Investigation of near optimum iterative equalizers and decoders for optical coherent Gbit/s transmission

Conference: Photonische Netze - 13. ITG-Fachtagung
05/07/2012 - 05/08/2012 at Leipzig, Germany

Proceedings: Photonische Netze

Pages: 7Language: englishTyp: PDF

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Oestreich, Klaus; Speidel, Joachim (Universität Stuttgart, Institut für Nachrichtenübertragung, 70569 Stuttgart)

We investigate a receiver for coherent optical communication with QPSK modulated signals. The receiver consists of a BCJR equalizer and LDPC decoding which are arranged as a turbo equalizer. Target is to find dedicated LDPC codes with overhead of about 7% to 14%. It turns out, that an LDPC code with overhead Oc = 12.5% and codeword length N = 9198 is most suitable with respect to performance, complexity and overhead. Furthermore the performance of the receiver is compared to a simpler receiver which compensates chromatic dispersion by the use of FIR filters. The comparison shows a gain of the turbo equalizer of up to 2.5 dB.