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The article discusses the importance of optical and photonic technologies in supporting 5G and future 6G mobile networks. These advanced technologies are necessary for the construction and implementation of these networks, particularly in the core networks, backhaul, midhaul, and fronthaul components. Optical technologies such as DWDM, CWDM, OTN, EON, and PON are used in these networks, and Li-Fi optical wireless connectivity is also expected to be utilized in 6G networks. The article highlights the need for efficient management of optical resources and the potential use of machine learning and artificial intelligence in optimizing future optical networks. The article also provides a summary of five contributions in the field of optics and photonics for telecommunications systems, including research on passive optical networks, advanced optical modulations, optical path analysis, and software management for optical converters. [Extracted from the article]

The enhanced capacity of optical networks is a significant advantage within the global telecommunications industry. Optical networks provides transmission of information over large distances with reduced latency. However, the growing intricacy of network topologies poses a significant challenge to network adaptability, network resilience, device compatibility, and service quality in the contemporary era of technology and 5G networks. In light of these challenges, recent studies leverages on disaggregation in the context of Software Defined Network (SDN) and network service orchestrators as a viable remedy. Disaggregated optical systems offer SDON (Software‐Defined Optical Networking) enhanced control options and third‐party dynamism streamlining upgrades and diminishing single vendor dependency. Although, the advancement of disaggregation improves network flexibility and vendor neutrality of Software Defined Optical Networking (SDON), this improvement comes at the cost of reduced scalability and network controllability performance. The current research paper posits two potential resolutions to the aforementioned challenge. The authors present recommendations and an enhanced architecture that leverages Open Network Operating System (ONOS) containers and Kubernetes orchestration to improve scalability inside the Software‐Defined Optical Networking (SDON) architecture. The suggested architectural design has underlining novel flow charts and algorithms that enhances scalability performance by 33% while also preserving flexibility and controllability in comparison to pre‐existing SDON architectures. This architecture also makes use of the Mininet‐Optical physical‐layer architecture to simulate a real‐time scenario, as well as yang models from the Open Disaggregated Transport Network (ODTN) working group, the pioneers of SDONs. A detailed analysis of the rules and procedural processes involved in the implementation of the proposed architecture. In order to demonstrate the practical application of this architectural framework to a real‐world Software‐Defined Optical Network (SDON) system, the pre‐existing SDON ONOS architecture within the Optical Transport Domain Networking (OTDN) working group was adjusted and refined. This adaptation aimed to illustrate the use of ONOS in conjunction with established optical network systems, highlighting the advantages it offers. [ABSTRACT FROM AUTHOR]

Safe and reliable data transport over optical networks is essential for a high-speed Internet. Optical fibres are the backbone of the Internet, allowing billions of people around the world to connect and exchange data. However, these cables can be compromised by both deliberate attacks and accidental damage. The disruption caused by these abnormalities may result in significant monetary and data losses, undermine the security of optical networks by enabling unauthorised parties to view the sent data, or progressively lower network performance. Based on an examination of data from optical networks, this research proposes an original strategy for hybrid machine learning-based network monitoring and security improvement. Here, an anomaly detection method called convolutional principal component network is utilised to keep an eye on the optical infrastructure. Then, we apply hybrid cloud vector Bayesian graph networks to fortify the system. Anomaly detection rate, accuracy, precision rate, and quality of service are all experimentally evaluated across a variety of security analysis datasets. We validate our research using data from operational networks and simulated data created in a realistic-looking simulator. The findings verify the efficacy of our approach for optimising routing decisions in real time and designing networks for the future. [ABSTRACT FROM AUTHOR]

Modern optical transport networks are extremely complicated systems that make managing and distributing management information accurate and recognisable difficult. The complexity of network management operations is increased by a variety of optical technologies and service delivery regulations. This study suggests a unique technique for analysing security as well as resource allocation in optical communication networks. Graph networks based on reinforcement beam propagation and wavelength multiplexing are used to allocate network resources. Next, software defined fuzzy logistic vector spatial networks are used to do a security study of the network. The accuracy, packet delivery ratio, routing, modulation, and spectrum assignment of the experimental investigation are all assessed. With the help of mobile edge computing resources as well as evaluation of functionality of nearby user equipment, causes causing this delay are anticipated. An effective communication network is developed to improve service quality, and a cognitive agent model is built to evaluate resource allocation. [ABSTRACT FROM AUTHOR]

Rapid growth is also being seen in the deployment of optical network equipment and the development of new network services for next-generation networks beyond 5G and 6G. Sybil attacks, wormhole assaults, and single-point failure are just some of the security threats that may affect optical networks. With the introduction of new B5G applications, the conventional setup is no longer enough to meet the need of real-time automatic configuration. A new automated setup approach for the underlying optical transport network is desired by operators. This research proposes a novel method for analysing the security and routing of radio optical networks by bringing together blockchain machine learning and quantum computing. Here, the security of the radio optical network is improved by using cryptanalysis through a federated blockchain model, and the routing is handled by means of sparse Fourier Q-adversarial Boltzmann neural networks. This research tackles a number of issues plaguing optical networks and proposes a strategy for protecting networks from intruders by using quantum-secured blockchain in these environments. Quality of service, data integrity, throughput, latency, packet delivery ratio, and end-to-end delay are all measured experimentally across a range of network security datasets. The proposed method achieved a 72% Quality of Service, 68% Data Integrity, 98% Throughput, 56% Latency, a 96% Packet Delivery Ratio, and a 49% End-to-End Delay. [ABSTRACT FROM AUTHOR]

The evolution of optical networks is enabled by both technological and architectural advances with the goal of reducing operational and capital expenditure per transmitted bit. While the former one stimulates significant system capacity, the latter paves the way for reducing the effective traffic load in network so that more traffic can be carried. Accordingly, optical node architectures have been transitioning from optical-electrical-optical mode to all-optical one, leveraging the scalability and efficiency of fully optical cross-connecting. Conventional wisdom in designing and architecting such switching nodes is nevertheless rooted in the intuition that when an optical channel crossing an intermediate node, it should be maximally isolated from other optical channels in order to avoid interference which may result in degrading signal quality. Such long-established paradigm perceiving the interference of optical channels transiting at the same node as an adversarial factor and should therefore circumvent, albeit reasonable, may leave vast unexplored opportunities. Indeed, the rapid advances in all-optical signal processing technologies has brought opportunities to re-define the optical node architecture by upgrading its naive functionalities from simply add/drop and cross-connecting to proactively mixing optical channels in photonic domain. Specifically, all-optical channel aggregation and de-aggregation technologies have been remarkably advancing in recent years, permitting two or more optical channels at lower bit-rate and/or modulation formats could be all-optically aggregated to a single channel of higher-rate and/or higher-order modulation format and vice versa. Such evolutionary technique is poised to disrupt the existing ecosystem for optical network design and planning, and thus necessitates for a radical change to unlock new potentials. To that end, this paper presents a new paradigm for future optical networks, namely, optical-processing-enabled networks, which are powered by in-network all-optical mixing capability. We introduce the operational principle of optical channel aggregation (de-aggregation) and show how spectrally beneficial such innovative operations could yield by an illustrative example. Next, in order to maximize the aggregation opportunity, we present a mathematical model for optimal routing based on integer linear programming model. Numerical results on the realistic network topology COST239 are provided to quantify the spectral gain of aggregation-aware routing compared to the conventional one. [ABSTRACT FROM AUTHOR]

Network security is an important component of today's networks to combat the security attacks. The passive optical network (PON) works at the medium access layer (MAC). A distributed denial of service (DDOS) attack may be launched from the network and transport layers of an Optical Network unit (ONU). Although there are various security techniques to mitigate its impact, however, these techniques cannot mitigate the impact on the MAC Layer of the PON and can cause an ONU to continuously drain too much bandwidth. This will result in reduced bandwidth availability to other ONUs and, thus, causing an increase in US delays and delay variance. In this work we argue that the impact of a DDOS attack can be mitigated by improving the Dynamic bandwidth assignment (DBA) scheme which is used in PON to manage the US bandwidth at the optical line terminal (OLT). The present DBA schemes do not have the capability to combat a security attack. Thus, this study, uses a machine learning approach to learn the ONU traffic demand patterns and presents a security aware DBA (SA-DBA) scheme that detects a rogue (attacker) ONU from its traffic demand pattern and limits its illegitimate bandwidth demand and only allows it the bandwidth assignment to it as per the agreed service level agreement (SLA). The simulation results show that the SA-DBA scheme results in up to 53%, 55% and 90% reduced US delays and up to 84%, 76% and 95% reduced US delay variance of T2, T3 and T4 traffic classes compared to existing insecure DBA schemes. [ABSTRACT FROM AUTHOR]

This article introduces the concept of the Delay Managed Network to control communication latency and the optical transport network (OTN) equipment, called OTN Anywhere, which has delay-measurement and delay-adjustment functionalities. NTT operating companies, NTT EAST and NTT WEST, released the first-version service of the All-Photonics Network (APN) of the Innovative Optical and Wireless Network (IOWN), APN IOWN1.0, in March 2023 that is based on OTN Anywhere. In addition to the benefit of low latency approaching the physical limit, this service provides end-to-end layer-1 paths without latency fluctuation and offers delay measurement and delay adjustment of each end-to-end layer-1 path. The Delay Managed Network can enhance user experience of various remote activities. [ABSTRACT FROM AUTHOR]

Copyright of Study on Optical Communications / Guangtongxin Yanjiu is the property of Study on Optical Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As next-generation networks begin to take shape, the necessity of Optical Transport Networks (OTNs) in helping achieve the performance requirements of future networks is evident. Future networks are characterized as being data-centric and are expected to have ubiquitous artificial intelligence integration and deployment. To this end, the efficient and timely transportation of fresh data from producer to consumer is critical. The work presented in this paper outlines the role of OTNs in future networking generations. Furthermore, key emerging OTN technologies are discussed. Additionally, the role intelligence will play in the Management and Orchestration (MANO) of next-generation OTNs is discussed. Moreover, a set of challenges and opportunities for innovation to guide the development of future OTNs is considered. Finally, a use case illustrating the impact of network dynamicity and demand uncertainty on OTN MANO decisions is presented. [ABSTRACT FROM AUTHOR]

This work concentrates on the problem of optimizing the cost of a passive wavelength division multiplexing (WDM) optical network used as a transport network for carrying the xHaul packet traffic between a set of remote radio sites and a central hub in a 5G radio access network (RAN). In this scope, we investigate the flexible use of optical add-drop multiplexers (OADMs) for the aggregation of traffic from a number of remote sites, where the type/capacity of optical devices—OADMs and optical multiplexers (MUXs)—is selected in accordance with the traffic demand. The approach is referred to as Flex-O. To this end, we formulate the xHaul network planning problem consisting in the joint provisioning of transmission paths (TPs) between the remote sites and the hub with optimized selection and placement of OADMs on the paths and proper selection of MUXs at the ends of the TPs. The problem formulation takes into accounts the optical power budget that limits the maximum transmission distance in a function of the amount and type of optical devices installed on the TPs. The network planning problem is modeled and solved as a mixed-integer linear programming (MILP) optimization problem. Several network scenarios are analyzed to evaluate the cost savings from the flexible (optimized) use of OADMs. The scenarios differ in terms of the availability of OADMs and the capacity of the WDM devices applied on the TPs. The numerical experiments performed in three mesh networks of different size show that the cost savings of up to between 35 and 45% can be achieved if the selection of OADMs is optimized comparing to the networks in which either single-type OADMs are used or the OADMs are not applied. [ABSTRACT FROM AUTHOR]

In the January 2022 issue of NTT Technical Review, we introduced the secure optical transport network for enabling secure optical transport even in the era of quantum computers. In this article, two concepts, cryptographic agility and Multi-Factor Security, which are key factors in the transition from current cryptographic techniques to quantum-resistant cryptographic techniques and need to be considered in the era of quantum computers, are explained, and our efforts to incorporate these concepts into secure optical transport networks (i.e., elastic-key-control technology and disaggregation technology for cryptographic processing) are introduced. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Al-Nahrain Journal for Engineering Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We describe optically transparent coding metasurfaces based on indium tin oxide (ITO) thin films with high optical transparency and good electric conductivity. Four optically transparent coding metasurfaces are designed to realize desired scattering patterns. Three of them produce anomalous reflections for normally incident electromagnetic (EM) waves by encoding specific digital coding patterns. The fourth achieves diffusion-like scattering to reduce the backward radar cross section (RCS) by encoding an optimized random coding sequence. An ITO coding element based on a glass substrate is applied to reflect 0° and 180° phase responses. Based on this element, three coding schemes for beam deflection and one scheme for the RCS reduction are presented. The consistency of simulation and measurement results fully proves the powerful abilities of the optically transparent coding metasurfaces on manipulating EM waves. The center working frequency of metasurfaces is 12 GHz, in which the reflection beam angles of three schemes are 24.6°, 12°, and 36°, respectively. The diffusion-like scattering is verified by experiments, in which the RCS reduction is more than 10 dB. Considering the high-transparency property of the designed metasurfaces, we expect the proposed method to be exploited for many applications in the microwave and optical spectral ranges. [ABSTRACT FROM AUTHOR]

Optical transport networks (OTNs) are widely used in backbone- and metro-area transmission networks to increase network transmission capacity. In the OTN, it is particularly crucial to rationally allocate routes and maximize network capacities. By employing deep reinforcement learning (DRL)- and software-defined networking (SDN)-based solutions, the capacity of optical networks can be effectively increased. However, because most DRL-based routing optimization methods have low sample usage and difficulty in coping with sudden network connectivity changes, converging in software-defined OTN scenarios is challenging. Additionally, the generalization ability of these methods is weak. This paper proposes an ensembles- and message-passing neural-network-based Deep Q-Network (EMDQN) method for optical network routing optimization to address this problem. To effectively explore the environment and improve agent performance, the multiple EMDQN agents select actions based on the highest upper-confidence bounds. Furthermore, the EMDQN agent captures the network's spatial feature information using a message passing neural network (MPNN)-based DRL policy network, which enables the DRL agent to have generalization capability. The experimental results show that the EMDQN algorithm proposed in this paper performs better in terms of convergence. EMDQN effectively improves the throughput rate and link utilization of optical networks and has better generalization capabilities. [ABSTRACT FROM AUTHOR]

In the evolution of optical networks, spectral efficiency (SE) enhancement has been the most cost-efficient and thus the main driver for capacity increase for decades. As a result, the development of optical transport systems has been focused on the $C$ - and $L$ -bands, where silica optical fiber exhibits the lowest attenuation, and erbium-doped fiber amplifiers provide an efficient solution to compensate for the optical loss. With a gradual maturity in the SE growth, however, the extension of the optical bandwidth beyond the $C + L$ -band is expected to play a significant role in future capacity upgrades of optical networks and, thus, attract increasing research interests. In this article, we discuss the merits and challenges of ultrawideband optical transport systems and networks beyond conventional bands. [ABSTRACT FROM AUTHOR]

Due to widespread applications and rapid development of cloud computing and Internet services, hyperscale data centers have experienced an unprecedented demand for networking. Data center networks are required not only to handle fast-growing traffic, which doubles almost every one to two years, but also to provide high flexibility and availability to support rapidly changing businesses as well. Therefore, hyperscale data center networks have become one of the main drivers for optical interconnect technologies in recent years. In this article, technologies for scaling optical interconnects for inter-data center interconnects (DCIs) are presented. We first describe hyperscale data center network architectures and requirements, as well as the differences between carrier’s optical transport networks and DCI optical networks, with the main focus on metro-DCI and campus-DCI networks. The scale and fast growth rates of DCI networks require innovations not only in data plane technologies but also in control and management planes as well. In data planes, high-capacity flexible coherent technology, pluggable wavelength-division-multiplexing (WDM) optical transponders, including 100G direct-detection four-level pulse-amplitude modulation (PAM4) and coherent 400ZR/800ZR, and flex-grid and disaggregated reconfigurable optical add-drop multiplexer (ROADM) optical networks are described. Control and management planes are an integral part of optical transport networks and crucial for effectively operating DCI networks. We show that standard protocols, data models, and modular design of a software platform are essential to building a scalable open and disaggregated optical network, which is fundamental to enabling high automation and intelligence in an optical network. An example control and management platform is discussed in detail. With current fiber capacity approaching the nonlinear Shannon limit, challenges to further scale DCI networks and some potential technologies to support ever-increasing traffic growth are discussed at the end. [ABSTRACT FROM AUTHOR]

NTT Network Innovation Center has developed a compact/power-saving optical open line system that can provide optical transmission of 100 Gbit/s per wavelength in an economical, space-saving, and power-saving manner. The goal with this system is to achieve large-capacity transmission up to edge buildings in the metro network to deal with the rapid increase in traffic accompanying the introduction of the 5th-generation mobile back haul. This article presents an overview of this system and its features. [ABSTRACT FROM AUTHOR]

In order to further increase the span length of the Optical Transport Network (OTN) transmission system, a combination of Raman amplifier and remotely optical pumped amplifier (ROPA) configuration scheme is recommended. Optimal EDF length, optimal ROPA position and OTN span limitation are obtained through simulations. A field-trial with 8*10 Gb/s in 380 km span system is carried out with the amplifier configuration of Raman amplifier plus first-order and second-order remotely pumped amplifier. By adding a second-order remote pump laser, the transmission limit is increased from 77.5 dB to 80.7 dB. Through detailed analysis of the system, it is concluded that the second-order remote pump can effectively transfer the pump power to the first-order remote pump wavelength, which greatly increases the pump power at the gain module, thereby increasing the gain of the RGU and reduce its noise. Moreover, the introduction of the second-order remote pump effectively weakened the self-excited effect and overcomes the shortcomings of the low pump power threshold of the first-order remote pump. [ABSTRACT FROM AUTHOR]

This article discusses the current state and prospects of scalable optical transport technologies that can dramatically expand the optical amplification and electrical signal processing bandwidths for achieving a Pbit/s-class long-range optical network toward IOWN (the Innovative Optical and Wireless Network) All-Photonics Network. We explain the optical parametric amplification repeater technology, which has the potential to achieve longer transmission distances while expanding the amplification bandwidth of conventional optical amplification repeaters by more than 2.5 times. We also look into the space division multiplexing optical communication technology that uses multiple-input and multiple-output signal processing and has the potential to increase transmission capacity by more than 10 times at the same cladding diameter as conventional optical fibers. [ABSTRACT FROM AUTHOR]

This paper introduces a practical comprehensive approach to optimize the cost of installed Optical Transport Network (OTN) interfaces, as well as the required number of wavelengths in the substrate Wavelength Division Multiplexing (WDM) optical network. The approach assumes grooming variable-bit-rate traffic demands on multi-rate OTN interfaces. We propose an Integer Linear Programming (ILP) formulation to address the combined problem of OTN interface deployment, virtual-network formation, traffic grooming on the established distinct-capacity virtual paths, and virtual network embedding on the WDM physical substrate. The presented model focuses on mitigating the capital expenditure required to deploy OTN interfaces, usually the most costly element in the network, as well as minimizing the required number of wavelengths in the Routing and Wavelength Assignment (RWA) problem, contributing to the overall reduction in network costs and ensuring open capacity for future expansions. As the RWA problem is NP-hard and involves significant computational costs, we also propose a multi-step heuristic approach to tackle larger network instances more efficiently. In this approach, the optimization steps for the OTN design and the RWA solutions are conducted independently. For the OTN-layer planning, the optimum ILP formulation (OTN-ILP) is maintained, so that the optimum solution for the cost of installed interfaces on the OTN layer is guaranteed. The RWA problem is proposed through either an ILP formulation (RWA-ILP) or a heuristic approach. The RWA-ILP model can find the same or slightly superior number of wavelengths compared to the optimum solution of the Integrated ILP formulation, but it can provide results in reasonable times only for small networks. On the other hand, the heuristic RWA is able to run any network size, but it requires more wavelengths compared to the RWA-ILP model. • An approach to optimize the cost of installed Optical Transport Network (OTN). • A formulation to address the OTN interface deployment and virtualization. • The model focuses on mitigating the capital expenditure required to deploy OTN. • The paper proposes a heuristic approach to tackle larger network instances. [ABSTRACT FROM AUTHOR]

The age of acceleration is taking place, driven by the revolutionary digital transformation creating basically a digital version of the physical world. Massive amount of data has thus been generated ranging from wearable devices monitoring our physical health every single millisecond to autonomous vehicles generating an order of magnitude of Terabytes hourly to even astronomical activities producing an order of Exabytes on a daily basis and then ultra-broadband Internet comes into play, moving such data to the cloud. As a result, Internet traffic has been experiencing explosive growth and in this context, optical transport networks forming the backbone of the Internet are pushed for transformation in system capacity. While the intuitive solution of deploying multiple fibers can address the pressing demand for increased capacity, doing so does not bring improvements in economic of scales with respect to cost, power consumption and spectral efficiency. This necessitates for a complementary approach so that the fiber capacity could be utilized in a more efficient manner. Indeed, optical-processing-enabled network has been emerging as a new architectural paradigm to attain greater fiber capacity thanks to permitting the superposition of in-transit lightpaths at intermediate nodes for optical signal processing purposes. In this paper, we focus on innovative techniques, that is, photonic network coding and partial protection, to reduce the effective traffic load for optical transport networks adopting optical-processing-enabled architecture. Specifically, the application of photonic network coding is investigated by upgrading the functionalities of intermediate nodes with all-optical processing (i.e., encoding and decoding) capabilities. Besides, partial protection relying on the premise of providing just enough bandwidth in case of failure events is exploited for saving the redundant protection capacity. That it takes two to tango, combining photonic network coding and partial protection therefore bring to light new opportunities and challenges. In mining such new avenue, we present insights on how to derive compounding gains to maximize spectral efficiency via a case study. [ABSTRACT FROM AUTHOR]

The deployment of a telecommunications network has become more colossal than before because of the complexity of the network and the rapid enhancement of technology. Optical transport networks are today the basic infrastructure of modern communications systems for the transfer of data between nodes. Before each deployment, engineering will take over designing and calculating each part of the network in order to optimize transmission resources, from TDM technology to WDM the bandwidth efficiency and relative costs for 100 Gb/s WDM transport and switching architectures is a the main challenge for telecommunication network. several studies have been published for several architectures, A10Gbit/s PON(Point a Multipoint) based on TDM was demonstrated with different length of fiber was implemented with a various budget. The purpose of this paper is to present the study and design of a TDM link with a bit rate of 10Gbit/s and WDM with 80Gbit/s transmission bit rate using ROADM architecture to exploit in telecommunication networks, which can be proposed as a solution for two potential different area. [ABSTRACT FROM AUTHOR]

Modern optical network schemes consist of eighty channels involving fixed grids and offering speeds of up to 400 Gbps per channel rendering the allocated bandwidths insufficient during certain timeframes and underutilized during others. These speeds will become inefficient when compared to the accelerated growth of traditional traffic, which threatens to be tripled by 2025. In order to exploit the capacity of elastic optical networks, efficient algorithms are essential. This article assesses Deep reinforcement learning RMCSA algorithms, focused on providing high availability to the allocation of routing, spectrum and modulation resources over a given network topology, in order to determine how to allocate physical resources in optical transport networks and increase capacity while accounting for traffic variability and demands. Reinforcement learning is currently used in many scientific fields for the solution of different problems. In optical networks, this work will use this method to determine the best path and resources for each type of traffic-related demand. Simulations are performed by increasing volumes of variable traffic over a fourteen-node topology. The results show a significant 40% improvement in blocking probability for 22 links with 100 frequency slots compared to current transmission systems. They also reflect low latency, higher speeds, and high availability, which can deliver better quality of service for the end user. [ABSTRACT FROM AUTHOR]

In this paper, the application example of 8 × 100 Gbit/s over 463 km (76.9 dB) optical transport network is realized by using commercial bidirectional Raman amplifier and additional auxiliary laser without any remotely pump amplifier. The positions of the auxiliary laser in the commercial Raman amplifier are compared and optimized experimentally. The results show that 7.3 dB and 10.2 dB more power budget is obtained with the auxiliary laser in the backward direction and forward direction respectively comparing to the situation without any auxiliary laser. The results also show that forward second order Raman amplifier is a good choice in the condition without remotely pump amplifier. [ABSTRACT FROM AUTHOR]

Optical multilayer optimization periodically reorganizes layer 0-1-2 network elements to handle both existing and dynamic traffic requirements in the most efficient manner. This delays the need for adding new resources in order to cope with the evolution of the traffic, thus saving CAPEX. The focus of this paper is on Layer 2, i.e., on capacity reoptimization at the optical transport network (OTN) layer when routes (e.g., LSPs in MPLS networks) are making unnecessarily long detours to evade congestion. Reconfiguration into optimized routes can be achieved by re-defining the routes, one at a time, so that they use the vacant resources generated by the disappearance of services using part of a path that transits the congested section. To maintain the Quality of Service, it is desirable to operate under a Make-Before-Break (MBB) paradigm, with the minimum number of reroutings. The challenge is to determine the best rerouting order while minimizing the bandwidth requirement. We propose an exact and scalable optimization model for computing a minimum bandwidth rerouting scheme subject to MBB in the OTN layer of an optical network. Numerical results show that we can successfully apply it on networks with up to 30 nodes, a very significant improvement with respect to the state of the art. We also provide some reoptimization analysis in terms of the bandwidth requirement vs. the number of reroutings. [ABSTRACT FROM AUTHOR]

The massive deployment of 5G and beyond will require high capacity and low latency connectivity services, so network operators will have either to overprovision capacity in their transport networks or to upgrade the optical network controllers to make decisions nearly in real time; both solutions entail high capital and operational expenditures. A different approach could be to move the decision making toward the nodes and subsystems, so they can adapt dynamically the capacity to the actual needs and thus reduce operational costs in terms of energy consumption. To achieve this, several technological challenges need to be addressed. In this paper, we focus on the autonomous operation of Digital Subcarrier Multiplexing (DSCM) systems, which enable the transmission of multiple and independent subcarriers (SC). Herein, we present several solutions enabling the autonomous DSCM operation, including: i) SC quality of transmission estimation; ii) autonomous SC operation at the transmitter side and blind SC configuration recognition at the receiver side; and iii) intent-based capacity management implemented through Reinforcement Learning. We provide useful guidelines for the application of autonomous SC management supported by the extensive results presented. [ABSTRACT FROM AUTHOR]

In this paper we study the performance of subcarrier-wave quantum key distribution (SCW QKD) in the presence of classical channels of optical transport network utilizing dense wavelength division multiplexing (DWDM). We consider the impact of spontaneous Raman scattering noise as well as the four-wave mixing and channel isolation efficiency. We calculate quantum bit error rate as well as the secure key generation rate of SCW-QKD protocol for different parameters of DWDM system and quantum channel allocations. Our calculations show, that quantum channel allocation at the wavelength of 1310 nm is preferable to allocation at C-band due to lower nonlinear noise, despite fiber's larger attenuation at this wavelength. [ABSTRACT FROM AUTHOR]

Summary: Shared mesh protection (SMP) protects service traffic on a working path and requires coordinated use of the shared resources on a protection path when the traffic is routed through the protection path. If there are many intermediate nodes on the protection path, the delay caused by the coordination at each node increases the protection switching time, resulting in losing more traffic. Considering the capacity of a link and the bandwidth required by the protection paths using that link, it appears that coordination is necessary. However, looking closely at the relationships with other links and their protection paths, there exist resources that may require no coordination at all. This observation leads to the fact that protection switching time can decrease when bypassing some intermediate nodes for coordination. This fact introduces an optimization problem, in which the objective is to exclude these resources as much as possible from the set of resources for which coordination is required. A sub‐problem is finding these excludable candidate resources. For both the main problem and the sub‐problem, which are NP‐hard, we propose a greedy algorithm and a branch‐and‐bound algorithm, respectively. The simulations show that the results using the proposed algorithms are near‐optimal. Furthermore, in an actual topology configured with the SMP environment, the protection switching time is improved by excluding resources for which coordination is not required, compared to the existing Optical Transport Network (OTN) SMP mechanism. [ABSTRACT FROM AUTHOR]

Network operators have been dealing with the necessity of a dynamic network resources allocation to provide a new generation of customer-tailored applications. In that sense, Telecom providers have to migrate their BSS/OSS systems and network infrastructure to more modern solutions to introduce end-to-end automation and support the new use cases derived from the 5G adoption and transport network slices. In general, there is a joint agreement on making this transition to an architecture defined by programmable interfaces and standard protocols. Hence, this paper uses the iFusion architecture to control and program the network infrastructure. The work presents an experimental validation of the network slicing instantiation in an IP/Optical environment using a set of standard protocols and interfaces. The work provides results of the creation, modification and deletion of the network slices. Furthermore, it demonstrates the usage of standard communication protocols (Netconf and Restconf) in combination with standard YANG data models. [ABSTRACT FROM AUTHOR]

This paper is focused on applying a polarization multiplex to passive optical networks to double their transmission bandwidth without significant changes in the distribution network. Although polarization multiplexes are already employed for high-speed optical transport networks with digital signal processing and coherent detection, we propose a system that could be used in existing older optical networks using a dynamic polarization controller in combination with a wavelength division multiplex. [ABSTRACT FROM AUTHOR]

The spectrally and spatially flexible optical networks (SS-FON) are the promising solution for future optical transport networks. The joint switching (J-Sw) paradigm is one of the possible switching schemes for SS-FON that brings optical component integration alongside with acceptable networking performance. The network planning of J-Sw is investigated in this paper. The formulation of resource allocation for J-Sw is introduced as in integer linear programming to find the optimal solution. To find the near-optimal solution, the heuristic algorithms are initiated with sorted connection demands. The way connection demands are sorted to initiate the heuristic algorithms affects the accuracy of algorithms. Therefore, six different sorting policies are introduced for J-Sw. Moreover, the heuristic algorithm called joint switching resource allocation (JSRA) algorithm is introduced, especially for J-Sw. The heuristic algorithm performance initiated with different sorting policies is investigated through simulation for a small-size network. The optimality gap is the most important indicator that shows the effect of each sorting policy on the near-optimal solution. The new sorting policy of connection demands called descending frequency width (DFW) policy achieved the least optimality gap. Also, the JSRA performance initiated with these sorting policies is investigated for a real network topology. The obtained results indicate that DFW shows better performance than other sorting policies in realistic networks, too.