کدهای بهم پیوسته (کد رهگیری) تصحیح خطا ارسالی (FEC) در سیستم های تسهیم طول موج متراکم (DWDM)

ABSTRACT Forward error correction concatenated code in DWDM systems

In recent years, with the rapid development of dense wavelength-division multiplexing (DWDM) systems, the ITU-T has developed researches on forward error correction (FEC) codes, and relative recommendations such as ITU-T G. 707, G. 975 and G. 709 have been proposed one after the other. All the applied coding code-types in these recommendations are the single linear system cyclic codes, such as the BCH code and RS code [1,2]. The single channel code can produce the moderate net coding gain (NCG), but it may not meet the requirements of high speed large-capacity DWDM systems. With the increasing development of DWDM systems toward longer distance, larger capacity and higher bit rate, further improvements of the transmission rate and distance are limited due to the accumulated optical effects such as the dispersion and polarization-mode dispersion (PMD), and the accumulated nonlinear optical effect such as four wave mixing (FWM), stimulated Raman scattering (SRS), and stimulated Brillouin scattering (SBS) in the DWDM systems [3–6]. As a result, it has become necessary to develop a novel and more powerful super forward error correction (Super-FEC) code-type to gain a higher NCG and better error-correction performance to meet the requirements of the rapid development for DWDM systems. It is also required that this new code-type is able to compensate for serious transmission quality degradation and avoid using dispersion-compensating technologies with expensive and complex devices. In view of this development trend of DWDM systems, it is necessary to do further researches on the novel scheme of the codetype, theoretical analysis and practically verify its application in DWDM systems to improve their communication quality and decrease their cost. Since the concatenated code has a very powerful outburst-error-correction and random-error-correction performance, it is the main research object of high efficient code-type in DWDM systems.