光纖通訊系統中串鎖式分波多工編碼之研究

Abstract

本論文提出應用於光纖通訊系統的「串鎖式WDM編碼系統」以徹底利用編碼增益。串鎖式WDM編碼系統是將外部ITU RS (255,239) code和內部WDM編碼系統串接起來，和傳統串鎖序列RS編碼不同。其中內部的WDM編碼系統將資料以並列的方式編碼，並且為了使系統位元率不變因此把編碼後產生的檢查碼置於額外的波長通道中，因此由於系統位元率改變而導致的損失只來自外部RS編碼。雖然作為內部編碼的漢明碼(Hamming code) 只擁有糾正單一錯誤能力，不像RS碼可以糾正多個錯誤，但是串鎖式WDM編碼系統的編碼增益和傳統串鎖序列RS編碼一樣好。不但如此，我們的編碼系統擁有其他優點：首先內部WDM編碼系統中的並列編碼方式比序列編碼簡單，在高速光通訊系統中較容易實現。再者和序列編碼比起來，內部WDM編碼可以大大減少編碼器與解碼器的數量。

The concatenated WDM coding system for optical communication system is proposed to fully utilize the FEC gain. The concatenated WDM coding system is concatenating an outer ITU RS (255,239) code with an inner WDM coding system which is different from conventional concatenated serial RS code. The inner WDM coding system encodes data in parallel and puts the parity-check bits in additional wavelength channels to achieve constant bit rate. Therefore, the penalty caused by increased bit rate is contributed by inner RS code only. Unlike the RS code with multiple-error-correcting capability, the Hamming code with single-error-correcting capability is adopted as the inner code. Nevertheless, the coding gain of the concatenated WDM coding system is as good as the conventional concatenated serial RS code. Moreover, our coding scheme provides other advantages. First, the parallel coding configuration of inner WDM coding system is simpler than that of serial codes, being easier to be implemented in high-speed optical systems. Second, compared with serial coding, inner WDM coding is able to reduce heavily the number of encoder/decoder pairs.