Design And Realization Of RS-BCH Concatenated Codec

With the continuously development of transmission network toward the direction of the ultra-high speed, ultra-long distance and ultra-high capacity, the problem of information reliability appeared gradually. Since always, improving the reliability of information has been the main purpose of the Forward-Error-Correction (FEC) technology, but with the rapid development of optical communications, the performance of the previous code-based FEC codes can no longer meet requirements.Thus, it is committed to the study of a kind of codes which have more stronger error correction performance, called super forward-error-correction code (SFEC).SFEC is mainly constructed with the ideas of constructing a long-code with two separated short-codes and then implement separatedly,thus avoiding the difficulties of the realization of the long-code. This thesis selected one of recommended SFECs in ITUT-G975.1,RS(1023,1007)+BCH(2047,1959),the outer code of the SFEC are the RS (781,765) and RS (778,762),the shortened codes of RS (1023,1007), while the inner code of the SFEC is BCH (2040,1952), the shortened code of BCH (2047,1959),and interleaver technology has been involved in this SFEC. In the ITUT-G.709 Optical Transport Network, with the redundancy of 6.69%, coding gain of the selected kind of SFEC is expected to access to 8.5dB. Therefore, the circuit realization of the SFEC can improve many aspects of optical communication system performance as follows:(1) reducing the channel bit error rate, and improve the reliability of information transmission; (2) increase the rate of single channel transmission; (3) increased non-repeater distance; (4) reducing the channel spacing; (5) increase the density of optical channels.In this thesis, in Chapter 1,according to the current development of optical system, the necessity and significance of the studying of SFEC was proposed firstly,and the development status at home and abroad,and trends of the technology of forward error correction coding in the future were analysed secondly, finally the main contents and innovative points were pointed out. In Chapter 2, the characteristics of optical communication channel were analyzed firstly on the basis of the introduction of the noise in the optical communication system, and then the channel model was established based on the error correction coding. In Chapter 3, the concepts in algebra used in correction coding were given, then the concept of encoding and decoding of cyclic code was introduced, and the performance of SFEC was finally analyzed theoretically.In Chapter 4,the SFEC coding method was given firstly on the basis of ITUT G.709 frame structure, and then the SFEC codec circuit implementation are introduced, including RS,BCH codec circuit realization etc. In Chapter 5, verification platform of the codec of RS-BCH is briefly introduced firstly, and then the simulation results are analyzed. Chapter 6 is the summary of this thesis.