Experimental evaluation of Data-Aided and non-Data-Aided dynamic equalization algorithms for low OSNR regimes

Optical transceivers with flexible code rates offer the possibility of reducing the required OSNR at the receiver by using higher-order modulation formats with longer FEC overheads. To work in such low OSNR scenarios, the performance of digital signal processing algorithms become critical. Therefore...

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Bibliographic Details
Published in:2015 SBMO IEEE MTT S International Microwave and Optoelectronics Conference (IMOC) pp. 1 - 5
Main Authors: Souza, Andre L. N., Mello, Darli A. A., Reis, Jacklyn D.
Format: Conference Proceeding
Language:English
Published: IEEE 01.11.2015
Subjects:
Bandwidth
Digital signal processing
Heuristic algorithms
Modulation
Optical noise
Signal processing algorithms
Signal to noise ratio
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Summary:Optical transceivers with flexible code rates offer the possibility of reducing the required OSNR at the receiver by using higher-order modulation formats with longer FEC overheads. To work in such low OSNR scenarios, the performance of digital signal processing algorithms become critical. Therefore, we compared an unsupervised and a supervised implementations of the Radially-Directed Estimation Algorithm (RDE), and an unsupervised Decision-Directed Least Mean Square (DD-LMS). Performance was evaluated by comparing the characteristics of SNR versus OSNR curves generated experimentally by offline post-processing, for OSNRs varying from 8 to 35 dB, and Nyquist 4/8/16/32/64-QAM modulation formats, for various symbol rates. The supervised algorithm resulted in expressive gains for high-order modulation formats (32-QAM and 64-QAM), while for low-order modulation formats (4-QAM, 8-QAM and 16-QAM) no noteworthy improvement was observed. The results indicate that, although supervised algorithms reduce spectral efficiency due to the transmission of pilot symbols, in low OSNR regimes (as in heavily-coded systems) they become an interesting option.
DOI:10.1109/IMOC.2015.7369122