基于LDPC-OFDM编码调制的无源光网络

LDPC-OFDM coded modulation-based passive optical network

在无源光接入网中,利用高编码增益的前向纠错编码和先进的调制技术可以降低系统对发射功率的要求,提升网络性能。本文将低密度奇偶校验(LDPC)码和正交频分复用(OFDM)调制技术引入无源光网络(PON),构建基于LDPC-OFDM编码调制的无源接入网系统,在20km单模光纤(SMF)上实现10Gbit/s LDPC-OFDM编码调制信号的下行传输,2Gbit/s编码OOK信号的上行传输。误码率(BER)均为10-3时,在下行链路LDPC-OFDM编码调制较未采用编码调制系统性能提升了3.9dB;在上行链路,LDPC编码信号性能较RS(255,223)和RS(255,239)分别有1.8dB和2.3dB的提升。

The forward error correction codes with high coding gain are used in passive optical access net- work to reduce requirement for transmission power and improve network performance. Low-density parity-check （LDPC） and orthogonal frequency division multiplexing （OFDM） modulation are introduced, and the passive optical network based on LDPC-OFDM coded modulation is built. 10 Gbit/s coded modulation signal and 2 Gbit/s on-off keying （OOK） coded signal are transmitted as downstream and upstream in the 20 km standard single mode fiber. The performance improvement of coded modulation over uncoded modulation is 3.9 dB in downlink at bit error rate （BER） of 10 ^-3. The performance comparison is also made between LDPC code and RS code in uplink, and the improvements of the LDPC code relative to RS（255,223） and RS（255,239） are 1.8 dB and 2.3 dB at BER of 10^-3 ,respectively.