Research On RS-LDPC Codes In Metropolitan Area Optical Networks

In optical transmission system,Metropolitan Area Network(MAN)based on optic is expanding speedily.However,there may be not only random error but also burst error because of noise and intersymbol interference.Product code,thanks to its property of self interleaving,may be a promising technique for future optical communication system to overcome hybrid interference.LDPC codes,with iterative soft-decision decoding algorithm,which can approach Shannon limit error performance,have attracted much attention,and been widely used in digital video broadcasting(DVB-S2),10G Ethernet and new broadband wireless access(WiMax)technology.RS code not only can overcome burst error,but also does well in removing error-floor phenomenon of LDPC code.As a consequence,RS code and LDPC code are suitable to constitute a product code.With parity-check matrix in LDPC organized based on certain column weight distribution,part of the received codes and the relevant column in parity-check matrix can be truncated as required when decoding.Simulation results show that the proposed decoding algorithm is computationally efficient and keeps good performance simultaneously.It will be introduce as follows:(1)We analyze the structure of the latest MAN optical transmission system as well as its encoding principle and different encoding methods,especially for RS code with high bit rate and LDPC code with high encoding gain.Then we try to find a proper encoding and decoding method for the new MAN optical transmission system.(2)Based on the encoding and decoding principle of RS code,which is widely used in MAN optical transmission system,we analyze a kind of soft-decision decoding algorism—GMD.And I put forward an optimization for GMD algorism by confining the degree of its error syndrome polynomial.(3)In RS-LDPC product code,the low-density-parity-check matrix is organized based on certain column weight distribution in my encoding algorithm.Besides,I propose a self-adaptable sliding puncturing decoding algorism,in order to reduce computationally complexity and keep good performance.