Showing papers on "Optical Transport Network published in 2007"

A Novel Radio-Over-Fiber Configuration Using Optical Phase Modulator to Generate an Optical mm-Wave and Centralized Lightwave for Uplink Connection

Abstract: We have designed a novel radio-over-fiber configuration using an optical phase modulator along with optical filtering to generate an optical millimeter-wave for carrying downstream data and centralized lightwave for carrying upstream data. Since the remaining optical carrier with high power has been reused, the optical power is effectively utilized; therefore, the system cost can be reduced. We have calculated the power margin, and found that the margin is large even if no boosted erbium-doped fiber amplifier is used in the system. The eye diagrams and bit-error-rate performance at the receivers have been evaluated

Translucent Optical Networks: The Way Forward

Abstract: The transmission reach of signals in optical transmission systems is limited. To go beyond these transparent reach limits, signal regeneration is necessary to re-amplify, reshape, and retime the optical signals. Translucent optical networks are a type of optical transport network specifically devised to address such a concern by allowing for sparse but strategic signal regeneration in the network. Translucent optical networks seek a graceful balance between network design cost and service provisioning performance, and can achieve performance comparable to that of an all-electronic switching network, but requiring far fewer signal regenerators. Despite massive progress, there are many outstanding issues regarding the implementation of translucent networks planning and operation. This article reviews a range of translucent optical networks and discusses various research issues, particularly involving network planning, lightpath routing and wavelength assignment, and network survivability. We also suggest other potential research topics such as traffic grooming, fault detection, and multicasting for translucent networks.

Fundamentals and challenges of optical multiple-input multiple-output multimode fiber links [Topics in Optical Communications]

Abstract: In this article we discuss the application of MIMO processing to multimode fiber links. MIMO processing is shown to increase the information capacity of communication links linearly as the minimum number of transmitters/receivers increases. The fundamentals of optical MIMO fiber links are presented, and the promises and challenges of such systems are elaborated

Translucent optical networks: the way forward [Topics in Optical Communications]

Abstract: The transmission reach of signals in optical transmission systems is limited. To go beyond these transparent reach limits, signal regeneration is necessary to re-amplify, reshape, and retime the optical signals. Translucent optical networks are a type of optical transport network specifically devised to address such a concern by allowing for sparse but strategic signal regeneration in the network. Translucent optical networks seek a graceful balance between network design cost and service provisioning performance, and can achieve performance comparable to that of an all-electronic switching network, but requiring far fewer signal regenerators. Despite massive progress, there are many outstanding issues regarding the implementation of translucent networks planning and operation. This article reviews a range of translucent optical networks and discusses various research issues, particularly involving network planning, lightpath routing and wavelength assignment, and network survivability. We also suggest other potential research topics such as traffic grooming, fault detection, and multicasting for translucent networks

Optical performance monitoring in coherent optical OFDM systems

Abstract: Optical performance monitoring is an indispensable feature for optical systems and networks. In this paper, we propose the concept of optical performance monitoring through channel estimation by receiver signal processing. We show that in coherent-optical-orthogonal-frequency-division-multiplexed (CO-OFDM) systems, critical optical system parameters including fiber chromatic dispersion, Q value, and optical signal-to-noise ratio (OSNR) can be accurately monitored without resorting to separate monitoring devices.

Systems and methods for the integration of framing oam&p, and forward error correction in pluggable optical transceiver devices

Abstract: The present invention provides integrated framing in pluggable optical transceivers to extend the OTN framework into metro, regional, and core applications. Additionally, the present invention provides integrated FEC and optical layer OAM&P features Ento pluggable optical transceivers. This integration is done with existing pluggable transceivers defined by MSAs such as, but not limited to, XFP, XPAK, XENPAK, X2, XFP-E, and SFP+. Further, the present invention can be extended to new, emerging pluggable transceiver standards and specifications. The integration of framing, FEC, and optical layer OAM&P is done so that the pluggable transceiver preserves the specifications in the MSAs. This allows systems designed for existing pluggable transceivers to realize carrier-grade, robust performance without needed additional equipment such as transponders and without redesigning host equipment such as the line card to support new specifications.

Long Reach Passive Optical Networks

Abstract: We discuss recent progress in the development of optically amplified, long reach passive optical networks, which aim to significantly reduce network complexity and cost by integrating metro and access into a single, all-optical communication system.

Amplified gigabit PON systems [Invited]

Abstract: Feature Issue on Passive Optical Network Architectures and TechnologiesWe describe how a passive optical network (PON) extender box can be implemented at standard PON wavelengths (1310 and 1490nm) using either optical fiber amplifiers (praseodymium and thulium) or semiconductor optical amplifiers to further increase the physical reach and split of a current standardized PON system such as a G-PON or GE-PON. The transparency to PON protocol of this approach means no changes to the existing standards are required. This is attractive as operators and vendors are keen to fully exploit the investment made in current PON standards.

Systems And Methods For On-Chip Data Communication

Abstract: An on-chip data communications infrastructure includes a hybrid, photonic/electronic network. The network includes a plurality of interconnected optical switches, each under the control of an electronic router. The electronic routers are connected in a fashion similar to the optical switches, forming a parallel, photonic/electronic network. Electronic path setup messages are routed through the electronic network. At each hop, a photonic switching element in a parallel, photonic network is reserved. When the electronic path setup message reaches its destination, a chain of reserved optical switches is ready to channel the optical data through the photonic network.

Code-division multiplexing for in-service out-of-band monitoring of live FTTH-PONs

Abstract: Feature Issue on Optical Code Division Multiple AccessWe propose, to the best of our knowledge, a novel in-service live fiber-to-the-home (FTTH) passive optical networks (PONs) management solution. Our solution uses a modified direct-sequence (DS) optical code-division multiplexing (OCDM) system and overcomes the optical time-domain reflectometry (OTDR) point-to-multipoint shortcomings. Our solution addresses various service provisioning and network maintenance challenges in PONs, alleviates their complexity, and reduces their operational cost. In addition, our system exploits passive devices (or encoders) to demark service provider ownership and responsibility from that of customers. Our OCDM-based management solution easily scales up from FTTH time-division multiplexing (TDM)-PON to WDM-PON and TDM/WDM-PON to support as many as a thousand customers, all using only one monitoring wavelength. We address the coding system and develop capacity curves for different PON scenarios.

Prototype 160-Gbit/s/port Optical Packet Switch Based on Optical Code Label Processing and Related Technologies

Abstract: We propose and experimentally demonstrate a prototype 160-Gbit/s/port optical packet switch with narrow-band all-optical code-label processing, optical switching, high-extinction-ratio optical buffering, electrical scheduling, and optical multiplexing/demultiplexing (MUX/DEMUX) As related technologies, we also propose and demonstrate a novel system for measuring variable-length packet bit error rate (BER) and loss and a burst-mode optical packet 3R receiver

Demonstration of a Novel WDM Passive Optical Network Architecture With Source-Free Optical Network Units

Abstract: A novel wavelength-division multiplexing passive optical network architecture with the capability to provide triple-play services (TPS) with a source-free optical network unit has been proposed and experimentally demonstrated. TPS provision with two 2.5-Gb/s, 10-Gb/s downstream signals and 10-Gb/s upstream signals per channel has been successfully realized

Method and Device for Transmitting Low Rate Signals Over an Optical Transport Network

Abstract: Embodiments of the present invention provide a method for transmitting low rate signals over an optical transport network, including: adapting the low rate signals into low rate optical channel data units of the same rate level with the low rate signals; asynchronously mapping each of the low rate optical channel data units into a low rate optical channel data tributary unit respectively, and generating justification overhead used for rate adaptation for each of the low rate optical channel data units; and forming a higher order optical channel data unit with at least one low rate optical channel data tributary unit and justification overhead corresponding to the low rate optical channel data tributary unit. The present invention enables the optical transport network to support mapping, multiplexing and highly efficient transmission of low rate signals.

Remotely amplified combined ring-tree dense access network architecture using reflective RSOA-based ONU

Abstract: Feature Issue on Passive Optical Network Architectures and TechnologiesA highly scalable access architecture achieving high density and featuring resiliency, centralized light-generation control, remote amplification, and colorless optical network unit with reflective semiconductor optical amplifier (RSOA) for upstream modulation is presented and experimentally demonstrated. It is based on a user-single-fiber completely passive outside plant and provides broadband connections to >1000 users distributed along large distances. It is believed to represent an intermediate step toward metro-access convergence and offers flexible configurations covering high- and low-density population areas.

Survivable MPLS Over Optical Transport Networks: Cost and Resource Usage Analysis

Abstract: In this paper we study different options for the survivability implementation in MPLS over optical transport networks (OTN) in terms of network resource usage and configuration cost. We investigate two approaches to the survivability deployment: single layer and multilayer survivability and present various methods for spare capacity allocation (SCA) to reroute disrupted traffic. The comparative analysis shows the influence of the offered traffic granularity and the physical network structure on the survivability cost: for high bandwidth LSPs, close to the optical channel capacity, the multilayer survivability outperforms the single layer one, whereas for low bandwidth LSPs the single layer survivability is more cost-efficient. On the other hand, sparse networks of low connectivity parameter use more wavelengths for optical path routing and increase the configuration cost, as compared with dense networks. We demonstrate that by mapping efficiently the spare capacity of the MPLS layer onto the resources of the optical layer one can achieve up to 22% savings in the total configuration cost and up to 37% in the optical layer cost. Further savings (up to 9 %) in the wavelength use can be obtained with the integrated approach to network configuration over the sequential one, however, at the increase in the optimization problem complexity. These results are based on a cost model with different cost variations, and were obtained for networks targeted to a nationwide coverage

Optical reflectometry based on correlation detection and its application to the in-service monitoring of WDM passive optical network

Abstract: We propose and demonstrate a novel technique for measuring the distribution of the reflectivity along an optical fiber transmission line. Unlike the conventional optical time-domain reflectometer (OTDR), the proposed technique utilizes the data-modulated transmitter itself instead of the optical short-pulse source, and monitors the distribution of the back-reflected light by calculating the cross-correlation of the transmitted and back-reflected signals. In this paper, we describe the operating principle of the proposed technique and discuss its potential limitation on the dynamic range. We also show that this limitation can be mitigated by using the discrete-component elimination algorithm. In addition, we experimentally demonstrate that the proposed technique can be used for the in-service monitoring of the transmission fibers in a wavelength-division multiplexed passive optical network (WDM PON).

Byte-interleaving systems and methods for 100G optical transport enabling multi-level optical transmission

Abstract: The present invention provides byte-interleaving systems and methods for Optical Transport Unit N (OTUN) (i.e. Optical Transport Unit 4 (OTU4)) and 100 Gb/s (100 G) optical transport enabling multi-level optical transmission. The byte-interleaving systems and methods of the present invention support the multiplexing of sub-rate clients, such as 10 Gb/s (10 G) clients, 40 Gb/s (40 G) clients, etc., into two 50 Gb/s (50 G) logical flows, for example, that can be forward error correction (FEC) encoded and carried on a single wavelength to provide useful, efficient, and cost-effective 100 G optical transport today. Signaling format support allows these two 50 G logical flows to be forward compatible with an evolving OTU4 and 100 G signaling format without waiting for optical and electronic technology advancement. Signaling format support also allows an evolving standard 100 G logical flow (i.e. OTU4, 100 Gb/s Ethernet (100 GbE), etc.) to be carried as 2×50 G logical flows, 4×25 G logical flows, or other lower rate formats on a single wavelength.

Optical polarization division multiplexing in optical communication

Abstract: Devices, systems and techniques for optical communication are provided based on polarization division multiplexing (PDM) to use an optical monitor channel at a distinct optical monitor wavelength to monitor optical polarization fluctuation and polarization mode dispersion during the transmission from the transmitter to the receiver to facilitate the effective demultiplexing of the two orthogonal signal channels at the receiver through automatic feedback control on a dynamic polarization controller and a polarization beam splitter.

Method, data interface and device for transporting data from high-speed ethernet to optical transport network

Abstract: The present invention provides a method, a data interface and a device for transporting data from a high-speed Ethernet to an OTN (Optical Transport Network), where seamless transport of Ethernet traffic to the OTN can be enabled through flow control, rate-matching, and mapping and encapsulation respectively performed at an Media Access Control Sub-layer, a Physical Coding Sub-layer, and an Optical Transport Network Interface Sub-layer. Thus, only one mapping and encapsulation of data is required to directly enable through a physical layer the transparent transport of the Ethernet traffic to the OTN, and due to the rate-matching implemented upon the mapping, the traffic transport can be enabled in a standard-compliant way with guaranteed efficiency and quality.

Optimal-Complexity Optical Router

Abstract: In the past years, electronic routers have had trouble keeping up with the increase in optical fiber capacity. As their power consumption has grown exponentially and already exceeds standards, it seems that an alternative solution is mandatory. Many have suggested all-optical routers as an alternative. However, these are deemed too complex, especially given the need to implement both switching and buffering, even though their fundamental complexity has apparently never been analyzed. In this paper, we study the number of fundamental optical components (2 times 2 switches and fiber delay lines) needed to emulate ideal routers. We first demonstrate that an N times N router with a buffer size of B per port needs at least thetas(N log(N B)) components, and then build a construction that achieves this lower bound. On the way, we also present an optical buffer construction of size B that works with thetas(log(B)) components, which is also shown to be a lower bound. Finally, we generalize this result to different router architectures and scheduling disciplines.

Systems and methods for mapping and multiplexing wider clock tolerance signals in optical transport network transponders and multiplexers

Abstract: The present invention provides systems and methods for mapping and multiplexing wider clock tolerance signals in Optical Transport Network (OTN) transponders and multiplexers. In one exemplary embodiment, the present invention allows wide tolerance signals, such as a 10 GbE with a ±100 PPM clock tolerance, to be 100% transparently mapped asynchronously into OTU2-LAN rate transport signals. In another exemplary embodiment, the present invention allows wide tolerance signals, such as a 10 GbE with a ±100 PPM clock tolerance, to be 100% transparently multiplexed asynchronously in to OTU3-LAN rate transport signals. The present invention utilizes extra Negative Justification Opportunities (NJO) in either unused OPUk overhead or in OPUk payload area and Positive Justification Opportunities (PJO) in OPUk payload area. Advantageously, the extra NJO and PJO provide additional bandwidth for client data rate offsets beyond OTN specifications.

Communication Network with Skew Path Monitoring and Adjustment

Abstract: Embodiments of the present invention route a WDM signal across multiple communication paths using skew characteristics of at least some of the communication paths. The network is an optical transport network, using either circuit or packet based switching, and wavelength division multiplexed wavelengths and/or optical carrier groups (“OCGs”) over a fiber link to another node in the network. The plurality of communication paths involves different signal and path attributes such as a plurality of carrier wavelengths, optical carrier groups, physical communication paths (different nodes, different fibers along a same path, or any combination of the foregoing), or any other differentiating factors between two paths.

Method and apparatus for network fault detection and protection switching using optical switches with integrated power detectors

Abstract: Current network switching architectures require communication with a higher level network control plane, which can be slow to reroute communications, resulting in unacceptable losses of communications for customers. Examples embodiments of the present invention reroute communications faster detecting optical power of an optical signal at optical switches coupled via optical communication paths, and causing at least one optical communication path between a first optical switch and second optical switch to switch to an alternative optical communication path, in part, through physical layer triggering in an event optical power at at least one of the first or second optical switches falls below a threshold level. Switching in response to physical layer triggering may result in reduced switching times and, consequently, faster restoration of communications to customers after a network fault interruption.

Multifunctional and reconfigurable optical node and optical network

Abstract: An optical node includes a reconfigurable optical add drop multiplexer (ROADM) core configured to transmit optical signals of multiple wavelengths to and receive optical signals of multiple wavelengths from another optical node. The ROADM core is also configured to add optical signals thereto and to drop optical signals therefrom. The node also includes two different types of add-on devices, each connected to the ROADM core device and configured to process optical signals of multiple wavelengths. As a result, a multifunctional and reconfigurable optical node can be provided.

Variable forward error correction for optical communication links

Abstract: A method and system for setting a variable forward error correction overhead in an optical transport network frame for an optical link at a node are disclosed. In one embodiment, a method includes selecting a forward error correction overhead, signaling an optical node the selected forward error correction overhead, and setting the forward error correction overhead in the optical network transport frame for use in transmission of data over the optical link. In one embodiment, the forward error correction overhead is complementary to the data payload to maintain total transmission rate.

Optical interconnect system providing communication between computer system components

Abstract: An optical interconnect system for communication between computer system components is described The system includes an optical data communication path and a plurality of optical taps, each optical tap optically coupling a respective computer system component to the optical data communication path Each optical tap splits power from an optical signal received from the data communication path or from a light source generating a data signal from its associated computer component resulting in another optical signal Each optical tap splits light in accordance with a respective power ratio relationship between reflectivity and transmissivity The ratio relationships of the optical taps together provide a predetermined communication reliability metric for signals traversing the optical interconnect system between computer system components

Photonic integrated circuit device and elements thereof

Abstract: A photonic integrated circuit (PIC) device is described. The PIC device includes a set of optical transceivers including optical transmitters and optical receivers, and an embedded optical interconnect mesh operatively associated with the set of optical transceivers and structured to enable at least one of the following network architectures: a star network architecture, a bus/broadcast network architecture, and a ring network architecture. Related apparatus and methods are also described.