| 1. |
- Rabbani, Hami, et al.
(författare)
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Improving the Achievable Rates of Optical Coherent Transmission with Back-Propagation
- 2018
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 30:14, s. 1273-1276
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Tidskriftsartikel (refereegranskat)abstract
- The power allocation in wavelength-division multi- plexed (WDM) fiber-optic links with digital back-propagation (BP) is optimized in order to improve the achievable rates (AR). The power allocation is performed using a convex optimization technique based on a modulation-format-dependent time-domain model capable of including the nonlinear Kerr effects. In a fully loaded WDM link with heterogeneous (uneven) nonlinear interference noise (NLIN) spectrum, the AR gain of nonlinear BP over linear electronic dispersion compensation is 60% larger if per-channel power optimization is allowed than if all transceivers use an equal (flat) optimized power. The heterogeneous NLIN spectrum results from performing BP on a subset of the channels. However, the gain of per-channel power optimization disappears for the homogeneous (nearly flat) NLIN spectrum. Moreover, we show that the improvement obtained by joint channel power allocation is more pronounced for links with a larger number of spans.
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| 2. |
- Rabbani, Hami, et al.
(författare)
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Quality of Transmission Aware Optical Networking Using Enhanced Gaussian Noise Model
- 2019
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 37:3, s. 831-838
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Tidskriftsartikel (refereegranskat)abstract
- We present a new joint routing, wavelength, and power allocation method for optical network planning. The introduced gradient-based convex optimization approach has a lower computational complexity, compared to common linear programming techniques, suitable for both static as well as time-critical dynamic network planning with fast convergence requirement. The proposed scheme takes physical-layer impairments into account, using the enhanced Gaussian noise nonlinear model. In contrast to methods exploiting the theoretical full link spectrum utilization assumption (fully occupied fiber-optic C-hand spectrum), we focus on maximizing the network achievable rate and minimum signal-to-noise ratio (SNR) margin of networks with partial spectrum utilization in their links, relevant to the majority of empirical metro network scenarios. According to numerical results, the network achievable rate can be improved around 17% by performing power optimization over the individual launch power of network lightpaths compared to optimizing a single flat (equal) launch power for all the lightpaths. Moreover, the minimum SNR margin of the simulated network is improved by about 23 dB. Finally, it is observed that maximizing the network minimum SNR margin needs the launch power of each lightpath to be proportional to the total nonlinear interference noise efficiency influencing the lightpath.
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| 3. |
- Rabbani, Hami, et al.
(författare)
-
Analytical Modeling of Nonlinear Fiber Propagation for Four Dimensional Symmetric Constellations
- 2021
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 39:9, s. 2704-2713
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Tidskriftsartikel (refereegranskat)abstract
- Coherent optical transmission systems naturally lead to a four dimensional (4D) signal space, i.e., two polarizations each with two quadratures. In this paper we derive an anlaytical model to quantify the impact of Kerr nonlinearity on such 4D spaces, taking the interpolarization dependency into account. This is in contrast to previous models such as the GN and EGN models, which are valid for polarization multiplexed (PM) formats, where the two polarizations are seen as independent channels on which data is multiplexed. The proposed model agrees with the EGN model in the special case of independent two-dimensional modulation in each polarization. The model accounts for the predominant nonlinear terms in a WDM system, namely self-phase modulation and and cross-phase modulation. Numerical results show that the EGN model may inaccurately estimate the nonlinear interference of 4D formats. This nonlinear interference discrepancy between the results of the proposed model and the EGN model could be up to 2.8 dB for a system with 80 WDM channels. The derived model is validated by split step Fourier simulations, and it is shown to follow simulations very closely.
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