We consider an IP/MPLS over WDM network, in which label switched routers (LSRs) in the IP/MPLS layer are interconnected through optical cross-connects (OXCs) in the optical core network (WDM layer) providing an end-to-end wavelength routing capability. In this paper, we study a dynamic label switched path (LSP) routing problem for the three different network models of the IP/MPLS over WDM network, namely, Overlay, Augmented, and Peer models. For the overlay model, we propose two algorithms: ECF_OVLY and MLH_OVLY. In ECF_OVLY, a network always tries to use existing capacity first, whereas in MLH_OVLY, a network finds a path with the minimum number of logical hops for an LSP request. We also propose, for the augmented model, two simple and efficient dynamic LSP provisioning algorithms, called MCPI_AUG and DCPI_AUG, utilizing different type/amount of summarized capacity information from the WDM layer, namely Minimum CaPacity Information (MCPI) and Detailed CaPacity Information (DCPI). We compare the proposed algorithms with the existing algorithms available for the overlay [1] and peer [2], [3] models. The algorithms are compared and evaluated using two key performance measures: LSP blocking probability and network (lightpath) utilization. Simulation results show that at low loads with a limited number of ports available in the network, DCPI_AUG achieves an order of magnitude better blocking performance than the algorithm in [2] and outperforms the one in [3] by more than three times. It also achieves higher network utilization than the one in [2] by more than 10 % and the one in [3] by 2-7 % depending on the traffic load. Considering the small amount of information that is exchanged between the layers in the augmented model, these results suggest that the augmented model can be a practically good compromise between the overlay and peer models.

We consider an IP/MPLS over WDM network, in which label switched routers (LSRs) in the IP/MPLS layer are interconnected through optical cross-connects (OXCs) in the optical core network (WDM layer) providing an end-to-end wavelength routing capability. In this paper, we study a dynamic label switched path (LSP) provisioning problem for the three different network models of the IP/MPLS over WDM network, namely, overlay, augmented, and peer models. For the overlay model, we propose an algorithm, called MLH/spl I.bar/OVLY, in which a network finds a path with the minimum number of logical hops for an LSP request. We also propose, for the augmented model, a simple and efficient dynamic LSP provisioning algorithm, called CAPA/spl I.bar/AUG, utilizing summarized capacity information from the WDM layer. We compare the proposed algorithms with the existing algorithms available for the overlay and peer models, and also provide an in-depth analysis of the algorithms. The algorithms are compared and evaluated using two key performance measures: LSP blocking probability and network (lightpath) utilization. Simulation results show that at low loads with a limited number of ports available in the network, CAPA/spl I.bar/AUG achieves an order of magnitude better blocking performance and outperforms all other algorithm. Considering the small amount of information that is exchanged between the layers in the augmented model, these results suggest that the augmented model can be a practically good compromise between the overlay and peer models.

We consider an IP/MPLS-over-WDM overlay network, which an IP/MPLS service layer exists independently over a WDM transport network. In the overlay model, two adjacent layers communicate with each other only through a pre-defined user-network interface (UNI) and the WDM topology information is not available to the service layer. In this paper, we concentrate on network design with a fault tolerance mechanism provided only in the IP/MPLS service layer in which the label-switched path (LSP) protection takes into account both node failures in the IP/MPLS service layer and failures in the WDM transport layer. In this design problem, the service layer must decide how lightpaths or logical links should be provisioned and how primary and backup LSPs should be routed in a cost-effective manner, such that failures do not affect both LSPs simultaneously. We formulate this survivable IP/MPLS overlay network design problem as a mixed integer linear program (MILP). Since the MILP is computationally intractable for large networks, we solve it only for a small network and present the optimal solution found by CPLEX 7.5, a commercial MILP solver. In order to find efficient solutions in larger networks we propose a heuristic algorithm that performs near-optimally in the cases studied. we then compare total costs for LSP protection from WDM link failures and LSR failures may not be much more expensive than protection from LSR failures only.

In this paper, we propose a simple, effective and robust method based on the statistical moments of instantaneous features to classify digital modulation signals. This method adopts a tree structure scheme and uses different features in each branch to make full use of distinguishing modulation type's characteristics. The proposed method is capable of differentiating ASK2, ASK4, FSK2, FSK4, PSK2 and PSK4 signals at the output of typical high frequency channel with white Gaussian noise, multi-path delay and Doppler shift. Unlike most other existing methods, our method assumes no prior information of the incoming signal (symbol rate, carrier frequency, amplitude etc.). Extensive simulation results demonstrate that this approach is robust in various practical situations.