An integer programming model was developed giving optimum bit rates for point-to-point loop feeder connections subject to a ten year forecast of service demand. The optimum choices for bit rate minimize a cost function covering all items that vary significantly with operating bit rate and cable fiber count. Solution of the model gives the optimum upgrading strategy for the multiplexing equipment and initial sizing for the fiber cable
Recent experiments have demonstrated the feasibility of high-bit-rate transmission over single-mode fiber using LED light sources. Such a system is attractive for the local distribution network, because it combines the high performance of single-mode fiber with the low cost and reliability of LEDs. This paper provides an overview of recent developments in this technology. System design considerations, including speed and material dispersion limitations, temperature effects, and LED/fiber coupling are discussed.
It is expected that there would be various demands for digital capacity, from a few kilobits per second for such services as facsimile, data entry, and provision of audio and graphic for teleconferencing, to about 56Kb/sec for electronic mail and integrated work stations, and higher speeds for cable television, high resolution TV, and computer-aided engineering. Fiber optics has been proven-in from an economic standpoint to provide the above-mentioned services. This is primarily due to the fact that in less than five years optical line rates have leaped from 45Mb/s to gigabit rates, therefore reducing the cost per DS3 of capacity, and the price of high quality fiber cable has taken a nosedive.
A specification for optical fiber loop feeder cable was drafted for use in feeder route design and cable procurement in the New England and New York Telephone companies. The specification describes two cable sheath designs and one grade of single mode fiber which satisfy the environmental and optical system requirements for most loop fiber applications. By using fiber cable manufactured to the specification, the telephone companies should realize savings in engineering expense and reductions in capital requirements for loop fiber projects.
The subscriber loop accounts for between 25% to 50% of the fiber optic cable installed by many operating telephone companies and represents one of the fastest growing markets for fiber optic systems. The increasing complexity of subscriber loop systems coupled with the unique requirements of these applications presents an interesting set of design and operational requirements. Addressing these issues during the planning stages of the system not only facilitates the cable installation but also provides a viable network with flexibility for future growth and expansion. This paper discusses the topologies being used in fiber optic subscriber feeder systems, the design and operational issues and concerns, and offers a solution presently being used by many operating companies.
Advances in system architecture for wideband Integrated-Service-Digital-Network (ISDN) has resulted in large demand for low cost and reliable opto-electronics components for the upcoming high-bit-rate optical-fiber communication network. This paper presents recent progress in the design of a high-speed LED transmitter which can modulate LEDs at > 560Mb/s with an active bias circuit and high a.c. current drive (~200mA). It achieves excellent extinction ratio (~15 dB) and launches -22 dBm power into single-mode fiber. The LED device has the advantages over the lasers because of low cost, temperature stability and high reliability. It requires less-complicated driver circuit so the LEDs are ideal light sources in term of ease of maintenance for high volume applications like the subscriber loop and local area data link networks.
Photonic networks of the future will be fundamentally different from present-day networks. Performing optical processing of the media access protocol raises the capacity of the entire LAN to that of the optical fiber itself. Optical processing also permits the use of novel baseband-expansion-type protocols and architectures. In this paper, the use of optical signal processing and novel optical architectures in networks is discussed. Examples of two experimental all-optical passive star networks are presented: asynchronous code-division multiple access (spread spectrum), and fixed assignment time-division multiple access (at 500 Mbps). An active star network, utilizing an all-optical, self-routing, strictly non-blocking photonic switch, is also presented. The feasibility of future photonic networks, with 10 Gbit capacity, is discussed.
FiberWay enables efficient and effective usage of the fiber optic communications medium. Current systems consist of fiber optic T/R pairs grafted onto an existing network, and are often simply a substitute for baseband electrical cable systems. In contrast, FiberWay provides the effect of a digital broadband network, wherein multiple independent protocols are transported simultaneously over the same fiber. A network of networks results. FiberWay enhances the value and performance of installed standard networks, providing the capability for the co-existance of varied standards for different applications, and presents an upward migration path for network growth.
The DUAL network offers both conventional (logical lines, X25, ISO 8802.3) and advanced (multicast, synchronization) services. It is based on multi-microprocessor nodes interlinked by means of fiber optics trunks. The DUAL ring is installed in a camput of several km2, interconnecting up to 40 buildings and serves as the backbone network for a number of other networks and as a test bed for the implementation of "second generation" data transmission and distributed informatics services.
This paper reports on the performance of a multichannel video fiber optic vestigial sideband (VSB) transmission experiment using commercially available equipment. The motivation behind such experiments is to make fiber optic systems more attractive in bringing video distribution services to the industrial or university campus. The on-going experiment consists of modulating up to eight different video channels onto a single fiber and characterizing the link in terms of distortion and noise.
A fiber distributed data interface (FDDI) standard is being developed in the Accredited Standards Committee (ASC) X3T9. This standard is for a 100 MB/s dual fiber (counter-rotating) ring. Stations on the ring are interconnected by optical fibers and provisions have been made to allow optional optical switches to bypass a station when needed.
This paper discusses the fiber optic specifications for the Fiber Distributed Data Interface (FDDI) standard being developed by the American National Standards Institute (ANSI). Analytical and empirical techniques used to derive the bandwidth and timing parameters for the optical data link specifications are described. An iterative process, involving tradeoffs between the transmitter, fiber, and receiver specifications, has resulted in a workable standard that is achievable within the current component vendor base.
The ANSC X3T9.5 draft proposed American National Standard for a Fiber Distributed Data Interface (FDDI) defines a 100 Mb/s fiber optic counter rotating token passing ring local area network (LAN). These networks are intended to be used for data communications between mainframes and peripherals, backbone interconnection of multiple lower speed LAN's, and eventually fully integrated voice, video and data communications (FDDI II).
Fibers installed in local area networks (LAN) provide a wide bandwidth path for distribution of many and varied services, such as, voice, voice and data, video, and combined integrated services. Total optical connection requirements for low loss cost effective LAN premises and campus systems include (i.e., simple office building to a multi-floor multi-customer LAN to a campus LAN made up of premises and outside cabling and distribution): (1) flexible rearrangement, (2) node or terminal pass-by protection, (3) small to large fiber count cables, (4) varied environment and (5) tapering. Typical star or hybrid LANs may be highly tapered; that is, many communication paths near the central switching node or remote terminal and fewer near the most remote customer. This tapering requires many different types of connections for dropping off fibers and branching to different fiber count cables.
Mr. Pazaris: Tonight we have here people from computer companies who are going to use these components. And we have the customers, and the owners of the local-area networks and the premises. So I think that all three groups are going to have different questions for each other. We might start off the questions with anybody who had some specific questions for any of tonight's speakers on their talks.
Jitter characterization for a portion of MCI's fiber optic network has been completed. Measurements were made to determine how many 405 Mb/s lightwave terminating equipment (LTE) can be cascaded before jitter accumulation would adversely affect the system performance. Parameters examined were maximum tolerable input jitter, intrinsic jitter, and jitter transfer function. Results demonstrate that jitter accumulates proportional to N.49, where N is the number of cascaded LTE sections. This implies that up to 1183 sections could be cascaded before jitter would become a problem in the system's performance. The results also show that MCI's system is operating within the jitter design objectives recognized by the telecommunications industry.
There have been many similar opinions expressed in recent months about there being an imminent bandwidth glut in the nation's long haul fiber optics network. These feelings are based largely on the vast magnitude of construction projects which are either in progress or completed by the major carriers, i.e., AT&T-Communications, MCI, NTN and US Sprint. Coupled with this advanced stage of construction and subsequent network operation, is the slowly developing demand for those applications which consume large amounts of bandwidth, namely those which are video-based.
New high-density Fiber optic trunk carrier systems are drastically lowering the TRANSMISSION/SWITCHING COST RATIO. Reducing the number of switches in an existing toll network may reduce the cost of the network. Overflow growth traffic from an exhausted switch in a toll network can be hauled to a distant location to be switched, which can defer replacement of the exhausted switch, and reduce the cost of the network.
The LDX NET, Inc. regional fiber optic network was constructed and operating in record time. It is currently operating in Texas, Louisiana, Oklahoma, Missouri, and Kansas. This paper presents the obstacles overcome during construction, as well as an overview of the design parameters.
In this invited tutorial review paper on single-mode fiber measurements, I discuss the various methods used to characterize the following important transmission parameters of single-mode fibers: attenuation, cut-off wavelength, mode-field diameter and chromatic dispersion. Single-mode fibers are being used increasingly in long-haul links and are even being considered for subscriber networks.
Highlights of the activities of several of the major organizations responsible for optical fiber standards is presented. Emphasis is on those optical parameters which have been recent discussion issues in the EIA standards committees. The activities of the EIA's newly formed component and systems joint working groups are described.
The accuracy of chromatic dispersion measurements made using a phase-shift technique utilizing only three lasers (with wavelengths in a neighborhood of the zero-dispersion wavelength) is calculated. It is shown that by defining and measuring the center wavelengths of the three lasers accurately, a measurement accuracy of better than ± 1.5 nm in the zero-dispersion wavelength (λo) and better than ± 0.007 ps/nm-km in the zero-dispersion slope (SO) can be obtained for long lengths of conventional fiber with λo near 1310 nm. This corresponds to an accuracy of better than ± 0.1 ps/nm-km in the dispersion at a wavelength of 1285 nm. The accuracy of extrapolating these 1300 nm dispersion results to 1550 nm using a three-term Sellmeier model is also calculated and compared with experimental results.
The purpose of this paper is to describe the accurate measurement of multimode bandwidth from a system measurements standpoint. The parameter of multimode bandwidth is probably the most difficult measurement to acheive. To describe the measurement, basic theory of multimode fiber waveguide propagation will be discussed. Types of measurement methods to measure multimode bandwidth will be discussed. This paper will explain why the frequency domain measurement method is an acceptable technique. The measured swept frequency bandwidth data for 50 micron 0.2 N.A. fiber will be compared to a reputable master reference bench, and differences in the results will be shown to be insignifigant. Finally, conclusions will be given.
A number of photodetector assemblies were constructed and evaluated for their suitability in an optical fiber attenuation measurement system operating in a production environment. The assembly exhibiting the best compromise among the critical performance parameters utilized a PIN photodiode with an achromatic lens assembly. This compromise required a trade off between measurement accuracy and the overall versatility of the photodetection system.
This paper addresses some of the special needs associated with accurate determination of dispersion at 1550nm in single mode fiber under field conditions. A comparison is made between various methods for dispersion measurement, and a hybrid technique is introduced.