Verizon Laboratories

Waltham, MA, United States

Verizon Laboratories

Waltham, MA, United States
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Magarini M.,Polytechnic of Milan | Essiambre R.-J.,Alcatel - Lucent | Basch B.E.,Verizon Laboratories | Ashikhmin A.,Alcatel - Lucent | And 2 more authors.
IEEE Photonics Technology Letters | Year: 2010

The use of trellis-coded modulation (TCM) in combination with an outer block code is considered for next-generation 100-Gb/s optical transmission systems. Two block codes are employed as an outer code: a 16 times interleaved byte-oriented (255,239) Reed Solomon (RS) code and a code consisting of two interleaved extended three-error correcting Bose Chaudhuri Hocquenghem (BCH) (1020,988) codes. Simulations show that soft-decision decoding of a selected TCM inner code in combination with hard-decision decoding of the outer RS code achieves a net coding gain (NCG) of 8.42 dB at a bit-error rate of 10 -13. When the concatenated code based on the two interleaved BCH codes is used as the outer code, the NCG is 9.7 dB. The impact of quantization on the performance of the concatenated TCM scheme with the two interleaved BCH outer codes is evaluated, and it is shown that 4-bit quantization is sufficient to approach the infinite precision performance to within 0.15 dB. © 2006 IEEE.


Gringeri S.,Verizon Laboratories | Bitar N.,Verizon Laboratories | Xia T.,Verizon Laboratories
IEEE Communications Magazine | Year: 2013

Software defined networks are based on the principle of a centralized control plane separated from the network forwarding or switching plane that it controls. The switching plane can be heterogeneous, composed of network elements from multiple vendors, and it can provide distinct services with different characteristics, configurations, and control at the packet and/or optical layers. Abstracting the control plane from the network elements allows network-platform- specific characteristics and differences that do not affect services to be hidden. In addition, software defined networking (SDN) is based on the principle that applications can request needed resources from the network via interfaces to the control plane. Through these interfaces, applications can dynamically request network resources or network information that may span disparate technologies. For instance, the application layer can dynamically request and obtain network resources at the packet flow, circuit, or even optical level based on application layer requirements. Current SDN implementations focus on Ethernet switching primarily for data center resource optimization. This article reviews the benefits and challenges of extending SDN concepts to various transport network architectures that include optical wavelength and fiber switches, circuit switches, and sub-wavelength optical burst switches. Control plane implementations for optical networks are more complex since they must account for physical constraints including optical signal reachability, bandwidth availability and granularity, light path routing, and light path reconfiguration speed. The longterm goal is to apply SDN concepts across multi-layer multivendor networks in order to support a unified control structure. © 1979-2012 IEEE.


Bitar N.,Verizon Laboratories | Gringeri S.,Verizon Laboratories | Tiejun J.X.,Verizon Laboratories
IEEE Communications Magazine | Year: 2013

Data center and cloud architectures continue to evolve to address the needs of large-scale multi-tenant data centers and clouds. These needs are centered around seven dimensions: scalability in computing, storage, and bandwidth, scalability in network services, efficiency in resource utilization, agility in service creation, cost efficiency, service reliability, and security. This article focuses on the first five dimensions as they pertain to networking. Large data centers are targeting support for tens of thousands of servers, exabytes of storage, terabits per second of traffic, and tens of thousands of tenants. In a data center, server and storage resources are interconnected with packet switches and routers that provide for the bandwidth and multi-tenant virtual networking needs. Data centers are interconnected across the wide area network via routing and transport technologies to provide a pool of resources, known as the cloud. High-speed optical interfaces and dense wavelength-division multiplexing optical transport are used to provide for high-capacity transport intra-and inter-datacenter. This article reviews various switching, routing, and optical transport technologies, and their applicability in addressing the networking needs of large-scale multi-tenant data centers. © 2013 IEEE.


Egorov R.,Verizon Laboratories
National Fiber Optic Engineers Conference, NFOEC 2013 | Year: 2013

Next Generation ROADM design that supports Colorless Directionless and Contentionless (CDC) architecture and supports Flexible grid is described. Benefits of CDC Flexible grid ROADM architecture are discussed. Tradeoffs between different aspects of design are presented. © 2013 Optical Society of America.


Gringeri S.,Verizon Laboratories | Basch E.B.,Verizon Laboratories | Xia T.J.,Verizon Laboratories
IEEE Communications Magazine | Year: 2012

As traffic demands continue to grow, supporting data rates beyond 100 Gb/s will be required to increase optical channel capacity and support higher-rate client interfaces. Advanced modulation formats that adapt to optimize spectral efficiency over a range of channel signal-tonoise ratio conditions are required. Channels can be constructed by varying parameters such as symbol rate, bits per symbol, number of polarizations, and number of optical and electrical subcarriers. Channel capacity can also be increased using advanced techniques such as optical time-division multiplexing, and fibers that support multiple cores and modes. Many channel designs can support higher data rates, but there are trade-offs between complexity, spectral efficiency, and optical reach. © 2012 IEEE.


Xia T.J.,Verizon Laboratories | Gringeri S.,Verizon Laboratories | Tomizawa M.,NTT
IEEE Communications Magazine | Year: 2012

Network traffic demands are forecast to increase for the foreseeable future, with the challenge being to meet the demand while maintaining or lowering network costs. Simply increasing capacity will not be sufficient; overall bandwidth utilization also needs to improve. A combination of improved transport capacity through increased spectral efficiency and bit rate along with better network utilization by integrating subchannel electrical grooming into the transmission system will be required. Smarter ways to utilize optical capacity are key since transmission costs have been decreasing slower than grooming and switching costs. Integrated transport and switching can improve the efficiency of the client network using techniques such as port virtualization and transit traffic reduction. The baseline for transport networks will be 100 Gb/s PM-QPSK using 50 GHz channel spacing. Moving from a fixed DWDM channel arrangement to support flexible grid and super channels will allow tighter channel (carrier) spacing and should increase capacity by 30 to 50 percent. For shorter distances higher-order modulation such as 16-QAM can double network capacity. To better optimize network efficiency, an architecture that flexibly combines lower rate (sub-100 Gb/s) clients to form channels (carriers) and then superchannels will be required. © 2012 IEEE.


Conway A.E.,Verizon Laboratories
IEEE/ACM Transactions on Networking | Year: 2011

A fast simulation technique based on importance sampling is developed for the analysis of path service availability in mesh networks with dynamic path restoration. The method combines the simulation of the path rerouting algorithm with a dynamic path failure importance sampling (DPFS) scheme to estimate path availabilities efficiently. In DPFS, the failure rates of network elements are biased at increased rates until path failures are observed under rerouting. The simulated model uses failure equivalence groups, with finite/infinite sources of failure events and finite/infinite pools of repair personnel, to facilitate the modeling of bidirectional link failures, multiple in-series link cuts, optical amplifier failures along links, node failures, and more general geographically distributed failure scenarios. The analysis of a large mesh network example demonstrates the practicality of the technique. © 2010 IEEE.


Detwiler T.F.,Georgia Institute of Technology | Searcy S.M.,Georgia Institute of Technology | Ralph S.E.,Georgia Institute of Technology | Basch B.,Verizon Laboratories
Journal of Lightwave Technology | Year: 2011

Advances in photonics, silicon electronics and digital signal processing (DSP) have converged to enable highly efficient transmission across fiber optic channels. Single wavelength data rates of 112 Gb/s are sought for wide deployment based on QPSK transmission, coherent detection, and digital demodulation. Here we examine continuous phase modulation (CPM) as a means to enhance performance and reach of coherent optical links. We quantify the robustness of the constant amplitude CPM format to spectral filtering and nonlinearities in comparison to QPSK. The challenges of generating and receiving the CPM waveform are considered and a novel CPM transmitter architecture is proposed. © 2011 IEEE.


Rahn J.,Infinera Corporation | Sun H.,Infinera Inc. | Wu K.-T.,Infinera Inc. | Basch B.E.,Verizon Laboratories
Journal of Lightwave Technology | Year: 2012

We present real-time polarization mode dispersion (PMD) tolerance measurement results with a commercially available 500 Gb/s coherent modem. The first- and second-order PMD space is explored, showing that peak values of 500 ps of static, first-order PMD (differential group delay) have small penalties. The system was stressed using fast scrambling, with polarization change of over 10000 rad/s, along with high mean PMD. Penalties were small with sufficient equalization. © 1983-2012 IEEE.


Gringeri S.,Verizon Laboratories | Basch B.,Verizon Laboratories | Shukla V.,Verizon Laboratories | Egorov R.,Verizon Laboratories | Xia T.,Verizon Laboratories
IEEE Communications Magazine | Year: 2010

Flexibility to support mesh topologies, dynamic capacity allocation, and automated network control and light path setup are key elements in the design of next-generation optical transport networks. To realize these capabilities, reconfigurable optical add/drop multiplexers with dynamic add/drop structures, embedded control planes, and lightpath characterization are required. This article presents the architectures and various ROADM implementations including colorless, directionless, and contentionless add/drop structures. The effect of scaling bit rates beyond 100 Gb/s on ROADM architectures is reviewed including providing variable channel bandwidth depending on bit rate. Automated provisioning and restoration using the GMPLS control plane and optical measurement approaches for lightpaths are also discussed. © 2006 IEEE.

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