Deming Wu

Combined impacts of group velocity dispersion, Kerr effect and polarization mode dispersion in optical fibers

This paper is contributed to discuss the impacts of group velocity dispersion, nonlinear Kerr effect and polarization mode dispersion in optical fibers. Using split-step Fourier method, we first analytically analyze that the interaction of Kerr effect and polarization mode dispersion results in the pulse asymmetric spectra. Then we study that polarization mode dispersion and group velocity dispersion play their roles independently, and that, depending on the relative magnitudes, the two factors affect the pulse differently. Finally, we research the combined impacts of group velocity dispersion, Kerr effect and polarization mode dispersion. Detailed investigation reveals that the combined effects are different in anomalous and normal group velocity dispersion regime. We point out that increased Kerr effect can suppress the impact of polarization mode dispersion in anomalous chromatic dispersion regime, and that, for the given values of incident power and polarization mode dispersion, anomalous group velocity should be large enough for the polarization mode dispersion to be effectively suppressed by the Kerr effect.

Dynamic routing and wavelength assignment in multi-granularity WDM networks

For the purpose of reducing the complexity and cost of optical large-scale cross-connect, wavelengths are grouped into wavebands or fiber to be switched as a single entity, which is called multi- granularity switching. However, it introduces more complexity into the routing and wavelength assignment problem. In this paper, we propose a novel graph model for describing the states of the multi-granularity switching WDM networks. Based on the model, the dynamic routing and wavelength assignment problems for multi-granularity traffic can be solved jointly, and different on-line wavelength grooming policies can be achieved simultaneously. By simulation, we compared the performance of our algorithms under different policy and different percent of fibers for fiber switching. The result proved that our algorithms yield better performance than those deal with the routing and wavelength assignment separately.

Design and performance analysis of MG-OXC

Multi-granularity switching in optical layer has gain significant importance due to the reduction of size and cost of the optical cross-connect. In this paper, we propose a novel structure of MG-OXC, named two-layer MG-OXC, and also give a new graph model for describing the function of the all kinds of MG-OXC. The network states can be represented completely through our auxiliary graph. In such an auxiliary graph, the optical tunnel allocation in multi-granularity switching network is reduced to the min-cost path find problem, and different traffic grooming policies can be archived simultaneously. We compare the performance of the two-layer MG-OXC to the normal three-layer MG-OXC and single-layer MG-OXC by the algorithm we proposed through simulation, and conclude that the novel MG-OXC can get very close performance to threelayer MG-OXC but smaller size of switching matrix. The simulation also proved the algorithms we proposed performs better than traditional RWA algorithms dealing the routing and wavelength sub problems separately.

Priority-based M:N Protection in GMPLS Networks

Abstract Axa0strict priority queueing model for generalized label switched paths (G.LSPs) M : N protection is developed in this letter. The analytical results are validated by simulation. The analytical model is helpful to the selection of appropriate number of backup paths in axa0priority-based M : N protection design to satisfy certain reliability requirement and to avoid resource over-provisioning.

Design and performance analysis of an IP wavelength routing network

The network architecture where each node integrates an IP router and an OXC (optical cross-connect) is an attractiveparadigm for the next generation optical Internet. LP wavelength routing or POW (packet over wavelengths) is based onthis kind of architecture. The goal of this architecture is to switch as much traffic as possible directly by means of OXCs,because IP forwarding is relatively expensive and causes large end-to-end delay by comparison. Based on analyzing theproblems and shortcomings of the previous node structure, a novel node structure is proposed to overcome the problemsencountered by the previous scheme. Then two IP switching protocols, IFMP (Ipsilon Flow Management Protocol) andGSMP (General Switch Management Protocol), are extended to support [P wavelength routing networks. Finally, theperformance of an IF wavelength routing network is analyzed with self-similar network traffic model. The simulatedresults show that the higher the network traffic self-similar degree, the higher switching gain the network gets.Keywords: IP over WDM, IP wavelength routing, Self-similar traffic, Switching gain

GVD compensation schemes with conideration for the combined effects of GVD, Kerr effect, and PMD

In this paper, we discuss three GVD compensation schemes, including the post-compensation, pre-compensation and hybrid-compensation schemes with considering combined impacts of GVD, Kerr effect and PMD. By means of the split-step Fourier method, we numerically solve the nonlinear coupling equations of two orthogonal polarization modes. With respect to the statistical character of PMD in the optical fiber, we employ the parameters of average eye-opening penalty to evaluate the combined impacts induced by GVD, Kerr effect and PMID. The numerical results are obtained on the base of 1000 times computation with average DGD less than 35% bit duration. Simulations show that, for the 10Gbit/s NRZ system, the GVD pre-compensation scheme performs best with more than 1dB of average eye-opening penalty better than the other two schemes when input power is greater than lOdBm. However, for the 4OGbitJs NRZ system, when input power P0 > 5.0dBm , the GVD post-compensation scheme performs best with more than 1dB average eye-opening penalty better than the other two schemes. This is different than the previous conclusion that GVD hybrid-compensation scheme has best performance without considering the impact of PIVID. We also define the parameter of eye-opening penalty at outage probability 10-5 to reflect the impact of DGD at the trailing of the Maxwellian distribution. The results also verify that GVD pre-compensation performs best in the lOGbitJs system and post-compensation performs best in the 40Gbit/s system. In both lOGbitJs and 40Gbit/s systems, either average eyeopening penalty or eye-opening penalty at outage probability iO indicates that the system performance with the best GVD compensation scheme can be improved with the increased input power up to 10dBm, and the performance will be worse if input power is greater than 13dBm. We analyze this behavior and conclude that PMD can be suppressed by the increased Kerr effect within a certain power range.