16-QAM polarizasyon bölmeli çoğullamalı evre-uyumlu optik OFDM sistemlerde kompleks sabit noktalı BBA kullanarak frekans düzlemi kanal kestirim verimliliğinin artırılması

Abstract

Polarizasyon bölmeli çoğullamalı evre-uyumlu optik OFDM (PDM-CO-OFDM) sistemleri uzun mesafeli haberleşmelerde, ışığa ait genlik, faz ve polarizasyon bilgilerinin aynı anda kullanımına imkân vererek yüksek veri hızlarına ulaşılmasını sağlayan bir yöntemdir. Fakat optik kanalın bozucu etkileri, veri iletim performansını düşürmektedir. Bu yüzden alıcıda bozucu etkileri düzeltmek için sinyal işleme tekniklerinden olan kanal denkleştiriciler kullanılmaktadır. Genel olarak kanal denkleştiricilerde, kanal bilgisinin kestirimi için periyodik eğitim sembolleri kullanılır. Fakat eğitim sembollerinin kullanımı, iletilen veri boyutunu artırmakta ve spektral verimliliği azaltmaktadır. Bu çalışmada, PDM-CO-OFDM sistemleri için eğitim sembollerine ihtiyaç duymayan, kompleks sabit noktalı bağımsız bileşen analiz (BBA) temelli kör kanal denkleştirici yöntemi, 16-QAM sinyaller için önerilmiştir. Elde edilen sonuçlar, kompleks sabit noktalı BBA algoritmasının eğitim sembollerine ihtiyaç duymadan kanal denkleştirici başarımını iyileştirdiği göstermektedir. Bu durum, başlatma gücü ve optik işaret gürültü oranı (OSNR) değerlerinin değişimine göre elde edilen sinyallerin bit hata oranı (BER) değerleri ile gösterilmiştir. Özellikle fiber kablonun doğrusal olmayan bozucu etkisinin etkin olduğu bölgede, önerilen yöntem diğer kanal denkleştiricilerden daha iyi başarıma sahip olduğu benzetim sonuçlarıyla gösterilmiştir.

Keywords

• Polarizasyon bölmeli çoğullamalı evre-uyumlu optik OFDM,Optik haberleşme,Bağımsız bileşen analiz,Kör kanal kestirimi

Improving the efficiency of frequency domain channel estimation in 16-QAM polarization division multiplexing coherent optical OFDM systems using complex fixed-point ICA

Abstract

Polarization division multiplexing coherent optical OFDM (PDM-CO-OFDM) systems are a method that provides to be achieved high data rate, offering the possibility for the use of information regarding polarization, amplitude and phase simultaneously. However, the impairment affects related to optic channel decrease the data transmission performance. For this reason, in the receiver, the channel equalizer, one of the signal processing techniques, are used for the impairments in order to compensate. Even though the periodic training symbols are generally used for the estimating of channel information in the channel equalizers, the use of training symbols increase system redundancy and decrease spectral efficiency. In this study, a blind channel equalizer based on complex fixed-point ICA without training symbols is suggested for the PDM-CO-OFDM systems with 16-QAM signals. The results show that the complex fixed-point ICA algorithm improves the performance of channel equalizer without the training symbols. This situation is indicated by the BER values of the signals obtained according to the change of the launch power values and optical signal noise ratio (OSNR) values. Simulation results have shown that the suggested channel equalizer has better performance than other channel equalizers, especially in the region where the effect of the fiber nonlinearity is effective.

Keywords

• Polarization division multiplexing coherent optical OFDM,Optical communication,Independent component analysis,Blind channel estimation

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