information transmission with OFDM technique over Ideal channel AWGN and worst channel Rayleigh Fading channel in terms of Bits Error Rate (BER). Analysis was made for different types of modulation schemes BPSK, QPSK, 4-QAM and 16-QAM gray coded bit mapping. Also, a feasibility of OFDM been used to combat multipath fading was analyzed with comparison between a single carrier technique and OFDM multicarrier technique. Variation between SNR results with respect to BER is plotted to show the trade off differences between the modulation schemes with the result showing that OFDM allows data transmission with minimal error over fading channel than a Single Carrier. Keywords: OFDM, Single Carrier, AWGN, Rayleigh fading, BER, M-ary PSK, M-ary QAM
techInvestigations with mode division multiplexed transmissionelelijjournal
This article presents proposed topology for mode division multiplexed link with SPDML and VCSEL, modulate electrical signal of 820nm wavelength. Transmission performance has been investigated for numerous modes, bit rates (2.5 to 10Gbps), transmission lengths of MMF (1 to 100km) and attenuation factor in conjunction with parabolic operational mode. Results illustrated successful performance up to nine modes in mode-division multiplexed transmission. Performance is improved at low data rates, illustrated higher OSNR with lower BER,-5dB attenuation factor. Though, at higher bit rate and longer
transmission length received OSNR is unsteady. It further inferred that transmission with large number of multiplexed modes result in degraded performance, augmented with minimization of mode coupling losses.Mode division multiplexed multimode optical communication can be a viable option for supplementary capacity augment in the preexisting and future fiber optic communication links.
In this work, high-speed transmission over the long-haul optical channel using orthogonal frequency division multiplexing (OFDM) was investigated. Furthermore, we recommend mixing polarization division multiplexing (PDM) with coherent OFDM (CO-OFDM) and quadrature amplitude modulation (16-QAM) to improve spectral efficiency (SE) while transmitting over a wavelength division multiplexing (WDM) system.
An 800 Gb/s WDM PDM-CO-OFDM-16QAM transmission system with various channel spacing of 100 GHz, 50 GHz, and 25 GHz is examined utilizing the OptiSystem (2021) version 18.0 software package over ten spans of 60 km standard single-mode fiber (SSMF). Different channel spacing WDM systems have been compared in terms of performance and SE. The results reveal that the WDM system with 100 GHz channel spacing has a longer transmission range and needs minimal optical signal to noise ratio (OSNR) at the reception. The 25 GHz channel spacing WDM system exceeds the others in terms of SE. Further, the effect of ultra-low loss and large effective area fiber in lowering span loss and nonlinear effects for
25 GHz channel spacing WDM system is investigated. The findings show that the system performance with the new fiber outperforms the SSMF.
The acceptable bit error rate (BER) for this study is 0.033 (20% concatenated forward error correction (FEC) threshold).
Design and Performance Study of MMDWDM Systemselelijjournal
The rising need for bandwidth created innumerable efforts from academic and industry group towards development of most efficient optical communication networks. In order to compete it numerous investigators have designed their own novel schemes. In this view the paper presents multiple modulation dense wavelength division multiplexed transmission designed links each with a total capacity of 640Gbps and with channel to channel to spacing of 100Ghz, employing multiple modulation schemes such as non return to zero rectangular, non return to zero raised cosine, return to zero rectangular, non return to zero raised cosine, return to zero soliton, return to zero Super Gaussian. The optical transmission performance characteristics like bit error rate, Q parameter at the output have been investigated by simulating different systems for a fixed transmission length of 260kilometers. Results show that transmission performance of DWDM system with non return to zero raised cosine scheme has been better with quality factor ranging from 16 to 23dB and bit error rate ranging from 10-11 to 10-40 for detected channels at selected transmission reach (260KM) and other schemes with good performance were RZ Super Guassian DWDM and RZ Soliton DWDM systems for the same transmission reach. The transmission parameter jitter have been also investigated for each system which depict that jitter effect is more severe for return to zero systems as compared to non return to zero DWDM systems. From the performance analysis for different optical links involving different modulation schemes it can be articulated that novel modulation scheme generally improves the transmission performance and must for modern optical communication systems operating at high bit rate and longer reach.
Performance evaluation of VLC system using new modulation approachjournalBEEI
We propose a modified OFDM modulation based on multiband scheme for visible light communications (VLC) system. The method called catenated-OFDM VLC system can efficiently boost the propagation distance and combat multipath induced the inter symbol interference and inter carrier interference. Design parameters such as number of optical bands, input power, distance and data rate are varied to see their effect on the system performances. Simulation analysis is done using Optisys software Ver. 11.0. The results show that the proposed system offers a good performance at longer transmission distance of 12 m for input power of 2 dBm in case of Band=3 with 10 Gbps data rate. BER curves also indicates that the proposed system can be operated at very high data rate of 15 Gbps. This exhibits the ability of the proposed system to be one of the candidate for future optical wireless communication system.
Amazon products reviews classification based on machine learning, deep learni...TELKOMNIKA JOURNAL
In recent times, the trend of online shopping through e-commerce stores and websites has grown to a huge extent. Whenever a product is purchased on an e-commerce platform, people leave their reviews about the product. These reviews are very helpful for the store owners and the product’s manufacturers for the betterment of their work process as well as product quality. An automated system is proposed in this work that operates on two datasets D1 and D2 obtained from Amazon. After certain preprocessing steps, N-gram and word embedding-based features are extracted using term frequency-inverse document frequency (TF-IDF), bag of words (BoW) and global vectors (GloVe), and Word2vec, respectively. Four machine learning (ML) models support vector machines (SVM), logistic regression (RF), logistic regression (LR), multinomial Naïve Bayes (MNB), two deep learning (DL) models convolutional neural network (CNN), long-short term memory (LSTM), and standalone bidirectional encoder representations (BERT) are used to classify reviews as either positive or negative. The results obtained by the standard ML, DL models and BERT are evaluated using certain performance evaluation measures. BERT turns out to be the best-performing model in the case of D1 with an accuracy of 90% on features derived by word embedding models while the CNN provides the best accuracy of 97% upon word embedding features in the case of D2. The proposed model shows better overall performance on D2 as compared to D1.
Design, simulation, and analysis of microstrip patch antenna for wireless app...TELKOMNIKA JOURNAL
In this study, a microstrip patch antenna that works at 3.6 GHz was built and tested to see how well it works. In this work, Rogers RT/Duroid 5880 has been used as the substrate material, with a dielectric permittivity of 2.2 and a thickness of 0.3451 mm; it serves as the base for the examined antenna. The computer simulation technology (CST) studio suite is utilized to show the recommended antenna design. The goal of this study was to get a more extensive transmission capacity, a lower voltage standing wave ratio (VSWR), and a lower return loss, but the main goal was to get a higher gain, directivity, and efficiency. After simulation, the return loss, gain, directivity, bandwidth, and efficiency of the supplied antenna are found to be -17.626 dB, 9.671 dBi, 9.924 dBi, 0.2 GHz, and 97.45%, respectively. Besides, the recreation uncovered that the transfer speed side-lobe level at phi was much better than those of the earlier works, at -28.8 dB, respectively. Thus, it makes a solid contender for remote innovation and more robust communication.
Design and simulation an optimal enhanced PI controller for congestion avoida...TELKOMNIKA JOURNAL
In this paper, snake optimization algorithm (SOA) is used to find the optimal gains of an enhanced controller for controlling congestion problem in computer networks. M-file and Simulink platform is adopted to evaluate the response of the active queue management (AQM) system, a comparison with two classical controllers is done, all tuned gains of controllers are obtained using SOA method and the fitness function chose to monitor the system performance is the integral time absolute error (ITAE). Transient analysis and robust analysis is used to show the proposed controller performance, two robustness tests are applied to the AQM system, one is done by varying the size of queue value in different period and the other test is done by changing the number of transmission control protocol (TCP) sessions with a value of ± 20% from its original value. The simulation results reflect a stable and robust behavior and best performance is appeared clearly to achieve the desired queue size without any noise or any transmission problems.
Improving the detection of intrusion in vehicular ad-hoc networks with modifi...TELKOMNIKA JOURNAL
Vehicular ad-hoc networks (VANETs) are wireless-equipped vehicles that form networks along the road. The security of this network has been a major challenge. The identity-based cryptosystem (IBC) previously used to secure the networks suffers from membership authentication security features. This paper focuses on improving the detection of intruders in VANETs with a modified identity-based cryptosystem (MIBC). The MIBC is developed using a non-singular elliptic curve with Lagrange interpolation. The public key of vehicles and roadside units on the network are derived from number plates and location identification numbers, respectively. Pseudo-identities are used to mask the real identity of users to preserve their privacy. The membership authentication mechanism ensures that only valid and authenticated members of the network are allowed to join the network. The performance of the MIBC is evaluated using intrusion detection ratio (IDR) and computation time (CT) and then validated with the existing IBC. The result obtained shows that the MIBC recorded an IDR of 99.3% against 94.3% obtained for the existing identity-based cryptosystem (EIBC) for 140 unregistered vehicles attempting to intrude on the network. The MIBC shows lower CT values of 1.17 ms against 1.70 ms for EIBC. The MIBC can be used to improve the security of VANETs.
Conceptual model of internet banking adoption with perceived risk and trust f...TELKOMNIKA JOURNAL
Understanding the primary factors of internet banking (IB) acceptance is critical for both banks and users; nevertheless, our knowledge of the role of users’ perceived risk and trust in IB adoption is limited. As a result, we develop a conceptual model by incorporating perceived risk and trust into the technology acceptance model (TAM) theory toward the IB. The proper research emphasized that the most essential component in explaining IB adoption behavior is behavioral intention to use IB adoption. TAM is helpful for figuring out how elements that affect IB adoption are connected to one another. According to previous literature on IB and the use of such technology in Iraq, one has to choose a theoretical foundation that may justify the acceptance of IB from the customer’s perspective. The conceptual model was therefore constructed using the TAM as a foundation. Furthermore, perceived risk and trust were added to the TAM dimensions as external factors. The key objective of this work was to extend the TAM to construct a conceptual model for IB adoption and to get sufficient theoretical support from the existing literature for the essential elements and their relationships in order to unearth new insights about factors responsible for IB adoption.
Efficient combined fuzzy logic and LMS algorithm for smart antennaTELKOMNIKA JOURNAL
The smart antennas are broadly used in wireless communication. The least mean square (LMS) algorithm is a procedure that is concerned in controlling the smart antenna pattern to accommodate specified requirements such as steering the beam toward the desired signal, in addition to placing the deep nulls in the direction of unwanted signals. The conventional LMS (C-LMS) has some drawbacks like slow convergence speed besides high steady state fluctuation error. To overcome these shortcomings, the present paper adopts an adaptive fuzzy control step size least mean square (FC-LMS) algorithm to adjust its step size. Computer simulation outcomes illustrate that the given model has fast convergence rate as well as low mean square error steady state.
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Wavelet-based sensing technique in cognitive radio networkTELKOMNIKA JOURNAL
Cognitive radio is a smart radio that can change its transmitter parameter based on interaction with the environment in which it operates. The demand for frequency spectrum is growing due to a big data issue as many Internet of Things (IoT) devices are in the network. Based on previous research, most frequency spectrum was used, but some spectrums were not used, called spectrum hole. Energy detection is one of the spectrum sensing methods that has been frequently used since it is easy to use and does not require license users to have any prior signal understanding. But this technique is incapable of detecting at low signal-to-noise ratio (SNR) levels. Therefore, the wavelet-based sensing is proposed to overcome this issue and detect spectrum holes. The main objective of this work is to evaluate the performance of wavelet-based sensing and compare it with the energy detection technique. The findings show that the percentage of detection in wavelet-based sensing is 83% higher than energy detection performance. This result indicates that the wavelet-based sensing has higher precision in detection and the interference towards primary user can be decreased.
A novel compact dual-band bandstop filter with enhanced rejection bandsTELKOMNIKA JOURNAL
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Deep learning approach to DDoS attack with imbalanced data at the application...TELKOMNIKA JOURNAL
A distributed denial of service (DDoS) attack is where one or more computers attack or target a server computer, by flooding internet traffic to the server. As a result, the server cannot be accessed by legitimate users. A result of this attack causes enormous losses for a company because it can reduce the level of user trust, and reduce the company’s reputation to lose customers due to downtime. One of the services at the application layer that can be accessed by users is a web-based lightweight directory access protocol (LDAP) service that can provide safe and easy services to access directory applications. We used a deep learning approach to detect DDoS attacks on the CICDDoS 2019 dataset on a complex computer network at the application layer to get fast and accurate results for dealing with unbalanced data. Based on the results obtained, it is observed that DDoS attack detection using a deep learning approach on imbalanced data performs better when implemented using synthetic minority oversampling technique (SMOTE) method for binary classes. On the other hand, the proposed deep learning approach performs better for detecting DDoS attacks in multiclass when implemented using the adaptive synthetic (ADASYN) method.
The appearance of uncertainties and disturbances often effects the characteristics of either linear or nonlinear systems. Plus, the stabilization process may be deteriorated thus incurring a catastrophic effect to the system performance. As such, this manuscript addresses the concept of matching condition for the systems that are suffering from miss-match uncertainties and exogeneous disturbances. The perturbation towards the system at hand is assumed to be known and unbounded. To reach this outcome, uncertainties and their classifications are reviewed thoroughly. The structural matching condition is proposed and tabulated in the proposition 1. Two types of mathematical expressions are presented to distinguish the system with matched uncertainty and the system with miss-matched uncertainty. Lastly, two-dimensional numerical expressions are provided to practice the proposed proposition. The outcome shows that matching condition has the ability to change the system to a design-friendly model for asymptotic stabilization.
Implementation of FinFET technology based low power 4×4 Wallace tree multipli...TELKOMNIKA JOURNAL
Many systems, including digital signal processors, finite impulse response (FIR) filters, application-specific integrated circuits, and microprocessors, use multipliers. The demand for low power multipliers is gradually rising day by day in the current technological trend. In this study, we describe a 4×4 Wallace multiplier based on a carry select adder (CSA) that uses less power and has a better power delay product than existing multipliers. HSPICE tool at 16 nm technology is used to simulate the results. In comparison to the traditional CSA-based multiplier, which has a power consumption of 1.7 µW and power delay product (PDP) of 57.3 fJ, the results demonstrate that the Wallace multiplier design employing CSA with first zero finding logic (FZF) logic has the lowest power consumption of 1.4 µW and PDP of 27.5 fJ.
Evaluation of the weighted-overlap add model with massive MIMO in a 5G systemTELKOMNIKA JOURNAL
The flaw in 5G orthogonal frequency division multiplexing (OFDM) becomes apparent in high-speed situations. Because the doppler effect causes frequency shifts, the orthogonality of OFDM subcarriers is broken, lowering both their bit error rate (BER) and throughput output. As part of this research, we use a novel design that combines massive multiple input multiple output (MIMO) and weighted overlap and add (WOLA) to improve the performance of 5G systems. To determine which design is superior, throughput and BER are calculated for both the proposed design and OFDM. The results of the improved system show a massive improvement in performance ver the conventional system and significant improvements with massive MIMO, including the best throughput and BER. When compared to conventional systems, the improved system has a throughput that is around 22% higher and the best performance in terms of BER, but it still has around 25% less error than OFDM.
Reflector antenna design in different frequencies using frequency selective s...TELKOMNIKA JOURNAL
In this study, it is aimed to obtain two different asymmetric radiation patterns obtained from antennas in the shape of the cross-section of a parabolic reflector (fan blade type antennas) and antennas with cosecant-square radiation characteristics at two different frequencies from a single antenna. For this purpose, firstly, a fan blade type antenna design will be made, and then the reflective surface of this antenna will be completed to the shape of the reflective surface of the antenna with the cosecant-square radiation characteristic with the frequency selective surface designed to provide the characteristics suitable for the purpose. The frequency selective surface designed and it provides the perfect transmission as possible at 4 GHz operating frequency, while it will act as a band-quenching filter for electromagnetic waves at 5 GHz operating frequency and will be a reflective surface. Thanks to this frequency selective surface to be used as a reflective surface in the antenna, a fan blade type radiation characteristic at 4 GHz operating frequency will be obtained, while a cosecant-square radiation characteristic at 5 GHz operating frequency will be obtained.
Reagentless iron detection in water based on unclad fiber optical sensorTELKOMNIKA JOURNAL
A simple and low-cost fiber based optical sensor for iron detection is demonstrated in this paper. The sensor head consist of an unclad optical fiber with the unclad length of 1 cm and it has a straight structure. Results obtained shows a linear relationship between the output light intensity and iron concentration, illustrating the functionality of this iron optical sensor. Based on the experimental results, the sensitivity and linearity are achieved at 0.0328/ppm and 0.9824 respectively at the wavelength of 690 nm. With the same wavelength, other performance parameters are also studied. Resolution and limit of detection (LOD) are found to be 0.3049 ppm and 0.0755 ppm correspondingly. This iron sensor is advantageous in that it does not require any reagent for detection, enabling it to be simpler and cost-effective in the implementation of the iron sensing.
Impact of CuS counter electrode calcination temperature on quantum dot sensit...TELKOMNIKA JOURNAL
In place of the commercial Pt electrode used in quantum sensitized solar cells, the low-cost CuS cathode is created using electrophoresis. High resolution scanning electron microscopy and X-ray diffraction were used to analyze the structure and morphology of structural cubic samples with diameters ranging from 40 nm to 200 nm. The conversion efficiency of solar cells is significantly impacted by the calcination temperatures of cathodes at 100 °C, 120 °C, 150 °C, and 180 °C under vacuum. The fluorine doped tin oxide (FTO)/CuS cathode electrode reached a maximum efficiency of 3.89% when it was calcined at 120 °C. Compared to other temperature combinations, CuS nanoparticles crystallize at 120 °C, which lowers resistance while increasing electron lifetime.
In place of the commercial Pt electrode used in quantum sensitized solar cells, the low-cost CuS cathode is created using electrophoresis. High resolution scanning electron microscopy and X-ray diffraction were used to analyze the structure and morphology of structural cubic samples with diameters ranging from 40 nm to 200 nm. The conversion efficiency of solar cells is significantly impacted by the calcination temperatures of cathodes at 100 °C, 120 °C, 150 °C, and 180 °C under vacuum. The fluorine doped tin oxide (FTO)/CuS cathode electrode reached a maximum efficiency of 3.89% when it was calcined at 120 °C. Compared to other temperature combinations, CuS nanoparticles crystallize at 120 °C, which lowers resistance while increasing electron lifetime.
A progressive learning for structural tolerance online sequential extreme lea...TELKOMNIKA JOURNAL
This article discusses the progressive learning for structural tolerance online sequential extreme learning machine (PSTOS-ELM). PSTOS-ELM can save robust accuracy while updating the new data and the new class data on the online training situation. The robustness accuracy arises from using the householder block exact QR decomposition recursive least squares (HBQRD-RLS) of the PSTOS-ELM. This method is suitable for applications that have data streaming and often have new class data. Our experiment compares the PSTOS-ELM accuracy and accuracy robustness while data is updating with the batch-extreme learning machine (ELM) and structural tolerance online sequential extreme learning machine (STOS-ELM) that both must retrain the data in a new class data case. The experimental results show that PSTOS-ELM has accuracy and robustness comparable to ELM and STOS-ELM while also can update new class data immediately.
Electroencephalography-based brain-computer interface using neural networksTELKOMNIKA JOURNAL
This study aimed to develop a brain-computer interface that can control an electric wheelchair using electroencephalography (EEG) signals. First, we used the Mind Wave Mobile 2 device to capture raw EEG signals from the surface of the scalp. The signals were transformed into the frequency domain using fast Fourier transform (FFT) and filtered to monitor changes in attention and relaxation. Next, we performed time and frequency domain analyses to identify features for five eye gestures: opened, closed, blink per second, double blink, and lookup. The base state was the opened-eyes gesture, and we compared the features of the remaining four action gestures to the base state to identify potential gestures. We then built a multilayer neural network to classify these features into five signals that control the wheelchair’s movement. Finally, we designed an experimental wheelchair system to test the effectiveness of the proposed approach. The results demonstrate that the EEG classification was highly accurate and computationally efficient. Moreover, the average performance of the brain-controlled wheelchair system was over 75% across different individuals, which suggests the feasibility of this approach.
Adaptive segmentation algorithm based on level set model in medical imagingTELKOMNIKA JOURNAL
For image segmentation, level set models are frequently employed. It offer best solution to overcome the main limitations of deformable parametric models. However, the challenge when applying those models in medical images stills deal with removing blurs in image edges which directly affects the edge indicator function, leads to not adaptively segmenting images and causes a wrong analysis of pathologies wich prevents to conclude a correct diagnosis. To overcome such issues, an effective process is suggested by simultaneously modelling and solving systems’ two-dimensional partial differential equations (PDE). The first PDE equation allows restoration using Euler’s equation similar to an anisotropic smoothing based on a regularized Perona and Malik filter that eliminates noise while preserving edge information in accordance with detected contours in the second equation that segments the image based on the first equation solutions. This approach allows developing a new algorithm which overcome the studied model drawbacks. Results of the proposed method give clear segments that can be applied to any application. Experiments on many medical images in particular blurry images with high information losses, demonstrate that the developed approach produces superior segmentation results in terms of quantity and quality compared to other models already presented in previeous works.
Automatic channel selection using shuffled frog leaping algorithm for EEG bas...TELKOMNIKA JOURNAL
Drug addiction is a complex neurobiological disorder that necessitates comprehensive treatment of both the body and mind. It is categorized as a brain disorder due to its impact on the brain. Various methods such as electroencephalography (EEG), functional magnetic resonance imaging (FMRI), and magnetoencephalography (MEG) can capture brain activities and structures. EEG signals provide valuable insights into neurological disorders, including drug addiction. Accurate classification of drug addiction from EEG signals relies on appropriate features and channel selection. Choosing the right EEG channels is essential to reduce computational costs and mitigate the risk of overfitting associated with using all available channels. To address the challenge of optimal channel selection in addiction detection from EEG signals, this work employs the shuffled frog leaping algorithm (SFLA). SFLA facilitates the selection of appropriate channels, leading to improved accuracy. Wavelet features extracted from the selected input channel signals are then analyzed using various machine learning classifiers to detect addiction. Experimental results indicate that after selecting features from the appropriate channels, classification accuracy significantly increased across all classifiers. Particularly, the multi-layer perceptron (MLP) classifier combined with SFLA demonstrated a remarkable accuracy improvement of 15.78% while reducing time complexity.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
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Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
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Mitigation of non-linear four-wave mixing phenomenon in a fully optical communication system
1. TELKOMNIKA Telecommunication, Computing, Electronics and Control
Vol. 18, No. 6, December 2020, pp. 2878~2885
ISSN: 1693-6930, accredited First Grade by Kemenristekdikti, Decree No: 21/E/KPT/2018
DOI: 10.12928/TELKOMNIKA.v18i6.16136 2878
Journal homepage: http://journal.uad.ac.id/index.php/TELKOMNIKA
Mitigation of non-linear four-wave mixing phenomenon in
a fully optical communication system
Petr Ivaniga1
, Tomáš Ivaniga2
1
Department of Information Networks, Faculty of Management Science and Informatics, University of Žilina, Slovakia
2
Department of Electronics and Multimedia Communications, Faculty of Electrical Engineering and Informatics,
University of Technology Košice, Slovakia
Article Info ABSTRACT
Article history:
Received Mar 25, 2020
Revised May 23, 2020
Accepted Jun 25, 2020
This paper aims to point out the nonlinear phenomenon occurring in coarse/dense
wavelength division multiplex (C/D-WDM) systems. This phenomenon has to be
taken into account during the design of the optical network itself, as wavelengths
in the optical fiber are constantly densified. The paper points out the emergence
of the non-linear four-wave mixing (FWM) phenomenon and how it relates to the
dispersion in the optical fiber together with the transmit power. The output of the
paper is a proposed design of the system that points to the improvement of the bit
error rate (BER) with a suitable choice of dispersion and suitable transmission
power.
Keywords:
Bit error rate
DWDM
Four-wave mixing
Q-factor
This is an open access article under the CC BY-SA license.
Corresponding Author:
Petr Ivaniga,
Department of Information Networks, Faculty of Management Science and Informatics,
University of Žilina,
Univerzitná 8215/1, 010 26 Žilina, Slovakia.
Email: petr.ivaniga@fri.uniza.sk
1. INTRODUCTION
Optical system providers are forced continuously to increase the overall transmission capacity of
the system by increasing the volume of data transferred. The increase in data transmission is mainly due to
the increasing popularity of cloud and multimedia services [1-3]. It is a logical and economically manageable
step for providers to make a gradual transition to higher data rates when increasing the capacity of systems,
provided that the existing infrastructure, in which considerable money has been invested, is used as much as
possible. In optical wavelength division multiplex (WDM) multiplexing systems, a suitable option is to replace
several original lower bit rate channels with a higher bit rate channel system. Thus, several optical systems
coexist and the newly deployed system is required to be backward compatible with the original system.
2. DENSE WAVELENGTH DIVISION MULTIPLEX
The idea of the realization of the wave division multiplex WDM was described and theoretically
processed in the last century in the early sixties. At the end of the seventies, two signals with different optical
wavelengths were practically transmitted through one optical fiber (OF). From now on, intensive development has
been underway to improve WDM. In the twenty-first century, these systems are an integral part of the backbone
optical transmission networks, as they can transmit thousands of optical signals with different optical wavelengths,
2. TELKOMNIKA Telecommun Comput El Control
Mitigation of non-linear four-wave mixing phenomenon in a fully optical… (Petr Ivaniga)
2879
one fiber by one. The whole system comprises n optical sources and n optical detectors, wherein an optical signal
is modulated for each wavelength used in the transmitting unit. Figure 1 ilustrates WDM system.
Transmitters are made up of optical radiation sources, with distributed feedback (DFB) lasers being
used most often because their spectral width is in units of MHz. The DFB uses a resonator that is made up of
a Bragg lattice with a periodic refractive index change, generating narrow spectral radiation whose width
does not exceed the width of a single dense wavelength division multiplex (DWDM) channel. Merging of all
wavelengths into one OF takes place in the multiplexer block. The opposite function, that is, dividing the
individual wavelengths, takes place in the demultiplexer block. There are diffraction multiplexers with Bragg
lattices or interference multiplexers arrayed waveguide grating (AWG) [4, 5]. AWGs are made of two
waveguides at the inlet and at the outlet of an ordered waveguide grid that is composed of long asymmetric
parallel waveguides. AWG technology allows us to do 50 GHz multiplexing of multiple channels, while it
can be integrated on the silicon layer and does not suffer from chromatic dispersion. However, its
disadvantage is its dependence on temperature. Multiplexers with Bragg grids achieve high accuracy and less
loss. It is also a disadvantage that they need additional components (circulators, couplers) to function, which
mainly introduces a chromatic dispersion into the system. It is also possible to add and allocate individual
wavelengths using optical add-drop multiplexer (OADM) or reconfigurable optical add-drop multiplexer
(ROADM), depending on customer requirements.
When the optical path is transmitted, the optical signal is attenuated and for this reason, it is
necessary to refresh the signal in individual sections. An optical amplifier can be inserted into the optical path
in three ways: as a booster, which is placed directly behind the optical transmitter and serves to amplify
the signal to the highest possible level that can be tied to the OF [6-8]. It can also be placed as an IN-Line,
which is inserted continuously into the optical path (80-120 km) or as a preamplifier, which is placed in front
of the receiver and amplifies the signal to a value acceptable to the receiver unit (bit error rate (BER)
acceptable). In practice, optical amplifiers such as erbium-doped fiber amplifier (EDFA), semiconductor
optical amplifier (SOA) and Raman optical amplifier (ROA) are used.
Upstream of the demultiplexer, the signal is converted from the optical domain to the electrical
domain using a PIN (P-I-N photodiode) or avalanche photodiode (APD) photodiode. Although
the photodetector converts only the intensity of the optical radiation into an electrical signal, in the case of
more advanced modulation formats, the receiver is equipped with additional elements such as a
Mach-Zhender interferometer or a 90° hybrid optical coupler. Currently, coarse wavelength division
multiplex (CWDM) and dense wavelength division multiplex (DWDM) standards are used. When choosing
which standard to use in practice, we decide on the end price, the number of users, the bit rate, and how the
network will grow.
Figure 1. Design of DWDM system [4]
The primary parameter of WDM systems is their total transmission capacity, also identified as
CWDM, which we calculate as follows:
𝐶 𝑊𝐷𝑀 = ∑ 𝑣 𝑝𝑘
𝑛
𝑘=1 , (1)
3. ISSN: 1693-6930
TELKOMNIKA Telecommun Comput El Control, Vol. 18, No. 6, December 2020: 2878 - 2885
2880
where vpk is the transmission rate of the k-th channel and n is the total number of channels of the WDM
system. Each channel is assigned a certain spectrum width, regardless of whether the channel uses it or not. If
the channel spacing is unnecessarily large, the system achieves worse overall spectral efficiencies, which can
be defined by the following relation:
𝜂 𝑊𝐷𝑀 =
𝐶 𝑊𝐷𝑀
𝐵 𝑊𝐷𝑀
(2)
where BWDM is the total bandwidth taken by the WDM system [8]. Nowadays, WDM technology can be used
directly in switches using small form-factor pluggable (SFP) or compact small form-factor pluggable (CSFP)
slot in the form of MiniGBIC modules.
3. FOUR WAVE MIXING
Four-wave mixing is a process that has a physical nature in non-linear polarization. A minimum
3-channel demultiplexer with frequencies i, j and k is required to create this phenomenon [9].
The condition is that the three frequency components are evenly distributed. Of all the signals that arise in
this mixing process, the ijk signal is the most disturbing signal is the signal of ijk
𝜔𝑖𝑗𝑘 = 𝜔𝑖 + 𝜔𝑗 − 𝜔 𝑘,pre 𝑖 ≠ 𝑘 ⋀ 𝑗 ≠ 𝑘. (3)
Depending on the particular frequencies, this signal (frequency) may be close to one of the original
frequencies and thus cause intense inter-channel interference [10-12]. In multi-channel WDM systems with
N-channels, the individual channels mix, resulting in a large number of interfering frequency components N
x (N – 1)2
. Figure 2 illustrates an example of mixing three initiation signals. According to the conversion,
1 to 12 undesirable frequency components may be created. FWM, unlike self phase modulation (SPM) and
cross phase modulation (XPM), is a process independent on transmission speed in the channel but is strongly
dependent on channel spacing periodicity and chromatic dispersion.
Figure 2. Principle of FWM
For dispersion shifted fiber (DSF) fibers, the phenomenon of four-wave mixing in WDM systems is a
severe issue. On the contrary, it does not act as a severe obstacle to the standard FWM OF. This motivated the
development of a non-zero dispersed shifted non-zero-dispersion shifted fiber (NZ-DSF) fiber. The effect of
four-wave mixing depends on the relationship between the phases of the interacting signals. Assuming there
was no chromatic dispersion phenomenon, all signals would be spread at the same group rated speed. In this
case, the FWM itself would be amplified [13, 14]. In real WDM systems, however, the chromatic dispersion
applies and therefore the individual signal components have different group rate speeds. The phases of these
frequency components alternate (overlap) and mix. The speed difference is more significant in systems where
channel spacing is more significant (in systems with chromatic dispersion). The following relationship
expresses the optical power loss caused by the FWM; in other words, the power of newly formed frequency
component Pijk:
𝑃𝑖𝑗𝑘 = (
𝜔 𝑖𝑗𝑘 𝑛̅𝑑 𝑖𝑗𝑘
3𝑐𝐴 𝑒
)
2
𝑃𝑖 𝑃𝑗 𝑃𝑘 𝐿2
, (4)
where L is the length of the line without increasing losses and chromatic dispersion. Pi, Pj, Pk correspond
to the power of the waves (frequency components) entering from the FWM process itself, n which is
4. TELKOMNIKA Telecommun Comput El Control
Mitigation of non-linear four-wave mixing phenomenon in a fully optical… (Petr Ivaniga)
2881
the non-linear component of the refractive index (3 x 10-8
m2
/W) and dijk is the so-called degradation factor
[15-18]. Since losses and chromatic dispersion cannot be avoided in real systems, the length of line L is
replaced by the effective length Le and with amplifiers distributed every n km
𝐿 𝑒 =
1−𝑒−𝛼𝐿
𝛼
(5)
The chromatic dispersion compensates for the effect of four-wave mixing. The actual Pijk value can be
modeled using the nijk mixing efficiency coefficient
𝑃𝑖𝑗𝑘 = 𝜂𝑖𝑗𝑘 (
𝜔 𝑖𝑗𝑘 𝑛̅𝑑 𝑖𝑗𝑘
3𝑐𝐴 𝑒
)
2
𝑃𝑖 𝑃𝑗 𝑃𝑘 𝐿 𝑒
2
, (6)
𝑛𝑖𝑗𝑘 =
𝛼2
𝛼2+(Δ𝛽)2 [1 +
4𝑒−𝛼𝑙 𝑠𝑖𝑛2(Δ𝛽𝑙/2)
(1−𝑒−𝛼𝑙)
2 ], (7)
where is the difference between the transmitting constants of the signals i, j, k a ijk:
Δ𝛽 = 𝛽𝑖 + 𝛽𝑗 − 𝛽𝑘 − 𝛽𝑖𝑗𝑘. (8)
In an optical network designed according to the DWDM standard, for which the channels are
100 GHz (0.8 nm) apart, there is a maximum of 1 dB of power loss per channel due to FWM. That is, if
the power attributed to all channels has a P-value, then the power loss for each channel must be less than P.
The FWM effect increases as the length of the transmission line increases and this limits the performance of
the individual channels [19]. The dependence of the maximum transmitted power per channel (mW) versus
distance (km) for standard SMF fiber and DSF fiber is shown in Figure 3 [20]. For the single SMF fiber,
the dispersion reference value is 17 ps/nm/km. In the case of dispersed displaced DSF, the chromatic
dispersion is zero.
Figure 3. Dependence of maximum transmitted power per channel depending on the distance
A comparison of SMF and DSF shows that DSF comes with significantly worse peak power than
the SMF fiber. This is due to the higher efficiency of DSF fiber mixing due to the low chromatic dispersion
value [21-23]. The power balance per channel deteriorates as the number of channels increases. There are
several ways to eliminate the adverse effect of FWM:
− Uneven channel placing. This solution is possible mainly in WDM systems with a small number of channels.
− Increase the frequency separation between channels, resulting in a more significant group speed
difference. This solution has the disadvantage of amplifying a disproportionately large portion of
the frequency spectrum and also amplifying the effect of the SRS.
− Utilization of larger wavelengths beyond 1560 nm using DSF [24, 25]. Despite the use of DSF,
a significant amount of chromatic dispersion is employed in such a WDM system, and this reduces the
FWM effect.
− Generally, in this type of non-linearity, FWM suppression is achieved by reducing the transmitted input
power and reducing the distance between the amplifiers.
If from an application point of view, the channels can be multiplexed or re-multiplexed at
approximately half the transmission path, or demultiplexing, in this case, it is possible to introduce different
delays for each channel. This step ensures some randomness between the phases of the information channels.
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4. DWDM IMPLEMENTATION FOR FWM EXAMINATION
DWDM technology is used for the FWM demonstration, its schematic model bases from Figure 1.
DWDM proposed system with different input values has been published in [26]. For a simulation is designed
model of an 8-channel DWDM system where input blocks of pseudo-random data are modulated by external
NRZ modulation with transmission speed 10 Gbit/s. The channel spacing between the channels is 100 GHz
and ranges from 192.8 THz to 193.5 THz. The data is multiplexed after modulation and the amplification
occurs before entering the OF through an EDFA amplifier. This is followed by 100 km of OF with an optical
grid to compensate for chromatic dispersion and an optical amplifier. After demultiplexing of the optical
signal, the signal is filtered according to the required channel by a PIN photodiode and the evaluation takes
place in the spectral and electrical analyzer from which we detect the signal spectrum, eye diagram, BER and
Q-factor. Two simulations are performed. In the first simulation, the dispersion in OF is changed and in the
second one, the optical signal with the dispersion is changed.
4.1. Changing dispersion in OF to alleviate FWM
The whole system will be evaluated based on BER and related Q-factor. Mathematical derivation of
BER and Q-factor has been published in [15, 22]. We varied the dispersion from 0 to 1 ps/nm/km with
an increment of 0.2 and from 1 to 9 ps/nm/km with an increment of 2. The resulting values are shown in
Table 1. In Figure 4, Figure 5 and Figure 6 are the resulting spectra with an eye diagram for dispersion values
of 0, 1 and 9 ps/nm/km.
From Table 1, we can conclude that the non-linear FWM phenomenon decreases with increasing
dispersion in OF, but at the same time, the signal is scattered at high dispersion in OF. For this reason, it is
necessary to choose the correct dispersion value at the design of the optical system itself in order to avoid
the generation of a side signal and thus not to decrease the BER at the output. In our system, the dispersion
value is only acceptable up to 5 ps/nm/km to maintain BER (1.92·10−14
).
Figure 4. Output spectrum and eye diagram for D = 0 ps/nm/km
Figure 5. Output spectrum and eye diagram for D = 1 ps/nm/km
6. TELKOMNIKA Telecommun Comput El Control
Mitigation of non-linear four-wave mixing phenomenon in a fully optical… (Petr Ivaniga)
2883
Figure 6. Output spectrum and eye diagram for D = 9 ps/nm/km
Table 1. The resulting BER values with changed dispersion in the OF
Dispersion [ps/nm/km] BER [-] Q[-] Q[dB]
0 1.87·10−04
3.574 11.065
0.2 3.53·10−11
6.675 16.489
0.4 6.25·10−40
13.826 22.814
0.6 2.67·10−38
13.036 22.303
0.8 1.00·10−40
15.702 23.919
1 5.22·10−36
12.569 21.986
3 6.87·10−13
7.229 17.182
5 1.92·10−14
7.673 17.699
7 1.87·10−08
5.641 15.027
9 2.99·10−04
3.308 10.392
4.2. Changing the input signal to mitigate the FWM
In this simulation, we point out the relation of the input signal to the FWM (the need for a suitable
transmit power at the input). In this system, D = 5 ps/nm/km from the previous simulation was set. The laser
power is varied from -5 to 9 dBm with an increment of 2 (The resulting BER and Q-factor for a particular
power are shown in Table 2). When the transmit power is set from -6 dBm to -9 dBm, the BER increases
from 2.91·10−12
to 4.99·10−7
. For this reason, it makes no sense to use a low input power value because using
optical amplifiers would distort the signal. In Figure 7, Figure 8 and Figure 9, we can see the resulting
spectrums with an eye diagram for a particular optical power.
Figure 7. Output spectrum and eye diagram for Tx = -5 dBm
As can be seen from Table 2, BER can be influenced by a suitable choice of Tx at the input. We can
conclude that the higher the signal level is above the noise, the better the BER. From the simulation, we can
further say that the lower value of the input signal causes less influence of FWM. The lowest power
Tx = -5 dBm produces the lowest FWM value as shown in Figure 7. Of the individual simulations, the best
signal value is when Tx is in the range of -5 to 3 dBm, which corresponds to BER values (<-10-12
).
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2884
Figure 8. Output spectrum and eye diagram for Tx = 3 dBm
Figure 9. Output spectrum and eye diagram for Tx = 9 dBm
Table 2. The resulting BER values when the Tx is changed in the transmitting portion
Tx [dBm] BER [-] Q[-] Q[dB]
-5 3.87·10−12
7.009 16.914
-3 5.06·10−11
7.075 16.989
-1 2.90·10−15
7.820 17.865
1 2.04·10−12
7.047 16.960
3 3.40·10−11
6.627 16.426
5 6.50·10−08
5.386 14.626
7 2.29·10−05
3.697 11.358
9 7.02·10−03
2.613 8.343
5. CONCLUSION
The paper aimed to describe the non-linear phenomenon of FWM since it is nowadays necessary to
consider it in the design itself. The paper described the basic mathematical principle of the phenomenon in
the DWDM system and its possible elimination at the output. In experimental simulations, we pointed out its
origin and how it relates to dispersion in optical fiber. We also pointed out that a suitable choice of dispersion
can minimize FWM. In the next simulation, with the appropriate dispersion choice D = 5 ps/nm/km, we
changed the transmit power at the input. From Table 1 and Table 2, we can create an optical system with
acceptable values at the output, unless the bit error rate rises above the value 10-9
when it is no longer
possible to distinguish the individual optical pulses of the output.
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