Sandro M. Rossi

Differentiated reliability (DiR) in mesh networks with shared path protection: theoretical and experimental results

Summary form only given. The concept of differentiated reliability (DiR) has been applied to dedicated path protection switching in wavelength division multiplexing (WDM) rings. By means of the DiR concept, a network can be designed to provide multiple degrees of reliability. It is thus possible to match the user-specific reliability requirement, yet minimizing the amount of standby resources required in the network, i.e., its total cost. When applied to shared path protection (SPP) switching, the DiR concept is expected to achieve a cost reduction that is synergistic with the sharing of standby resources. The paper illustrated the potential network cost reduction achievable using the novel concept of shared path protection with differentiated reliability (SPP-DiR). The technological feasibility of the proposed concept was experimentally demonstrated on the optical metro network for gigabit applications (/spl Omega/) test bed.

Experimental demonstration and numerical simulation of an optical recirculating loop operating at 10 gb/s

We demonstrate an optical recirculating loop as a tool for performance evaluation of cascades of effects or elements in an optical communication system. We describe the critical issues to operate the recirculating loop properly and we present experimental results on the cascading of a dispersive fiber link and an optical amplifier. Additionally, we conduct a numerical simulation of the recirculating loop experimental conditions. Simulation and experimental results are in good agreement.

Impact of polarization mode dispersion in multi-hop multi-rate WDM rings

Fiber polarization mode dispersion (PMD) is perhaps the most critical transmission impairment in optical networks at transmission rates of 10 Gb/s and higher. Since the bandwidth-distance product, or transparency,of the optical circuit is limited by PMD, the overall network design and cost may be significantly altered by the actual fiber PMD values. The paper has three objectives. First, an accurate model for evaluating the PMD effects is presented and verified experimentally. Second, the cost increase of WDM rings due to PMD in a number of design scenarios—first generation, single-hop,multi-hop, and multi-rate networks—is assessed. Third, the polynomial-time algorithm proposed in Cerutti et al. [1] is modified to provide sub-optimal solutions for the above WDM rings, taking into account the limited bandwidth-distance product imposed by PMD. Presented results reveal that at high transmission rates, the cost of the multi-hop ring is less affected by PMD than the costs of first generation and single-hop rings.

An EDFA hybrid gain control technique for extended input power and dynamic gain ranges with suppressed transients

A new approach for a hybrid gain control scheme based on an improved overlap of the all-optical and electrical feedforward gain control techniques for a single EDFA is presented. A wide input power operation range and a multi-level dynamic gain range are possible, enabling efficient gain control performance and allowing EDFA operation as pre, in line or booster amplifier. An EDFA characterization during add and drop of 1, 3, 7, 15, and 31 out of 32 input channels is also presented. The results show a maximum 0.6 dB deviation from the set EDFA gain value. By considering the EDFA response time, the interaction between optical and electrical controls shows a drastic reduction on EDFA transient impact to less than 2 ms with maximum overshoot/undershoot lower than 0.7 dB.

Project GIGA-high-speed experimental IP/WDM network

This paper describes Project GIGA-high-speed Experimental Network, a multiinstitutional, multidisciplinary, national project funded by the Brazilian government. The main goal of Project GIGA is to promote research, development and experimentation of technology at all layers, aiming at generating knowledge, products and services that will make it possible for Brazilian individuals and companies to play a role in the converged telecom sector. The project centres on the high-speed Network Testbed, a platform for experimentation and validation of technology, equipment, protocols, services and applications, whether they be developed in the project or not. The paper explains the objectives, the expected impact and the organisation of the project. It also describes the architecture of the network testbed, the ongoing research and development activities and some of the results obtained.

Effective penalty reduction in an L-Band WDM system using hybrid amplifier with a dispersion-compensating module

We demonstrate the combined use of a single laser diode and a fiber ring laser for pumping a Raman-amplified dispersion compensating fiber (DCF) to upgrade an L-Band WDM transmission system at 10 Gbit/s. The broadband DCF module is placed at the output of an L-Band Erbium-doped fiber pre-amplifier, to reduce the power penalties associated to chromatic dispersion. The hybrid DCF-Raman amplifier, provided by two pump-wavelengths originated from a single pump source, permits the L-band channel allocation with efficient transmission performance through a metro-scaled (100 km) standard single mode fiber (SSMF). The performance of eight WDM channels in the L-Band is presented with nearly penalty free operation at 10 Gbit/s, which are corroborated by numerical simulation analysis. The residual power penalties obtained were either close to 1 dB or less for all channels in the L-band. The L-band hybrid pre-amplifier, composed by a single-stage EDFA and a Raman-pumped DCF module, is proposed as an alternative solution for the capacity upgrade of metropolitan WDM transmission systems.

Q-factor penalty evaluation in a cascade of all-, optical nodes using a re-circulating loop

The impact of all-optical node concatenation effects on the performance of a WDM transmission through 350 km of standard fiber is investigated with re-circulating loop experiments. A node of the OMEGA test bed is used to simulate a chain of fourteen nodes. Each link comprises a combination between one node (mux/demux, thermal optical switch and erbium-doped fiber optical amplifier) and 25 km of standard single mode fiber. Amplifier noise accumulation has been found to be the most detrimental effect.

An IP-centric control plane for survivable WDM mesh networks: experimental results on the OMEGA test-bed

It is well known that IP over WDM is a promising and simplified network architecture for future high speed networking, in which the EP layer can be used as the control plane to manage the optical layer, in addition to providing users data transmission functionalities. Among others, key functions of the IP control plane are the provisioning of optical circuits for end-to-end data transmission between routers and fault management. An open question is what protocols are most suitable for providing such functions. The paper describes a suite of protocols that was implemented to accomplish both optical circuit provisioning and fault management in an EP over WDM network. The protocols were implemented and tested using the /spl Omega/ (Optical Mesh network for Emerging Gigabit Applications) test-bed. Experimental results indicate good scalability properties of the implemented protocols. For example, it is possible to handle more than a hundred wavelengths with restoration times that are below few tens of milliseconds.

Digital Nonlinear Compensation for Spectrally Sliced Optical Receivers With MIMO Reconstruction

We experimentally investigate, in a 20×56-GBd 400 G WDM transmission system, different approaches for nonlinear compensation in spectrally sliced optical receivers with MIMO-based signal reconstruction. Slice-by-slice nonlinear compensation shows comparable performance to inter-slice nonlinear compensation in a WDM system. In addition, an eight-stages compensation yields a 0.4-dB Q2 gain equivalent to 250-km distance increase, resulting in 2000-km transparent reach.

Unrepeatered Transmission of

We demonstrate unrepeatered transmission of 10 × 400-Gb/s PM-16QAM Nyquist wavelength-division multiplexing (WDM) dual-carrier superchannels (75-GHz flexigrid) at the SE = 5.33 b/s/Hz, where each superchannel is coherently detected by a single wideband receiver. A 350-km transmission is achieved by using optimized amplification map to efficiently design remote optically pumped amplifier and hybrid amplifiers. Additional digital domain nonlinear compensation allows to increase the transmission distance up to 370 km.