Tiago M. F. Alves

Ultra-Wideband Radio Signals Distribution in FTTH Networks

The use of an ultra-wideband (UWB) radio technique is proposed as a viable solution for the distribution of high-definition audio/video content in fiber-to-the-home (FTTH) networks. The approach suitability is demonstrated by the transmission of standards-based UWB signals at 1.25 Gb/s along different FTTH fiber links with 25 km up to 60 km of standard single-mode fiber length in a laboratory experiment. Experimental results suggest that orthogonal frequency-division-multiplexed UWB signals exhibit better transmission performance in FFTH networks than impulse radio UWB signals.

Performance Degradation Due to OFDM-UWB Radio Signal Transmission Along Dispersive Single-Mode Fiber

The performance degradation of orthogonal frequency-division multiplexing (OFDM) ultra-wideband (UWB) radio signals caused by transmission along dispersive single-mode fiber is assessed theoretically and by numerical simulation. It is shown that the performance degradation of OFDM-UWB signals caused by fiber dispersion is due to the power fading induced on the subcarrier showing stronger fading. Results show that the power fading description based on a small signal analysis provides good estimates of the optical signal-to-noise ratio degradation for OFDM-UWB signals with modulation index (defined as the ratio between the root-mean-square voltage of the OFDM-UWB signal and the bias voltage of the Mach-Zehnder modulator) values up to 18%. This is a pessimistic value for some OFDM-UWB carrier frequencies.

Semi-analytical approach for performance evaluation of direct-detection OFDM optical communication systems

A semi-analytical method to evaluate the bit error ratio (BER) in direct-detection (DD) optical fibre transmission systems employing orthogonal frequency division multiplexing (OFDM) and optically pre-amplified receivers is proposed. The method considers a Gaussian approach for the signal at the equalizer output and allows evaluating accurately the BER of each OFDM subcarrier for the receiver structure considered and for practical optical and electrical filters shapes, being a powerful tool to perform the optimization of these systems. The results obtained by the proposed method have shown excellent agreement with Monte Carlo estimates for DD-OFDM ultra-wideband radio signals and for two different DD-OFDM signals proposed for long-haul systems.

High Granularity Multiband OFDM Virtual Carrier-Assisted Direct-Detection Metro Networks

A direct-detection metropolitan (metro) network employing multiband orthogonal frequency division multiplexing (MB-OFDM) signals (MORFEUS network) is proposed. The MORFEUS network employs virtual carriers to assist the detection of each OFDM band. It represents a cost-effective network enabling high granularity and flexibility, while requiring a reduced receiver bandwidth. The MB-OFDM signal structure and their main constraints are presented. Each MB-OFDM metro node is described and discussed, with particular attention dedicated to the blocks required to insert and extract a given OFDM band of the MB-OFDM signal. Conceptual solutions for the MORFEUS insertion and extraction blocks are also proposed and discussed. The performance of a 42.8-Gb/s MORFEUS network is evaluated through numerical simulation, and the network operation design is optimized. The impact of the optical filtering effect due to band add/drop operations is assessed as well. These studies are accomplished for systems employing band selectors (BS) with different selectivity to assess the performance tolerance to interband crosstalk and in-band amplitude distortion. The studies are performed for three MORFEUS networks, with granularity of 2-, 3-, and 4-bands. A required optical signal-to-noise ratio (OSNR) of 24 dB is demonstrated in a 240-km-long MORFEUS network without optical filtering cascade effect for a bit error ratio of

Transmission impairment compensation using broadband channel sounding in multi-format OFDM-based long-reach PONs

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Transmission of OFDM wired-wireless quintuple-play services along WDM LR-PONs using centralized broadband impairment compensation

. This required OSNR level is achieved for the three networks with different granularity and for the two BS analyzed after suitable optimization of the MB-OFDM system parameters. Compared with an ideal MORFEUS network employing ideal rectangular BS, the analyzed networks present an OSNR penalty not exceeding 2.5 dB. A required OSNR penalty of 1 dB due to optical filtering cascade is obtained after six nodes with band filtering, for BS with a second order super-Gaussian shape.

Optical Distribution of OFDM and Impulse-Radio UWB in FTTH networks

A centralized impairment compensation technique using outband RF-pilots in OFDM-based long-reach PONs supporting quadruple-play services is proposed. With this technique, a 6.7dB EVM improvement is achieved, and all signals are EVM-compliant after 100km of SSMF.

Analysis of Methods of Performance Evaluation of Direct-Detection Orthogonal Frequency Division Multiplexing Communication Systems

The simultaneous transmission of four orthogonal frequency-division multiplexing (OFDM)-based signals used to provide quintuple-play services along wavelength division multiplexing (WDM) long-reach passive optical networks (LR-PONs) is demonstrated experimentally. Particularly, the transmission performance of custom signal bearing Gigabit Ethernet data, Worldwide Interoperability for Microwave Access, Long Term Evolution and Ultra Wideband (sub-bands 2 and 3) signals is evaluated for different LR-PONs reaches, considering single-wavelength and WDM transmission, and using a centralized impairment compensation technique at the central office that is transparent to the services provided.It is shown that error vector magnitude-compliant levels are obtained for all the OFDM-based signals in WDM LR-PONs reaching 100 km and that negligible inter-channel crosstalk is obtained for a channel spacing of 100 GHz regardless the OFDM-based signal considered. The successful multi-format OFDM transmission along the 100 km-long WDM LR-PON is achieved in the absence of optical dispersion compensation or single sideband modulation, and it is enabled by the performance improvement provided by the centralized impairment compensation realized.

Performance Comparison of OFDM-UWB Radio Signals Distribution in Long-Reach PONs Using Mach-Zehnder and Linearized Modulators

Proposal, experimental demonstration and performance comparison of impulse-radio UWB and OFDM UWB distribution in FTTH networks for high-definition audio/video broadcasting is presented. OFDM-UWB exhibits better performance compared with its impulse- radio counterpart with better spectral efficiency.

100-Gb/s DD-MB-OFDM Metro Network With 11-Gb/s Granularity and 2.85-GHz Receiver

Abstract The performance assessment of orthogonal frequency division multiplexing signals in direct-detection transmission systems by using the error vector magnitude and several bit error ratio approaches is analyzed and compared through numerical simulation. It is shown that excellent accuracy of the bit error ratio estimates is obtained by a semi-analytical Gaussian approach for all the orthogonal frequency division multiplexing system configurations analyzed and that the error vector magnitude only provides reliable estimates of the system performance when the system is dominantly impaired by noise. Additionally, a novel Q-factor approach for orthogonal frequency division multiplexing optical signals showing improved bit error ratio estimates is also presented.