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Project: Metro Networks Based on Multi-Band Orthogonal Frequency-Division Multiplexing Signals

Acronym: MORFEUS
Main Objective: The general objective of this project consists in demonstrating the new paradigm related to the increase of the flexibility and granularity of the transmission capacity in metropolitan (metro) optical networks. Particularly, the implementation of metro networks based on high data-rate multi-band orthogonal frequency-division multiplexing (MB-OFDM) signals employing wavelength division multiplexing (WDM) is analysed and demonstrated as an excellent solution to provide, simultaneously, high flexibility in capacity allocation, high spectral efficiency and the possibility of upgrading the network capacity while keeping the system architecture almost unchanged.
Recently, optical transmission systems with high capacity granularity have been appointed as the most promising solution to be employed in the integration of the metro and access networks in a single hybrid optical network. Systems based on MB-OFDM signals have been recognized as an excellent solution as they allow the integration of several final users who usually require a capacity quite below the total network capacity. This access technology has been indicated as a good alternative to the solutions based on time-division multiplexing currently deployed.
Previous works have experimentally shown the dynamic allocation of OFDM subcarriers or individual bands of MB-OFDM signals as an excellent solution to increase the granularity of capacity allocation. However, these works were presented as a proof-of-concept: the MB-OFDM transmission impairments and the traffic allocation optimization were not analyzed. In addition, the main performance limitations were not identified as well.
This project has two particular objectives. First, it is focused on the investigation of the performance impairments imposed by the physical layer on the high data-rate (maximum bit rate of 40 Gbit/s per wavelength) MB-OFDM signals transmission in WDM metro networks and on the system parameters optimization using analytical, simulation and experimental work. Particularly, the study and the assessment of the main system impairments is performed, such as: (i) linear crosstalk associated with the MB-OFDM transmission and with the finite selectivity of the optical devices required to select the different bands and wavelengths at each node of the metro network, (ii) linear and nonlinear fibre effects, (iii) joint nonlinear effect introduced by the electro-optic and opto-electric conversion processes.
Second, this project is focused also on the study of the network layer of WDM metro networks based on MB-OFDM signals. Particularly, the assignment of OFDM bands and wavelengths, and the traffic distribution along the network are analysed. Routing, wavelength and band assignment (RWBA) algorithms are developed based on maximum wavelength and band reuse in MB-OFDM metro networks. These algorithms are developed considering the impairments imposed by the physical layer of the WDM MB-OFDM metro network (cross layer design).
The work to carry out along this project is focused on MB-OFDM signals with intensity modulation - direct detection (IM-DD) systems for transmitter and receiver cost reduction, an imperative of metro networks. Different MB-OFDM transmitters are analysed, e. g. MB-OFDM transmitters using single sideband modulation implemented using appropriate (I,Q) modulators or the generation of electrical MB-OFDM signals with adequate properties to provide strong robustness to fibre dispersion induced power fading.
The ultimate goal of the project consists in the experimental demonstration of the simultaneous transmission of, at least, three optical channels using MB-OFDM signals in a metro optical network with insertion/extraction capabilities at the OFDM band level.
Reference: PTDC/EEI-TEL/2573/2012
Funding: FCT/PTDC
Start Date: 01-04-2013
End Date: 01-09-2015
Team: Adolfo da Visitação Tregeira Cartaxo, Iguatemi Fonseca, João Lopes Rebola, Tiago Manuel Ferreira Alves, Pedro Emanuel Domingos da Cruz
Groups: Optical Networking – Lx
Local Coordinator: Adolfo da Visitação Tregeira Cartaxo
Associated Publications