Replacing the Soft-Decision FEC Limit Paradigm in the Design of Optical Communication Systems
Replacing the Soft-Decision FEC Limit Paradigm in the Design of Optical Communication Systems
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DOI：
10.1109/jlt.2015.2482718
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发表时间：
2015-03
影响因子：
4.7
通讯作者：
A. Alvarado;E. Agrell;D. Lavery;R. Maher;P. Bayvel
中科院分区：
文献类型：
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作者：
A. Alvarado;E. Agrell;D. Lavery;R. Maher;P. Bayvel
FEC极限范例是设计光通信系统以在没有前向纠错（FEC）的情况下获得特定误码率（BER）的普遍实践。这种做法假设存在FEC码，该FEC码将在解码后将BER降低到期望的水平。在本文中，我们挑战这种做法，并表明，一个独立的信道FEC限制的概念是无效的软决策逐位解码。结果表明，对于低码率和高阶调制格式，使用软判决FEC限制范例可以低估频谱效率高达20%。一个更好的预测解码后的BER是广义互信息，这是给一致的后FEC BER预测在不同的信道条件和调制格式。广泛的光学全场模拟和实验进行了线性和非线性传输制度，以证实理论分析。
The FEC limit paradigm is the prevalent practice for designing optical communication systems to attain a certain bit error rate (BER) without forward error correction (FEC). This practice assumes that there is an FEC code that will reduce the BER after decoding to the desired level. In this paper, we challenge this practice and show that the concept of a channel-independent FEC limit is invalid for soft-decision bit-wise decoding. It is shown that for low code rates and high-order modulation formats, the use of the soft-decision FEC limit paradigm can underestimate the spectral efficiencies by up to 20%. A better predictor for the BER after decoding is the generalized mutual information, which is shown to give consistent post-FEC BER predictions across different channel conditions and modulation formats. Extensive optical full-field simulations and experiments are carried out in both the linear and nonlinear transmission regimes to confirm the theoretical analysis.