Wavelength Assignment Algorithm Research Articles

Routing and Wavelength Assignment Algorithm for Mesh-based Multiple Multicasts in Optical Network-on-chip

Routing and Wavelength Assignment Algorithm for Mesh-based Multiple Multicasts in Optical Network-on-chip

Re-routable and Low-latency All Optical Switching Algorithm for Next Generation DCN

Digital infrastructure is now indispensable to the function of society and quality of life of the citizen. All over the world there is leveraging of digital infrastructure that comprises use of data, computerized devices, methods and systems. During COVID-19 pandemic it comes more prominently in front. India being the most popular and populated country in the world, comprises nearly half billion internet users expected to transform the digital ecosystem. With the increasing demand of smartphone application, online activities gigantic amount of data has been generated, so evolution and development of data centers be the high importance not only for India but as well as for the world. Thus, it is the need to promote and create robust data center network infrastructure that supports emerging technologies such as 5G, IoT, AI, machine learning, adaptive manufacturing, smart agriculture, and automation and so on. In this paper we propose an all Optical re-routable, low latency Data Center Network (DCN) architecture using Passive Optical Datacenter Switch (PODS). The PODS consists of an Arrayed Waveguide Grating Router (AWGR) in association with a controller unit. An efficient wavelength assignment algorithm is integrated in PODS, to reroute the packet for congestion avoidance and packet loss.. This feature makes the DCN architecture more scalable, proficient with high throughput, low latency, power efficient under high traffic and bursty traffic conditions. The performance of the proposed PODS-based DCN is compared with existing passive optical DCN architectures PODCA and finds improved characteristics in terms of delay, throughput and blocking probability. Simulation of the framework is done in Python platform and executed on google COLAB in the Windows environment and the result shows 46.3% improvement in latency and throughput in terms of 90% network load compared with PODCA architecture.

Link duration-aware shared backup path protection (LD-SBPP) against SRLG failure in LEO-satellite-terrestrial integrated optical networks

Large-scale disasters are very destructive to terrestrial optical networks (TONs), and most existing survivability technologies that rely solely on TONs themselves can hardly combat disasters. Satellite networks, as a promising complement to terrestrial systems, can help to improve the survivability of TONs against disasters. However, the time-varying nature of satellite networks poses new challenges to traditional survivability technologies. This paper considers the low earth orbit (LEO) satellite network-assisted shared backup path protection. Since the link-switching consumes a certain amount of time and would cause the delay jitter and the quality of transmission (QoT) fluctuation of the space lightpath, a link duration-aware shared backup path protection (LD-SBPP) scheme is proposed to search space backup lightpaths with the minimum number of link-switching. A pre-calculated snapshot continuous routing and wavelength assignment (P-SCRWA) algorithm is proposed to pre-calculate the routing and reserve spectrum resources at each continuous snapshot. Simulations show that user requests cannot be effectively protected by relying on the TON solely, while the protection can be achieved with the help of LEO satellites. The LD-SBPP scheme has high wavelength utilization efficiency, resulting in lower blocking probability. Besides, the link duration-aware strategy can greatly reduce the number of link-switching along space backup lightpaths.

Fragmentation aware heuristic algorithm for routing and wavelength assignment in optical networks

Wavelength division multiplexing (WDM) is one of the dominating technologies with high-capacity back bone networks. The cost associated with the high-capacity networks given more importance. The major issue is allocating and managing the available resources. To achieve this most efficient algorithms has to be used. We are considering the routing of lightpath and wavelength assignment problem, called as the routing and wavelength assignment (RWA) problem. The optimization of wavelength fragmentation in the WDM network is very much important in resource utilization. Wavelength fragmentation is one of the most important challenges in the area of the WDM network. Where it leads to some serious issues for the operators, such as the rejection of new requests. We are using integer linear program (ILP), here the problem is based on the node link formation. It is based on the multilayer concept and the original WDM network consists of several layers. We propose an efficient heuristic approach to solve this problem of finding the shortest path and assigning a wavelength without wavelength conversion. The model achieves better performance with fragmentation aware wavelength allocation strategy that minimizes fragmentation.

Bee colony optimization algorithm for routing and wavelength assignment based on directional guidance in satellite optical networks

Bee colony optimization algorithm for routing and wavelength assignment based on directional guidance in satellite optical networks

Benefits of counterpropagating Raman amplification for multiband optical networks

Multiband (MB) optical fiber transmission systems can unlock additional capacity in existing optical fiber infrastructures, enabling them to keep up with the increase in traffic demand while postponing costly optical fiber deployments. However, due to the worse transmission characteristics of MB systems than C-band-only transmission, the network’s overall spectral efficiency decreases when increasing the transmission bandwidth. The extent of this performance degradation is paramount to determining the commercial viability of deploying MB systems. By estimating the generalized signal-to-noise ratio using the GNPy library, this work analyzes the impact of using counterpropagating Raman amplification to improve the performance of an S + C + L -band transmission system comprising a total bandwidth of 15.5 THz. Raman amplification is proposed to mitigate the worse system performance resulting from the stimulated Raman scattering effect and the worse noise figure of the S-band optical amplifier. We show that the optimized deployment of a counterpropagating Raman pump makes it possible not only to improve but also to equalize the network-wide optical performance of the S + C + L -band transmission system, which potentially reduces the complexity of routing and wavelength assignment algorithms. The capacity, spectral efficiency, and number of feasible lightpaths of the S + C + L -band system are compared with C- and C + L -band systems with and without Raman amplification on two reference networks. Results show that the spectral efficiency of the S + C + L -band system with Raman amplification is similar to the C-band-only system without Raman amplification. These results provide evidence that this strategy can be effectively used to compensate for the worse transmission characteristics of MB systems, the higher noise figure of the S-band optical amplifier, the SRS effect, and the additional losses from the band demultiplexer and coupler required at every amplification stage to separate the transmission bands. Overall, the simulation results highlight that a single optical fiber can approximately carry the same data when using a 15.5 THz transmission band (and Raman amplification) as three parallel fibers using C-band-only transmission (without Raman amplification).

Congestion avoidance based on artificial bee colony algorithm for routing and wavelength assignment in optical satellite networks

Massive data traffic demand for satellite networks has been increased with the emergence of global broadband services. Due to limited onboard processing capacity and imbalanced distribution of global traffic, severe link congestion may occur in hot spots, deteriorating the performance of the whole network. A link cost modification applied in load balancing algorithm based on artificial bee colony is proposed for routing and wavelength assignment problem to distribute traffic in advance. Moreover, congestion avoidance based on wavelength utilization is designed for unexpected congestion to minimize the adverse impact of congestion on network performance. Experiment results show that the method we proposed realizes high performance in communication success rate and average transmission delay and also achieves the maximum utilization of wavelength utilization under the condition of low blocking rate and the equalization of traffic load.

Lightpath routing and wavelength assignment for static demand in translucent optical networks

Translucent optical networks use sparsely located regenerator nodes to increase the optical reach, otherwise limited by the physical layer impairments. Routing in translucent networks often causes the lightpath to traverse a fiber more than once, requiring the use of multiple wavelengths on a fiber for the same lightpath. Most of the routing and wavelength assignment (RWA) algorithms for static demand in translucent networks (termed static RWA) require loop-free routes for shortest path routing and also are agnostic to traffic load. In this paper, we address the problem of static RWA in translucent networks without using physical layer information and show how to route lightpaths on paths with a loop (i.e., not a simple path). We propose integer linear programming formulation to get the exact solutions to the static RWA problem. This work is the first one to optimally solve the static RWA problem for non-simple paths, providing the lower bound on the number of wavelengths and regeneration needed for static lightpath establishment when regeneration facilities are limited. We propose a heuristic algorithm based on the concept of Wardrop equilibrium, to adaptively equalize the mean delay along all the lightpath routes from source to destination. The proposed heuristic can not only accommodate the correlation between feasible lightpath routes but also account for the fact that alternate routes correspond to different levels of choice randomness. Wavelength assignment is done using graph coloring with branch-and-price method. Numerical results demonstrate that the proposed heuristic reduces the number of regenerators and wavelengths required to satisfy a given demand.

A biased random-key genetic algorithm for routing and wavelength assignment under a sliding scheduled traffic model

The problem of routing and wavelength assignment in optical networks consists in minimizing the number of wavelengths that are needed to route a set of demands, such that demands routed using lightpaths that share common links are assigned to different wavelengths. We present a biased random-key genetic algorithm for approximately solving the problem of routing and wavelength assignment of sliding scheduled lightpath demands in optical networks. In this problem variant, each demand is characterized not only by a source and a destination, but also by a duration and a time window in which it has to be met. Computational experiments show that the numerical results obtained by the proposed heuristic improved upon those obtained by a multistart constructive heuristic. In addition, the biased random-key genetic algorithm obtained much better results than an existing algorithm for the problem, finding solutions that use roughly 50% of the number of wavelengths determined by the latter.

A Routing and Wavelength Assignment Algorithm Based on Two Types of LEO Constellations in Optical Satellite Networks

Research on LEO inter-satellite laser communication based on wavelength division multiplexing inter-satellite links and its routing and wavelength assignment (RWA) technology is an important way to solve the problem of low-latency, high-capacity, high-speed transmission, and low-cost on-orbit real-time routing of free-space optical communications. Since both the transmitting and receiving sides of the inter-satellite communication are high-speed moving satellites, the network topology in the whole inter-satellite communication process is time-varying. Therefore, based on this particularity, we propose the SpacePro constellation and combined the classical NeLS constellation for mathematical modeling, and the network topology and inter-satellite links are predicted and analyzed in their entire cycles. The RWA under the super satellite nodes with computation and storage functions algorithm (SCSA) is proposed and its effect is compared and analyzed in the wavelength resource requirement and connectivity. The results showed that the SCSA algorithm can save up to 50% in wavelength requirements, and the SpacePro constellation can achieve the same network connectivity effect with fewer on-board processors and wavelengths than NeLS. Satellite optical network node connectivity and wavelength demand are a trade-off problem. Studying the RWA problem in this scenario has a very critical reference for how the future satellite optical network performs wavelength usage configuration to help improve the performance of networks.

Correction to: A controllable deflection routing and wavelength assignment algorithm in OBS networks

The article, A controllable deflection routing and wavelength assignment algorithm in OBS networks, written by Philani Khumalo, Bakhe Nleya, Andrew Mutsvangwa, was originally published electronically on the publisher’s Internet portal.

An Efficient Scheme on Adaptable Priority-Based Routing and Wavelength Assignment Algorithm for Enhanced Quality of Service

Current research interests have diverted towards the efficient priority-based routing and wavelength assignment strategy in order to enhance the quality of service in the distributed optical networks. The traditional RWA techniques such as Adaptive Routing (AR), Non priority based RWA schemes etc. are lacking of capability to reduce both the blocking probability and average end to end delay simultaneously during the transmission of networks. In this paper, an Adaptable Priority-based RWA (APRWA) schemes for optical network has been demonstrated and evaluated by utilizing the performance enhancing metric such as reduction in hop count while simultaneously handling distinguishable traffic volume. The simulation result shows considerable reduction both in the blocking probability (approx. 25%) as well as in average end to end delay near around (15 msec.) in comparison to conventional RWA techniques.

A controllable deflection routing and wavelength assignment algorithm in OBS networks

Heterogeneous IoT-enabled networks generally accommodate both jitter-tolerant traffic and jitter-intolerant traffic. Optical burst-switched backbone networks are handling the resultant volumes of such traffic by transmitting it in huge-size chunks called bursts. Because of the lack or limited buffering capabilities within the core network, contentions as well as congestion may frequently occur, thus affecting overall supportable quality of service (QoS). Both contention and congestion will be characterized by frequent burst losses, especially when traffic levels surge. The congestion is normally resolved by way of deflecting contending bursts to other less congested paths even though this may lead to differential delays incurred by bursts as they traverse the network. This will contribute to undesirable jitter that may ultimately compromise overall QoS. Noting that jitter is mostly caused by deflection routing which itself is a result of poor wavelength and routing assigning, in this paper we propose a controllable deflection routing scheme that allows the deflection of bursts to alternate paths only after controller buffer preset thresholds are surpassed. In this way, bursts intended for a common destination are always most likely to be routed on the same or least-cost path end-to-end. We describe the scheme and compare its performance to other existing approaches. Both analytical and simulation results overall show that the proposed scheme does lower both congestion and jitter, thus also improving throughput as well as avoiding congestion on deflection paths.

Towards programmable on‐demand lightpath services: current state‐of‐the‐art and open research areas

With emerging programmable network architectures gaining momentum in the networking industry, it is necessary to look at how the services currently offered on traditional network architectures can be fully migrated to the programmable networks. In traditional networks, lightpaths are used for providing high-bandwidth consuming services that are usually sensitive to delay. Lightpath scheduling requires admission control mechanisms, routing and wavelength assignment algorithms, and protection and restoration mechanisms that ensure reliable and efficient lightpath routing. Software defined networking (SDN) is the emerging programmable network architecture that paves the way for easier network management and configuration by using application programming interfaces. The state-of-the-art in lightpath routing for wavelength division multiplexing networks focusing on lightpath scheduling, routing, protection and restoration in optical software defined networks is surveyed. Moreover, open research issues for SDN lightpath routing solution are discussed.

Scalable Capacity Estimation for Nonlinear Elastic All-Optical Core Networks

Routing and wavelength assignment (RWA) algorithms must strike a balance between finding routes with high quality of transmission (QoT) and finding routes that will not interfere with allocating future traffic. Too much emphasis on the first will concentrate traffic along major routes causing congestion whilst too much emphasis on the second will cause individual transceivers to operate below their capabilities increasing both cost and power consumption. This paper presents a low-complexity algorithm that shows that focusing on wavelength packing allows for greater overall traffic whilst giving only slight penalties for latency and required transceivers. Our algorithm comfortably outperforms kSP-FF routing for the same complexity and typically betters congestion aware routing whilst reducing complexity. We show these results on 4 simplified networks based on deployed topologies before replicating them on 2,000 artificially generated topologies based on real node locations in Germany and the USA. Capacity for each topology was found with an integer linear program to which our algorithm compares favorably suggesting it provides a scalable alternative to global optimization.

Wavelength Converter Based Optimized RWA for All Optical Networks

Wavelength converters are used in WDM networks to avoid call blocking and minimizing the blocking probability. Optimal placement of wavelength converters restricts the call blocking probability, the complexity and improves the overall network performance of the network. In this paper, we propose a new weight dependent routing and wavelength assignment algorithm for the optimal placement of the wavelength converters. The wavelength converter placement was considered separately at all the nodes and the partial nodes. Our algorithm outperforms the previously reported studies and requires a lesser number of wavelength converters to achieve the required performance. It reduces the blocking probabilities up to 5.4% and shows that the first four nodes primarily control the blocking performance of the network. The study also reveals that instead of merely increasing the number of converters, their placement at the right location plays a crucial role in improving the performance. Initially, although an increase in the number of the wavelengths also improves the network performance, the further increase does not contribute much to the reduction of the blocking probability.

Multi-dimensional resources allocation based on reconfigurable radio-wavelength selective switch in cloud radio over fiber networks.

To support the bandwidth-hungry applications and ubiquitous services, cloud radio access network (C-RAN) provides the large bandwidth connecting hundreds of terminals for different demands. Applying the technology of radio over fiber (RoF), cloud radio over fiber network (C-RoFN) migrates the processing and calculation functions of the base station to processing unit (PU) which simplifies the system complexity and reduces the data flood caused by digitization in 5G and beyond. The flexible allocation of multi-dimensional resources including radio and optical resources is necessary for C-RoFN to enhance the resource utilization and the quality of services. However, there is a lack of effective method to adjust spectral resources occupied by the RoF signal in C-RoFN. In our previous work, we realized multi-stratum resources optimization between processing and optical resources for C-RoFN from the perspective of network layer. In view of this, this work extends to consider the elastic switching architecture in the physical layer of C-RoFN and the scheduling of radio and optical spectral resources based on the proposed architecture. We propose a novel flexible switching and scheduling mechanism for multi-dimensional resources allocation in software defined C-RoFN. The main contributions on this work are twofold. 1) According to the flexible control demand of multi-dimensional resources, a reconfigurable radio-wavelength selective switch (RWSS) architecture is designed in a C-RoFN scenario to realize the tunability of spectral resources occupied by the RoF signal in optical network layer, which aims to break the restrictions of wavelength consistency and wavelength conflict. 2) Based on the proposed RWSS architecture, a routing, radio and wavelength assignment (RRWA) algorithm considering wavelength-frequency unsaturation is provided to implement the flexibility and allocation of radio and optical spectral resources. The feasibility and efficiency of the architecture are demonstrated on the testbed including date plane using software defined optical and wireless nodes experimentally. The performances of RRWA algorithm under heavy traffic load scenario are also quantitatively evaluated compared with the other algorithm in terms of resource utilization rate, blocking probability, and provisioning latency.

Routing and wavelength assignment vs. EDFA reliability performance in optical backbone networks: An operational cost perspective

A failure in optical backbone network can cause tremendous consequences as a substantial number of connections often each carrying a large amount of data can be interrupted. Therefore, high reliability performance is essential for the network operators. Many existing works that aim at improving network reliability performance implicitly assume that the lifetime of devices is constant and independent of the traffic load. However, the reliability performance of a device is related to its occupancy. For example, the failure rate of erbium doped fiber amplifier (EDFA) can be expressed as a function of the number of amplified wavelengths. On the other hand, the choice of routing and wavelength assignment (RWA) algorithm impacts the link load and, as a consequence, can influence the number of EDFA failures in the network.In this paper we examine how RWA can impact the failure reparation related network operational costs. Several types of RWA approaches are considered, namely load-balancing, energy-awareness, and reliability-awareness. Among all the considered RWA algorithms, the reliability-aware RWA (RA-RWA) approach leverages on EDFA reliability profile to reduce the number of EDFA failures in the network and the related operational costs.The simulation results show that the RWA algorithm impacts in a significant way the operational costs caused by EDFA failures. The cost associated with reparation of an EDFA decreases by 7.8% (in case of RA-RWA) and increases by up to 40% (in case of a load-balancing approach) compared to the classical Shortest Path (SP) approach. Moreover, the cost caused by connection rerouting due to link unavailability triggered by EDFA failure exhibits a 20% decrease (RA-RWA) and up to 94% increase (energy-aware algorithm). We also analyze some key network performance metrics that may be affected by RWA, including blocking probability, link occupancy distribution, and path length.

Realizing Exchanged Crossed Cube Communication Patterns on Linear Array WDM Optical Networks

The exchanged crossed cube, denoted by [Formula: see text], is a novel interconnection network with fewer edges and smaller diameter compared to other variations of the corresponding hypercube. The linear array, denoted by [Formula: see text], is one of the most popular topologies in optical networks. This paper addresses the routing and wavelength assignment for realizing [Formula: see text] communication pattern on wavelength division multiplexing (WDM) optical network [Formula: see text], where [Formula: see text]. We prove that the congestion for [Formula: see text] on [Formula: see text] is equal to [Formula: see text], which is the lower bound of the minimum number of required wavelengths. In addition, an embedding scheme and an optimal wavelength assignment algorithm that achieve this bound are also proposed.

Link Fault Tolerant Algorithms to Optimize the Blocking in Optical Burst Switching Networks

Abstract In this paper, link fault tolerant algorithms (LFTAs) are employed for optimization of blocking performance in optical burst switching (OBS) networks for dynamic establishment of wavelength-routed lightpaths. This paper presents two algorithms: link fault tolerance algorithm for least congestion (LFTALC) and link fault tolerance algorithm for optimized blocking (LFTAOB). In former algorithm, the path with least congestion is selected and in the latter algorithm the path with least blocking probability is selected and then both the algorithms check for the availability of fault on the links present in the selected path. The findings indicate that methods of developing link based fault tolerant algorithms keep good performance and fairness among all the connections. The key advantage of these proposed algorithms as compared to routing and wavelength assignment algorithm is that these are very simple in nature and require less service disruption time.