Valeria Carrozzo

Optical wireless transmission at 1.6-Tbit/s (16×100 Gbit/s) for next-generation convergent urban infrastructures

Abstract. We present a high-data rate optical wireless system. The implemented system exploits polarization (PM) and wavelength multiplexing, achieving the transmission of a total capacity of 1.6  Tbit/s over hybrid fiber free-space optics (FSO) system with no optical-electronic-optical conversion at the interfaces with air. Quadrature phase shift keying modulation in each channel and coherent detection were used. The system allows enough power budget to support the record transmission of 16 channels, operating each at 100  Gbit/s over 40 km of fiber and 80 m of FSO between two buildings. Performance of the fully transparent connection is presented in terms of bit-error rate.

Ultra-High-Capacity Passive Optical Network Systems with Free-Space Optical Communications

Abstract This article experimentally demonstrates a hybrid fiber–free-space passive optical network that enables high spectral density, aggregated capacity, and total throughput through ultra-dense wavelength-division multiplexing baseband and radio-over-fiber channels. Ultra-dense wavelength-division multiplexing 10-Gb/s Nyquist-shaped 16-ary quadrature amplitude modulation, 10-Gb/s radio-over-fiber orthogonal frequency-division multiplexing, and 8.75-Gb/s baseband orthogonal frequency-division multiplexing signals per user were transmitted through a maximum 40-km passive optical network, which includes a 6-m free-space optics link with acceptable performance.

Model analysis of hydrometeor scattering effects on free space near-infrared links

A promising technology for peer-to-peer connections and urban area networks is represented by wireless communications through free space using optical carrier (Free Space Optics, FSO). This technology ensures high data rates, with relatively low error rates, low power consumption and inherent security. Nevertheless FSO links are quite sensitive to atmospheric condition. Fog droplets, but also raindrops and snowflakes, may introduce severe path attenuation which drastically reduces the channel availability. A parametric model to simulate droplets scattering effects over the FSO link in terms of extinction coefficient, albedo factor and asymmetry coefficient as function of the particle water content will be presented. Both single and multiple scattering effects will be shown.

Performance Evaluation of a Hybrid Satellite Network Based on High-Altitude-Platforms

The proposed system architecture is quickly configurable and suitable for disaster aid or war scenarios, where the rapid event changes must be monitored at a higher rate than the one offered by common Earth observation systems. Moreover, high altitude platforms (HAPs) represent an easy and affordable solution for providing Internet access in absence of infrastructure. This system is based on several HAPs located on different sites within the same GEO visibility area. Each HAP is equipped with an optical payload in order to establish an optical link to a satellite and a WiMAX interface to the ground. The satellite acts as the optical transponder. The advantage of these platforms is that HAPs are easily accessible from Earth for their maintenance. High transmission performance in the optical links can be achieved by systems operating at 1550 nm wavelength, where the Erbium doped fiber amplifier (EDFA) can improve the optical signal-to-noise ratio (OSNR) on the receiver end, and phase modulation schemes (i.e. differential phase shift keying -DPSK) can be used jointly with error correction codes so to ensure reliable high performance transmission. The aim of this paper is to define the operative conditions that guarantee a high effectiveness in the band exploiting, as well as in power consumption.

Optical Packet Network With Limited-Range Wavelength Conversion: A Novel Formalization of the Optimal Scheduling Problem

In this paper, we consider synchronous optical packet networks formed by switches equipped with a complete set of limited-range wavelength converters. On these networks, we dealt with scheduling algorithm that maximizes the switch throughput. So far, previous literature works have formalized this scheduling problem as the finding of a maximum bipartite matching (MBM) in a convex graph. The MBM formalization has collected various follow-ups, mainly focused on measuring switch-level performance. We revise the MBM formalization by measuring network-level performance. Surprisingly, we find out that when optical switches are cascaded, MBM formalization has two not negligible lacks: (1) a useless degradation of optical signal quality and (2) a tendency of shifting optical packets toward lower wavelengths, thus increasing the occurrence of wavelength contention. To solve these issues, we propose a novel formalization of the scheduling problem as the finding of a MBM with minimum edges weights (MW-MBM). We show that MW-MBM outperforms MBM in terms of both network throughput and optical SNR. Performance evaluation is carried out by means of NS2 simulator that we extend to toughly model optical components (e.g., semiconductor optical amplifier four-wave-mixing wavelength converter). The simulator is provided as open source.

Radio-over-Fiber (RoF) Techniques for Broadband Wireless LAN

Radio-over-fiber (RoF) techniques are attractive for realizing high performance integrated networks. The growth of mobile and wireless communications fuels increasing demand for multimedia services with a guaranteed quality of service. This requires realization of broadband distribution and access networks. Within this framework, RoF schemes can be applied for realizing seamless wireless networks since they allow for the easy distribution of microwaves and millimeter waves over long distances along optical fibers. Some of the applications of RoF technology include cellular networks, satellite communications, multipoint video distribution services (MVDS), mobile broadband system (MBS), wireless LANs over optical networks.

Ultra high capacity PON systems

This work will address the potential of a set of techniques such as coherent detection, advanced modulation formats, advanced filtering to enable ultra-high flexible bandwidth PONs as well as hybrid deployment scenarios. These enabling techniques will be shortly addressed and a revision on a set of experimental lab trials of different technologies under different propagation conditions and media, including partly free space optics, will be presented and discussed.

Broadband Free Space Optical urban links for next generation infrastructures and services

Authors present the implementation of a building to building 100 Gbit/s Free Space Optical (FSO) link. The FSO point to point (P2P) connection, 80 meters long, exploited the transmission of a dual polarization multiplexed (PM) QPSK signal. The performances of the implemented broadband coherent system have been evaluated, with fiber propagation to simulate downstream and upstream network configurations, in terms of both bit error rate (BER) and error vector magnitude (EVM).

FSO for broadband multi service delivery in future networks

Future optical access networks can take advantage of Free Space Optics in heterogeneous environments, relying on several advanced techniques which provide high capacity and make the transmission robust and flexible. In this work, several experimental scenarios are tested and presented, showing the potential of integrating optical wireless in fiber based scenarios for broadband multi service delivery.

Integration of optical telecommunications and radio access networks to assure quality of service

In this work, we show how to control a Quality of Service in optical networks integrated with WiMAX access radio by means of the MPLS and WiMAX Class of Services, even in condition of traffic congestions.