Luiz Henrique Bonani

The effects of polarization mode dispersion on 2D wavelength-hopping time spreading code routed networks

In this study, we investigate the effects of multiple access interference (MAI) and polarization mode dispersion (PMD) in 2D wavelength-hopping time spreading optical code paths. The main results show the MAI effects and PMD constraint at the outage probability. The contribution of these sources of interference is analysed to choose the better design of code parameters in order to increase the performance of networks based on optical code paths. These results could be applied to determine the parameters design in code/wavelength routed networks.

Analysis of electronic buffers in optical packet/burst switched mesh networks

We present in this paper the study of electronic buffering in an innovative architecture for optical packet/burst switched network (OPSN). This architecture comprises optical bufferless nodes with electronic packet queuing out of the optical layer, deflection routing to perform contention resolution and fully connected mesh topologies under uniform traffic distribution. We demonstrate, by means of simulation, that the studied architecture has a great improvement in performance when we introduce such electronic buffers, which are more efficient when used with the optimized mesh topologies.

Estimating the blocking probability in wavelength-routed optical networks

Abstract In this work, a new methodology to compute the blocking probability in wavelength-routed optical networks is presented. The proposal is based on an interactive procedure, named Interactive Matrix Methodology (IMM), that executes actualization of the network traffic distribution in order to reach a precise blocking performance. The IMM updates an initial network link load continuously and computes the blocking probability for each output link considering that the traffic among the links is dependent and related with all links and nodes in the network, not only with all links in a given path or route. The simulation results obtained in the same conditions and in several optical network scenarios match very well with the theoretical approximation achieved with this methodology. The advantage of this theoretical methodology is to be fast, accurate and applicable in low load regions, where a discrete event simulation is not precise. Furthermore, this method can be used to compute the estimative of blocking probabilities per node and in the network, including the cases where the number of wavelengths is different on each node.

Performance comparison of hybrid 1-D WDM/OCDMA and 2-D OCDMA towards future access network migration scenario

In this paper, we provide a performance comparison and analysis between a hybrid 1-D WDM/OCDMA system and a 2-D WHTS OCDMA system. In the hybrid system, OOC is employed as users code sequence of the OCDMA dimension. The simulation results show that the hybrid system presents better performance than the 2-D WHTS OCDMA system, and show also that under a standard BER scenario, i.e., BER = 10-9, the hybrid system can support at least 75% more simultaneous users than the 2-D OCDMA system for the analyzed case study. The analysis suggests that the hybrid 1-D WDM/OCDMA system is a qualified migration scenario since it can provide a smooth migration path from current networks towards OCDMA networks.

Evaluation of throughput and protection in optically switched metropolitan network architectures

In this study, we investigate the performance of optical packet/burst switched (OPS/OBS) architectures connected as mesh and as ring topologies for future optical metropolitan networks. Network throughput and protection to link failure under uniform traffic distribution for all nodes are investigated to evaluate the sensitivity of OPS/OBSN performance. Our data are based on analytic results and computer simulations that include a comparison between various mesh and ring topologies. We also consider detailed traffic distributions over the network links and the impact caused by failure of more or less loaded links, thus providing a method to select links that require protection, which can be very useful in network planning.

Dynamic traffic analysis of metro-access optical packet switching networks having mesh topologies

We have investigated the performance of various optical packet switched network (OPSN) architectures comprising optical bufferless nodes and fully connected mesh topologies, under uniform traffic distribution, i.e., all nodes generate the same traffic. We demonstrate that increasing the number of nodes in OSPNs does not necessarily increase performance, or even capacity. By establishing an efficiency parameter based on average number of hops and effective network capacity, decision tables and graphs can be generated and utilized in network planning. Moreover, regular and quasi- regular optimized topologies lead to lower latency, higher throughput, and lightpaths with significantly better traffic distribution. The optical nodes have simple configuration and are totally compatible with WDM networks.

Contribution to future metropolitan access network planning considering link failures in photonic switched networks

Photonic switching for traffic optimization in Metropolitan Access Optical Networks using technologies of optical packet/burst switching (OPS/OBS) seems to be a future-proof solution considering high capacity and the highly variable traffic in these networks. Looking for this future, we propose a study based on the analyze of survivability of traffic unconsidering protection mechanism but considering mesh and ring efficient topologies with node architecture to OPS. The results are obtained through computer modeling and simulation. The main parameters analyzed are as follows: capacity, average number of hops, packet loss fraction, and link utilization for each topology. These parameters are adopted to evaluate the performance of each topology considering failures. Minimum electronic buffering is included at node ingress (client side) to avoid packet loss in the access to the optical layer: high throughput and low latency. It is also observed that optical buffering is not necessary for adequate network performance.

A study in photonic switched networks considering link failure and ingress buffering

In this paper we study the behavior of traffic in Metropolitan Access Optical Networks with technologies of optical packet/burst switching (OPS/OBS), using computer modeling and simulations. We analyze network performance and the impact of link failure when electronic buffering at ingress (client input) to optical network is implemented. Mesh and ring topologies are chosen and parameters packet loss fraction and average number of hops are adopted for performance metrics. The use of minimum electronic buffering at ingress is demonstrated to improve access to the optical layer, and necessary to keep the packet loss fraction low and throughput high with low latency. We also show that optical buffering is not necessary for adequate network performance.

Improved Method for Evaluation of Network Throughput and Protection in Future Optically Switched Metropolitan Networks

In this work we investigate the performance of optical packet/burst switched (OPS/OBS) architectures connected as mesh and as ring topologies, for future optical metropolitan networks. Network throughput and protection to link failure under uniform traffic distribution for all nodes is investigated in order to evaluate the sensitivity of OPS/OBSN performance. Our results are based on analysis of simulations and comparison between various mesh (Manhattan St. type) and ring topologies. We also consider the detailed traffic distributions over the network links and the impact caused by failure of more or less loaded links, thus providing a way to select links that require protection.

Performance Evolution of Optical Code Conversion Architectures in Hybrid WDM/OCDM OBS Network

This paper investigates the performance of optical code conversion architectures in hybrid technology using wavelength and optical code division multiplexing for optical burst switching network. An OCDM-based multigranularity optical cross-connect is used to enable and convert the optical path switching in bandwidth granularity finer than the wavelength-based path. Such an optical path switched by OCDM-based MG-OXC is capable of hybrid optical code/wavelength conversion along the path from a source to destination. Simulation results indicate that increasing the number of optical codes per wavelength and applying optical code conversion considerably decreases the burst blocking probability and latency, and also increases network throughput. In addition, the results show the advantages of are using sparse-partial optical code conversion architecture in WDM/OCDM OBS network.