Joint adaptive code rate technique and bit interleaver for direct-detection optical OFDM system

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• 作者：Qi Tang^a ; Jianjun Yu^a ; ^b ; Zizheng Cao^a ; Jiangnan Xiao^a ; Xinying Li^b ; Mango Fall^a ; Lin Chen^a ; ^{liliuchen12@vip.163.com}
• 关键词：Optical fiber communication ; Orthogonal frequency division multiplexing (OFDM) ; Direct detection (DD) ; Adaptive code rate technique (ACT) ; Bit interleaver
• 刊名：Optical Fiber Technology
• 出版年：2013
• 出版时间：January, 2013
• 年：2013
• 卷：19
• 期：1
• 页码：35-39
• 全文大小：1075 K

文摘

In this paper, we have theoretically analyzed that the existence of inter-subcarrier mixing interferences (ISMI) and frequency selective fading (FF) in the directed-detection optical orthogonal-frequency-division-multiplexing (DDO-OFDM) system will cause an unbalanced error distribution and degrade the system performance. Then we propose to employ the adaptive code rate technique (ACT) and bit interleaver in the DDO-OFDM system to combat ISMI and FF. The experimental results show that the receiver sensitivity of 5.9-Gb/s 64-ary quadrature-amplitude-modulation (64QAM) OFDM signal employing ACT(9.43 Gb/s after encoding) is improved more than 2 dB compared with the 5.9-Gb/s OFDM signal with 0.66 turbo coding rate (8.85 Gb/s after encoding) at the bit-error ratio (BER) of 1e-4. When the coding rate is all 0.625, the OFDM signal employing ACT has more than 1-dB gain improvement compared with the OFDM signal encoded with fixed-rate turbo coding. And additional ¡«1-dB receiver sensitivity improvement is enabled when the OFDM signal employ ACT and bit-interleaver simultaneously.