Showing papers on "Optical Transport Network published in 2010"

Distance-adaptive spectrum resource allocation in spectrum-sliced elastic optical path network [Topics in Optical Communications]

Abstract: The rigid nature of current wavelength-routed optical networks brings limitations on network utilization efficiency. One limitation originates from mismatch of granularities between the client layer and the wavelength layer. The recently proposed spectrum-sliced elastic optical path network (SLICE) is expected to mitigate this problem by adaptively allocating spectral resources according to client traffic demands. This article discusses another limitation of the current optical networks associated with worst case design in terms of transmission performance. In order to address this problem, we present a concept of a novel adaptation scheme in SLICE called distance-adaptive spectrum resource allocation. In the presented scheme the minimum necessary spectral resource is adaptively allocated according to the end-to-end physical condition of an optical path. Modulation format and optical filter width are used as parameters to determine the necessary spectral resources to be allocated for an optical path. Evaluation of network utilization efficiency shows that distance-adaptive SLICE can save more than 45 percent of required spectrum resources for a 12-node ring network. Finally, we introduce the concept of a frequency slot to extend the current frequency grid standard, and discuss possible spectral resource designation schemes.

Beyond 100G Ethernet

Abstract: With 100G technologies standardized, in the context of both Ethernet and the optical transport network (OTN), 100G router ports and 100G optical transport interfaces are commercially available. At the same time, heavily data-centric users are starting to ask for higher-rate interfaces. First speculations include 400G as well as 1T as the next possible Ethernet standards. In this article we discuss interface technology options for Ethernet and OTN beyond 100G in light of the current 100G standards, taking into account likely evolution paths of interface technologies over the next 10 years.

Long-reach optical access networks: A survey of research challenges, demonstrations, and bandwidth assignment mechanisms

Abstract: Long-Reach optical access is a promising proposal for future access networks. This technology can enable broadband access for a large number of customers in the access/metro area, while decreasing capital and operational expenditures for the network operator. First, the paper reviews the evolutionary path of access networks and shows the drivers from technology and business perspectives for high bandwidth and low cost. A variety of research challenges in this field is reviewed, from optical components in the physical layer to the control and management issues in the upper layers. We discuss the requisites for optical sources, optical amplifiers, and optical receivers when used in networks with high transmission rate (10 Gbps) and large power attenuation (due to large split, transmission over 100 km and beyond, and propagation), and the key topological structures that allow to guarantee physical protection (tree-and-branch, ring-and-spur). Then, some relevant demonstrations of Long-Reach Optical Access Networks developed worldwide by different research institutes are presented. Finally, Dynamic Bandwidth Allocation (DBA) algorithms that allow to mitigate the effect of the increased control-plane delay in an extended-reach network are investigated.

Cascaded multiplexed optical link on a telecommunication network for frequency dissemination

Abstract: We demonstrate a cascaded optical link for ultrastable frequency dissemination comprised of two compensated links of 150 km and a repeater station. Each link includes 114 km of Internet fiber simultaneously carrying data traffic through a dense wavelength division multiplexing technology, and passes through two routing centers of the telecommunication network. The optical reference signal is inserted in and extracted from the communication network using bidirectional optical add-drop multiplexers. The repeater station operates autonomously ensuring noise compensation on the two links and the ultra-stable signal optical regeneration. The compensated link shows a fractional frequency instability of 3 x 10(-15) at one second measurement time and 5 x 10(-20) at 20 hours. This work paves the way to a wide dissemination of ultra-stable optical clock signals between distant laboratories via the Internet network.

Eco-sustainable system and network architectures for future transport networks

Abstract: Technology analysis indicates that silicon technology evolution will not be able to catch up with future global Internet traffic growth rates. As a result, current network and system designs as well as network architectures may need to be revised significantly. This paper provides a detailed analysis of various network element types (e.g., IP routers, Ethernet switches, and synchronous optical network/synchronous digital hierarchy [SDH/SONET] switches) and their components with respect to power dissipation e 2010 Alcatel-Lucent.

Polarization-multiplexed rate-adaptive non-binary-quasi-cyclic-LDPC-coded multilevel modulation with coherent detection for optical transport networks

Abstract: In order to achieve high-speed transmission over optical transport networks (OTNs) and maximize its throughput, we propose using a rate-adaptive polarization-multiplexed coded multilevel modulation with coherent detection based on component non-binary quasi-cyclic (QC) LDPC codes. Compared to prior-art bit-interleaved LDPC-coded modulation (BI-LDPC-CM) scheme, the proposed non-binary LDPC-coded modulation (NB-LDPC-CM) scheme not only reduces latency due to symbol- instead of bit-level processing but also provides either impressive reduction in computational complexity or striking improvements in coding gain depending on the constellation size. As the paper presents, compared to its prior-art binary counterpart, the proposed NB-LDPC-CM scheme addresses the needs of future OTNs, which are achieving the target BER performance and providing maximum possible throughput both over the entire lifetime of the OTN, better.

Experimental demonstration of spectrum-sliced elastic optical path network (SLICE)

Abstract: We describe experimental demonstration of spectrum-sliced elastic optical path network (SLICE) architecture. We employ optical orthogonal frequency-division multiplexing (OFDM) modulation format and bandwidth-variable optical cross-connects (OXC) to generate, transmit and receive optical paths with bandwidths of up to 1 Tb/s. We experimentally demonstrate elastic optical path setup and spectrally-efficient transmission of multiple channels with bit rates ranging from 40 to 140 Gb/s between six nodes of a mesh network. We show dynamic bandwidth scalability for optical paths with bit rates of 40 to 440 Gb/s. Moreover, we demonstrate multihop transmission of a 1 Tb/s optical path over 400 km of standard single-mode fiber (SMF). Finally, we investigate the filtering properties and the required guard band width for spectrally-efficient allocation of optical paths in SLICE.

Generating Realistic Optical Transport Network Topologies

Abstract: We address the problem of generating physical realistic optical transport network topologies. This type of network has characteristics that differ from scale-free networks, such as the Internet. Based on the analysis of a set of real transport topologies, we identify and assess relevant characteristics. A method to generate realistic topologies is proposed. The proposed method is validated by comparing the characteristics of computer-generated and real-world optical transport networks.

Error correcting coding for OTN

Abstract: Forward error correction codes for 100 Gb/s optical transmission are currently receiving much attention from transport network operators and technology providers. We discuss the performance of hard decision decoding using product type codes that cover a single OTN frame or a small number of such frames. In particular we argue that a three-error correcting BCH is the best choice for the component code in such systems.

Optical Path Aggregation for 1-Tb/s Transmission in Spectrum-Sliced Elastic Optical Path Network

Abstract: We propose and experimentally demonstrate optical path aggregation in a spectrum-sliced elastic optical path network (SLICE). Multiple optical orthogonal frequency-division-multiplexed (OFDM) 100-Gb/s optical paths are aggregated in the optical domain to form a spectrally continuous 1-Tb/s super-wavelength optical path and transmitted over a network of bandwidth-variable wavelength cross-connects. We evaluate the potential implementation issues and conclude that the OFDM paths can be optically aggregated with optical signal-to-noise ratio penalty of less than 1 dB.

Method for data transmission in an optical transport network

Abstract: It is disclosed a method for data transmission in an optical transport network, comprising the steps of - receiving client data from a client, - mapping said client data into a frame structure (ODU-flex), - mapping said frame structure (ODU-flex) info tributary slots (TS) of a data transport structure (HO-ODU), - transmitting said data transport structure (HO-ODU), wherein said data transport structure (HO-ODU) contains a fixed number of tributary slots (TS), and wherein the size of said frame structure (ODU-flex) is selectable in granularity of said tributary slots (TS) of said data transport structure (HO-ODU).

Advanced optical modulation and multiplexing technologies for high-capacity OTN based on 100 Gb/s channel and beyond

Abstract: Digital signal processing technologies are key enablers for realizing high-capacity Optical Transport Network based on over 100 Gb/s and above channels. Novel no-guard-interval OFDM with frequency domain equalization is proposed and shown to offer excellent long-haul transport with capacity well above 10 Tb/s.

SIMTON: A Simulator for Transparent Optical Networks

Abstract: In this article we present a software to simulate Transparent Optical Networks (SIMTON). SIMTON is an eventdriven simulation software implemented in C++ which takes into account optical device characteristics for the evaluation of network blocking probability in wavelength routed transparent optical networks. The simulator uses a physical layer model that considers the following effects: device losses, fiber attenuation, four wave mixing, residual chromatic dispersion and polarization mode dispersion in optical fibers, gain saturation in optical amplifiers (Erbium Doped Fiber Amplifier), dependence of the amplified spontaneous emission noise with the input power in EDFA, in-band crosstalk in optical switches, and source spontaneous emission noise of the laser transmitter. By using SIMTON it is possible to adjust the parameters of the optical devices, as well as to choose the routing and wavelength assignment algorithm. Moreover, the tool has a graphical interface. We also present some examples of network analysis results obtained from SIMTON.

Coherent 100 Gb/s PM-QPSK field trial

Abstract: The development of 100 Gb/s transponder technology is progressing rapidly to meet the needs of next-generation optical/IP carrier networks. Video-driven IP traffic growth continues together with the need for ever higher-speed ports on IP routers, Ethernet switches, and OTN cross-connects, thus driving the requirements for cost-effective client and line side 100 Gb/s transponders. For a short time to market, 100 Gb/s transponders should be deployable using 10 Gb/s link-engineering rules over existing fiber and DWDM infrastructure. In this article we describe the upgrade of an installed 10 Gb/s field system to 100 Gb/s using a real-time single carrier coherent 100G polarization multiplexed quadrature phase shift keyed (PM-QPSK) channel. Performance sufficient for error-free operation after forward error correction was achieved over installed 900 km and 1800 km links, proving the viability of 100 Gb/s upgrades to most installed systems. Excellent tolerance to fiber polarization mode dispersion and narrowband optical filtering demonstrates the applicability of this technology over the majority of installed fiber plant and through existing 50 GHz reconfigurable optical add/drop multiplexers.

Optical Communication Fundamentals

Abstract: This chapter describes the key optical components used in a contemporary optical communication system; basic signal and noise parameters; major channel impairments, including chromatic dispersion, polarization mode dispersion (PMD), and fiber nonlinearities; and the system design process. The ultimate goal of the optical signal transmission is to achieve the predetermined bit error ratio (BER) between any two nodes in an optical network. The optical transmission system has to be properly designed to provide reliable operation during its lifetime, which includes the management of key engineering parameters. The optical transmission system design involves accounting for different effects that may degrade the signal during modulation, propagation, and detection processes. The transmission quality is assessed by the received signal-to-noise ratio (SNR), which is the ratio between signal power and noise power at the decision point. In digital optical communications, BER, defined as the ratio of bits in error to total number of transmitted bits at the decision point, is commonly used as a figure of merit. In that sense, the receiver sensitivity is defined as the minimum required received optical power to keep BER below a given value.

Self-Consistent Simulation of Opto-Electronic Circuits Using a Modified Nodal Analysis Formulation

Abstract: This paper addresses the need for self-consistent simulation of mixed electrical and optical circuits and systems. Drawing on the use of modified nodal analysis (MNA) techniques ubiquitous in circuit simulation, an optical node is formulated which includes the magnitude and phase of the optical signal being simulated. This node consists of two propagating complex envelopes one for the forward direction and the other for the reverse direction. Using this formulation models are developed for a variety of devices including: lasers, photodiodes, multimode fiber, and optical connectors. The formulation allows for definition of multiple optical channels at different carrier frequencies, enables quick simulation of systems with large optical delays and optical interference effects. Several numerical examples are presented in this paper to illustrate the capability of the proposed framework and where practicable the results were compared to commercial simulators. These examples include a multimode fiber optical link, an integrated array of laser sources and a feedback controlled laser source used in a optical link with modulation achieved by the use of an electro-absorption device.

Coherent optical channel substitution

Abstract: In an optical data transmission system, one channel is removed from a group of wavelength division multiplexed optical channels and another channel carrying different information at the same wavelength is inserted in its place. The process occurs by adding an optical signal whose electric field is the difference between the electric field of the new and old channels. The difference calculation takes into account the phase of the incoming WDM channel and phase of the laser source of the difference signal. The method has applications in optical transmission networks as add-drop nodes and optical regenerators, for generation of high bandwidth optical signals, and for secret optical communications.

Optical access beyond 10 Gb/s PON

Abstract: Innovation in optical access network architectures has always been tightly coupled to innovation in enabling components and subsystems. We explore some of the candidate architectures for next-generation optical access with an emphasis on enabling technologies.

Demonstration of RSOA-Based 20 Gb/s Linear Bus WDM-PON with Simple Optical Add-Drop Node Structure

Abstract: We demonstrate a linear bus wavelength-reused gigabit wavelength-division multiplexing passive optical network (WDM-PON) with multiple optical add-drop nodes. A commercially available reflective semiconductor optical amplifier-based WDM-PON has a sufficient power budget to provide multiple optical add/drop nodes in 16 WDM channels. Sixteen 1.25 Gb/s WDM channels are successfully transmitted over 20 km of single-mode fiber with four optical add/drop multiplexers, even with 32 dB reflection and chromatic dispersion in the link.

Method and apparatus for mapping and de-mapping in an optical transport network

Abstract: The embodiments of the present invention disclose method and apparatus for mapping and de-mapping in an optical transport network, where the mapping method includes: constructing an Optical Channel Data Tributary Unit (ODTU) according to an amount M of time slots of a High Order Optical Channel Payload Unit (HO OPU) to be occupied by a Low Order Optical Channel Data Unit (LO ODU); mapping the LO ODU to a payload area of the ODTU in a M-byte granularity; encapsulating overhead information to the payload area of the ODTU; and multiplexing the ODTU, which has been mapped the LO ODU and encapsulated with the overhead information, to the HO OPU, so as to provide a high-efficient and universal mode for mapping the LO ODU to the HO OPU.

Introducing elasticity and adaptation into the optical domain toward more efficient and scalable optical transport networks

Abstract: There is growing recognition that we are rapidly approaching the physical capacity limit of standard optical fiber. It is important to make better use of optical network resources to accommodate the ever-increasing traffic demand to support the future Internet and services. We first introduce an architecture, enabling technologies, and the benefits of recently proposed spectrum-efficient and scalable elastic optical path networks. In these networks, the required minimum spectral resources are adaptively allocated to an optical path based on traffic demand and network conditions. We then present possible adoption scenarios from current rigid optical networks to elastic optical path networks. We also discuss some possible study items that are relevant to the future activities of ITU-T. These items include optical transport network (OTN) architecture, structure and mapping of the optical transport unit, automatically switched optical network (ASON) control plane issues, and some physical aspects with possible extension of the current frequency grid.

Time transfer using fiber links

Abstract: This paper describes two-way time transfer over an optical network. The method is based on newly developed adapters utilizing channels in a DWDM (Dense Wavelength-Division Multiplexing) all-optical network. Results of several tests performed in real production network including the time transfer between atomic clocks in Prague and Vienna over more than 500 km long optical link are presented. In addition, the comparison of Common View GPS and optical time transfers is given.

Bandwidth defragmentation systems and methods in optical networks

Abstract: The present disclosure provides bandwidth defragmentation systems and methods in optical networks such as Optical Transport Network (OTN), Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), Ethernet, and the like. In particular, the present invention includes bandwidth defragmentation algorithms that may be used within the context of a signaling and routing protocol to avoid bandwidth defragmentation. As such, the present invention defines a mechanism for computing an end to end path for a connection in a manner that avoids bandwidth fragmentation and provides for better network utilization. For example, the present invention may include a path computation based upon administrative weight and upon fragmentation costs. This may be implemented in existing signaling and routing protocols without changes to existing protocol messages used in topology discovery. Further, the present invention optimizes available bandwidth allowing a higher probability of higher bandwidth request being admitted.

A New All-Optical Switching Node Including Virtual Memory and Synchronizer

Abstract: This paper presents an architecture for an all optical switching node. The architecture is suitable for optical packet and optical burst switching and provides appropriate contention resolution schemes and QoS guarantees. A concept, called virtual memory, is developed to allow controllable and reasonable periods for delaying optical traffics. Related to its implementation, several engineering issues are discussed, including the use of loopbased optical delay lines, fiber Bragg gratings, and limited number of signal amplifications. In particular, two implementations using optical flip-flop and laser neuron network based control units are analyzed. This paper also discusses the implementation and performance of an alloptical synchronizer that is able to synchronize arriving data units to be aligned on the clock signal associated with the beginning time of slots, in the node, with an acceptable error.

Optical network in-band control plane signaling, virtualized channels, and tandem connection monitoring systems and methods

Abstract: The present disclosure provides improvements with respect to in-band control plane signaling, virtualized channels, and tandem connection monitoring in optical networks utilizing Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), Optical Transport Network (OTN), and the like In an exemplary embodiment, the present disclosure includes an optical network operating a control plane with in-band signaling utilizing SONET/SDH path level overhead In another exemplary embodiment, the present disclosure includes an optical network operating virtualized SONET/SDH or OTN channels with manually cross-connections at intermediate line terminating elements In yet another exemplary embodiment, the present disclosure includes a tandem connection monitoring selection method across multiple operator domains

A novel subcarrier OFDM-MSK WDM passive optical network

Abstract: We experimentally propose and demonstrate generation, transmission and reception of the optical OFDM-MSK modulation in WDM-PON. Our experimental results suggest that OFDM-MSK modulation scheme will be a promising candidate for future optical access network.

Service-Oriented Multigranular Optical Network Architecture for Clouds

Abstract: This paper presents a novel service-oriented network architecture to bridge the informational gap between user applications and optical networks providing technology-agnostic multigranular optical network services for clouds. A mediation layer (service plane) between user applications and network control is proposed to facilitate a mapping process between user application requests and the network services. At the network level, a multigranular optical network (MGON) is proposed and implemented to support dynamic wavelength and subwavelength granularities with different transport formats [optical burst switched (OBS), optical burst transport (OBT)], reservation protocols (one-way, two-way), and different quality-of-service (QoS) levels per service type. The service-oriented multigranular optical network has been designed, implemented, and demonstrated on an experimental testbed. The testbed consists of service and network resource provisioning, service abstraction, and network resource virtualization. The service-to-network interoperation is provided by means of a gateway that maps service requests to technology-specific parameters and a common signaling channel for both service and network resource provisioning.

Mesh restoration in optical transport networks

Abstract: The present disclosure provides mesh restoration systems and methods with Optical Transport Network (OTN) links using a signaling and routing protocol, such as Optical Signaling and Routing Protocol (OSRP), Automatically Switched Optical Network (ASON), Generalized Multi Protocol Label Switching (GMPLS), and the like. The present invention includes an optical node, network, and method using the signaling and routing protocol for OTN lines of differing bandwidth granularities. The present invention utilizes OTN overhead for in-band signaling and may include capability for supporting SONET/SDH lines as well as OTN lines in the same system using the signaling and routing protocol.

Integrated optical receiver architecture for high speed optical I/O applications

Abstract: An integrated optical receiver architecture may be used to couple light between a multi-mode fiber (MMF) and silicon chip which includes integration of a silicon de-multiplexer and a high-speed Ge photo-detector. The proposed architecture may be used for both parallel and wavelength division multiplexing (WDM) based optical links with a data rate of 25 Gb/s and beyond.