WDM Optical Networks Research Articles

Routing and wavelength assignment for folded hypercube in linear array WDM optical networks

The folded hypercube is one of the hypercube variants and is of great significance in the study of interconnection networks. In a folded hypercube, information can be broadcast using efficient distributed algorithms. In the context of parallel computing, folded hypercube has been studied as a possible network topology as an alternative to the hypercube. The routing and wavelength assignment (RWA) problem is significant, since it improves the performance of wavelength-routed all-optical networks constructed using wavelength division multiplexing approach. Given the physical network topology, the aim of the RWA problem is to establish routes for the connection requests and assign the fewest possible wavelengths in accordance with the wavelength continuity and distinct wavelength constraints. This paper discusses the RWA problem in a linear array for the folded hypercube communication pattern by using the congestion technique.

WDM Optical Network Monitoring Technology Based on PAM4 Digital Optical Label

WDM Optical Network Monitoring Technology Based on PAM4 Digital Optical Label

Theoretical study of the EDFA optical amplifier implementation scheme improving the performance of a quantum key distribution system integrated with an WDM optical transport network

Theoretical study of the EDFA optical amplifier implementation scheme improving the performance of a quantum key distribution system integrated with an WDM optical transport network

Improving MDM–WDM optical network performance via optimized power allocation using Gaussian noise model

The few-mode fiber nonlinearity has been well modeled by an additive Gaussian Noise (GN) source. The available GN models in Mode Division Multiplexing–Wavelength Division Multiplexing (MDM–WDM) systems are incoherent and neglect the dispersion slope. The incoherent GN model assumes that the Nonlinear Interference (NLI) noise created at each span is summed up in power incoherently at the receiver and leads to underestimating the NLI noise power. In the first part of this paper, a coherent GN model is derived by taking into account the dispersion slope and verified through Split-Step Fourier Method (SSFM) simulations. In the second part of this paper, the total capacity maximization, as well as the minimum Signal to Noise Ratio (SNR) margin maximization problems are presented and solved based on the obtained GN model. MDM–WDM multi-node nonlinear network under different scenarios including Equal/Non-Equal Required SNR (ERS/NERS), and Flat/Non-Flat Amplifier Gain (FG/NFG) are considered in the numerical simulations. Considering 200 different sets of randomized traffic demands (random channel-mode distributions) the cumulative distribution function of minimum SNR margin improvement in optimized power allocation compared with the best flat power allocation is in 99% more than 1 dB, 1.2 dB, 2.4 dB, and 2.8 dB, for ERS-FG, ERS-NFG, NERS-FG, and NERS-NFG scenarios, respectively.

Analysis of QAM Based Wavelength Division Multiplexing – Free Space Optical Communication Systems

Free-space optical communication (FSO) is a technology that entails the transmission of information through the atmosphere from one point to the other. Optical signal traversing the atmospheric channel suffers attenuation due to scattering and absorption of the signal by aerosols, fog, atmospheric gases. This work is focused on improving the performance of the system by increasing the capacity using WDM optical networks in free space using QAM modulation technique. The system is evaluated by using eight independent information sources and analyzing the BER and eye diagrams.

Dynamic multicasting using traffic grooming in WDM optical split light trail networks

Multicasting is inevitable in the advent of the age of online video streaming. Light trail, the unidirectional optical bus, enhances multicasting by facilitating sub wavelength granularity. Splitting a light trail into segments increases the bandwidth utilization. To remove the overburden of the auxiliary graph of the existing works lead the motivation of the proposed heuristic algorithm known as Dynamic Multicast Traffic Grooming and Split Light Trail Assignment (DMTG-SLTA), which further aims to reduce the blocking probability and other network resources while satisfying the dynamic connection requests. Simulation results are verified though numerical analysis and compared to the existing well known algorithms, thereby concluding the proposed work to be successful only after minimizing its computational complexity.

Wide-Sense Nonblocking Multicast in WDM Optical Linear Array and Ring Networks with 2-Length Extension under Index Based Routing

Multicast communication is the concurrent transmission of data from one source node to many destination. It is widely deployed in high performance computing and communication networks.In this paper, a linear array and ring networks are extended by directly linking all nodes which are separated by one intermediate node with additional fibers which is referred as linear array and ring network with 2-length extension and wide sense nonblocking multicast is studied. The wavelength allotment methods are proposed to realize one-to-many communication over wavelength division multiplexing optical linear array and ring with 2-length extension under index-based routing and the minimum wavelength number needed is determined. The minimum wavelength number needed to support for the extended linear array and ring topologies is reduced approximately by half when compared with that of a linear array network and ring network.

All-to-all Broadcast in Optical WDM Ring with 2-length Extension and 3-length Extension

All-to-all broadcast communication is to transmit a distinctive data from each node to every other node available in the network. This is a fundamental prerequisite in high performance computing and telecommunication networks including enterprises operating datacenters which may spread across thousands of nodes by means of WDM optical networks. Wavelengths are scarce resources in WDM optical networks. Reducing the wavelengths usage is essential to decrease the price and complication of the network. In this article, a ring network is extended by additionally connecting alternate nodes in order to provide alternate paths so as to reduce the effective number of hops between the communicating nodes and also to reduce the wavelength requirements and this network is referred as a ring network with 2-length extension. Similarly, a ring network is extended by directly linking all nodes which are separated by two intermediate nodes with additional fibers and this network is referred as a ring network with 3-length extension. For the ring network with 2-length extension the optimum wavelength number necessary to establish all-to-all broadcast under unidirectional routing is derived by grouping nonoverlapping connections on a common wavelength. The wavelength number necessary atmost to establish all-to-all broadcast in a unidirectional ring with 3-length extension is derived using longest link first routing algorithm.

Disaster-resilient lightpath routing in WDM optical networks

Disaster-resilient lightpath routing in WDM optical networks

Applications of machine learning techniques in next-generation optical WDM networks

Applications of machine learning techniques in next-generation optical WDM networks

SMF/FSO integrated dual-rate reliable and energy efficient WDM optical access network for smart and urban communities.

To handle the massive high-speed internet traffic, free space optics (FSO) or single-mode fiber (SMF) based fiber optic communication is being used everywhere across the world. These technologies are capable of providing huge bandwidth and transmitting the data at very high speed with low energy consumption. FSO is a very convenient technology to quickly expand the legacy network in the adverse geographical areas. However, its link performance is highly dependent of inconsistent weather conditions. SMF based fiber optic link has a very low loss and its performance is almost independent on the weather conditions. Though, the installation and maintenance of fibers are quite complex and costly. Individually, FSO or SMF links have their limitations and have to be integrated to leverage their benefits. In this paper, we integrated FSO/SMF links and compared the performance of the proposed architecture which is capable of providing high-speed dual-rate data transmission. The proposed architecture transmits data over either FSO or SMF or both links simultaneously and has 100% more reliability against any one of the link failures. In case of operational link failure (FSO/SMF), data may be switched to the alternative working link (SMF/FSO), simply by tuning the transmitted signal by 50 GHz. The proposed architecture is also reliable against the optical line terminal transceiver (TRx) failure as each user located in the network can be served by two transceivers (1 Gbps and 10 Gbps). The proposed architecture also supports the wavelength division multiplexing overlay transmission for broadcasting the common signal to all the available users in the networks. The architecture reduces ~ 27% of the energy consumption by utilizing the appropriate link of hybrid architecture and TRx according to weather conditions and traffic load. The integrated architecture looks attractive for providing energy-efficient, high speed, and reliable internet coverage to the areas where there is a difficulty of laying fibers and has frequent fiber faults. The architecture is useful for strengthening and boosting rural and urban development.

A topological photonic crystal with ultra wide dual bandwidth

We demonstrated a sandwich topological photonic crystal (PC) structure with C6 honeycomb medium column, the background material of PC is E7 liquid crystal. The results show that the working bandwidth of the laminated PC with liquid crystal as the background material can be changed by voltage, i.e., 0.428–0.442(2πc/a)(without voltage) to 0.416–0.426(2πc/a)(with voltage), and the transmission efficiency of the laminated PC is over 90%. Besides, when the liquid crystal material is only added in the nontrivial layer structure, the working bandwidth of the PC has changed, which is 0.433–0.453(2πc/a) and 0.425–0.446(2πc/a), respectively, and it has a common bandwidth 0.433–0.446(2πc/a). The proposed topology photonic crystals are of great importance for their applications in optical communication devices and WDM optical networks.

Analysis of RWA in WDM optical networks using machine learning for traffic prediction and pattern extraction

Analysis of RWA in WDM optical networks using machine learning for traffic prediction and pattern extraction

Multi-hop traffic grooming routing and wavelength assignment using split light trail in WDM all optical mesh networks

For the last few decades, fiber optic cables not only replaced copper cables but also made drastic evolution in the technology to overcome the optoelectronic bandwidth mismatch. Light trail concept is such an attempt to minimize the optoelectronic bandwidth gap between actual WDM bandwidth and end user access bandwidth. A light trail is an optical bus that connects two nodes of an all optical WDM network. In this paper, we studied the concept of split light trail and proposed an algorithm namely Static Multi-Hop Split Light Trail Assignment (SMSLTA), which aims to minimize blocking probability, the number of static split light trails assigned and also the number of network resources used, at the same time maximizing the network throughput. Our proposed algorithm works competently with the existing algorithms and generates better performance in polynomial time complexity.

A Multi-Objective Optimization Algorithm for Routing Path Selection and Wavelength Allocation for Dynamic WDM Network using MO-HLO

The data transmission system in the optical WDM network increases the speed of packet transmission by the wavelength of light beams . The Selection of the wavelength and the shortest path to transmit the packets form source to destination is a challenge in a large network architecture. To solve these two problems, the optimization model must handle both the objectives. In this paper we are proposing a novel multi-objective optimization algorithm to solve both the problem of wavelength allocation and shortest path identification in a WDM network. This can be achieved by the enhanced model of Multi-Objective Hunger Locust Optimization algorithm (MO-HLO). In this, it analyse traffic level in a network path and the availability of wavelength present at each time instant. The proposed system retrieves the parameters of network architecture and with the weight value of dynamic traffic occur in the routing path. Among these data, the optimization selects the best among overall feature set of the WDM arrangement. The MO-HLO algorithm extracts the combination of each attribute to form the cluster that segregates the routing path along with the traffic range. From the fitness of the objective function of MO-HLO, the best routing path and the availability of wavelength for a node can be analysed at each time instant.

IR emission of Er3+ ion-doped fluoroborotellurite glass for communication application

We have successfully synthesized Er3+ ion-doped TeO2-B2O3-ZnF2-BaO using conventional melt and quenching technique to explore their possible future application. The physical properties were determined by their density and molar volume, while the structural properties were observed by FTIR spectra. The optical absorption spectra and emission spectra were measured to study their optical and photoluminescence properties. The optical absorption spectra were measured between 400 to 1800 nm. It shows the hypersensitive transition at 521 nm due to the 4I15/2→2H11/2 transition. The intense emission was shown in the peak of 1541 nm excited by 521 nm due to 4I13/2 to 4I15/ 2 transition. From the analysis of Judd-Ofelt theory, it is found that 1.5 mol% Er2O3 in the glass system possesses JO trendline Ω2 > Ω4 > Ω6 and 2.94 × 10−21 cm2 stimulated emission cross-section with the long radiative lifetime around 12.19 ms. The gain cross-section of prepared glass calculated using the Mc Cumber theory reveals the inversion population of prepared glass at γ≥0.4. It could be concluded from all results that 1.5 mol% Er2O3 doped fluoroborotellurite glass have a high potential for future communication application such as IR optical amplifier, IR laser, and WDM network system in C and L communication band.

Assignment of dynamic light trail in WDM optical mesh networks

Light trail is a unidirectional optical bus between the source and the destination node of a WDM network. In this paper, a novel algorithm is proposed for dynamic light trail assignment, which competently works for unicast dynamic connection requests. The routing is based on Hoffman k-shortest path algorithm. The proposed algorithm is solvable in polynomial time complexity and generates better results when compared with other existing algorithms. The existing algorithms are either dependent on the complex auxiliary graph, or they have a huge run time complexity. This motivated us to lay down our research work, which is free from the complex auxiliary graph and works in lesser time complexity. The aim of the paper is to satisfy the dynamic connection requests by assigning minimum number of dynamic light trails with the objective of minimizing the blocking probability, while maximizing the capacity utilization of each dynamic light trail assigned.

Spectral width reduction using apodized cascaded fiber Bragg grating for post-dispersion compensation in WDM optical networks

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.

Differentiated services and its importance in fault tolerant WDM optical network

The focus of this paper is on developing and evaluating a practical methodology for determining if and when different types of traffic can be safely managed within different class of services and satisfying reliability criteria. Our approach relies on an analytical model developed under a number of simplifying assumptions, which we test using several real traffic traces under fault condition corresponding to different types of services for clients and satisfying reliability degree for the connection request of link failure and searching of backup path dynamically that can give rise to substantial performance deviations with different class of service that is high, medium and low class. The results show that a hop-by-hop, link-state routing protocol, like Open shortest path first, can be extended to efficiently support class-based Quality of Service traffic differentiation. We have used auxiliary graph based open shortest path heuristic (AGBOSPH) technique to select back up path as a restoration strategy. It is found that average bandwidth utilization for large scale network is 12.62% less than previous studies. At the time of starting both have similar performance but under restoration AGBOSPH is more satisfactory and give excellent performance for higher scale of network. The proposed algorithm shows improvements at all traffic loads. At heavy loads the improvement is more pronounced and average improved performance for high degree of traffic load is of the order of 28.56%.

Performance Modeling and Analysis of WDM Optical Networks under Wavelength Continuity Constraint using MILP

Performance Modeling and Analysis of WDM Optical Networks under Wavelength Continuity Constraint using MILP