基于水印位的信道估计对100 Gb/sPDM-DQPSK光通信系统中低密度奇偶校验码纠错性能的提升  

Performance Enhancement of LDPC in 100 Gb/s PDM-DQPSK Optical Communication Using a Water-Bit Based on Channel Estimation

作　　者：李超[1] 张文博[2] 张晓光[1] 席丽霞[1] 唐先锋[1] 何文雪[1] 

机构地区：[1]北京邮电大学信息光子学与光通信国家重点实验室,北京100876 [2]北京邮电大学理学院,北京100876

出　　处：《中国激光》2014年第6期141-147,共7页Chinese Journal of Lasers

基　　金：国家自然科学基金(61205065);国家863项目(2013AA013401);山东省自然基金项目(ZR2010FM043);区域光纤通信网与新型光通信系统国家重点实验室(上海交大)开放基金(2013GZKF031310)

摘　　要：针对高速光通信系统中高斯白噪声和偏振模色散(PMD)引起的干扰问题,研究了一种改进的前向纠错方法,通过向低密度奇偶校验(LDPC)码中插入具有固定信息的比特位("水印位")来估计信道,并将其与译码算法结合构成新的算法。研究发现,若以误比特率(BER)低于10-9为标准,则在纠错性能方面,高斯信道中含16、32位水印位的LDPC码与卡方信道中传统的LDPC码相比,所需的光信噪比(OSNR)值可分别减少约0.25dB、0.35dB;当考虑高速光通信中的PMD时,在差分群时延(DGD)为20ps和30ps时,含16、32位水印位的LDPC码与传统LDPC码字相比,所需OSNR值可分别减少约0.63dB、0.98dB和1.16dB、1.87dB。To reduce the interference caused by channel noise and polarization mode dispersion （PMD） in the optical communication, a modified forward error correction method is studied. By inserting fixed bits which are defined as the watermark bits （water-bit） into the low density parity check （LDPC） codes to estimate the channel, a new decoding algorithm which is combined with channel estimation is proposed. The results show that the LDPC code with 16, 32 water- bit transmitted over Gaussian channel outperforms the conventional LDPC code transmitted over Chi-square channel in the error correction performance, and with bit error rate （BER） below 10^-9 as standard, the optical signal to noise ratio （OSNR） value can reduce about 0.25 dB, 0.35 dB. When PMD is considered in the high-speed optical communications, the LDPC code with 16, 32 water-bit has a better tolerance than the conventional LDPC code, when differential group delay （DGD） is 20 ps and 30 ps, the OSNR value can reduce about 0.63 dB, 0.98 dB and 1.16 dB, 1.87 dB.

关 键 词：光通信 信道估计 低密度奇偶校验码 前向纠错 偏振模色散 

分 类 号：TN911.22[电子电信—通信与信息系统]