Estimação de parâmetros em sistemas de transmissão com multiplexação por divisão espacial baseada em processamento digital de sinais

Author(s)

Ruby Stella Bravo Ospina

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Elétrica e de Computação
• Defense date: 2023-04-04

Examining board members

Darli Augusto de Arruda Mello; Carmelo José Albanez Bastos Filho; Jacklyn Dias Reis; Hugo Enrique Hernández Figueroa; Renato da Rocha Lopes

• Advisor: Darli Augusto de Arruda Mello

Abstract

Coupled space division multiplexing (SDM) transmission is subject to random power coupling that demands multiple-input multiple-output (MIMO) equalizers to compensate for any crosstalk between multiple propagation paths. The multiplicity of transmission paths also introduces modal dispersion, an effect that also needs to be addressed at the receiver, increasing its complexity. Moreover, due to in-line components, SDM transmission experiences an imbalance of losses and gains among different transmission paths, a perturbation known as mode-dependent loss (MDL) and mode-dependent gain (MDG). Along with amplification noise, MDL and MDG reduce the channel capacity and represent a fundamental limit for the deployment of long-haul SDM systems. In SDM systems, channel parameter estimation is essential for system design, performance evaluation, and troubleshooting. Therefore, in this thesis, techniques for channel parameter estimation in the scope of SDM systems are investigated. We show that conventional methods for MDG and signal-to-noise ratio (SNR) estimation present critical performance limitations at certain operation regimes. One improved technique for MDG estimation using a correction factor, and one novel technique for MDG and SNR estimation based on multilayer perceptron artificial neural networks (ANNs) are proposed. The results show that the correction factor technique substantially improves the MDG estimation accuracy in a simulated 3-mode transmission over 2,500 km and in an experimental 3-mode transmission over fiber links of 32.5-m and 73-km length. Similarly, the results show that the ANN-based MDG and SNR estimator outperforms the conventional methods presenting a suitable performance over all the regimes of MDG and SNR evaluated in an experimental 3-mode transmission setup over a 73-km fiber link. In addition, the ANN-based MDG and SNR estimator presents consistent performance when applied to a case study of an experimental long-distance transmission of 6 spatial modes. We also evaluate three scanning-based methods for estimating the accumulated chromatic dispersion (CD) in a simulated 3-mode SDM transmission setup. The results show that scanning methods are very susceptible to crosstalk and that only the delay-tap sampling technique can be applied to SDM systems with very high accuracy, even for high crosstalk levels. Finally, as a lateral topic, the potential reduction of the MIMO equalizer complexity in an experimental 55-mode fiber transmission with weak mode-group coupling is studied. The results show that a 21.5% complexity reduction can be achieved with only a 4.9% data rate loss by selective finite impulse response (FIR) filter deactivation (AU)

• FAPESP's process: 17/25537-8 - Distance-adaptive modulation for space-division multiplexed optical systems
• Grantee: Ruby Stella Bravo Ospina
• Support Opportunities: Scholarships in Brazil - Doctorate