Terms Of Q-factor Research Articles

Minimalist Deployment of Neural Network Equalizers in a Bandwidth-Limited Optical Wireless Communication System with Knowledge Distillation.

An equalizer based on a recurrent neural network (RNN), especially with a bidirectional gated recurrent unit (biGRU) structure, is a good choice to deal with nonlinear damage and inter-symbol interference (ISI) in optical communication systems because of its excellent performance in processing time series information. However, its recursive structure prevents the parallelization of the computation, resulting in a low equalization rate. In order to improve the speed without compromising the equalization performance, we propose a minimalist 1D convolutional neural network (CNN) equalizer, which is reconverted from a biGRU with knowledge distillation (KD). In this work, we applied KD to regression problems and explain how KD helps students learn from teachers in solving regression problems. In addition, we compared the biGRU, 1D-CNN after KD and 1D-CNN without KD in terms of Q-factor and equalization velocity. The experimental data showed that the Q-factor of the 1D-CNN increased by 1 dB after KD learning from the biGRU, and KD increased the RoP sensitivity of the 1D-CNN by 0.89 dB with the HD-FEC threshold of 1 × 10-3. At the same time, compared with the biGRU, the proposed 1D-CNN equalizer reduced the computational time consumption by 97% and the number of trainable parameters by 99.3%, with only a 0.5 dB Q-factor penalty. The results demonstrate that the proposed minimalist 1D-CNN equalizer holds significant promise for future practical deployments in optical wireless communication systems.

Analysis of hybrid integrated-alternate mark inversion (I-AMI) modulation and symmetrical-symmetrical-post (SSP) dispersion compensation technique in single-tone radio over fiber (RoF) system

Abstract This paper presents the high capacity single-tone Radio over Fiber (RoF) system utilizing advanced modulation technique in conjunction with optimized dispersion compensation scheme to support the high data rate transmission upto 120 Gbps. The proposed system incorporates the Integrated-Alternate Mark Inversion (I-AMI) modulation and Symmetrical-Symmetrical-Post (SSP) compensation technique to enhance the spectral efficiency as well as to reduce the chromatic dispersion effects in long-haul RoF link. The proposed system i.e., I-AMI with SSP has been examined at 60, 80, 100 and 120 Gbps bit rate for various transmission distance. The simulation results obtained in terms of Q-factor, Bit Error Rate (BER) and eye diagram reveal that the proposed system provides wider eye-opening, low BER and high Q-factor as compared to the existing system. The proposed I-AMI with SSP provides the Q-factor of 30.47 whereas the I-AMI with PSP and AMI with SSP provides the Q-factor of 18.77 and 18.40 respectively at 80 Gbps bit rate over a transmission distance of 800 km.

Performance Analysis of 8 * 112 Gbps (0.896 Tbps) WDM ROF Link Using 32 QAM - OFDM Modulation Scheme for Achieving Extended Range

We propose an advanced optical transport system utilizing higher order modulation formats and coherent detection. Our innovation introduces an 8 x 112 Gbps WDM ROF link using a 32 QAM-OFDM modulation scheme, capable for extending its reach. Our proposed research stands out from existing studies due to its distinctive use of the 32-QAM format and a 112Gbps data rate per channel, especially when considering a channel span of 3000 kilometers Our analysis covers Wavelength Division Multiplexing - Radio over Fiber (WDM-ROF) link systems, including a pre-optical amplifier within the link, one optical amplifier outside the channel loop span, and one within the loop span, representing distinct scenarios. We operated optical amplifiers in the gain-controlled mode. Remarkably, exclusive of employing precise dispersion or non-linearity improvement techniques, carried out simulations reveal optimal transmission distance for our anticipated system having considered specification parameters is 3000 Km. We conducted extensive simulations to assess the system performance in terms of Q-factor, ESE, and EVM over link spans ranging since 1000 to 15000 Kilometers.

Design and analysis of SOA-MZI based optical digital circuits for high speed optical networks

This paper explores using Semiconductor Optical Amplifier assisted Mach-Zehnder Interferometer (SOA-MZI) configuration for designing various all-optical digital circuits. A specific focus on the design and analysis of all-optical inverters, decimal-to-binary code converters, and hexa decimal-to-binary code converters operating at a speed of 10 Gbps is given. These circuits employ OR, XOR, and NOR gates. The SOA-MZI configuration capitalizes on the nonlinear properties of the SOA to achieve all-optical logic functions. Phase modulation can be transformed into intensity modulation by incorporating the SOA within an interferometer setup and using 3-dB couplers. The Cross-Phase Modulation (XPM) technique, which offers superior performance compared to other types of SOA non-linearity, is employed to make the incoming signal insensitive to polarization. The system was analyzed using an optisystem. The performance achieved was 0.0109 in terms of Eye height, 3.45 e−70 in terms of Bit Error Rate (BER), and 17.66 in terms of Q-factor.

Improved passive optical network RoF system based vertical cavity-surface emitting laser (VCSEL) optical source external modulation

Passive Optical Network (PON) is a promising 5 G optical fiber network technology, that can enhance reliability data rate, and bandwidth saving. This simulation-based study investigates the feasibility of implementing a vertical cavity-surface emitting laser (VCSEL) optical source along with wavelength-division multiplexing (WDM) for designing a PON radio over fiber (RoF) system that can authorize multi-subscribers, users, to simultaneously use the same optical fiber for Front long-haul data transmission. Three scenarios are proposed: First, a VCSEL, and a Mach–Zehnder Modulator with a distinctive frequency are made accessible to every user in the PON system. Whereas, in the second scenario, a continuous wave (CW) laser is used to replace the VCSEL in the same PON. 16 users are multiplexed by a WDM and transmitted over a link length of 200 km. The system performance is, thus measured in terms of Q-factor, and it is revealed that the VCSEL-based system outperforms the system utilized CW laser to a distance of 150 km, with a maximum gain in the Q-factor of about 4.5. Both postulated systems are able to achieve a maximum transmission distance of 180 km with a minimum Q-factor of 6. Moreover, to minimize, the input current of around 1 mA and the system complexity, a third scenario is presented in which one VCSEL with 193.1 THz is shared among multiple users. The Q-factor performance is then simulated for up to 72 users, revealing that the minimum level of acceptable Q-factor has been maintained up to a link length of 180 km.

A Filter-Free Third Overtone Quartz Oscillator Based on Micromachining Technology.

This work investigates an AT-cut quartz crystal oscillator (XO) operating at its enhanced third overtone thickness shear (TS) mode while suppressing the fundamental TS mode by micromachining technology. A unique quartz plate structure has been proposed to alleviate the strong resonant signal from the first mode. A finite-element method (FEM) was used to characterize the first mode suppression while improving the performance of third overtone in terms of Q -factor and motional resistance ( Rm ) of the proposed device. In measurement, the unloaded Q -factor of the fundamental TS mode is from several tens of thousands (the reference design) to only several hundred (the proposed design). Meanwhile, the unloaded Q -factor of the third overtone response for the proposed design could reach Q ∼95 000 with a decent Rm . The Q -factor ratio attains 170-180 between the third overtone and fundamental modes. With the feature of low Q -factor on the fundamental mode, the oscillator system could successfully oscillate at a higher frequency without the help of bandpass filtering. Finally, the closed-loop oscillation measurement is performed for the phase noise (PN) characterization. The PN performance could reach -154.5 dBc/Hz at a 1-kHz offset at the carrier frequency of ∼ 60 MHz. This technique has proven its potential as a future solution of high-frequency quartz oscillator technology.

COMPARING DISPERSION COMPENSATION METHODS FOR 120 GB/S OPTICAL TRANSMISSION: PRE, POST, AND SYMMETRICAL SCHEMES

One of the major factors that limit the performance of an optical fiber communication system isdispersion. In order to get a high transmission range with high data rates, techniques must be in place to compensate for the dispersion caused by fiber nonlinearity. Dispersion Compensating Fiber (DCF) and Fiber Bragg Grating (FBG) are the trending dispersion compensation techniques in optical fiber communication. The use of DCF and FBG as a method of dispersion compensation can notably enhance the overall performance of the system. Broadening is a function of distance as well as the Dispersion parameter (D). The dispersion parameter is given in ps/nm/km and changes from fiber to fiber and also is a function of wavelength. In this paper, we investigate pre-, post-, and symmetrical compensating schemes in three different compensating models: DCF, FBG, and DCF cascaded to FBG. The system performance was evaluated in terms of Q-factor and Bit Error Rate (BER) for one optical channel communication system at 120 Gbps Return to Zero (RZ) signal launched over Single-Mode Fiber (SMF) of 100 km by using OptiSystem 7.0 software.

Performance enhancement of duobinary modulation-based DWDM system using particle swarm optimization

Abstract The next-generation light wave communication DWDM networks can accommodate large number of channels to efficiently utilize the bandwidth (BW). However, in the deployment of DWDM system mixing of two or more waves limits the performance due to four wave mixing (FWM) nonlinearity in fiber. This article, presents improved performance analysis of DWDM using a proposed improved duobinary modulation (IDBM), modified duobinary modulation (MDBM) and duobinary modulation (DBM) model for mitigation of FWM nonlinearities has been estimated experimentally through interference of noise on optical signal, FWM efficiency, FWM power etc. In IDBM, a unit delay in addition to time delay parameter is also utilized for generation of electrical duobinary pulses. The parameters of both delay blocks are tuned through particle swarm optimization (PSO) technique to improve the performance. The overall proposed IDBM effectively decreases the FWM. The results obtained for IDBM in terms of Q-factor 8.9, OSNR 18 dB, FWM power −87 dBm and FWM efficiency −70 dB shows substantial improvement with the recommended IDBM technique in comparison to DBM and MDBM schemes.

Chromatic dispersion compensation by cascaded FBG with duobinary modulation scheme

In this paper, we propose a dispersion compensation model to minimize the chromatic dispersion to enhance system performance. The proposed model is based on applying the duobinary modulation scheme on 4-stages of cascaded identical apodized uniform fiber Bragg grating. Different apodization functions are tested to determine the one that provides the best performance. The proposed model is connected in three different connection schemes: pre, post and symmetrical, to get the best connection. To evaluate the performance of the proposed system, a comparative study is conducted using non-return to zero (NRZ) and modified duobinary (MDB) modulation schemes. For evaluation, a 10 Gbps WDM link is simulated at a distance of 100 km under a set of predefined operating parameters. Optisystem 17.0 is used for simulation and evaluation. Both quality factor (Q-factor) and bit error rate (BER) are used as performance indices. All cases of NRZ modulation scheme do not meet the minimum operational requirements in terms of Q-factor and BER. Only in the case of MDB modulation scheme, the symmetrical compensation with tanh apodization meets the minimum operational requirements with a Q-factor of 6.39 and BER of 8.44 × 10–11. The proposed model achieves better results as compared to the other modulation schemes: a maximum Q-factor values of 8.964 and a BER of 1.3 × 10–19 with tanh apodization in the pre-compensation scheme. As compared to related work, the system performance achieves ~ 99% improvement.

Investigation of Inter-Satellite OWC Incorporating Dense WDM and Polarization Interleaving (PI)

Inter-satellite communication based on lasers (LIC) is a possible choice for future satellite networks because to ultra-high capacity and speed systems that may be achieved using compact, light-weight, and low-power optical equipment. The performance of a 64 × 40 GB/s optical wireless system with polarisation diversity for dense WDM is investigated in this research paper. Using a DWDM system with a channel spacing of 50 GHz, a high-speed system is achieved to meet the broad bandwidth needs of data services in satellites. A polarisation diversity approach is implemented in the system to decrease polarisation crosstalk and nonlinearities among nearby WDM channels. Furthermore, a comparison of the polarisation interleaved and traditional DWDM-OWC systems is performed. In addition, it was discovered that a system with varying states of polarisation across neighbouring channels performs better in terms of Q-factor and BER than a traditional system.

Study on increasing the capacity of RoF systems for long distance optical communication using solitons

In order to enable long distance communication, the light signal in Radio-over-fiber (RoF) technique is modulated by a radio signal. WDM (wavelength division multiplexing) technology is an effective way which can be used in the optical fiber feeder network to increase the capacity of RoF systems. In spite of the advantages RoF has nonlinear effects such as dispersion which can be mitigated by selecting appropriate dispersion management techniques. One of the challenges of WDM is the proper wavelength spacing. It must be properly designed so that signal interference does not occur. In this paper we try to review which dispersion management technique provides greater efficiency for long haul optical networks. The performance efficiency of different modulation techniques and different orders of modulation is also reviewed. So, by this work we try to propose a model which will provide better output power and low dispersion level which is the primary concern of any optical transmission system. The proposed model incorporates a WDM RoF system with soliton dispersion management system and the modulation technique employed is 64 QAM/DPSK and the results are analyzed in terms of Q-factor and Bit Error Rate (BER).

Performance Evaluation of 4*15 Gbps CWDM Optical Transmission Link for Metropolitan Areas

In this growing world, communication to every corner of the globe is the most important factor. Although technology is touching heights it is a great challenge to connect to subscribers present at different territories. For long distance transmission, Dense Wave Length Division Multiplexing (DWDM) has been preferred always as it provides a better bandwidth to operate, but when we comes to short term or short distance transmission it has some drawbacks, such as wide band change, more power consumption, and high cost factor for lower channels. CWDM can easily overcome these disadvantages. In this paper, the performance of 4*15 Gbps optical transmission link for Coarse Wavelength Division Multiplexing (CWDM) based optical network has been analyzed and compared using different photodetectors. Here we’ve compared the performances in terms of Q-Factor (Quality Factor), BER (Bit Error Rate), and eye height in the eye diagram. For experimental setup and simulation, Optisystem-18 software is used.

Performance Analysis of a High-Speed Optical Transmission System Using Various Pulse Generator

The future generation technology needs network expansion, large bandwidth capacity, and modern application development. Due to dielectric in nature, having electromagnetic immunity, having larger bandwidth, and being a lightweight cable, the demand for optical fiber has grown expeditiously. ISI (Inter Symbol Interference) hampers the performance of optical communication drastically. It induces a superabundant increment in pulse duration, rolling out in time and space engrossed by the pulse as it propagates. As the pulse propagate along the optical fiber, this spread can be so enormous that a photo detector can no longer discriminate boundaries between pulses. Due to ISI, path loss increases rapidly and causes broadening of pulses and achieving high data rates becomes difficult. To reduce the effect of ISI pulse shaping technique is used. In this paper the channeling performance of optical fiber and DCF is estimated by using different pulse generator. Here we collated the performance of APD photo diode and PIN photo diode value in terms of Q-Factor and Bit Error Rate in the eye diagram. We have used a DCF to mitigate the effect of dispersion produced in the channel.

Enhanced spectrum slicing: wavelength division multiplexing approach for mitigating atmospheric attenuation in optical communication

Over last decades, the free space optics (FSO) emerged as most prominent way of communication over radio frequency communication and microwave communication. The FSO works in the same way optical fiber cable (OFC) network works with the only difference that the optical beams were transmitted through the free space and not by using the OFC core i.e. the glass fiber. The presence of mist, fog, rain and clouds in the atmosphere directly affects the performance of FSO and the power of propagating signal is degraded significantly. Since the wavelength of propagating beam is comparable to size of fog particles, they mainly lead to atmospheric attenuation. To mitigate the impact of atmospheric attenuation on signals, the present study develops a spectrum slicing (SS)-wavelength division multiplexing (WDM) system with Pre and Post Amplification. The performance of the proposed SS-WDM-Pre and SS-WDM-Post scheme is analyzed and then compared with the traditional SS-WDM model in the Opti-system in terms of Q-factor and BER values. The analysis of the proposed and traditional scheme is done under varying attenuation and power signals during summer, winter, autumn and spring season.The comparative analysis proved that the performance of the proposed SS-WDM-Post and SS-WDM-Pre-model is more effective and efficient when compared with the traditional SS-WDM model in terms of Q-Factor and BER during all 4 seasons.

Design and Performance Study of Soliton based WDM systems for long distance optical communication

The global demand for secure, large distance and high-speed internet services are increasing day by day with the increase in number of users. In order to meet these rising demands, the technologies used in optical communication system need to improve rapidly to keep up the pace. The evolution of fiber optics thus results in broadband connections which provide uninterrupted high speed internet services for large distances. The achievement of having some high data rate communication schemes in any optical fiber systems used for communication is limited by dispersion. Dispersion affects the transmission capacity of the system badly and thus the bandwidth gets reduced. Solitons are an effective solution for overcoming attenuations occurring due to dispersion. Solitons are narrow pulses that can retain their shape after propagating through a large distance but it undergoes interactions and distortions while used in DWDM systems. In this paper, performance of an 8 channel DWDM system at 40 Gbps bit rate employing different dispersion compensation is done and are analyzed in terms of Q-factor and Bit Error Rate (BER). In this design both Dispersion Compensation Fiber (DCF) and Fiber Bragg Grating (FBG) are used for improving Q-factor. The results shows that a Q-factor of about 52.1526 with a min BER of zero is obtained.

WRELM based CO-OFDM system with improved performance, spectral efficiency and computational complexity

Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) system with Pilot-free phase noise compensator was introduced in order to accomplish the need of high spectral efficiency in the optical communication. In CO-OFDM system Discrete wavelet packet transforms (DWPTs) in place of Fast Fourier Transforms (FFTs) had attracted more attention since it has removed the need of cyclic prefix used to compensate fiber dispersion. In this paper, a DWPT based CO-OFDM system with Wilcoxon Robust Extreme Learning Machine based pilot-free phase noise compensator using multi-level QPSK partitioning of 16-QAM has been proposed. From the results of this work it has been seen that the percentage improvement in performance (in terms of Q-Factor) and spectral efficiency over traditional pilot-aided techniques is approximately 6 and 21 respectively. Moreover, this proposed work will comparatively reduce the overall system complexity.

Performance analysis of beam divergence propagation through rainwater and snow pack in free space optical communication

In the present work the future communication requirements need to fulfill with high data rate, FSO (free space optic) with it is tremendous potential is the solution. This research observed the effectiveness analysis of FSO systems by modifying one of the most important FSO parameters beam divergence, under the most affected weather attenuating condition Rainwater and snow pack. The simulation is obtained and analyzed under single channels CSRZ-FSO (carrier-suppressed return-to-zero/free space optical) systems having capacity of 40 Gbps between two transceivers with variable distance. The connection is presently under 5 meteorological turbulences (light rain, medium rain, wet snow, heavy rain and dry snow). The results show the heavy rain and dry snow have a very high attenuation carried out in terms of Q-factor. this result led us to conclude that small divergence offers significant performance improvement for FSO link and this performance decrease every time the beam divergence increase, Therefore, to build inexpensive and reliable transmission media, we go with new method that still in the experiment area called hybrid RF/FSO (radio frequency/free space optical) that compatible with atmospherically status.

Enhancing Performance of Coherent Optical OFDM FSO Communication Link Using Cascaded EDFA

Coherent communication aims to support high-speed dynamic networks by making their installation easier along with their monitoring and maintenance. In addition, Orthogonal Frequency Division Multiplexing (OFDM) which has shown gradual emergence in radio frequency (RF) domain during the past years, has now encroached into the optical domain. Combination of these two provides vigorous dispersion transmission as well as enhanced spectral efficiency. Free Space Optical (FSO) communication link performance deteriorates with scintillations, atmospheric turbulences and weather induced attenuations. The optical amplifiers, their arrangement used in the FSO link design has a drastic influence on the performance of the link. This work involves evaluating the proposed Coherent Optical OFDM FSO communication link at 30 Gbps data rate using Cascaded Erbium Doped Fiber Amplifier. The system has been evaluated in clear weather, rainfall and fog (Moderate to Dense) in terms of Q-Factor, BER, SNR and constellation diagram. The system has been designed considering moderate turbulent environment and geometric losses. The FSO communication link shows optimal performance up to 26 km for clear weather, 3.73 km under rainfall, 1.44 km under moderate foggy and 0.66 km under dense foggy environment.

PENGEMBANGAN MODUL PRAKTIKUM UNTUK PERBANDINGAN UNJUK KERJA LINE CODING RZ DAN NRZ PADA JARINGAN FIBER OPTIK

The important thing to consider in the process of sending optical fiber network signals is theselection of line coding types. Line coding is a process of converting digital data into digital signals sothat they can be transmitted in optical fiber networks. Line codings commonly used are NRZ and RZ.Therefore, this research discussed the comparison of the performance of NRZ and RZ line codings infiber-optic networks in terms of Q-Factor, BER, and Eye Diagram. The result of this research was thecharacteristic form of the electric signal line coding NRZ with one data element using one signalelement, while in the RZ coding line, one data element used two signal elements. The maximum risetime variable using the RZ coding line is 0.3 bits, while the NRZ coding line is 0.7 bits. The bestrectangle shape model using line coding RZ is sine while line coding NRZ is exponential. Themaximum bit rate using the RZ coding line is 11.5 Gbps while using the NRZ coding line is 18 Gbps.The maximum transmission distance using the RZ and NRZ coding line is 75 km. Another output ofthis research is a practicum module that can be used by students of the Electrical Engineering StudyProgram to understand optical communication systems, especially line coding RZ and NRZ. Based onthe results of student assessments of 87.6% and the post-test score which is higher than the pre-testscore, the practicum module is feasible as teaching material.

Performance Analysis of Different Modulation Techniques for Super Dense System with RAMAN–EDFA–RAMAN HOA

This paper has shown the analysis of 380 × 10 Gbps super dense wavelength division system using different modulation formats such as non-return to zero (NRZ), Electro absorption modulator (MZM), Mach–Zehnder modulator (MZM), return to zero (RZ) and differential phase shift keying for the features of quality factor (Q-factor), bit error rate (BER), output power and eye closure respectively. Amplification has maintained with the help of RAMAN–EDFA–RAMAN hybrid optical amplifier (HOA) for super dense system. Recorded results from NRZ declare to maintain better super dense optical communication with acceptable rating features in terms of Q-factor, BER, output power and eye closure for the distance of 50 to 400 km and 60 to 360 km respectively.