| 1. |
- Ahmed, Jawwad, et al.
(author)
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A Dynamic Bulk Provisioning Framework for Concurrent Optimization in PCE-Based WDM Networks
- 2012
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In: Journal of Lightwave Technology. - : IEEE. - 0733-8724 .- 1558-2213. ; 30:14, s. 2229-2239
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Journal article (peer-reviewed)abstract
- A centralized network control and management plane, such as the one based on a path computation element (PCE), is highly beneficial in terms of resource optimization in wavelength division multiplexing optical networks. Benefits of centralized provisioning are even more evident when connection requests are provisioned in batches, i.e., they allow a better use of network resources via concurrent optimization. In this study, a dynamic bulk provisioning framework is presented with the objective of optimizing the use of network resources that also presents, as an additional benefit, the ability to yield a reduction of the control plane overhead. The rationale behind the proposed framework is based on a mechanism in which the PCE client is allowed to bundle and simultaneously send multiple labeled switch path (LSP) requests to the PCE where, in turn, several bundles can be concurrently processed together as a single bulk. From the network deployment perspective, a PCE-based network architecture is proposed to practically realize this approach. For dynamic bulk provisioning of optical LSP requests, a time-efficient integer linear programming (ILP) model (LSP BP ILP) is presented to minimize the request blocking, the network resource consumption, and the network congestion. In addition, a heuristic based on a greedy randomized adaptive search procedure (GRASP), namely LSP_BP_GRASP, is also proposed as a scalable alternative. The presented results demonstrate significant advantages of the proposed PCE bulk provisioning framework based on concurrent optimization in terms of reduced blocking probability and control overhead when compared with conventional dynamic connection provisioning approaches processing a single connection request at a time.
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| 2. |
- Alic, N., et al.
(author)
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Joint Statistics and MLSD in Filtered Incoherent High-Speed Fiber-Optic Communications
- 2010
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 28:10, s. 1564-1572
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Journal article (peer-reviewed)abstract
- In this paper, signal statistics and their utilization for detection in narrowly filtered equalized high-speed fiber-optic communications are investigated experimentally. Tradeoffs between log-likelihood metric applications and oversampling are covered in detail. It is, for the first time, demonstrated that performance loss in bandwidth-limited systems can be nearly fully recovered (to within 0.5 dB) by taking advantage of band-width-limitation-induced noise correlations and oversampling.
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| 3. |
- Beygi, Lotfollah, 1977, et al.
(author)
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Signal Statistics in Fiber-Optical Channels with Polarization Multiplexing and Self-Phase Modulation
- 2011
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:16, s. 2379 - 2386
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Journal article (peer-reviewed)abstract
- In this paper, the statistics of received signals in a single-channel dispersion-managed dual-polarization fiber-optical channel are derived in the limit of low dispersion. The joint probability density function (pdf) of the received amplitudes and phases of such a system is derived for both lumped and distributed amplification. The new pdf expressions are used to numerically evaluate the performance of modulation formats over channels with nonlinear phase noise. For example, a sensitivity gain of up to 2 dB is calculated for a specific system using polarization-multiplexed 8-ary phase shift keying compared with a similar single-polarization system at the same spectral efficiency and a symbol error rate of 5*10^(-4). Moreover, the accuracy of the derived pdf is evaluated for some single-channel dispersion-managed fiber-optical links with different dispersion-maps using the split-step Fourier transform method.
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| 4. |
- Cavdar, Cicek, 1977-, et al.
(author)
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Shared-Path Protection With Delay Tolerance (SDT) in Optical WDM Mesh Networks
- 2010
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 28:14, s. 2068-2076
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Journal article (peer-reviewed)abstract
- Optical wavelength-division-multiplexing (WDM) networks have emerged as an ideal backbone for the dynamic transport of bandwidth-intensive applications. Most emerging applications require end-to-end survivable connections to be set up for specific time durations that have sliding or fixed setup times (such as IPTV, grid computing backup storage). It is critical for the development of future network infrastructure that user-centric, dynamic, and end-to-end management and control mechanisms are devised to bridge the gap between the transport capacity and the needs of new applications at the customer edges. In this paper, we study the problem of dynamic provisioning of user-controlled connection requests that have specified holding times and delay tolerances. Delay tolerance is a measure of customer patience, and it is defined as the duration a connection request can be held until it is set up. A connection that cannot be established at the instant of its request could potentially be set up in the remaining duration of its delay tolerance. In this study, different dynamic scheduling algorithms are developed and compared by giving priority to connections according to their arrival rates, delay tolerances, and holding times. Using a mathematical model for impatient requests and simulation experiments, we show that delay tolerance flexibility in the traffic model provides a reduction of up to 50% on blocking probability, without the use of extra backup capacity.
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| 5. |
- Chatzidiamantis, N. D., et al.
(author)
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Inverse Gaussian Modeling of Turbulence-Induced Fading in Free-Space Optical Systems
- 2011
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In: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 29:10, s. 1590-1596
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Journal article (peer-reviewed)abstract
- We propose the inverse Gaussian distribution, as a less complex alternative to the classical log-normal model, to describe turbulence-induced fading in free-space optical (FSO) systems operating in weak turbulence conditions and/or in the presence of aperture averaging effects. By conducting goodness of fit tests, we define the range of values of the scintillation index for various multiple-input multiple-output (MIMO) FSO configurations, where the two distributions approximate each other with a certain significance level. Furthermore, the bit error rate performance of two typical MIMO FSO systems is investigated over the new turbulence model; an intensity-modulation/direct detection MIMO FSO system with Q-ary pulse position modulation that employs repetition coding at the transmitter and equal gain combining at the receiver, and a heterodyne MIMO FSO system with differential phase-shift keying and maximal ratio combining at the receiver. Finally, numerical results are presented that validate the theoretical analysis and provide useful insights into the implications of the model parameters on the overall system performance.
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| 6. |
- Drummond, Miguel V., et al.
(author)
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Tunable Optical Dispersion Compensator Based on Power Splitting Between Two Dispersive Media
- 2010
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 28:8, s. 1164-1175
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Journal article (peer-reviewed)abstract
- In this paper, we propose and experimentally demonstrate a novel tunable optical dispersion compensator (TODC). Dispersion compensation is achieved by splitting the input signal between two dispersive media and adding the resulting signals thereafter. Tunable compensation is attained by controlling the power splitting ratio of the input signal between both dispersive media. The frequency response of the TODC is theoretically assessed considering signal addition in the optical and electrical domains. The latter case is enabled by using optical single side-band (OSSB) modulation, which allows preserving the phase information of dispersive media output signals after direct detection. This is the only case experimentally tested, since it avoids stability problems related with coherent addition of optical signals. A TODC with a tuning range of -340 to 0 ps/nm was designed and experimentally assessed for a 40 Gb/s nonreturn-to-zero OSSB signal. The tunable power splitter consisted of an automatic polarization controller and a polarization beam splitter, which offered a tuning time lower than 150 mu s. A bit error rate lower than 10(-8) was measured on the entire compensation range with a maximum power penalty of 3.3 dB relatively to an SSB signal in back-to-back.
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| 7. |
- Gao, Ying, et al.
(author)
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Optical Multi-Level Signal Generation Using Four-Wave-Mixing
- 2011
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:14, s. 2166-2172
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Journal article (peer-reviewed)abstract
- We propose and demonstrate a novel optical method to generate multi-level signals with reduced driving voltage through degenerate four-wave mixing processes. With the present approach, it is possible to extend the size of the signal constellations and at the same time reduce the modulator driving voltage without bandwidth degradations. In our experiments, one amplitude shift keying (ASK) signal and one differential phase shift keying (DPSK) signal are used to generate one ASK-DPSK signal with clearly opened eye-diagrams and error-free demodulation results. Our numerical simulations show that the proposed method is applicable for generating several 8-ary and 16-ary quadrature amplitude modulation (QAM) signals with silicon waveguides at a higher modulation baud rate.
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| 8. |
- Guo, Changjian, et al.
(author)
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Picosecond and Sub-Picosecond Flat-Top Pulse Shaping Using Abrupt Taper Interferometers
- 2010
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 28:6, s. 876-881
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Journal article (peer-reviewed)abstract
- A picosecond flat-top pulse shaper using an abrupt taper interferometer is proposed and experimentally demonstrated. A theoretical model based on coupled mode equations is also derived to simulate the propagation of picosecond pulses through the abrupt taper interferometer. Through properly designing the abrupt taper interferometer, a 3.8-ps flat-top pulse with less than 4% ripple is successfully generated from a 2.2-ps Gaussian pulse. The proposed technique can also be used in the sub-picosecond regime.
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| 9. |
- Johannisson, Pontus, 1976, et al.
(author)
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A Blind Phase Stabilization Algorithm for Parallel Coherent Receivers
- 2011
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:24, s. 3737-3743
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Journal article (peer-reviewed)abstract
- The impact from phase drifts in the different branches of parallel coherent receivers is investigated and it is shown how the spectrum is broadened when the receiver branches are not phase stabilized. Based on this, we propose a blind algorithm for compensating these phase drifts in digital signal processing by minimization of the spectral width. The algorithm performance is then evaluated by numerical simulations of quadrature phase-shift keying data using return-to-zero modulation. It is found that the algorithm is capable of identifying the phases with sufficient accuracy to make the residual effect of the phase mismatches negligible compared to the signal distortion by noise at a bit error rate of 0.001.
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| 10. |
- Johannisson, Pontus, 1976, et al.
(author)
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Perturbation Analysis of Nonlinear Propagation in a Strongly Dispersive Optical Communication System
- 2013
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 31:8, s. 1273-1282
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Journal article (peer-reviewed)abstract
- We discuss an analytical model that predicts the impact of the Kerr nonlinearity in optical communication systems when the signal spectrum is wide and the accumulated dispersion during propagation is large. A detailed derivation of this model is given for a generalized system by means of a perturbation analysis of the Manakov equation with attenuation, gain, and third order dispersion included. As in the case with previous studies, three simplifying assumptions are necessary. These are that (i) the nonlinearity is weak, (ii) the input signal is of a given specific form, and (iii) the signal-noise interaction can be neglected. Under these assumptions, the result is found exactly. We also discuss the accuracy of the analytical result and show that third order dispersion has a small impact in practice.
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