Showing papers in "Photonic Network Communications in 2021"
TL;DR: The design of proposed logic gates works on beam interference principle and operates efficiently by changing phase of light beams at 1550 nm wavelength and is implemented with only one structure with variations in the phase of applied input signals.
Abstract: We propose a photonic crystal-based all-optical AND, OR, and XOR logic gates using square lattice silicon rods with air background. The design of proposed logic gates works on beam interference principle and operates efficiently by changing phase of light beams at 1550 nm wavelength. The proposed AOX logic gates are implemented with only one structure with variations in the phase of applied input signals. Simulation and verification of design are done by using finite-difference time-domain method. The design offers a contrast ratio of 33.05 dB, 10.50 dB, and 8.29 dB of proposed AND, OR, and XOR logic gates correspondingly with optimized refractive index and silicon rod radius values.
51 citations
TL;DR: A theoretical model for the FWM effects and its mitigation is presented and validated through simulation results, and the transmission performance of the proposed OCS model is evaluated on the basis of bit error rate, optical signal-to-noise ratio and quality factor.
Abstract: Optical communication systems (OCSs) mainly represent the backbone of modern long-haul communication networks because of low loss transmission over long distances and ultra-high capacity. However high data-rate transmission through optical fiber suffers from deterioration due to nonlinear impairments, such as four-wave mixing (FWM) in particular. At high launch power levels, which are required for the long-haul transmission over hundreds of km, these nonlinear effects become more severe which imposes a challenge to achieve satisfactory transmission performance. In this paper, a theoretical model for the FWM effects and its mitigation is presented and validated through simulation results. Moreover, two other nonlinear effects, polarization mode dispersion and nonlinear dispersion variations are also investigated for various values of launch power level. The transmission performance of the proposed OCS model is evaluated on the basis of bit error rate, optical signal-to-noise ratio and quality factor using different transmission channel parameters such as effective area, nonlinear refractive index, nonlinear dispersion, and linear dispersion.
27 citations
TL;DR: It is found that Cauchy apodization function is the best one that reduces the reflective spectral width, Δλ, and achieves a maximum Q-factor and minimum BER at distances 30, 40 and 50 km at the last stage.
Abstract: This paper proposes a system that aims to reduce the spectral width, Δλ, of the optical signal at transmitter for WDM system over distance 100 km. Also, a chirped fiber Bragg grating (CFBG) at the receiver is used to compensate dispersion. The proposed system consists of four cascaded FBGs connected between light source and optical fiber. Many apodization functions are investigated to enhance the performance of the FBG in the proposed system, and Δλ is obtained at every stage and apodization function. The Q-factor and bit error rate (BER) are obtained at distances 30, 40 and 50 km. It is found that Cauchy apodization function is the best one that reduces the reflective spectral width, Δλ, and achieves a maximum Q-factor and minimum BER at distances 30, 40 and 50 km at the last stage.
18 citations
TL;DR: In this paper, the design and performance of all optical ternary NOT and XOR gate using the dual semiconductor optical amplifier (SOA)-based technology is investigated, the basic principal behind the operation of these logic gates is nonlinear cross-polarization modulation (XPolM) effect in SOA.
Abstract: Design and performance of all optical ternary NOT & XOR gate using the Dual semiconductor optical amplifier (SOA)-based technology is investigated. The basic principal behind the operation of these logic gates is nonlinear cross-polarization modulation (XPolM) effect in SOA. Optical NOT gate is universal logic gate, and optical XOR gates are very useful in designing higher order optical devices like flip-flops, parity checker and generator circuits, etc. The Q-value of the design is greater than 50 dB maintaining high operational speed (~ 100Gbit/s) ensures negligible bit error rate. Numerical simulation using MATLAB ensures CR values more than 55 dB and ER values more than 50 dB. These high values ensure practical feasibility of the proposed devices. The large relative eye opening(> 94%) ensures clear transmissions of the information.
15 citations
TL;DR: In this paper, the authors proposed a one-bit multi-layer fulladder cell, which has efficient cell usage against all the prior designs regarding cell counts and area occupation leading to around 7% improvement in cell number than the common fulladder design.
Abstract: Some of the vital problems around the conventional CMOS technology are leakage-power consumption, physical-scalability limits, and short-channel effects. These deficiencies have led to many studies about nano-scale designs. Quantum dot cellular automata (QCA) is a potential answer in nanotechnology. Scholars have considered the four-dot squared cell as the main factor in the QCA. Also, a full-adder is a fundamental unit in every digital system. However, the importance of cell and area consumption limitation in circuit designing has been completely ignored in most of the related studies. Therefore, in this paper, we have offered a one-bit multi-layer full-adder cell. The practical accuracy of the proposed circuits has been assessed using QCADesigner. According to the obtained results and the design, the presented design has efficient cell usage against all the prior designs regarding cell counts and area occupation, leading to around 7% improvement in cell number than the common full-adder design. The simulation outcomes have also shown that the introduced design has excellent efficiency regarding cell and area aspects.
11 citations
TL;DR: A new QCA-based 4-bit binary to gray converter circuit employing the appropriate configuration of the XOR gate as a basic building block has been suggested and performance results indicated that the proposed converter works properly and has optimum performance parameters such as latency, complexity, and consumed area as compared to the current schemes.
Abstract: Quantum-dot cellular automata (QCA) is one of the most prominent technologies in nanometer-scale with appreciable reduction of size and power consumption and high switching frequency to overcome the scaling limitations of complementary metal-oxide semiconductor. On the other hand, code converters play a key role in signal processing and efficient network designs. The researchers have focused on emerging nano-devices that can identify errors throughout information transfer. Therefore, in this research, a new QCA-based 4-bit binary to gray converter circuit employing the appropriate configuration of the XOR gate as a basic building block has been suggested. The layout has been generated using the QCADesigner simulation tool to test the functionality of the code converter. The performance results indicated that the proposed converter works properly and has optimum performance parameters such as latency, complexity, and consumed area as compared to the current schemes.
11 citations
TL;DR: A new photonic crystal-based full-adder for the summation of three bits has been proposed and demonstrates that it is more compact than the previous works and is capable of considering optical processing circuits.
Abstract: In this paper, a new photonic crystal-based full-adder for the summation of three bits has been proposed. For realizing this device, three input waveguides are connected to the main waveguide. An optical power splitter is placed at the end of this waveguide. Concerning the amount of optical intensity inside this waveguide, two nonlinear resonant cavities transmit the waves toward the correct ports. When the cavities do not drop the optical waves, the splitter guides them toward the output ports. The maximum delay time of the presented structure is around 0.5 ps and shows the fastest response among the reported works. This improvement is obtained due to using the resonant cavities. The time analysis results in a maximum working frequency of 2 THz. Also, designing the structure in 93 µm2 demonstrates that it is more compact than the previous works. The normalized low and high margins are obtained around 10% and 85%, respectively. So, the proposed device is capable of considering optical processing circuits.
11 citations
TL;DR: A comprehensive review of the principle structure of ADF, coupled mode theory (CMT), types and recent applications in WDMs, accelerometer and bio/chemical sensors is reported.
Abstract: Add–drop filter (ADF) is a key component in optical integrated circuits that can be used in all-optical communication networks and wavelength division multiplexing (WDM) systems. The quality factor, coupling efficiency, transmission efficiency and coupling length are important parameters in add–drop filters. Photonic crystal (PC) optical devices have become popular among researchers because their structure is suitable to embed into optical circuits. This paper covers a comprehensive review of the principle structure of ADF, coupled mode theory (CMT), types and recent applications in WDMs, accelerometer and bio/chemical sensors. Although there are some different categories of photonic crystal ring resonator-based ADF in general, all of them can be divided into photonic to two class of non-circular and circular. This article is reported a comprehensive study about ADF and improvement of these ADF.
9 citations
TL;DR: In this paper, a fuzzy logic control-based handover decision (FLC-HD) algorithm is proposed to ensure real-time and reliable communication in free space optical communication (FSO).
Abstract: Because of multiple advantages such as high bandwidth, high security, and flexible networking, the free space optical communication (FSO) has attracted more and more attention. However, the narrow beam of laser and the constrained access degree of optical node limit the development of mobile FSO networks, especially in the aspect of handover. In this paper, we propose a fuzzy logic control-based handover decision (FLC-HD) algorithm to ensure real-time and reliable communication. First, according to the predictive position and the motion information of mobile nodes obtained by the error correction extend Kalman filter algorithm, we obtain the received signal strength and the relative motion angles at next transmission. Second, we put forward the concept of threshold to ensure the completion of handover operations before the current link breaking. Third, the fuzzy logic control method is designed to select the optimal access point (AP) with three critical parameters, i.e., the received signal strength, the relative motion angles, and the access degrees of nodes. Simulation results show that the FLC-HD algorithm can improve the handover efficiency and relieve the ping-pong effect in mobile FSO networks.
7 citations
TL;DR: In this paper, the authors used reflective semiconductor optical amplifier (RSOA) based gain dynamics to design and analyze the NOR gate using soliton pulses for the first time in this communication.
Abstract: Reflective semiconductor optical amplifier (RSOA) is an efficient gain medium and finds application in passive optical network. Due to its double-pass characteristics compared to ordinary semiconductor optical amplifier, gives better switching performance. RSOA based gain dynamics is utilized to design and analyze the NOR gate using soliton pulses for the first time in this communication. The simulation results using MATLAB show an efficient performance (Q value more than 80 dB) of this gate with less complexity in hardware. The NOR gate is characterized by calculating extinction ratio (ER ~ 14 dB), contrast ratio (CR ~ 15 dB), Q value (~ 90 dB), and the effect of amplified spontaneous emission noise is also investigated. This NOR gate uses a single RSOA and can be used to design any optical logic processors in future.
7 citations
TL;DR: In this paper, the performance of underwater wireless optical communication (UWOC) with different vertical water channel conditions is experimentally analyzed, where the best fit with the experimental data in terms of received optical power as a function of transmission depth and attenuation is obtained.
Abstract: Performance of underwater wireless optical communication (UWOC) with different vertical water channel conditions is experimentally analyzed. Experiment has been carried out by varying temperature and salinity of the vertical water channel. Underwater vertical channel is modeled by obtaining the best fit with the experimental data in terms of received optical power as a function of transmission depth and attenuation. This mathematical model is used to simulate UWOC system in Optisystem software to analyze the performance of UWOC in terms of Q factor and BER. Analysis has been carried out to obtain maximum reachable transmission depth at different data rates for fixed input power and maximum achievable data rate at different input power for fixed transmission depth. Maximum reachable transmission depth is also analyzed for different modulation index of the amplitude modulator. These analyses are carried out for optimal performance parameters such as Q factor (≥ 6) and BER (≤ 10–9). Apart from Q factor and BER, performance of the UWOC channel is analyzed through eye diagrams obtained at the receiver of the UWOC system in terms of eye height which reflects the quality of signal. This analysis will be helpful for power budgeting, data rate restriction with transmission depth in different water channel conditions to establish vertical UWOC link.
TL;DR: In this article, an M/D design is introduced based on the surface plasmon resonance in optical ring resonators, and the number of inputs and outputs of the system is 3 × 1 and 1 × 3, respectively.
Abstract: The development of devices for communication networks to transmit information has become an active and growing field of research. Multiplexer/demultiplexer (M/D) is one of the basic devices in this field. In this paper, an M/D design is introduced based on the surface plasmon resonance in optical ring resonators. The number of inputs and outputs of M/D is 3 × 1 and 1 × 3, respectively. All parameters of the structure, including radius and width of ring resonators and waveguides, have been evaluated to obtain the optimal response. Also, we used the nonlinear gold property to expand the range of M/D performance and simulated the results for intensities less than 100 MW/cm2. Selectivity in the number of inputs and outputs, controllability using several parameters, all optically, selectivity in operation frequency, nanoscale size, reconfigurability, and integrated capability are the features of this design. In our simulation, we consider transmission and reflection of light in each port based on the finite difference time domain for evaluation of results.
TL;DR: In this article, the authors proposed an algorithm for flow routing based on three steps: (1) a linear algorithm is developed to extract the path between each source and destination in the controller, (2) non-dominated ranking is used to categorize the extracted paths, and finally, the crowd distance sorting algorithm is implemented to select the optimized route from all performance dimensions.
Abstract: Software-defined network (SDN) is an architecture with a physical or conceptual central controller. This architecture separates data and control plane causing network flexibility, programmability, and manageability. A packet when is received by the forwarding element (FE) as the first packet of the flow is forwarded towards the controller in the packet-in message; then, the controller decides for all packets belonging to the flow. The controller imposes the rule for the flow to the FE; thus, the FE acts based on the matching rules with the ingress packet in the flow table. Routing can be done by considering performance metrics to improve entire network performance in SDN. Performance and cost metrics include utilization, delay, jitter, packet loss ratio (PLR), blocking probability (BP), and link cost, so an optimized path selection is a multi-objective optimization problem and NP-Hard that we will consider. In this paper, we try to provide a comprehensive algorithm for optimizing the entire network performance in SDN. We propose the novel algorithm for flow routing based on three steps: (1) a linear algorithm is developed to extract the path between each source and destination in the controller, (2) non-dominated ranking is used to categorize the extracted paths, and finally, (3) the crowd distance sorting algorithm is implemented to select the optimized route from all performance dimensions. To evaluate the proposed algorithm, the shortest path and greedy-based routing algorithms will be simulated by Java, and the simulation results show that the proposed optimization algorithm improves the all mentioned performance criteria, simultaneously.
TL;DR: The proposed adaptive optical-RF transmission system is optimized so that the system performance is maximized under all channel conditions, and the performance gain of more than 1 dB is achieved under the minimum power level.
Abstract: Radio frequency (RF) spectrum is already dense enough and hard to add more broadband channels to meet the current user demands. Optical free-space communications could be an excellent alternative to the RF communications system, and it provides additional benefits, e.g., large bandwidth, high data rates and reliable communication link. Therefore, free-space optical (FSO) communication system becomes more attractive for the deployment of additional broadband channels, and it fulfils the current user demands of bandwidth-hungry applications. FSO communication links are susceptible to numerous meteorological conditions such as fog, snow, dust, smoke, scintillation and smog. Achieving better connectivity under the above-mentioned severe conditions is a crucial research question. Joint optical-RF communication system is developed to overcome the problems as mentioned earlier. The proposed adaptive optical-RF transmission system is optimized so that the system performance is maximized under all channel conditions. Optimization is achieved over the respective channel mappings, and the total required power by exploiting the proposed algorithm. The mapping schemes of each link are optimally chosen such that the total mutual information is maximized while distributing optimal power to the individual channel. Simulations are performed and verified with the analytical results to validate the proposed design. A comparison of the adaptive joint system (i.e., hybrid FSO-RF) over the non-adaptive system under various weather conditions is provided. From simulation results, the performance gain of more than 1 dB is achieved under the minimum power level. It is, therefore, recommended that the adaptive hybrid FSO-RF communication system is always an optimum solution for all weather conditions.
TL;DR: This proposed resilient architecture can efficiently support not only the fixed users but also the mobile users in the downstream direction under normal and failure operating scenarios, while minimizing the average traffic delivery time and without using extra redundant fibers for protection purposes.
Abstract: This work proposes a resilient wheel-based wavelength-division-multiplexed passive optical network optical access network architecture for backhauling network traffic. This proposed resilient architecture can efficiently support not only the fixed users but also the mobile users in the downstream direction under normal and failure operating scenarios, while minimizing the average traffic delivery time and without using extra redundant fibers for protection purposes.
TL;DR: In this paper, the flip-flop is designed by using two NOR gates, photonic crystal waveguides, four silicon ring resonators, four input ports and two output ports.
Abstract: The presented research deals with designing of a new ultra compact all-optical RS flip-flop on a two-dimensional (2-D) hexagonal photonic crystal platform. The flip-flop is designed by using two NOR gates, photonic crystal waveguides, four silicon ring resonators, four input ports and two output ports. The designed flip-flop structure has hexagonal silicon rods in the air host with a lattice constant a of 630 nm. Si rods have a radius of 0.2a and operating waveleangth of 1550 nm. The novel design provides proper distinction between logic 1 and logic 0 at the output by giving 8.7 dB and 4 dB contrast ratio at Q and Qbar output, respectively. Furthermore, uncomplicated structure resulting in small dimension of 28 μm * 28 μm makes it appropriate for optical integrated circuit in optical networks. FDTD method is used to model the proposed structure and simulated using RSoft FullWAVE simulator tool.
TL;DR: An overview of linearization of two different microwave photonic links based on phase modulator and dual-electrode Mach–Zehnder modulator is provided, taking into account the problem of intermodulation distortion which can severely degrade the performance of the system.
Abstract: This paper provides an overview of linearization of two different microwave photonic links based on phase modulator and dual-electrode Mach–Zehnder modulator. It takes into account the problem of intermodulation distortion which can severely degrade the performance of the system. Spurious free dynamic range has been analyzed through numerical and simulation for both the modulator links which are linearized using mixed polarization. Improvements of 7.3 dB and 15.1 dB are found in SFDR using polarizers in phase and Mach–Zehnder modulator, respectively.
TL;DR: This paper presents a minimum spectrum utilization (SU) and average path length (APL) approach to solve the (off-line) routing and spectrum allocation problem (RSA) based on combining a simple ordering pre-computation strategy, namely most subcarriers first (MSF) with three nature-inspired algorithms.
Abstract: Flexible optical network architectures are considered a very promising solution where spectrum resources are allocated within flexible frequency grids. This paper presents a minimum spectrum utilization (SU) and average path length (APL) approach to solve the (off-line) routing and spectrum allocation problem (RSA) based on combining a simple ordering pre-computation strategy, namely most subcarriers first (MSF) with three nature-inspired algorithms. These algorithms are ant colony optimization, differential evolution based relative position indexing (DE-RPI), and differential evolution general combinatorial (DE-GC). We begin by showing that MSF is the most effective ordering pre-computation strategy when compared to other well-known typical heuristics in the literature, such as first-fit, and longest path first. Then, we apply MSF in combination with the three nature-inspired algorithms to simultaneously optimize the SU and APL. The usefulness of MSF ordering pre-computation strategy is presented via a comparison of results obtained when using and not using MSF under the same scenarios. The algorithms are evaluated in benchmark optical networks, such as the NSFNet, the European optical network, and the 40-node USA network. We show that DE-RPI with MSF ordering pre-computation is the best option to solve the RSA problem, obtaining an average improvement percentage in the range of 0.9772–4.4086% on the SU and from $$-0.1668$$
to 0.8511% on the APL when compared to other meta-heuristics, either with or without the MSF ordering policy.
TL;DR: In this paper, the authors proposed a twin symbol hybrid optimization (TSHO-PTS) method of cyclic prefix OFDM (CP-OFDM) to find the new OFDM-based waveform to be used in 5G telecommunication standards.
Abstract: Orthogonal frequency division multiplexing (OFDM) is considered as one of the most significant transmission methodologies of the recent past Moreover, it permits easy demodulation and modulation To find the new OFDM-based waveform to be used in fifth generation which is one of the foremost open issues for wireless networks of the next generation In addition, the OFDM is affected by the maximum Peak-to-Average Power Ratio (PAPR) In order to minimize these problems, this paper proposed a Twin Symbol Hybrid Optimization used as a basis of the Partial Transmit Sequence (TSHO-PTS) method of Cyclic Prefix-OFDM (CP-OFDM) This CP-OFDM achieves the requirements of 5G telecommunication standards Moreover, the exhaustive searching for optimal phase factors might increase the computational cost of PTS To beat this problem, a hybrid version of slap swarm optimization (SSO) and Bald Eagle Search (BES) algorithm is introduced to investigate the phase factor optimally by the PTS method Digital chaotic sequences are used to ensure the physical layer security during the data transmission scheme for the Discrete Fourier Transform Spread OFDM (DFT-S-OFDM) subcarrier allocation The simulation takes place in the MATLAB platform, and the performances are evaluated by several performance metrics like Complementary cumulative distribution function (CCDF), Bit Error Rate (BER), and computational complexity The performance of the proposed model is compared with various existing approaches and previous works From the implemented results, the proposed strategy achieved less (5 dB) PAPR, minimum (10–8) BER, less processing time (018 s) than the existing schemes, and hence the complexity also very low (7%) than others
TL;DR: In this article, the authors proposed a signal demodulation method by measuring the time interval between adjacent photons and realized the recovery of the original signal from the discrete random pulse sequence output by the single-photon detector.
Abstract: We proposed a signal demodulation method by measuring the time interval between adjacent photons and realized the recovery of the original signal from the discrete random pulse sequence output by the single-photon detector. On this basis, a new communication system model is established by comprehensively considering the photon statistical characteristics of the emitted light field, the statistical distribution of adjacent photon time interval and the performance of the detector. Finally, an underwater optical wireless communication (UOWC) system was built. The effects of the average time interval between adjacent photons, baud rate and demodulation threshold in the time-slot on the system bit error rate (BER) were verified by experiments. The experimental results show that when the baud rate is 100 Kbps and the average time interval between adjacent photons is 111 ns, the BER of the system is 2.52 × 10−5.
TL;DR: In this article, the authors present the impact of putting a limit to the number of transmitters and receivers available at each node of an EON, and also develop a transceiver-aware heuristic algorithm for routing and spectrum assignment in EONs.
Abstract: The continuous increase of data traffic for present-day applications necessitates the development of Elastic Optical Networks (EONs). Significant advancements in efficient Routing and Spectrum Assignment (RSA) algorithms for EONs have been noticed in the recent past. These existing algorithms did not mention constraints on the number of transceivers per node in a network. However, for the planning of a realistic network, it is necessary to estimate the number of transceivers required at each node for the efficient operation of a network. Therefore, transceiver constraints should be taken into account while designing the RSA algorithms. In this paper, we present the impact of putting a limit to the number of transmitters and receivers available at each node of an EON. Moreover, the cost of a network heavily depends on the number of transceivers that each node in the network may offer. Hence, estimating the required number of transceivers per node in a network is vital to approximate the design cost of a network. Here, we present an Integer Linear Programming (ILP) formulation that includes the transceiver constraints and also develop a transceiver-aware heuristic algorithm for routing and spectrum assignment in EONs. Simulation results help us provide a proper design tool to estimate the number of transceivers per node in elastic optical networks.
TL;DR: In this article, the authors proposed a new QCA-based design in one layer for sign detection of three-moduli set {2n+1 − 1, 2n−−
Abstract: Sign detection has a wide application in digital fixed-point signal processing; however, it seems hard to conduct it in residue number systems (RNSs) based on complementary metal oxide semiconductor (CMOS). Also, quantum-dot cellular automata (QCA), as a useful substitution for CMOS technologies, provide many benefits such as low energy utilization and high velocity. However, up to now, there is not any paper that investigated the design of the QCA-based sign detection system. Therefore, here, we will introduce a method for RNS sign detection in the three-moduli set {2n+1 − 1, 2n − 1, 2n}. In the suggested design, we offer a new QCA-based design in one layer for sign detection of three-moduli set {2n+1 − 1, 2n − 1, 2n}. It is not only used for arithmetic units of RNS but also applied for cost and performance improvement of the total system. We simulate and analyze the proposed detection method using the QCADesigner simulator. We also compare the cell count, delay, and occupied area. Experimental results showed that the proposed architecture requires 5.60 µm2 of the circuit area, and the delay is decreased.
TL;DR: The proposed method named IAM (IWO algorithm mapping) is an enhanced 2D-mesh-based-NoC mapping method which adapts the invasive weed optimization (IwO) algorithm, in order to efficiently map the IP cores to routers.
Abstract: Based on the recent research, the communication cost has been the most important open issue in network on chip (NoC). In other words, the lower the communication cost, the better the performance of the NoC and the lower the energy consumption. In this regard, although different mapping algorithms are proposed, they could not efficiently address some important challenges such as high complexity, early convergence at the local optimum, and performing well for all task graphs. The proposed method named IAM (IWO algorithm mapping) is an enhanced 2D-mesh-based-NoC mapping method which adapts the invasive weed optimization (IWO) algorithm, in order to efficiently map the IP cores to routers. The obtained results indicate that the communication cost improved 13, 9, 8, 4, and 4 percent in comparison with the LMAP, the CASTNET, the CLUSTER, the NMAP, and the PSO algorithm, respectively. Regarding energy consumption, IAM outperforms the NMAP, the CASTNET, and the CMAP and the Onyx algorithms by providing 15, 10, 7, and 7 percent improvement in energy consumption, respectively. Max delay was reduced by 11, 4, 5, and 5 percent compared to NMAP, CASTNET, CMAP, and Onyx algorithms, respectively. Throughput was improved by 9, 9, 4, and 10 percent compared to NMAP, CASTNET, CMAP, and Onyx algorithms, respectively.
TL;DR: In this article, the authors proposed analytical models for evaluating the power saving potentials of optimal PON dimensioning, sleep modes, and next-generation PON candidates like bit-interleaved PON (Bi-PON), wavelength split time and wavelength division multiplexed (TWDM)-PON, and wavelength-switched TWDM -PON.
Abstract: Passive optical networks (PONs) are a preferred technology for implementing fiber-to-the-home networks. Though PONs minimize power consumption compared to digital subscriber loops (DSL), they still constitute a significant portion of the power consumed in the telecommunication network. Several research efforts have thus focused on minimizing power consumption in a PON network, e.g., optimal PON dimensioning, sleep modes, and designing next-generation power efficient PON candidates, like bit-interleaved PON (Bi-PON), wavelength split time and wavelength division multiplexed PON (TWDM-PON) and wavelength-switched TWDM-PON. A natural question thus arise is what are the power savings of these various mechanisms and are there some synergy gains if these efforts can be combined? In this work, we propose analytical models for evaluating the power saving potentials of optimal PON dimensioning, sleep modes, and next-generation PON candidates like Bi-PON, wavelength split and wavelength switched TWDM-PON. For optimal PON dimensioning, we consider a promised grade of service to the users, while to explore the sleep mode functionality, we consider state-of-the-art dynamic bandwidth allocation (DBA) algorithms like sleep mode aware (SMA) and hybrid sleep mode aware (HSMA). We then propose the power models to assess the power efficiency of sleep modes in combination with the optimal dimensioning. In addition, we further extend these mechanisms to the next-generation PON candidates and evaluate the power saving potentials. Furthermore, in order to show the accuracy of the proposed models, we validate all these analytical models with the simulation results.
TL;DR: This paper focuses on energy-efficient network planning (including traffic provisioning) along with optimal placement of virtualized elastic regenerators (VERs) for IP-over-elastic optical networks based on a static traffic profile, using a mixed integer linear programming-based optimization model.
Abstract: In this paper, we focus on energy-efficient network planning (including traffic provisioning) along with optimal placement of virtualized elastic regenerators (VERs) for IP-over-elastic optical networks based on a static traffic profile, using a mixed integer linear programming-based optimization model. The proposed model judiciously exploits flexibility of IP core routers, sliceable bandwidth variable transponders (SBVTs) and VERs to accommodate the traffic demands with the minimum power consumption (PC). Optical layer traffic grooming allows to simultaneously originate/terminate multiple lightpaths of different capacities, data slots and maximum transparent reach by a single SBVT. The proposed model also allows to use all functionalities of VER, such as simultaneous regeneration, distance-adaptive transmission option selection, frequency slot merging to be used concurrently for the given static traffic profile. In addition, the proposed model includes lifetime awareness of Erbium-doped fiber amplifier (EDFA) to reduce EDFA failure and associated repairing cost in long run. Using the proposed model, we enhance the average EDFA lifetime by restricting average EDFA occupancy, represented by the ratio of the (average) number of lightpaths being amplified in an EDFA and the maximum possible number of lightpaths that can be amplified in it, even though in the process, the overall PC in network may increase, with reference to the scenario with no EDFA occupancy restriction. The variation in PC and average EDFA lifetime for different permissible (user-defined) average EDFA occupancy are studied. We exhaustively study performance of the model under different network conditions.
TL;DR: In this article, the authors present scintillation and bit error rate (BER) behavior of Airyprime beam in turbulent atmosphere using numerical setup random phase screen which is used in wave optics to simulate the atmosphere.
Abstract: In this paper, we present scintillation and bit error rate (BER) behavior of Airyprime beam in turbulent atmosphere. We use numerical setup random phase screen which is used in wave optics to simulate the atmosphere. Our results indicate that symmetric Airyprime beams where $$\alpha_{sx} = \alpha_{sy}$$
have lower point-like scintillation than Gauss beam under strong turbulence conditions. Considering aperture averaged scintillation, all selected beams show better performance than Gauss beam. This lower point-like scintillation brings us lower BER value which means to increase in performance of communication link. According to our results, we can say that $$10^{ - 3}$$
times lower BER value can be obtained using Airyprime beam in free space optics systems.
TL;DR: In this paper, a 3-D orthogonal modulation scheme is proposed, which simultaneously capitalizes on different signal properties of an optical laser beam, i.e., intensity, phase, and state of polarization to transmit three independent 40-bit/s data streams on a single optical carrier signal, realizing a net 120-Gb/s transmission rate per wavelength channel.
Abstract: The present work discusses the development and simulative investigation of a high-capacity wavelength division multiplexed free space optics (FSO) transmission system. A novel 3-D orthogonal modulation scheme is proposed, which simultaneously capitalizes on different signal properties of an optical laser beam, i.e., intensity, phase, and state of polarization to transmit three independent 40 Gb/s data streams on a single optical carrier signal, realizing a net 120 Gb/s transmission rate per wavelength channel. 32 such independent wavelength channels are multiplexed in the proposed FSO system and its performance is numerically investigated over different climate conditions with respect to range, Quality factor, bit error rate, and eye diagrams of the information signal using Optisystem simulation software. Through numerical simulations, we report faithful 3.84 Tb/s transmission over free space channel with maximum link range varying from 1.6 to 40 km depending on the external climate conditions.
TL;DR: In this paper, a thermometer code-to-gray code converter with quantum-dot cellular automata (QCA) was proposed, which eliminates the requirement of binary code converter to generate gray codes in different digital modulation techniques like pulse code modulation.
Abstract: This article proposes the thermometer code converter, which eliminates the requirement of binary code converter to generate gray codes in different digital modulation techniques like pulse code modulation. The nanoscale faster low-power circuit for these thermometer code-to-gray code converter has been achieved with quantum-dot cellular automata (QCA). The proposed converter circuit is made up with new QCA 2:1 multiplexer, which dominates the other existing designs in terms of QCA cells and device density. The circuits are evaluated based on area and operating speed. The design consistency is verified through theoretical values. The dissipated energy explores that the designs have lower energy dissipation. Stuck-at-fault effect analysis on the circuits has been performed. Besides, defect analysis caused by single missing cells, single extra added cells and misplaced cells is also explored. Test vectors are proposed to achieve 100% defect coverage. As encoders, these circuits can be widely employed in those high-performance functions that impose extraordinary design constraints with respect to high frequency, minimal area and low energy consumption.
TL;DR: In this article, the issues affecting TCP performance in data center networks are studied and different congestion control schemes, such as CUBIC, DCTCP, HighSpeed, NewReno and Vegas, are presented and evaluated by means of computer simulations in realistic data center network scenarios.
Abstract: In recent years, cloud data centers have received increased attention by the research community, due to their key function of hosting a big number of cloud applications and services. At the same time, however, various and conflicting requirements have emerged, such as a mixture of different type of flows in shallow buffer switches, which are interconnected via fiber optics in many-to-one network topology. In this environment, the conventional transmission control protocol (TCP) exhibits severe performance degradation. In this paper, the issues affecting TCP performance in data center networks are studied and different congestion control schemes, such as CUBIC, DCTCP, HighSpeed, NewReno and Vegas, are presented and evaluated by means of computer simulations in realistic data center network scenarios. Our results show that DCTCP eliminates the performance problems of conventional TCP in data center networks and exhibits the performance and fairness properties required for efficient network deployment.
TL;DR: In this paper, the authors proposed a nanoscale Crypto-Codec circuit which produces cipher texts in order to obtain security during nanocommunication, and the circuit density of the design is calculated to prove that QCA circuits possess higher devise density in comparison to CMOS.
Abstract: Security in quantum dot cellular automata (SQCA) is an emerging trend in the arena of nanotechnology. Its features are high computing speed, smaller size and low power depletion in comparison to transistor oriented technology. This article proposes a nanoscale Crypto-Codec circuit which produces cipher texts in order to obtain security during nanocommunication. Single layer crossing is used to design the Crypto-Codec circuit to minimize the fabrication difficulty. In this article higher attention is given to obtain high level of security by providing two layers of security using two different keys at two levels. Cryptographic communication architecture is proposed employing Crypto-Codecs and 2 × 2 Crossbar switch for authentic information sharing. The result resembles with the theoretical values, which endorse the precision of the proposed circuit. Circuit density of the design is calculated to prove that QCA circuits possess higher devise density in comparison to CMOS circuit. Stuck-at-fault analysis is performed to obtain faultless design. The proposed circuit is designed using QCA designer tool.