João L. Rebola

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A new Gaussian approximation (GA) which takes into account the influence of arbitrary optical and electrical filters is proposed for the performance evaluation of optically preamplified receivers. Using the new GA, the receiver sensitivity is evaluated and notable performance differences were observed for several Fabry-Perot optical filters.
Four-level (quaternary) signalling in optical communication systems is investigated and the optimisation of quaternary signal level spacing is carried out considering signal-amplified spontaneous emission beat noise dominance. The optimised quaternary signal is propagated through an optical dispersive fibre and sensitivity improvements can be found for(More)
Optical coherent technology leads to the coexistence of signals with different modulation formats and different bit rates in optical networks. Due to this coexistence, several in-band crosstalk scenarios are possible. In this work, the impact of in-band crosstalk due to M-QAM interferers on the performance of PDM-QPSK and PDM-16-QAM coherent receivers at a(More)
The Gaussian approach (GA) is used to assess the impact of in-band crosstalk on the performance of direct-detection orthogonal frequency division multiplexing (OFDM) optical communication systems. The GA accuracy is compared with estimates of the bit error probability (BEP) and crosstalk penalty obtained using Monte Carlo (MC) simulation. The GA revealed a(More)
An analytical tool based on the moment generating function of the receiver decision variable that can evaluate the impact of multi-format in-band crosstalk in optical differential quadrature phase-shift keying (DQPSK) systems is presented. It is shown that the on-off keying (OOK) interferer is the most detrimental interferer in terms of performance(More)
In-band crosstalk is a major physical impairment in optical networks. Due to its robustness to in-band crosstalk differential phase-shift keying (DPSK) has surged as an attractive modulation scheme to be used in such environments. In this paper a stochastic simulation based on the Monte Carlo (MC) method that permits to assess the impact of in-band(More)
An analytical method based on the moment generating function (MGF) is proposed for assessing the performance of direct-detection (DD) orthogonal frequency division multiplexing (OFDM) optical receivers with radio-frequency (RF) demodulation. The MGF-based method is a generalization of the method previously reported in the literature for DD baseband OFDM(More)
In this work, the tolerance to in-band crosstalk of virtual carrier (VC)-assisted direct detection (DD) multi-band orthogonal frequency division multiplexing (MB-OFDM) metro networks, with and without signal-to-signal beat interference (SSBI) mitigation, is compared numerically for 4-ary, 16-ary and 64-ary quadrature amplitude modulation (QAM) formats in(More)