The prevailing vision for next generation multimedia communication systems is a digital one. However, we anticipate a transitional period in which hybrid networks involving both analog and digital technology will coexist. These analog facilities will include crossbar audio-video switches, CATV distribution systems, and dedicated lines. For some scale of use, these facilities may offer economies for connectivity to conventional analog video equipment. We are interested in connection routing that will be needed in such hybrid networks for services including video conferencing and broadcast results. The routing problem in such topologies resembles but is not identical to that found in telephone systems because of the presence of broadcast connections. We discuss representative topologies, review related work, and describe algorithms and simulation results. In addition we describe a hybrid system that we have implemented in our research lab which involves several A/V switches, CATV channels, digital video on a LAN, and a point-to-point link to an offsite conference area.
Single-mode optical fibers can offer an enormous transmission bandwidth. However, the use of electronic signal processing limits the channel capacity. To eliminate the throughput bottleneck, all-optical processing techniques should be employed. In this paper, we investigate all-optical medium across protocols and network architectures to implement ultrahigh capacity fiber optic networks which can support real-time multimedia communication services. Optical Time Division Multiple Access (OTDMA) and Wavelength Division Multiple Access (WDMA) are described. We present several novel schemes to implement OTDMA networks with the emphasis on optical clock distribution, synchronization, and all-optical detection. The fast switching bistable laser diode is proposed as an all-optical threshold detector and data regenerator. In order to improve the reliability of ultrashort signal detection in optical domain, the self-slot decision technique is presented. A new technique called dual-wavelength OTDMA is investigated. Then we propose an efficient multiple access protocol called WDMA with Optical Time Division Multiplexing (WDMA-OTDM) for multimedia applications. It is shown that the proposed WDMA-OTDM has all advantages possessed by individual OTDMA and WDMA while the network flexibility and efficiency are greatly improved by using WDMA- OTDM.
Real success in the residential broadband market is contingent on a platform that most efficiently shares broadband port costs while at the same time affords us an elegant, and cost efficient, upgrade from today's analog to tomorrow's digital world. Spectrum transport, whether it be over new or existing fiber/coax systems or FTTC, is that platform. It is compatible with today's home entertainment market, can be evolved to future digital transport, and effectively shares the cost of interfacing with a broadband network.
The study of integrated opto-electrical circuits has lead to the evolution of silica-based planer lightwave circuit (PLC) technology. PLC technology can be applied to the filtering of optical signals. Optical filters for AM-FDM signals that use the subcarrier multiplexing (SCM) technique can access two optical carrier wavelengths simultaneously, and can be used with point-to-multipoint wiring using coaxial cable to home videos. The use of optical fibers in subscriber networks has become a priority in telecommunications and video transmissions. In our network, the optical network unit (ONU) which is installed in an outside plant is designed so that three kinds of optical fiber systems are terminated simultaneously. They are for the video fiber backbone, personal communications and narrow band ISDN. The radius of the service area offered by the ONU is a few hundred meters. This network configuration is suitable for powering and operation, administration and maintenance (OA&M) from the viewpoint of feeder fiber network design.
Passive Optical Networks (PONs) have been demonstrated to be cost-attractive approach for the deployment of Fiber-In-The-Loop systems (FITL) having POTS services capability. In the future these systems must be able to carry broadband services in ATM format as defined by CCITT. The present paper describes an ATM-based PON (APON) and presents the results of feasibility tests for the most critical parts of the system: high-speed medium access protocol for upstream transmission (TDMA), burst mode clock synchronization technique and high- speed electro-optic transceivers applicable to burst mode transmission. System design options such as the downstream and upstream bit rates, the sharing factor and the multiplexing technique used for the bidirectional transport of ATM cells are discussed. Issues such as analog CATV services delivery and the provision of digital video-on-demand (VOD) are covered as well.
This presentation will review the current status of passive optical splitters and directional couplers. Erbium-doped fiber amplifiers (EDFAs) and dispersion-shifted fiber technologies. It also will focus on system performance when 1550 nm AM video systems are deployed.
During the last several years a number of different transmitter options have been developed for the distribution of video signals over fiber optic links. These options, for the AM-SCM modulation format, include intensity-modulated DFM lasers and externally modulated CW light sources. In this paper several design alternatives are reviewed in terms of intrinsic performance and suitability for linearization. Laboratory data are also presented for a 1550 nm transmitter comprising a linearized external modulator and fiber amplifier.
The Fiber-In-The-Loop debate is dominated by two perspectives, each with it's own set of biases. Those of us in the telephone industry have a perspective based in narrowband switched services. The Cable-TV industry is obviously biased toward delivering entertainment video. These perspectives tend to color the way we think about Fiber-In-TheLoop architectures. Both perspectives, however, may be short sighted. The fact is that consumers don't really care much about our technologies or whether fiber ever comes near their door. The just want services that save them time or money or enable them to enjoy themselves. Unfortunately, consumers can't always tell us in advance exactly what services satisfy their needs. As a result many consumers just get annoyed by new technologies. Today we find ourselves in a sea of change. Communication services and the industry structure will be transformed over the next decade. In the meantime, we face having to make architectural choices without knowing the nature of the services consumers will want. A look at the most talked about revenue sources however, tells you what we are really doing by stringing fiber closer to the home. The rock solid telephone industry is about to enter the flashy media business. Media is defined not only as a channel for information and entertainment, but most importantly as a vehicle for advertising. Today, there are four primary media. The advent of Fiber-In-The-Loop is creating the infrastructure for an entirely new media, one American Demographics calls The 5th Medium. The 5th Medium will derive its power from its unique ability to direct advertising instantaneously to highly targeted consumer segments.
Loop economics (capital, operating cost, revenues, and present worth) is not well known for any loop technology, hampering deployment of new loop technologies. Local Exchange Carriers (LECs) must establish a base economic case for copper since the LECs have generally required fiber to be deployed when 'cost competitive with copper for POTS.' However, LEC management information systems do not capture copper costs in a format useful to loop planners. Results of one detailed analysis of loop economics are presented, showing loop density as key cost driver. Work in progress suggests how fiber in the loop (FITL) can be compared to copper's POTS cost, revenue and value structures. Using different revenue streams due to fiber's service enhancements, present worth analysis will demonstrate the range of loop densities that fiber may have an advantage in today.
A study is currently underway in Telecom Corporation of New Zealand (TCNZ) on the economics of providing telephony and entertainment video services to residential and small business customers via a Passive Optical Network (PON). It investigates the installed first costs, life-cycle costs, cost trends and possible timings for deployment of FITL systems in New Zealand. In this study, two variants of PON, Fiber To The Curb (FTTC) and Fiber To The Home (FTTH), are compared with a copper cable network for services and costs. The paper describes the architectures, methodology, modeling techniques, results and conclusions of the study.
The issue of powering is one of the major hindrances to general deployment of Fiber In The Loop (FITL) systems. Glass is dielectric and therefore a means to support operation of the active opto-electrical components is required. Several powering alternatives are available today and they fall in the categories of either central or local powering architectures.
This paper examines the use of probabilistic techniques for the calculation of through-losses in optical distribution networks for the transmission of Frequency Division Multiplexed (FDM) AM signals for Cable Television (CATV). Application of worst case versus statistical calculations are shown, as well as the benefits of the statistical approach. The paper provides theoretical analysis, a statistical field application, and provides the measurement results of an installed network based on this approach. The field planning calculations are compared to data measured in the deployed network, a system supplying Cable Television service to approximately 4500 subscribers via a branched fiber-optic distribution network.
To match the inherent needs of data traffic, office communications demand medium-speed connectionless packet transport in addition to circuit-switched voice and data transmission. Optical solutions to this requirement should be low in cost rather than extremely high in performance to be cost competitive with copper systems. A subscriber-premises system will be proposed which combines a digital private automatic branch exchange (PABX) with local area network (LAN) functionality. It is based on a double-star passive optical network, extending to optical wall outlets. The subsets with telephone functionality provide the opto/electrical conversion and give access to the packet channel via Terminal Adaptors (TA). Different types of customer LANs may coexist on the same network, since their data frames are embedded in an intermediate MAC-layer. The feasibility of transmission over multimode fibers at not aggregate bit rate of approx. 140 Mb/s at 1300 nm downstream and 780 nm upstream allowing the use of low-cost components (e.g. 780 nm compact-disc laser diodes) has been experimentally investigated. Calculations predict cost-of-ownership parity with conventional copper-based PABXs without LAN functionality and a cost-advantage over the usual separate LAN+PABX installations. The network topology, protocol and the implications of multimode transmission on the system will be discussed.
Results are presented from the first installed Brazilian link in which four independent optical channels operating at 1.30 and 1.52 micron have been combined using duplex-diplex wavelength-division multiplex (WDM) configuration on a standard single-mode fiber link. The optical emitters and detectors were linked to a 24 km installed single-mode route through two MUX devices. This dual-wavelength and bidirectional scheme of transmission has been installed last year in Brasilia - Brazil, and it supports commercial traffic at 34 Mbit/s ever since. Power penalties observed in previous laboratorial experiments are discussed and compared to the results obtained from the installed dual wavelength bidirectional route.
During the last years a number of FITL (Fiber-In-The-Loop) systems have been tested with the aim of providing narrowband services and distributive video signals. In this contribution we propose an advanced system able to support mobile services over the Alcatel passive optical system. Service flexibility between fixed and mobile subscribers is achieved by defining a common interface to the last-drop copper and radio base station.
In Europe, massive deployment of Fiber in the Loop (FITL) in the 1990's will require that systems meet different national standards as well as international (CCITT and ETSI) recommendations. In addition, the US based Bellcore recommendations are used as a reference by some European operating companies. A number of technical issues are under study, and data from field trials is being collected by various operating companies to aid in definition of system specifications and requirements. However, specification differences between countries will continue to exist, and arriving at general and global specifications will require detailed study of a number of issues. In this paper we examine such issues encompassing: 1-fiber and 2-fiber transmission techniques for FITL telephony systems, including Time Division Multiplexing/Time Division Multiple Access (TDM/TDMA) and Time Compression Multiplexing (TCM), optical plant requirements including backreflection and directivity requirements on passive optical network components, and the effect of FITL round trip delay (RTD) on network performance. The goal of this work is to provide an analysis of these issues in order to clarify some of the discrepancies between standardization organizations and provide operating companies a global solution for FITL.
This NYNEX internal trial was designed to test a variety of technical concepts pertaining to a true video on demand system. A three building complex was selected for the trial using coaxial and fiber optic transport systems. The trial period was approximately six weeks long with a total of eighteen movies available twenty four hours a day. A fully automated system was designed at the NYNEX Science and Technology Laboratory that incorporated video equipment and laser disk players. This system is controlled by a pair of Sun Microsystems workstations communicating via a local area network. Valuable knowledge was gained in the area of jukebox design, control systems, and menuing. Fiber optic delivery systems were investigated along with coaxial systems. The user base for this trial consisted of NYNEX employees instead of residential customers. Although the user base was not ideal, we gained insight into how people interact with a fully automated system.
An integrated services network is being developed for U.S. Government command and control aircraft. These aircraft require voice, data, and control systems to perform their missions. A future requirement for video is anticipated. The current systems' configurations are entirely point-to-point between the various pieces of equipment onboard the aircraft. A broadband network, known as the Onboard Connectivity Network (OCN), is being prototyped to consolidate communications within the aircraft. The OCN will significantly reduce aircraft weight and will simplify the process of new system integration. The initial OCN uses a unique broadband backbone topology based on a combination of single mode fiber and coaxial cable. A fiber cable interconnects active star units located in forward and aft compartments. The star units connect via fiber to coaxial conversion boxes located in each compartment. Coaxial cable interconnects network nodes within the compartments. Node configurations are being designed using a VMEbus topology. Use of VME facilitates the application of off-the-shelf interface boards and will simplify the evolution of the network to future backbone network standards. Automated workstations will be employed for network control and monitoring, voice subnetwork management, radio operations, and mission technical control.
Today's cable network is migrating from the traditional tree-and-branch topology originally designed for point-to-multipoint video entertainment to a distributed star, tree-and-branch topology with a robust, dynamic capability for a wide range of applications beyond video entertainment. One of the major research efforts at CableLabs is focused on leveraging this newly-evolving topology so that it can support multimedia applications. The cable network is positioned to deliver digital signals which will reside above analog spectrum and to provide analog and digital fiber within the same sheath. This will allow the transparent transport of multimedia applications. This paper addresses the transport and interface requirements for multimedia applications; the regional hub concept, which provides connectivity to regional and national networks; the attributes of interactivity and bi-directionality in cable's network design; and reliability and system performance over cable's infrastructure.
Advances in fiber optics, video compression and transmission technologies are driving the development and deployment of a new generation of CATV equipment. Optical fiber super- trunks are now expanding program delivery capabilities to over 150 channels and digital video compression will soon increase the capacity of existing satellite, fiber and cable systems by a factor of 5 to 10 or more. These next generation CATV systems will support Video on Demand (VOD) and advanced communications services such as broad band LAN/WAN networking and Personal Communications Services (PCS).
We demonstrate a 42 channel, low distortion, high link budget 1.55 micrometers lightwave AM- VSB CATV transport system based on modulated laser and erbium doped fiber amplifier. The link budget is enhanced by 21 db by the erbium doped fiber amplifier, an increase of 13 dB, while maintaining the carrier to noise ratio of 52 dB with a single stage amplifier. For the distortion due to the fiber amplifier (independent of carrier frequency) and fiber dispersion (linearly dependent on the carrier frequency), we employ a unique electronic compensation technique to effectively suppress the distortion to satisfy the stringent system requirement of lower than -60 dBc.
Active Optical Networks that implement a logical star topology, provide an economic way to introduce Fiber In The Loop. This network type is matched to 'service scenarios' with switched (interactive) digital video as the main revenue generating network service. These broadband services can easily be integrated with narrow-band communication services due to (de)multiplexer functionality in the network modes. Broadband scenarios of this kind will become a reality in the near future in the wake of the massive effort (especially in the USA) put in the development of high-quality, low-bit-rate digital video systems. In addition, FITL service scenarios provide business opportunities not only for the telcos but also for CATV operators.
This paper brings together three concepts which together can be applied to tomorrow's broadband, mostly digital video, networks and services. These concepts are: high speed burst transmission of digital video from storage or service centers to local access or delivery networks, use of a ATM-threaded circuit switched paths for efficient transmission of blocks of digital video, and use of quadrature amplitude modulation methods to deliver digital video and data to the home, business or institution via fiber feeders and coaxial cable or twisted pair drops. Some business enabling factors and potential social implications of broadband services to the home are summarized.