S. Di Bartolo

QoE and QoS comparison in an anycast digital television platform operating on passive optical network

We report an experimental investigation on QoE, compared with the QoS, for a complete digital television platform able to deliver broadcast, multicast and unicast services in wide geographical area network, with broadband access based on passive optical network (PON). In particular, we show the service degradation due both to network impairments and to the TCP limits on operating systems. Multicast forwarding was tested in PBB-TE environment to exploit a Carrier Ethernet behavior. Concerning broadcasting, such a network allows the user to see the DVB-T by using the same optical infrastructure by means of the specific wavelength foreseen by the GPON standard.

Hydrometeor scattering and stochastic modeling for free-space optical channel characterization

Free space communications, using optical carriers (Free Space Optics, FSO) technology, ensure high data rates, with relatively low error rates, low power consumption and inherent security. However, FSO links are quite sensitive to atmospheric conditions. 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 on FSO links (from visible to near infrared wavelengths) is proposed in terms of scattering coefficients, albedo factor and asymmetry coefficient as function of the particle water content. Both single and multiple scattering effects are shown and discussed. A prototype of a stochastic time series generator of FSO rain attenuation is also presented.

Giga Ethernet Free-Space Passive Optical Networks

Abstract Fully passive optical networks with wavelength division multiplexing capabilities will open the access network to the real broad band. Integration with optical wireless is a further step to add low-cost characteristics with high bandwidth capabilities.

Remote optical monitoring in remotely power assisted passive optical networks

In this paper, the authors present the latest results on a simple and low cost method to achieve a dynamic and flexible network monitoring. By placing several fiber Bragg gratings (FBG) along the passive optical gigabit Ethernet infrastructure (GePON), the proposed modified optical time domain reflectometer (OTDR) is able to monitor the entire system by simply tuning its working wavelength. Furthermore, the optical network terminals (ONT), at the end users premises, have been interconnected to the trunk via an innovative cable able to both carry the optical signal as well as the power supply.

Reducing Complexity and Consumption in Future Networks

The authors report the main results of the EU FP7 SARDANA project, a future network architecture able to provide large bandwidth to the end user in a flexible and intelligent way. The remote amplification for network reach extension, the remote monitoring of the network infrastructure, and the possibility of remotely powering ONUs are fundamental capabilities to maintain the passiveness of the network outside plant, so important for reducing power consumption and maintenance costs, without compromising network reach and coverage.

Modulation effect induced by continuous waves in semiconductor optical amplifiers

Nonlinearities in SOAs have been deeply investigated both theoretically and experimentally. Moreover, many simulative models have been proposed, so far. The most used simulative approach is based on Rate Equations, relating the carrier density to the overall optical power traveling the amplifier. Aim of this paper is to propose an enhanced general model for nonlinearities induced in SOAs employed in WDM systems, overcoming the limitations of Rate Equations based model. Our model relates the carrier density to the optical field, and it allows to evaluate the interchannel crosstalk due to nonlinear interaction between channels, as a function of the signal waveform. Besides the theoretical approach, preliminary experimental results confirm the accuracy of this model in describing the demonstrates the crosstalk due to nonlinear interaction.

Effects of Semiconductor Optical Amplifier Phase Distortion in Radio Over Fiber Signals

In this paper the effects boosting a phase modulated radio over fiber signal with a semiconductor optical amplifier are analyzed. The resulting distortion is characterized in the case of a single radio over fiber signal or in presence of an amplitude modulated signal.

Experimental investigation on the role of optical amplification for TV broadcasting optical networks

Experimental investigations are presented concerning on the use of optical amplifiers in Fiber-to-the-Building/Home (FTTB/H) access networks sharing TV channels for broadcasting DVB-T signals. Both Erbium Doped Fibre Amplifier (EDFA) and Semiconductor Optical Amplifiers (SOA) have been considered and the experimental results show that SOA can induce severe constraints that have to be suitably faced in the case of its application for TV broadcasting via optical fibre links.

Experimental demonstration of the all optical network wavelength conversion in a passive optical network

In this work we experimentally demonstrate the All Optical Wavelength Conversion in an EPON included in a GMPLS test bed based on Virtual Private LAN Service technique for QoS control.

All-optical multi-wavelength devices for ultrafast WDM signal processing

In this paper, the authors present results based on a 2R (re-amplification and re-shaping) multiwavelength regeneration system, with wavelength conversion capabilities. In a counter propagation approach, the system is able to regenerate several end user data stream at the same time opening the way to efficient wavelength allocation, network congestion reduction and QoS enhancement in the wide area optical network segment. A short review on the state of the art will be presented too.