Showing papers on "Optical Transport Network published in 2018"

5G C-RAN With Optical Fronthaul: An Analysis From a Deployment Perspective

Abstract: The fifth generation (5G) wireless technology is designed to provide significantly faster Internet access, with lower latency, and ubiquitous mobile coverage compared to its predecessors. However, as there will be hundreds and thousands of wireless cells deployed in the 5G network, transporting the enormous volume of data instigated from high capacity 5G wireless cells to the core network in a cost-effective and greener manner with a low latency still remains one of the major hurdles. Therefore, in this paper, we exploit different optical transport network architectures and technologies that can be used to build an efficient fronthaul network for 5G, in order to carry data between wireless cells and the central office. Particularly, we equitably compare multiple fronthaul architectures in terms of major requirements of 5G fronthaul network such as bandwidth requirements, delay budgets, deployment costs, complexity of radio remote head, and the ability to support advanced wireless functions. In order to analyze the deployment cost of entire 5G transport and wireless networks, we develop a joint optimization framework to optimally deploy fiber-based fronthaul network and 5G wireless network simultaneously. Our framework is also capable of setting limits on the required network coverage and capacity. We analyze the optimal deployment costs under different deployment scenarios and different fronthaul technologies. Our analyses provide insights into modeling future-proof optical transport networks to realize 5G network deployment.

Toward the Integration of CV Quantum Key Distribution in Deployed Optical Networks

Abstract: In this letter, we report on the advances toward the integration of our developed continuous variables (CV) quantum key distribution (QKD) system in existing optical infrastructure and wavelength division multiplexed (WDM) networks. First, we investigate the tolerance of the CV-QKD system to spontaneous Raman scattering (SRS) noise, the latter being the most dominant impairment in a WDM co-existence environment for QKD. In particular, we investigate by experiment the impact of a WDM 10 × 10 Gb/s ON-OFF-keying signal in terms of induced SRS noise in the QKD channel. The spontaneous SRS noise influence is assessed for different transmission scenarios, i.e., for various optical launch powers of the WDM signal, and for different transmission links of 20, 40, 60, and 80 km. Based on the experimental data and on the measured system's parameters, we estimate the key rates and reach capabilities of the proposed CV-QKD system. The scheme supports a key rate of 90 kbit/s over 20 km, for an ideal QKD system multiplexed with 2-mW optical power. A step further, we demonstrate for first time the use of the aforementioned CV-QKD system to encrypt a 10GE client service over deployable optical transport network legacy equipment over 20 km. Our results prove the feasibility of the integration of our proposed scheme with legacy telecom equipment in existing WDM optical networks.

Two use cases of machine learning for SDN-enabled ip/optical networks: traffic matrix prediction and optical path performance prediction [Invited]

Abstract: We describe two applications ofmachine learning in the context of internet protocol (IP)/Optical networks. The first one allows agilemanagement of resources in a core IP/Optical network by using machine learning for shorttermand long-term prediction of traffic flows. It also allows joint global optimization of IP and optical layers using colorless/ directionless (CD) reconfigurable optical add-drop multiplexers (ROADMs). Multilayer coordination allows for significant cost savings, flexible new services to meet dynamic capacity needs, and improved robustness by being able to proactively adapt to new traffic patterns and network conditions. The second application is important as we migrate our networks to Open ROADM networks to allow physical routing without the need for detailed knowledge of optical parameters. We discuss a proof-of-concept study, where detailed performance data for established wavelengths in an existing ROADM network is used for machine learning to predict the optical performance of each wavelength. Both applications can be efficiently implemented by using a software-defined network controller.

Ultra-Dense Wavelength Switched Network: A Special EON Paradigm for Metro Optical Networks

Abstract: Intensive video and cloud computing services are putting much pressure on metro networks to meet stringent requirements such as low latency, low power consumption, and high spectral efficiency, where the system cost is sensitive To address this challenge, we introduce a special elastic optical network paradigm called the ultradense wavelength switched network (UD-WSN) for metro optical networks The architecture supports a spectrum granularity (eg, 625 GHz or even 5 GHz) finer than the current smallest standardized 125 GHz, which enables more efficient spectrum utilization when provisioning metro lowspeed service connections (eg, sub-1G/1G/10G services) The performance of UD-WSN is evaluated from the techno-economic perspective in comparison with the conventional OTN over DWDM network Case studies demonstrate the merits of the proposed architecture Considering the promising potential of UD-WSN, we also suggest several open research issues for it

Dimensioning Models of Optical WDM Rings in Xhaul Access Architectures for the Transport of Ethernet/CPRI Traffic

Abstract: The Centralized Radio Access Network (C-RAN) provides a valid solution to overcome the problem of traditional RAN in scaling up to the needed processing resource and quality expected in 5G. The Common Public Rate Interface has been defined to transport traffic flows in C-RAN and recently some market solutions are available. Its disadvantage is to increase by at least 10 times the needed bandwidth and for this reason its introduction will be gradual and will coexist with traditional RAN solutions in which Ethernet traffic is carried towards the radio base stations. In this paper, we propose an Xhaul optical network architecture based on Optical Transport Network (OTN) and Dense Wavelength Division Multiplexing (DWDM) technologies. The network allows for a dynamic allocation of the bandwidth resources according to the current traffic demand. The network topology is composed of OTN/DWDM rings and the objective of the paper is to evaluate the best configuration (number of rings and number of wavelengths needed) to both to minimize the cost and to provide an implementable solution. We introduce an analytical model for the evaluation of the number of wavelengths needed in each optical ring and provide some results for 5G case studies. We show how, although the single ring configuration provides the least cost solution due to the high statistical multiplexing advantage, it is not implementable because it needs switching apparatus with a too high number of ports. For this reason, more than one ring is needed and its value depends on several parameters as the offered traffic, the number of Radio Remote Units (RRU), the percentage of business sub-area and so on. Finally, the analytical model allows us to evaluate the advantages of the proposed dynamic resource allocation solution with respect to the static one in which the network is provided with a number of wavelengths determined in the scenario in which the radio station works at full load. The bandwidth saving can be in the order of 90% in a 5G traffic scenario.

OTN Interface Standards for Rates Beyond 100 Gb/s

Abstract: The optical transport network (OTN) protocol defined by the ITU-T (Recommendation G.709) has become the backbone of service provider long haul and metro networks. Its flexibility has allowed it to support the converged transparent transport for the full variety of both constant bit rate and packet-oriented digital WAN client signals, and its overhead is optimized to reduce the equipment and operational costs for service provider networks. The emerging technologies that enable interface rates beyond 100 Gb/s have created multiple challenges and opportunities for the next generation of OTN. This paper first discusses the challenges and considerations behind the new extension of OTN for rates beyond 100 Gb/s (OTN B100G). This paper then provides a tutorial for the new OTN B100G standard in light of the flexible and modular manner in which it addressed these considerations. This paper also gives a tutorial overview of the new flexible OTN “FlexO” protocol. FlexO was developed as a modular PHY technology for OTN B100G, allowing it to reuse IP and modules from the Ethernet ecosystem. In addition, this paper provides a tutorial overview of the new flexible Ethernet “FlexE” technology from the optical internetworking forum. FlexE provides both an important new client for transport over OTN, and technology that has been incorporated into the OTN B100G standard. The complementary synergies between OTN and 200G/400G Ethernet and FlexE will become apparent.

Multi-layer mechanisms to optimize optical transport network margin allocation

Abstract: A method and apparatus for optimizing optical transport using a software defined network (SDN) controller are disclosed herein. The SDN controller may define a margin optimization function based on at least one optical system performance metric. The function may include at least one related initiation criterion. Further, the SDN controller may collect at least one measurement for the performance metric. The measurement may include an assessment of deployed carriers not carrying client data. The SDN controller may determine whether the initiation criterion is met based on at least one collected measurement. The SDN controller may select a system margin optimization mechanism and define a system margin optimization threshold criterion on a condition that the initiation criterion is met. The SDN controller may determine whether the optimization threshold criterion is met. The SDN controller may implement one or more optimization events on a condition that the optimization threshold criterion is met.

Dimensioning of OTN/WDM Rings for the transport of Ethernet/CPRI Flows in 5G Scenario

Abstract: In this paper we propose and investigate an OTN/WDM network architecture for the transport of Ethernet/CPRI flows in 5G scenario. The proposed solution allows for a dynamic bandwidth resource allocation dependent on the current traffic. The network is composed by OTN/WDM rings interconnecting Access Switches and interconnected to an OTN/WDM Hub. We introduce an analytical model for the dimensioning of wavelengths of the optical rings. We show how the proposed solution allows for a high saving of wavelengths with respect to a static solution in which the network is dimensioned in maximum load conditions that is in the case in which the radio stations are working at full load. The saving can be in the order of 70% in a typical 5G traffic scenario.

OpenROADM Compliant SDN Controller for a Full Interoperability of the Optical Transport Network

Abstract: We demonstrate the ability of TransportPCE SDN controller to automatically create and delete services in multi-vendor optical networks. Using opensource projects, TransportPCE relies on “OpenDayLight” as a development framework and “OpenROADM” for service, network and device data models ensuring interoperability.

Introduction of 12 Cores Optical Amplifiers in Optical Transport Network: Performance Study and Economic Impact

Abstract: We investigate the techno-economic impact of the introduction of 12-core Multicore Erbium-Ytterbium doped fiber amplifiers (MC-EYDFA) in optical transport networks. We evaluate the CAPEX gain involved by their utilization as line amplifiers and the energy consumption reduction induced by the pump sharing between the 12 cores. We also evaluate the impact of the inter-core crosstalk in the MC-EYDFA on the quality of transmission through the use of the Gaussian noise model.

Transmission and Switching Technologies for 5G Transport Networks

Abstract: 5G is requiring higher capacity and performance to the optical transport network while demanding lower cost and energy consumption. This work illustrates new technologies such as novel modulation formats and Photonic Integrated Circuits (PICs) for cost effective transmission and switching of high speed (50 Gbit/s and beyond) signals in 5G fronthaul and backhaul networks.

Networking: Wired and Wireless: All Devices Talking to One Another

Abstract: This chapter covers both wired and wireless networks. Networks are defined, and the main types of networks are identified. Network topologies are discussed. Wired network coverage emphasizes the most widely used technology called Ethernet. Optical networking is explained, and the Sonet and optical transport network technologies are briefly covered. A complete section focuses on the Internet and how it works. Wireless networking is introduced and the most widely used standards including Wi-Fi, Bluetooth, and ZigBee are described. In conclusion, broadband networking technologies such as the cable TV, telecom digital subscriber line, and wireless broadband technologies are explained. A project using ISM band radios is provided.

Efficient Make Before Break Capacity Defragmentation

Abstract: Optical multilayer optimization continuously reorganizes layer 0-1-2 network elements to handle both existing and dynamic traffic requirements in the most efficient manner. This delays the need to add new resources for new requests, saving CAPEX and leads to optical network defragmentation. The focus of this paper is on Layer 2, i.e., on capacity defragmentation at the 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. For the Quality of Service, it is desirable to operate under Make Before Break (MBB), with the minimum number of rerouting. The challenge is to identify the rerouting order, one connection at a time, 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 the state of the art. We also provide some defragmentation analysis in terms of the bandwidth requirement vs. the number of reroutings.

Can OTN be replaced by Ethernet? A network level comparison of OTN and Ethernet with a 5G perspective

Abstract: Ethernet has evolved from a protocol for local area network transport to advanced carrier class metro transport as new features are brought in. Recently, industrial, automotive and 5G mobile fronthaul network applications have been addressed. Several new mechanisms are proposed and standardized, e.g. enabling deterministic latency. In light of 5G requirements, this paper reviews and discusses differences between Ethernet and ITU-T G.709 — Optical Transport Network OTN, and analyses Ethernet as an alternative to OTN for optical transport and access network applications.

Advanced DSP Technologies with Symbol-rate over 100-Gbaud for High-capacity Optical Transport Network

Abstract: 100-Gbaud-class systems are promising candidates for over 400-Gbps serial long-haul transport without increasing the number of transponders. We review DSP technologies, e.g. signal generation, calibration, post compensation and advanced modulation for realizing 100-Gbaud-class transceivers.

Method, apparatus and system for determining fusion path of IP network and optical transport network

Abstract: The invention provides a method, apparatus and system for determining a fusion path of an IP network and an optical transport network. The method comprises the following steps: when a transmission service request crossing an optical network domain is received, allocating a virtual link meeting service requirements in an IP network domain for the transmission service; determining a target service layer path matched with the virtual link in a pre-stored service layer path, wherein the service layer path is located in the optical network domain; and sending an activation request of activating thetarget service layer path to the controller of the optical network domain. By adoption of the method, apparatus and system, the technical problem of low efficiency of providing the required service layer path for the IP layer by an optical layer in the related art is solved.

Low-Latency Optical Networks for 5G Wireless

Abstract: We review recent advances in the evolution of optical networks to better address the demands of 5G wireless systems by providing high-bandwidth and low-latency connectivity. Particularly, the evolution of optical cross connect and optical transport network will be discussed.

Simplified encryption key generation in optical networks

Abstract: Methods and systems for simplified encryption key generation in optical networks use a Transport Layer Security (TLS) protocol to securely generate an encryption key at both endpoints of an optical path provisioned in an optical transport network. Instead of generating yet another key for payload data transmission, the encryption key from TLS is used for encrypting payload data transmission without using the TLS protocol.

Use of optical transport network overhead data for encryption

Abstract: Methods and systems may use optical transport network overhead data for encryption. In particular, specific overhead encryption bits and other encryption data may be stored in an OTN header and used for signaling between a transmitter and a receiver for encrypted transmission without lost data frames.

SDN-based traffic engineering in data centers, Interconnects, and Carrier Networks

Abstract: Server virtualization and cloud computing have escalated the bandwidth and performance demands on the DCN (data center network). The main challenges in DCN are maximizing network utilization and ensuring fault tolerance to address multiple node-and-link failures. A multitenant and highly dynamic virtualized environment consists of a large number of endstations, leading to a very large number of flows that challenge the scalability of a solution to network throughput maximization. The challenges are scalability, in terms of address learning, forwarding decision convergence, and forwarding state size, as well as flexibility for offloading with VM migration. Geographically distributed data centers are inter-connected through service providers’ carrier network. Service providers offer wide-area network (WAN) connection such as private lines and MPLS circuits between edges of data centers. DC sides of network operators try to maximize the utilization of such defined overlay WAN connection i.e. data center interconnection (DCI), which applies to edges of DC networks. Service provider sides of network operators try to optimize the core of carrier network. Along with the increasing adoption of ROADM, OTN, and packet switching technologies, traditional two-layer IP/MPLS-over-WDM network has evolved into three-layer IP/MPLS-over-OTN-over-DWDM network and once defined overlay topology is now transitioning to dynamic topologies based on on-demand traffic demands. Network operations are thus divided into three physical sub-networks: DCN, overlay DCI, and multi-layer carrier network. Server virtualization, cloud computing and evolving multilayer carrier network challenge traffic engineering to maximize utilization on all physical subnetworks. The emerging software-defined networking (SDN) architecture moves path computation towards a centralized controller, which has global visibility. Carriers indicate a strong preference for SDN to be interoperable between multiple vendors in heterogeneous transport networks. SDN is a natural way to create a unified control plane across multiple administrative divisions. This thesis contributes SDN-based traffic engineering techniques for maximizing network utilization of DCN, DCI, and carrier network. The first part of the thesis focuses on DCN traffic engineering. Traditional forwarding mechanisms using a single path are not able to take advantages of available multiple physical paths. The state-of-the-art MPTCP (Multipath Transmission Control Protocol) solution uses multiple randomly selected paths, but cannot give total aggregated capacity. Moreover, it works as a TCP process, and so does not support other protocols like UDP. To address these issues, this thesis presents a solution using adaptive multipath routing in a Layer-2 network with static (capacity and latency) metrics, which adapts link and path failures. This solution provides innetwork aggregated path capacity to individual flows, as well as scalability and multitenancy, by separating end-station services from the provider’s network. The results demonstrate an improvement of 14% in the worst bisection bandwidth utilization, compared to the MPTCP with 5 sub-flows. The second part of the thesis focuses on DCI traffic engineering. The existing approaches to reservation services provide limited reservation capabilities, e.g. limited connections over links returned by the traceroute over traditional IP-based networks. Moreover, most existing approaches do not address fault tolerance in the event of node or link failures. To address these issues, this thesis presents ECMP-like multipath routing algorithm and forwarding assignment scheme that increase reservation acceptance rate compared to state-of-art reservation frameworks in the WAN-links between data centers, and such reservations can be configured with a limited number of static forwarding rules on switches. Our prototype provides the RESTful web service interface for link-fail event management and re-routes paths for all the affected reservations. In the final part of the thesis, we focused on multi-layer carrier network traffic engineering. New dynamic traffic trends in upper layers (e.g. IP routing) require dynamic configuration of the optical transport to re-direct the traffic, and this in turn requires an integration of multiple administrative control layers. When multiple bandwidth path requests come from different nodes in different layers, a distributed sequential computation cannot optimize the entire network. Most prior research has focused on the two-layer problem, and recent three-layer research studies are limited to the capacity dimensioning problem. In this thesis, we present an optimization model with MILP formulation for dynamic traffic in a three-layer network, especially taking into account the unique technological constraints of the distinct OTN layer. Our experimental results show how unit cost values of different layers affect network cost and parameters in the presence of multiple sets of traffic loads. We also demonstrate the effectiveness of our proposed heuristic approach.

Counter-Propagating Core Assignment in Multi-Core Fiber Optical Networks to Reduce Inter-Core Crosstalk and Capacity Wastage.

Abstract: Inter-core crosstalk is one of the most serious impairments for signal transmission in a multi-core fiber (MCF) optical network. On the other hand, because of wide deployment of data centers (DCs), we are seeing an increasing bidirectional traffic demand asymmetry, which leads to significant capacity wastage in designing and operating an optical transport network. To alleviate these effects, for an MCF optical network, we propose to assign fiber cores in an MCF in an asymmetric and counter-propagating manner. This can not only significantly reduce inter-core crosstalk between counter-propagating fiber cores but also flexibly assign different numbers of fiber cores in the opposite directions of a fiber link, thereby overcoming network capacity wastage due to the bidirectional traffic demand asymmetry. To evaluate the benefits of the proposed strategy, we consider the routing, spectrum, and core assignment (RSCA) problem for the MCF optical network. An integer linear programming (ILP) model and an auxiliary graph (AG) based heuristic algorithm are developed to optimize network spectrum resource utilization. Simulation studies show the effectiveness of the proposed core counter-propagation strategy, which can significantly outperform its counterpart, i.e., the co-propagation scheme, in terms of the total number of MCFs used and average inter-core crosstalk. In addition, the proposed RSCA heuristic algorithm is efficient to perform close to the ILP model, which can minimize the number of MCFs used and crosstalk between neighboring cores.

Service transmission method, network device and network system

Abstract: The invention discloses a service transmission method, a network device and a network system, which relate to the technical field of communication. The transmission method of the service comprises thefollowing steps: Within an OTN device, A corresponding virtual interface is created for a plurality of ODUk channels on the line side, a logical connection between the virtual interface and the client side interface is established, and the virtual interface is aggregated according to the received configuration information to obtain at least one aggregation port, so that packet Ethernet services are transmitted between the ODUk channel and the client side interface through the aggregation port. The invention dynamically adjusts the bandwidth of the OTN network side according to the bandwidth requirement of the access side packet Ethernet service, and improves the bandwidth utilization ratio of the network side.

Route selection method for OTN (optical transport network)

Abstract: The invention discloses a route selection method for an OTN (optical transport network), and the method comprises the steps: S100, determining the conditions of an optical network element transfer path in the OTN; S200, determining a source node and a target node; S300, searching each feasible path from the source node to the target node according to a node route model; S400, calculating the costof each feasible path, and selecting the optimal path; S500, writing the optimal path into the route selection table. According to the invention, the visited nodes and the feasible optical paths are sequentially numbered, an all visited nodes and feasible optical paths between the source node and the target node are connected sequentially, thereby forming a feasible path. Moreover, through the calculation of the cost of each feasible path, the method determines the optimal path and a path selection sequence table, so a data package can be transferred through the optimal path during the transferring. When the optimal path has a fault, the data package can be transferred according to the sequence of the path selection sequence table, thereby reducing the communication cost of the OTN, and improves the communication quality.

Client signal transporting method in optical transport network, and transport equipment

Abstract: The embodiment of the invention discloses a client signal transporting method in an optical transport network, and transport equipment; the method comprises the following steps: dividing the payload of an optical payload unit signal into m first particle time slots, and dividing the first particle time slot of the m first particle time slots into n second particle time slots, wherein the first particle time slot rate equals n times of the second particle time slot rate, m is a positive integer, and n is a positive integer bigger than 1; mapping the first client signal to the payload to which one or more second particle time slots of the n second particle time slots are located; adding the first particle time slot cost and the second particle time slot cost for the optical payment unit signal so as to form an optical data unit signal; sending the optical data unit signal. The method and equipment can improve the bandwidth transmission efficiency.

A Heuristic Algorithm for Network Optimization of OTN over DWDM Network

Abstract: While the network traffic has seen exponential increase, the revenues have not maintained the same pace New methods have to be explored to reduce this gap between traffic and revenue One such method is convergence in networking layers In this work, we study the convergence of OTN and DWDM layer from a network planning perspective We compare the costs of planning networks without and with convergence and show that the multilayer planning offers least cost for higher traffic volumes

Method and device for processing packet optical transmission network (POTN) service

Abstract: The invention provides a method and device for processing a packet optical transmission network (POTN) service. The method comprises the following steps: adding a flag bit for identifying the type ofa POTN service in the POTN service; and determining the type of the POTN service according to the flag bit, and selecting a corresponding physical channel number according to the type of the POTN service that is determined. According to the method and device provided by the invention, the problems that the configuration of the POTN service still needs to distinguish PTN and OTN service types and the redundant configuration of POTN service boards is caused in related technologies can be solved, and the effect of improving the efficiency and service convergence degree of the POTN service board configuration can be achieved.

Flexible ethernet client mapping procedure

Abstract: This application relates to a method for converting a server signal to an optical transport signal to be transmitted over an Optical Transport Network. The server signal carries one or more client signals and the optical transport signal has a frame structure referred to as Optical Transport Units, each of which comprises at least one Optical Data Unit. The method comprises receiving the server signal at an edge network node of the Optical Transport Network and demapping the one or more client signals from the server signal. The method further comprises extracting a server signal clock from the server signal and generating one or more client signal clocks for the one or more client signals based on the server signal clock. Moreover, the method comprises mapping synchronously the one or more client signals to the Optical Data Units of the optical transport signal using the one or more client signal clocks and transmitting the optical transport signal on the Optical Transport Network. According to the disclosure, each of the client signals comprises a time-division-multiplex (TDM) signal with a corresponding transmission rate, and each of the client signal clocks associated with one of the client signals.

Network Optimization for Unified Packet and Circuit Switched Networks

Abstract: Internet traffic continues to grow relentlessly, driven largely by increasingly high resolution video content. Although studies have shown that the majority of packets processed by Internet routers are pass-through traffic, they nonetheless have to be queued and routed at every hop in current networks, which unnecessarily adds substantial delays and processing costs. Such pass-through traffic can be better circuit-switched through the underlying optical transport network by means of pre-established circuits, which is possible in a unified packet and circuit switched network. In this paper, we propose a novel convex optimization framework based on a new destination-based multicommodity flow formulation for the allocation of circuits in such unified networks. In particular, we consider two deployment settings, one based on real-time traffic monitoring, and the other relying upon history-based traffic predictions. In both cases, we formulate global network optimization objectives as concave functions that capture the fair sharing of network capacity among competing traffic flows. The convexity of our problem formulations ensures globally optimal solutions.