200 S Laurel Ave - Bldg A
Middletown, NJ
Shared Mesh Restoration in ROADM Based Service Velocity Network
Inwoong Kim, Paparao Palacharla, Xi Wang, Qiong Zhang, Daniel Bihon, Mark Feuer, Sheryl Woodward
OFC/NFOEC 2013,
2013.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in 2012. , Issue NW4I.3, 2013-03-17
{Simulations of shared mesh restoration in a backbone network supporting rapid provisioning show up to 27% fewer regenerators than dedicated protection, plus ~40% increase in capacity. Regenerator site concentration and minimum-regenerator routing provide best results.}
ROADM options in optical networks: flexible grid or not?
Sheryl Woodward
OFC/NFOEC 2013,
2013.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in 2012. , Volume OTh3B.1, 2013-03-17
{Flexible-grid networks are attractive because they claim greater spectral efficiency and the ability to accommodate future modulation formats that may need wider channel bandwidths. We compare flexible-grid networks to alternative approaches.}
Cost Optimization Using Regenerator Site Concentration and Routing in ROADM Networks
Rakesh Sinha, Angela Chiu, Mark Feuer, Guangzhi Li, Sheryl Woodward, Weiyi Zhang, Balagangadhar G Bathula, Keren Bergman, Robert Doverspike, Peter Magill
DRCN 2013,
2013.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in 2012. , 2013-03-04
{The advent of colorless and non-directional reconfigurable
optical-add-drop multiplexers (ROADMs) will enable
flexible pre-deployment of optoelectronic regenerators in future
optical networks. Compared to the current practice of installing
regenerators only when a circuit needs them, pre-deployment
will allow service providers to achieve rapid provisioning and
restoration. The pre-deployed regenerators should be concentrated
in a selected subset of ROADM sites in order to attain high
utilization and to reduce operational costs. We prove that the
resulting optimization problem is NP-hard and present an efficient
heuristic for this problem that takes into account both the cost of
individual circuits (regenerator cost and transmission line system
cost) and the probability of a given circuit request, as well as
the number of regenerator sites. We provide various methods
to reduce the number of regenerator sites, if low probability
demands are allowed to have slightly costlier paths. Specific
network examples show that the proposed heuristic has near
optimal performance under most studied scenarios. We present
results for several different cost models. We have also evaluated
the heuristic for survivable optical networks, in which a second,
disjoint path must be supported for each circuit.}
Simulations of a Service Velocity Network Employing Regenerator Site Concentration
Mark Feuer, Balagangadhar Bathula, Daniel Bihon, Angela Chiu, Inwoong Kim, Guangzhi Li, Paparao Palacharla, Rakesh Sinha, Xi Wang, Sheryl Woodward, Weiyi Zhang
OFC/NFOEC2012 conference,
2012.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in OFC/NFOEC2012 conference. , 2012-03-04
{We use Monte Carlo simulations of quasi-static traffic growth to study concentration of regenerator sites in dynamic photonic networks supporting service velocity. Idle regenerators can be reduced by >60% compared to unrestricted regeneration sites.}
On Concentrating Regenerator Sites in ROADM Networks
Rakesh Sinha, Angela Chiu, Guangzhi Li, Weiyi Zhang, Mark Feuer, Sheryl Woodward, Balagangadhar G. Bathula, Keren Bergman, Inwoong Kim, Paparao Palacharla
OFC/NFOEC2012 conference,
2012.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in OFC 2012. , 2012-03-04
{Concentrating optical regenerators in a subset of network nodes provides significant savings. We present a
heuristic for choosing this subset. Our results are within 1 or 2 of optimal in the studied cases.}
Joint Digital Signal Processing Receivers for Spatial Superchannels
Mark Feuer, Lynn Nelson, Xiang Zhou, Sheryl Woodward, Rejoy Isaac, Benyuan Zhu, Thierry F. Taunay, Michael Fishteyn, John F. Fini, Man F. Yan
IEEE Photonics Technology Letters,
2012.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in 2012. , Volume 24, Issue 21, 2012-11-01
{We discuss the advantages of spatial superchannels for future terabit networks based on space division multiplexing (SDM), and demonstrate reception of spatial superchannels by a coherent receiver utilizing joint digital signal processing (DSP). In a spatial superchannel, the SDM modes at a given wavelength are routed together, allowing simplified design of both transponders and optical routing equipment. For example, common-mode impairments can be exploited to streamline the receiver’s DSP. Our lab measurements reveal that the phase fluctuations between the cores of a multicore fiber are strongly correlated, and therefore constitute such a common-mode impairment. We have implemented master-slave phase recovery of two simultaneous 112Gbps subchannels in a 7-core fiber, demonstrating reduced processing complexity with no increase in the bit-error ratio. Furthermore, we have investigated the feasibility of applying this technique to subchannels carried on separate single-mode fibers, a potential transition strategy to evolve today’s fiber networks toward future networks using multicore fibers.}
Demonstration of Joint DSP Receivers for Spatial Superchannels
Mark Feuer, Lynn Nelson, Xiang Zhou, Sheryl Woodward, Rejoy Isaac, B. Zhu, T. F. Taunay, M. Fishteyn, J. F. Fini, M. F. Yan
IEEE Photonics Summer Topicals 2012 conference,
2012.
[PDF]
[BIB]
IEEE Copyright
The definitive version was published in 2012. , 2012-07-09
{We report lab measurements of joint digital signal processing of simultaneous 112Gbps links in a 7-core fiber. Strongly-correlated phase fluctuations between the cores permit reduced processing complexity with no increase in the bit-error ratio.}
Advanced ROADM Networks
Mark Feuer, Sheryl Woodward
OFC/NFOEC2012 conference,
2012.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in OFC/NFOEC2012 conference. , 2012-03-04
{We discuss the growing list of features being proposed for reconfigurable optical add/drop multiplexers (ROADMs), including colorless, directionless, contentionless, and gridless operation. Is �less� always more for network operators?}
Research Highlights: Optical Systems Research at AT&T Labs
Martin Birk, Mikhail Brodsky, Mark Feuer, Patrick Iannone, Peter Magill, Jonathan Nagel, Lynn Nelson, Kenneth Reichmann, Sheryl Woodward, Xiang Zhou
IEEE Photonics Newsletter,
2011.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in IEEE Photonics Newsletter. , 2011-07-01
{}
Intra-Node Contention in Dynamic Photonic Networks
Mark Feuer, Sheryl Woodward, Paparao Palacharla, Xi Wang, Inwoong Kim, Daniel Bihon
IEEE J. Lightwave Technology,
2011.
[BIB]
{Dynamic photonic networks rely on colorless, non-directional Reconfigurable Optical Add/Drop Multiplexer (ROADM) nodes to enable rapid re-routing of wavelength channels without optoelectronic conversion. We report numerical simulations of the wavelength contention that can occur in such multi-degree ROADM nodes. Intra-node blocking rates and transponder utilization are computed for node designs with and without a client-side fiber cross-connect, and both are compared to results predicted for an ideally contention-free ROADM.}
Bandwidth on Demand for Inter-Data Center Communication
Ajay Mahimkar, Robert Doverspike, Emmanuil Mavrogiorgis, Jorge Pastor, Jennifer Yates, Mark Feuer, Sheryl Woodward, Peter Magill, Angela Chiu
ACM SIGCOMM Workshop on Hot Topics in Networks,
2011.
[PDF]
[BIB]
ACM Copyright
(c) ACM, 2011. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM SIGCOMM Workshop on Hot Topics in Networks , 2011-10-15.
{Cloud service providers use replication across geographically distributed data centers to improve end-to-end performance as well as to offer high reliability under failures. Content replication often involves the transfer of huge data sets over the wide area network and demands high backbone transport capacity. In this paper, we discuss how a Globally Reconfigurable Intelligent Photonic Network (GRIPhoN) between data centers could improve operational flexibility for cloud service providers. The proposed GRIPhoN architecture is an extension of earlier work [34] and can provide a bandwidth-on-demand service ranging from low data rates (e.g., 1 Gbps) to high data rates (e.g., 10-40 Gbps). The inter-data center communication network which is currently statically provisioned could be dynamically configured based on demand. Today's backbone optical networks can take several weeks to provision a customer's private line connection. GRIPhoN would enable cloud operators to dynamically set up and tear down their connections (sub-wavelength or wavelength rates) within a few minutes. GRIPhoN also offers cost-effective restoration capabilities at wavelength rates and automated bridge-and-roll of private line connections to minimize the impact of planned maintenance activities.}
Capabilities of Real-Time Digital Coherent Transceivers
Lynn Nelson, Sheryl Woodward
2010 European Conference on Optical Communication,
2010.
[BIB]
{We discuss the capabilities inherent in digital coherent transceivers that make them attractive for core networks. The desirable attributes of these transceivers are presented, from a transmission perspective and from a network perspective, as are future design challenges. }
A regression approach to infer electricity consumption of legacy telecom equipment
Steven Phillips, Sheryl Woodward, Mark Feuer, Peter Magill
ACM SIGMETRICS Performance Evaluation Review,
2010.
[PDF]
[BIB]
ACM Copyright
(c) ACM, 2010. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution.
The definitive version was published in ACM GreenMetrics Workshop , Volume 38, Issue 3, 2010-10-10.
{Information and communications technology accounts for
a significant fraction of worldwide electricity consumption.
Given the relentless growth of demand for communications
services, telecommunications providers will need to transition
to more energy-efficient technology in order to limit
their environmental impact. Here we focus on priority-setting
for the transition process. In particular, we introduce a
method for statistically inferring the electricity consumption
of different components of the installed base of telecommunications
equipment, while avoiding the high cost of performing
direct measurements. Our method relies only on
databases of installed equipment in central offices, together
with aggregate electricity consumption per office. It takes
advantage of inter-office variation in installed equipment to
partition per-office electricity consumption by major equipment
type. When applied to a collection of 3,918 central
offices of a major U.S. telecommunications provider, our approach
reveals the (previously unknown) network-wide energy
consumption of each major type of equipment. In particular,
we find that electricity consumption is dominated by
Class-5 telephone switches, which account for 43% of aggregate
consumption, and which should therefore be a primary
target of central office electricity conservation efforts.}
Tunable Bidirectional Multiplexer/DeMultiplexer For Optical Transmission System,
Tue Mar 06 16:09:30 EST 2012
A tunable bidirectional multiplexer/demultiplexer (MUX/DEMUX) is disclosed for adding and dropping wavelength channels between an optical transmission system and at least one optical transceiver. The MUX/DEMUX includes at least one add port for adding wavelength channels, at least one drop port for dropping wavelength channels, and at least one first optical circulator coupled to the at least one drop port and the at least one add port. The MUX/DEMUX further includes at least one 1.times.N wavelength-selective switch coupled to the at least one first optical circulator, and at least one second optical circulator coupled to at least one transceiver port on a second side of the at least one wavelength-selective switch, where the optical circulators and switching components are disposed within a common housing. The at least one wavelength-selective switch and ports are configured such that an optical signal communicated from the at least one transceiver port to the at least one add port follows a first optical path, and an optical signal communicated from the at least one drop port to the at least one transceiver port follows a second optical path, where a portion of the first and second optical paths are the same.
Receive Device For A Cable Data Service,
Tue Aug 16 16:05:59 EDT 2011
A receive device includes a plurality of demodulators and a tunnel destination. The demodulators are configured to receive multiple data streams, each of the multiple data streams having a bit rate that is lower than a bit rate of a transmit data stream. The tunnel destination is configured to recombine the multiple data streams to provide a receive data stream having a bit rate equal to the bit rate of the transmit data stream. At least one of multiple radio frequency channels is connected to a legacy user between a transmit site and the receive device.
Fiber Access Architecture Capable Of Being Seamlessly Upgraded,
Tue Jan 04 16:04:18 EST 2011
Disclosed is an architecture enabling premium services to be provided over fiber to high-end users/customers. This architecture has a plurality of nodes and a passive optical device inserted prior to one of the nodes. The optical device allows wavelengths provisioned for original service(s) to pass through with minimal loss, while other wavelengths provisioned for the premium services are diverted onto a new fiber. This new fiber may be installed at the time of the upgrade, but, sometimes, dark fiber is available. Dark fiber is fiber that carries no optical signals.
Fiber And Wire Communication System,
Tue Nov 09 15:05:00 EST 2010
This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node. The mux-node may route upstream communication signals received from the mini-fiber nodes as downstream signals to other mini-fiber nodes also connected to the mux-node without head-end interaction.
Fiber And Wire Communication System,
Tue Aug 24 15:04:29 EDT 2010
This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node. The mux-node may route upstream communication signals received from the mini-fiber nodes as downstream signals to other mini-fiber nodes also connected to the mux-node without head-end interaction.
Fiber/Wired Communication System,
Tue Jun 08 15:04:00 EDT 2010
A communication system between head-ends and end-users is provided which expands bandwidth and reliability. A concentrator receives communication signals from a head-end and forwards the received communication signals to one or more fiber nodes and/or one or more mini-fiber nodes. The concentrator demultiplexes/splits received signals for the mini-fiber nodes and the fiber nodes and forwards demultiplexed/split signals respectively. The mini-fiber nodes may combine signals received from the head-end with loop-back signals used for local medium access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and/or fiber node and transmitted to the concentrator. The concentrator multiplexes/couples the mini-fiber node and the fiber node upstream signals and forwards multiplexed/coupled signals to the head-end. Communication signals received from the mini-fiber nodes that are destined to other end-users also connected to the mini-fiber nodes may be routed by the concentrator without head-end interaction.
Fiber and wire communication system,
Tue Nov 11 18:13:10 EST 2008
This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node. The mux-node may route upstream communication signals received from the mini-fiber nodes as downstream signals to other mini-fiber nodes also connected to the mux-node without head-end interaction.
Fiber access architecture capable of being seamlessly upgraded,
Tue Jul 01 18:12:56 EDT 2008
Disclosed is an architecture enabling premium services to be provided over fiber to high-end users/customers. This architecture has a plurality of nodes and a passive optical device inserted prior to one of the nodes. The optical device allows wavelengths provisioned for original service(s) to pass through with minimal loss, while other wavelengths provisioned for the premium services are diverted onto a new fiber. This new fiber may be installed at the time of the upgrade, but, sometimes, dark fiber is available. Dark fiber is fiber that carries no optical signals.
Fiber and wire communication system,
Tue Oct 16 18:12:18 EDT 2007
This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node. The mux-node may route upstream communication signals received from the mini-fiber nodes as downstream signals to other mini-fiber nodes also connected to the mux-node without head-end interaction.
Fiber and wire communication system,
Tue Mar 13 18:11:57 EDT 2007
This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node. The mux-node may route upstream communication signals received from the mini-fiber nodes as downstream signals to other mini-fiber nodes also connected to the mux-node without head-end interaction.
System for mitigating the effects of fiber dispersion by separate detection of two transmitted sidebands,
Tue Oct 24 18:11:40 EDT 2006
Link robustness, chromatic dispersion and polarization mode dispersion (PMD) immunity can be improved in fiber optical system by using a method for receiving an optical double sideband signal over an optical fiber system, comprising the steps of splitting the received optical double sideband signal into an upper sideband signal and a lower sideband signal, photodetecting the upper sideband and the lower sideband, equalizing the photodetected upper sideband signal and the lower sideband signal, and combining the equalized upper sideband signal with the equalized lower sideband signal. While PMD compensation is envisioned as a major application, one may also use the method and system for chromatic dispersion compensation or dispersion slope compensation in high bit rate systems, i.e. using dispersion compensation fiber (DCF) for coarse compensation and diversity receiver with electrical equalizer for fine tuning.
Fiber access architecture capable of being seamlessly upgraded,
Tue Aug 22 18:11:31 EDT 2006
Disclosed is an architecture enabling premium services to be provided over fiber to high-end users/customers. The architecture has a plurality of nodes and a passive optical device inserted prior to one of the nodes. The optical device allows wavelengths provisioned for original service(s) to pass through with minimal loss, while other wavelengths provisioned for the premium services are diverted onto a new fiber. This new fiber may be installed at the time of the upgrade, but, sometimes, dark fiber is available. Dark fiber is fiber that carries no optical signals.
System and method for monitoring and controlling light propagation in an optical transmission system,
Tue Jun 27 18:11:21 EDT 2006
According to the present invention, a system and method provides for monitoring and controlling light propagation in optical transmission systems. The system either includes an optical circulator coupled to an optical add mechanism and is used to detect light propagation, or an optical monitoring device is coupled to the optical circulator and to the optical add device via a feedback path to control light propagation.
Fiber and wire communication system,
Tue Jun 27 18:11:20 EDT 2006
This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node. The mux-node may route upstream communication signals received from the mini-fiber nodes as downstream signals to other mini-fiber nodes also connected to the mux-node without head-end interaction.
Fiber-optic access network utilizing CATV technology in an efficient manner,
Tue Feb 28 18:10:59 EST 2006
A system is provided for combining conventional HFC plants with fiber-optic access systems (e.g., fiber-to-the-home or fiber-to-the-curb) that share a head-end and other equipment. A robust modulation format, such as QPSK, having a sufficient SNR to transmit information (e.g., data, digital audio and digital video) downstream to users' premises via a fiber-optic access system is used. Also, a method and apparatus is provided for converting a first modulation format for information received via a fiber-optic access system to a modulation format compatible with customer premises equipment.
Cable data service method,
Tue Jan 31 17:08:41 EST 2006
A method for sending data from a transmit site to a receive site which includes dividing a transmit data stream having a first bit rate into multiple data streams with each of the multiple data streams having a bit rate which is lower than the first bit rate, transmitting each of the multiple data streams over a plurality of RF channels and recombining the multiple data streams at the receive site to provide a receive data stream having a bit rate equal to the first bit rate.
Transmit and receive system for cable data service,
Tue Jan 31 17:08:40 EST 2006
A transmit and receive system for transmitting data between a transmit site and a receive site. The system includes a tunnel source, router and modulator for dividing a transmit data stream having a first bit rate into multiple data streams with each of the multiple data streams having a bit rate which is lower than the first bit rate, transmitting each of the multiple data streams over a plurality of RF channels. The system further includes a demodulator and destination source for recombining the multiple data streams at the receive site to provide a receive data stream having a bit rate equal to the first bit rate.
Diversity Receiver For Mitigating The Effects Of Fiber Dispersion By Separate Detection Of Two Transmitted Sidebands,
Tue Oct 25 18:10:36 EDT 2005
Link robustness, chromatic dispersion and polarization mode dispersion (PMD) immunity can be improved in fiber optical system by using a method for receiving an optical double sideband signal over an optical fiber system, comprising the steps of splitting the received optical double sideband signal into an upper sideband signal and a lower sideband signal, photodetecting the upper sideband and the lower sideband, equalizing the photodetected upper sideband signal and the lower sideband signal, and combining the equalized upper sideband signal with the equalized lower sideband signal. While PMD compensation is envisioned as a major application, one may also use the method and system for chromatic dispersion compesation or dispersion slope compensation in high bit rate systems, i.e. using dispersion compensation fiber (DCF) for coarse compensation and diversity receiver with electrical equalizer for fine tuning.
Fiber and wire communication system,
Tue Jun 15 18:09:48 EDT 2004
This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node. The mux-node may route upstream communication signals received from the mini-fiber nodes as downstream signals to other mini-fiber nodes also connected to the mux-node without head-end interaction.
Method and system for single-sideband optical signal generation and transmission,
Tue Dec 09 18:08:55 EST 2003
A method and system for generating and transmitting optical signals with only one sideband. Single-sideband optical signal transmission reduces the signal impairment effects associated with dispersion. Such transmission also increases the spectral efficiency of optical transmission systems. Single-sideband modulation also makes possible electrical compensation for optical link dispersion during transmission. Single-sideband modulation is generated using the modulating data signal and its Hilbert transform, which is approximated by a tapped-delay time filter. Line coding is used to remove the low-frequency content in the modulating data signal, avoiding the inefficiencies of tapped-delay-line filter approximated Hilbert transformers at low frequencies. Line coding can also help optical single side band signal generation and transmission using a simple optical filter instead of Hilbert transformers.
Fiber/wired communication system,
Tue Nov 25 18:08:53 EST 2003
A communication system between head-ends and end-users is provided which expands bandwidth and reliability. A concentrator receives communication signals from a head-end and forwards the received communication signals to one or more fiber nodes and/or one or more mini-fiber nodes. The concentrator demultiplexes/splits received signals for the mini-fiber nodes and the fiber nodes and forwards demultiplexed/split signals respectively. The mini-fiber nodes may combine signals received from the head-end with loop-back signals used for local medium access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and/or fiber node and transmitted to the concentrator. The concentrator multiplexes/couples the mini-fiber node and the fiber node upstream signals and forwards multiplexed/coupled signals to the head-end. Communication signals received from the mini-fiber nodes that are destined to other end-users also connected to the mini-fiber nodes may be routed by the concentrator without head-end interaction.
Method And Device For Broadcasting Signals Over A Wavelength-Division Multiplexed Network,
Tue Aug 19 18:08:50 EDT 2003
The optical device is located at a node connected of an optical network. The optical device receives optical signals, each received signal having a different wavelength. The optical device comprises a wavelength-selective optical tap that selectively drops a first portion of the optical power of a received optical signal having a specific wavelength. The optical device also optically conveys the optical signal having the specific wavelength to a next node, the conveyed optical signal having a second portion of the optical power of the received optical signal having the specific wavelength.
Method and system for providing low-cost high-speed data services,
Tue Dec 10 18:08:33 EST 2002
A communication network uses intermediate nodes to resolve local traffic contention. Intermediate nodes receive upstream signals from end users, derive traffic information signals from the upstream signals, and transmit the traffic information signals to end users. By listening to the traffic information signals from the intermediate node, the end users know whether the upstream transmission channels are idle or busy, or whether a collision has occurred. The intermediate nodes derive and transmit the traffic information signals with or without the assistance of the central office or head end.
Passive optical network using a fabry-perot laser as a multiwavelength source,
Tue Apr 30 18:07:54 EDT 2002
A passive optical network (PON) comprises an optical device for producing light at a plurality of optical frequencies, an optical receiver for receiving light produced by the optical device, and a wavelength division multiplexer for transmitting the light produced by the optical device to the optical receiver, the wavelength division multiplexer having passbands centered at respective center frequencies, the center frequencies being different than the optical frequencies.
Bi-directional optical transmission system,
Tue Jan 15 18:07:21 EST 2002
A bi-directional optical transmission system provides communications between at least two locations over a single optical fiber. The transmitters at the respective locations are defined to have different optical spectra characteristics to avoid production of optical beat interference.
Semiconductor optical amplifier with adjustable gain,
Tue Jun 19 18:07:06 EDT 2001
A semiconductor optical amplifier includes an optical signal input and an active section surrounded by two mirrors. A current is applied to the second mirror, for example by a current generator. Thus, the central wavelength of the reflection range of the second mirror is modifiable, the loss of the semiconductor-optical amplifier is changeable and the gain of the amplifier is adjustable.
Current control for an analog optical link,
Tue Oct 05 18:05:23 EDT 1999
A control circuit for an injection laser provides a pre-bias current which prevents clipping induced errors in the laser output. An analog modulating signal is provided directly to the laser which receives the sum of a feedback current (Ifb) and a current source (Io) as the pre-bias current (Ipb). A monitor diode detects the laser light output and provides a current (Idet). A feedback circuit operates in a limited dynamic range, e.g. I.sub.l +/-40 mA or is incapable of outputting a negative current (Ifb>0). The feedback circuit responds to changes in Idet and adjusts the laser pre-bias current to hold Idet equal to a preset value, which effectively holds the laser's average output power constant. If the pre-bias current necessary to hold Idet fixed falls below some minimum level, Imin, the feedback circuit will run out of dynamic range and the laser's average power will increase. By preventing Ipb from falling below Imin clipping induced errors and distortion are avoided.
Network Apparatus And Method To Provide Compressed Digital Video Over Mini-Fiber Nodes,
Tue Sep 28 18:05:22 EDT 1999
Previously mini-fiber-node technology (see patent # 5,864,672) had been proposed to upgrade existing cable TV systems to provide bi-directional broadband capabilities. This patent covers how the mFN's can simultaneously add additional broadcast and narrowcast digital video services to existing CATV plant.
Transmission of CDMA Signals Over an Analog Optical Link,
Tue Aug 10 18:05:14 EDT 1999
As demand for wireless telephony increases the capacity of these systems needs to be increased. One way to do this is to deploy more antennas. It was previously known that there are advantages to transmitting the signals from the antennas to a centralized base station, where the system's performance can be optimized. An inexpensive optical link can transmit these signals without degrading signal quality if the RF current driving the laser transmitter is kept above a predetermined level, so that the dynamic range of the link is optimized. A method of testing the optical link is presented which avoids the expense of using a real CDMA system to test each link.
System for Converter for Providing Downstream Second FDM Signals Over Access Path and Upstream FDM Signals Sent to Central Office over the Second Path,
Tue Jan 26 18:05:08 EST 1999
Using low-cost, analog-lightwave transmission, and RF technology, this invention increases the ability of CATV networks to provide two-way, broadband services. This approach provides far greater bandwidth per user than traditional upgrades to CATV systems, yet remains cost-effective. Optical fibers are run from a central hub to mini-Fiber Nodes. The mini-Fiber nodes are adjacent to each coaxial amplifier, so that the connectin from the mini-Fiber Node to the home is over passive coaxial cable.
