Renato Baldini Filho

Fiber powered extender for XG-PON/G-PON applications

This work proposes a new approach to power passive optical network (PON) extenders using the power-over-fiber technique, turning them virtually passive. This approach eliminates the batteries in the remote sites, improving the reliability and the security of the system. The limits and the perspectives for this approach are discussed in this work. The performance of fiber powered semiconductor optical amplifiers based on the extender is shown with a 10 gigabit passive optical network (XG-PON)/gigabit passive optical network (G-PON) system setup using a 1:32 splitter and 50 km reach. The conventional method to power the extenders is also presented for the sake of comparison with the proposed power-over-fiber technique.

Clipping Distortion Performance of Nonsquare

Orthogonal frequency-division multiplexing (OFDM) systems usually make use of a set of square M quadrature-amplitude modulation ( M-QAM) constellations to obtain a good tradeoff between throughput and symbol-error robustness. However, the switch to the next constellation increases the number of bits per modulation symbol by two. The introduction of nonsquare M -QAM constellations in such systems brings extra advantages such as smoother transition among bit rates and a reduction of the peak-to-average ratio of the OFDM signal. Therefore, this paper unfolds analytical expressions to evaluate the symbol-error performance of nonsquare M-QAM OFDM on nonlinear time-variant additive white Gaussian noise channels, taking clipping distortion into account. Cross and overlaid M-QAM are considered. Analytical performances are evaluated and compared with computational simulations, which show good agreement.

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This paper presents a new approach to upgrade and extend the reach of the current passive optical network (PON) by using wavelength division multiplexing (WDM) in the standardized optical grid of gigabit PON (In-band WDM PON overlay). The aim is to increase the number of optical distribution networks (ODNs) fed by a single fiber while preserving the users bandwidth. In this approach four downstream (DS) wavelength signals are transmitted from an optical line terminal (OLT) to four different ODNs using the standard DS PON spectrum ranging from 1480 to 1500 nm. The upstream (US) signals from the four different ODNs are also wavelength multiplexed within the standardized US PON spectrum ranging from 1270 to 1330 nm. Experimental proofs of concept are presented in a 20 km PON serving 32 ONTs and in a 58 km extended PON in order to demonstrate the feasibility of this proposal.

-QAM OFDM Systems on Nonlinear Time-Variant Channels

This paper presents a new approach to upgrade the current passive optical network (PON) by using wavelength division multiplexing (WDM) in the standardized optical grid of gigabit PON (In-band WDM PON overlay). The aim is to increase the number of optical distribution networks (ODNs) fed by a single fiber while preserving the users bandwidth. In this approach four downstream (DS) wavelengths signals are transmitted from an optical line terminal (OLT) to four different ODNs using the standard DS PON spectrum ranging from 1480 to 1500 nm. The upstream (US) signals from the four different ODNs are also wavelength multiplexed within the standardized US PON spectrum ranging from 1270 to 1330 nm. Proofs of concept are presented in a 20 km PON serving 32 ONTs in order to demonstrate the feasibility of this proposal.

Upgrading and extending PON by using in-band WDM overlay

In 2005 the Brazilian government supported researches in order to design a new DTV standard which would employ the most recent technologies. One of the proposals for the new standards physical layer was named Innovative Modulation for the Brazilian Digital TV System (MI-SBTVD). This proposal employs OFDM and has an operation mode where space-time diversity at the transmitter may be employed, requiring at the receiver side a channel estimation algorithm capable of identifying the MIMO channel. This paper presents some algorithms where the estimation at pilot subcarriers is obtained through a linear combination of two received symbols, and interpolation is done to provide channel gains at data carriers. As the proposed system has the pilot subcarriers positioned in such manner to allow bi-dimensional interpolation, four possible algorithms are evaluated through computer simulations. The results for digital TV channel models are compared.