Abstract:

The lowdensity paritycheck codes and orthogonal frequency division multiplexing are used in the passive optical network in this paper,and the downlink transmission performance of PON system based on LDPCOFDM is simulated by using Optisystem and Mablab.The results show that the 10 Gbit·s-1 LDPCOFDM coded modulation signal can be realized in the downlink transmission in passive optical network.The transmission performance of the system based on LDPCOFDM is improved by 4.2 dB over that of the uncoded modulation at the bit error rate of.When the SNR is greater than 2.6 dB,the Gallager method has better error rate performance than the Mackay method and BIBD method,and the system has better performance with LLRBP or its improved algorithm when the SNR is greater than 4.6 dB.

Key words: low density parity check;orthogonal frequency division multiplexing;passive optical network