Showing papers on "Optical Transport Network published in 1994"

Efficient routing in all-optical networks

Abstract: Communication in all-optical networks requires novel routing paradigms. The high bandwidth of the optic fiber is utilized through wavelengthdivision multiplexing: a single physical optical link can carry several logical signals, provided that they are transmitted on different wavelengths. We study the problem of routing a set of requests (each of which is a pair of nodes to be connected by a path) on sparse networks using a limited number of wavelengths, ensuring that different paths using the same wavelength never use the same physical link. The constraints on the selection of paths and wavelengths depend on the type of photonic switches used in the network. We present eflicient routing techniques for the two types of photonic switches that dominate current research in all-optical networks. Our results es*IBM T.J. Watson Research Center, Yorktown. This work was supported in part by grant MDA 97292-C-0075 from ARPA. t The Weizmann Institute, Israel, and IBM Alrnaden Research Center, California. Work at the Weizmann Institute supported in part by the Norman D. Cohen Professorial Chair of Computer Science. Permission to co y without fee all or part of this material is granted provicf~hatthecopies are not madeorcfistrfbutedfor direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association of Computing Machinery. To copy otherwke, or to republish, requires a fee andJor specific permission. STOC 945/84 Montreal, Quebec, Canada (!3 1984 ACM 0-89791 -663-6/94/0005.. $3.50 tablish a connection between the expansion of a network and the number of wavelengths required for routing on it.

Optical time division multiplexing: systems and networks

Abstract: The recent advances in optical time division multiplexed (OTDM) systems and components research show the technique to be highly suited to the generation and transmission of high capacity data on a single optical carrier. This approach uses a single wavelength to carry capacities of at least 40 Gb/s. Such systems are based on a clock frequency and tributary data rates which are easily accessible using electronic components. Short optical pulses are used in a return-to-zero data transmission format with temporal interleaving to map a number of optical data channels into a single electronic clock cycle. It is an approach that can be used to achieve extremely high data-rate bit interleaved systems. This article summarizes the developments in this field and outlines a possible methodology to evolve transport networks to encompass the potential that both WDM and OTDM have to offer. >

System for wavelength division multiplexing/asynchronous transfer mode switching for network communication

Abstract: The present invention is directed to a system for the wavelength division multiplexing/asynchronous transfer mode (WDM/ATM) operation of high-capacity optical communication networks The optical components of the network can transport vast amounts of information, while the ATM-based electronics provides data processing, and information distribution The capacity of the communications network to reconfigure and rearrange itself is maximized through wavelength translation of its data signals using a limited set of fixed-wavelength channels The system incorporates an optical fiber communication network ring, or several optical fiber communication network rings that are connected to each other, through which data signals are transmitted and received Optical WDM cross-connecting switch devices 4a-4e connect adjacent optical fiber rings 3a, 3b to each other, and control the routing of the data signals into and out of the optical fiber rings 3a, 3b Access node circuits 2a-2d connected to the WDM cross-connecting switch devices 4a-4d can access the data signals in the optical fiber rings 3a, 3b Each of the access node circuits 2a-2d can then route the data signals to individual user stations 5a-5h connected to it A network controller 8 configures the WDM cross-connecting switch devices 4a-4e through their corresponding local node controllers 7

Optical synchronous clock distribution network and high-speed signal distribution network

Abstract: An optical waveguide H-tree design is provided for global clock distribution on multichip modules (MCM) which has nearly zero clock skew and is useful for a distributed computer system environment. The optical waveguide H-tree design utilizes channel waveguides, curved sections and directional couplers formed using silica glass and silicon oxynitride (SiON) channel waveguide technologies. A hybrid combination of both SiON and silica glass is disclosed which has the advantages of each. The achievable clock speed is limited by the laser diode source and photodiode receiver at each chip module, and not by the optical waveguide distribution network. The high-speed optical waveguide can be configured to transmit clock signals, or for use as a multi-wavelength communication network that communicates signals to various integrated circuits (ICs) mounted on the multichip module. This is achieved using multiple laser diodes having different output wavelengths and directing their outputs into an optical multiplexer. At the receiving points on the ICs, optical demultiplexers filter the optical signals into individual output signals. In addition, multiple "stacked" optical waveguides can be constructed on the MCM to transmit multiple optical signals, and such optical signals can be either of single wavelength or multiple wavelength type.

Wavelength division multiplexed multi-frequency optical source and broadband incoherent optical source

Abstract: A wavelength division multiplexing multi-frequency optical source is used to provide downstream transmission of information signals at discrete optical wavelengths from a central office to a plurality of optical network units. A passive optical demultiplexer in a remote node routes the downstream information signals to the optical networks according to optical wavelength. Broadband incoherent sources are used to provide upstream information signals at discrete optical wavelengths which are multiplexed and then routed to the central office for demultiplexing by the passive optical demultiplexer. A wavelength selective coupler in the central office and in each optical network unit combines and segregates downstream and upstream signals of different optical wavelengths for routing to a desired destination.

The double-layer network architecture for photonic switching

Abstract: This paper introduces a new architecture for strictly nonblocking multistage photonic space networks implemented using the switched directional couplers. This switching architecture has the lowest path loss and the best SNR performance of any nondilated network. The architecture can also be dilated, giving it even better SNR. >

The scalable lightwave network

Abstract: In principle, an optical network employing wavelength routing, wavelength reuse, and multihop packet switching is modularly scalable to very large configurations in both the hardware and software sense. As such, it is a viable architecture for a new ATM-based telecommunications infrastructure The network architecture considered for a new, scalable, broadband telecommunications infrastructure is based on (1) the use of wavelength division multiplexing (WDM) and wavelength routing; (2) the translation of signals from one wavelength to another at the access stations; and (3) the use of multihop ATM packet switching. These principles permit networks to be built whose size is essentially unlimited. >

Bidirectional multi-channel optical ring network using WDM techniques

Abstract: A bidirectional multi-channel all-optical ring network is provided, this network comprising a number of nodes linked by optical cables, each of the node comprising two of WDM/WDDM, packet switching devices, and a node controller, in which network a first optical signal group of wavelength channel signals (for example, λ1, λ3, λ5, . . . ) are transferred in a counter-clockwise direction, and a second optical signal group of wavelength channel signals (for example, λ2, λ4, λ6, . . .) are transferred in a clockwise direction, thereby allowing an optical data signal to be transmitted through the channel of shorter distance.

Passive optical network with bi-directional optical spectral slicing and loop-back

Abstract: A passive optical network is provided that spectrally slices optical signals transmitted in both upstream and downstream directions utilizing wavelength division multiplexing routing. The passive optical network preferably includes a broadband optical signal source at both ends to provide signals that are spectrally sliced according to optical frequency. The downstream information may be transmitted in a conventional data format. The upstream transmissions may be segregated by subcarrier multiplexing, time scheduling or wavelength division multiplexing. At the subscriber end of the network there is an optical network unit which includes a device coupling the downstream fiber to the upstream fiber. Such coupling allows the passive optical network to perform enhanced diagnostic tests.

High Capacity Optical Fiber Network

Abstract: A high capacity optical fiber network operative with wavelength division multiplexing. Contemplated systems can utilize span distances in excess of 100 km, signal amplification within spans, and provide plural multiplexed channels operative at multiple gigabits per second.

On the design of optical deflection-routing networks

Abstract: Deflection routing plays a prominent role in many optical network architectures, because it can be implemented with modest packet-buffering requirements. From the practical perspective, however, the implementation of deflection routing, which is normally based on global time slotting, might pose challenges. The authors develop approaches to the implementation of both slotted and unslotted deflection-routing optical networks. They analyse important tradeoffs that are inherent to the design of optical deflection-routing networks and compare the performance of slotted and unslotted networks. Under a reasonable set of assumptions about optical technology, the results suggest that the unslotted link protocol should be the preferred approach to building the optical deflection-routing network. >

Optical local area network technologies

Abstract: To utilize the large bandwidth of optical fiber, optical LANs must employ architectures that fundamentally differ from current single-channel LAN architectures. With computer processor speeds continuing to grow exponentially and multimedia applications growing even faster, there is a strong need for higher-speed local area networks (LANs) that can handle the traffic generated by tomorrow's LAN users. Optical fiber is well suited for high-speed traffic transport, but the busty nature of computer traffic and large number of users makes it difficult to utilize the fiber's capacity in LANs. The incorporation of multiple payload channels in future LANs is seen as a necessity; WDM is a good candidate for achieving this. The rapidly improving optical component technologies allow more flexible WDM architecture designs for various emerging applications. >

One-dimensional optical data arrays implemented within optical networks

Abstract: An optical network is provided at a lowered cost and improved data throughput due to adoption herein of laser and receiver arrays in lieu of discrete transmitters and receivers. The arrays are referred to as one-dimensional optical data arrays. Preferably, the network includes optical network units that return a portion of the signals they receive in a looped-back mode. The returned portion, which may or may not be remodulated at the optical network unit, acts as a substantially continuous test to verify the optical integrity of the system.

Method of detecting breaks in multi-drop feeder system

Abstract: A passive distribution net connects a host digital terminal to a number of optical network units which service respective subscribers Transmit and receive feeder fibers branch out to the optical network units with optical power splitters An out-of-band laser light is blended with the communications wavelength on the transmit feeder at the host digital terminal and is stripped at the receive feeder using wave division multiplexers Similar wave division multiplexers at the optical network units are coupled by an optical shunt to carry the out-of-band light around each optical network unit This arrangement monitors network integrity and can discern fiber failure from optical network unit failure

Optical wavelength selection control system in optical networks

Abstract: An optical wavelength selection control system in an optical network includes an optical center node device and a plurality of terminal devices each comprised of a work station and an interface. The optical center node device includes a control circuit, a plurality of optical switches and a plurality of tunable wavelength filters. When there occurs a collision among the plurality of terminal devices wherein a plurality of terminal devices send simultaneously optical packets to the same terminal device, the control circuit operates to control the optical switches and the tunable wavelength filters such that they select only one optical packet, based on information relating to, for example, a data length to be transferred. The control circuit sends out an acknowledgment (ACK) signal to the terminal device whose optical packet has been selected. To each of the terminal devices whose optical packets have not been selected, the control circuit sends out, in addition to a not-acknowledgement (NACK) signal, a signal indicating a resending time schedule. There are no possibilities any more for at least these optical packets to be involved in the collision problems, and this ensures an enhancement of the throughput of the network system.

Optical paths and realization technologies

Abstract: This paper explores the transport technologies that will enable a further leap forward in transport network evolution. It is demonstrated that optical path technologies such as WP (wavelength path) and VWP (virtual wavelength path) enhance not only the transmission capacity, but also cross-connect node throughput cost-effectively by capitalizing on the wavelength routing scheme. This results in significant transport network cost reduction. Optical path realization technologies focusing on optical path cross-connect systems are examined. Requirements for the optical path cross-connect system are elucidated and a new cross-connect system architecture is proposed. The architecture exploits PLC (planar lightwave circuit) and other commercially available technologies suitable for mass-production. It is proved that the architecture has various advantages such as highly modular-growth capability, low optical loss, and the maximum commonality for WP and VWP. The optical path technologies introduced in this paper will pave the way for a new transport network paradigm, a ubiquitous, bandwidth-abundant and affordable broadband ISDN.

Technologies for local-access fibering

Abstract: The authors describe passive optical networks (PON), optical wavelength allocation, device and system technologies. Some examples of PON systems are given including SDM, WDM, FDM, and TCM. The authors go on to discuss optical modules LSI and optical amplifiers. The paper concludes with a discussion of upgrading PONs. >

Ultra high bit rate all optical communication system

Abstract: A system that uses all optical elements for transmission, regeneration and reception of solitons in point-to-point, broadcast, ring and multi-user trunk type communication systems. Soliton pulses from an optical clock source are modulated by optical data pulses in an optical modulator producing a modulated channel of data pulses. Several channels are combined by an optical multiplexer into a network optical bit stream. This stream is carried by an optical fiber and one or more of optical regenerators which recover the system clock and regenerate the signal with the recovered system clock rather than just amplifying the signal. Each of the regenerators can, in addition to regenerating the data, act as part of a data drop or insert node in a ring network where the node can synchronously remove data from or insert data into the stream. Intermediate nodes can include packet drop/replace nodes if the network is a packet type network. The destination can include an optical demultiplexer which demultiplexes the network stream into the individual channels, an optical clock recovery system that recovers the clock of the system and a receiver that receives the pulses of one of the demultiplexed channels. The system can also include optical logic for decoding and routing optical packets.

Toward the service-rich era /spl lsqb/optical access networks/spl rsqb/

Abstract: In order to remain viable the common carriers to develop "optical access network" based on FTTH as soon as possible. Many problems must be overcome in moving from the "metallic" world to the "optical" world, but if carriers hesitate and fail to make this move then they will be in a hopeless situation in the 21st century. This article discusses concepts for realizing optical access networks that are competitive with other media systems and for introducing them to the telephone world, to provide various attractive services to their customers and so gain their continued support. >

The hidden benefits of optical transparency

Abstract: The optical fiber amplifier will bring about network transparency and reductions in manning levels, interface problems, software and operating costs, while improving reliability and performance. It is in the area of economics that optical transparency affords a unique opportunity. What is generally not recognized is that there is a raft of hidden benefits, specifically: major reductions in interface technology, network control, and management software; reliability improvements; and reductions in the number of switching sites and craft people. System and network operating costs that are a small (even trivial) fraction of that today look certain to be realized. >

The potential of photonic networks

Abstract: Simple and flexible photonic networks will provide the basic technologies for the telecommunication networks of the 21st century, broadband-ISDN, and fiber-to-the-home. It is recognized that SDH and ATM systems have much difficulty increasing the throughput by electrical signal processing technologies, such as signal processing speed, latency, and so on. Photonic networks have the potential to solve these problems and to construct ultra-high-capacity, simple, and flexible transport networks. This becomes very promising with the development of optical fiber amplifier and other new optical device technologies. This article reviews trends in optical transmission technologies and discusses the possibilities of the photonic network. Conceptual photonic network examples for the transport network, access network, and customer premises network considering the present network are shown. Future research items for constructing the photonic network are also discussed. >

Studies on optical digital cross-connect systems for very-high-speed optical communications networks

Abstract: Optical time- and wavelength-domain paths in future very-high-speed optical communications networks are discussed taking into account trends in current optical transmission and optical signal processing technologies. It is important to investigate optical STM cross-connect systems for time-domain paths in the earlier research phase to ensure the deployment of optical cross-connect technology. The configuration of an optical cross-connect system and the issues that need to be investigated are presented. We also report, for the first time, a preliminary experiment of an optical STM cross-connect system, using 20 Gbit/s optical signals. >

All-optical signal processing in ultrahigh-speed optical transmission

Abstract: The coming broadband era will require very high-speed technologies that can handle more than 100-Gb/s for both transmission lines and transmission nodes. Novel all-optical signal processing technologies that offer unsurpassed performance are urgently required. This article briefly reviews the essential photonic technologies required for high-speed optical TDM transmission, including ultrashort optical pulse generation, all-optical multiplexing/demultiplexing, and optical timing extraction techniques. Recent all-optical TDM transmission experiments up to 100 Gb/s are introduced together with major issues and future prospects. >

Wavelength-routed optical networks

Abstract: Summary form only given. Research and development of wavelength-division multiplexing and routing technology is being pursued very actively. A primary application is to convert the single-channel optical links of today's networks into multi-channel WDM optical links for increased capacity. The use of wavelength-routing technology offers more functionality than electronic-WDM networks which consist of electronic switches and WDM links. Wavelength-routing enables the re-use of wavelengths in different parts of transparent optical networks to overcome some of the limits of a finite number of available wavelengths. Wavelength-routed networks can offer large capacities with transparent optical paths that do not undergo optical-to-electronic conversion. Assuming that WDM technology is available, it is important to realize that wavelength-routed optical networks must be compared to electronic-WDM networks rather than today's electronic networks with single-channel optical links.

TBONE: TestBed For all-Optical NEtworking

Abstract: The TBONE project is an ARPA-sponsored three-,year collaborative effort between MITRE, Optivision, and TASC. The objectives of the project are twofold: to implement and demonstrate a switched all-optical, multi-user image communications network in an applications environment, and to provide a testbed for developing and demonstrating optical network protocols, and other optical network technology. The testbed network will comprise two optical crossbar switches and two full-duplex single mode dark fiber links spanning the -20km distance between TASC and MITRE. High performance workstations and image servers at the two sites will be linked by the network (see Figure 1).

Free space optical message routing for high performance parallel computers

Abstract: We survey various electrooptical message routing systems for sending N messages between N processors and discuss the theory and practice of these systems. In particular, we compare these proposed systems with respect to various metrics including time, space, number of switches, bandwidth, energy, as well as estimates to scalability and cost in current technology. There are two classes of interconnection networks for parallel computers: multistage networks and single stage networks. Optical multistage networks are often the optical realization of conventional multistage electronic networks. Optical single stage networks use free space optical routing techniques to achieve a virtual crossbar. We describe various optical single stage networks based on some quite diverse techniques including matrix-vector multiplication, various dynamic and static holographic methods, as well as frequency multiplexing. >

Dual wavelength optical fiber HDTV distribution networks using self-synchronization technique and multistar topology

Abstract: A new optical fiber time-division multiple-access (TDMA) network is proposed for HDTV distributions. It uses two wavelengths to carry optical TDMA and clock signals through the common fibers to each subscriber. At the receiver, both signals are easily separated by using a wavelength division multiplexing (WDM) demultiplexer, and therefore, the frame and time-slot synchronizations are feasibly achieved by using optical fiber delay lines to independently process the separated clock and TDMA signals. This self-synchronization characteristic can be used to improve the network flexibility, which allows one to build a large-scale HDTV distribution network based on a multistar topology. Furthermore, a sensitivity analysis of optical TDMA receivers is carried out. It is shown that, compared with a point-to-point optical fiber digital system, the multi-user optical TDMA system requires a lower extinction ratio to alleviate the performance degradation. >

Broadband optical local area network technologies

Abstract: Summary form only given. We will present recent work on all optical technologies for ultrahigh bit rate optical TDM transmission. These results include a demonstration of a new ultrafast source, an 80 Gb/s optical transmission, rate conversion and demultiplexing, and a prototype optical network unit. The system experiments are combined with computer simulation studies to investigate transmission architectures for a 100 Gb/s local area optical network.