Research On Advanced Modulation And Related Channel Coding In Optical Networks

With the development of the internet and its market, the demand in data traffic and bandwidth of internet services such as video streaming,social media and cloud computing has increased rapidly. Ethernet in Local Acess Network(LAN) has speeded up from 10M, 100M, 1G, 10G to 40G/100G, and now is moving towards 400G. Meanwhile, the excellent performance has also led it into a more wide area like Metropolitan Area Network(MAN) and Wide Area Network(WAN). In the field of Optical Metropolitan Area Network, the research on high modulation formats with intensity modulation and direct detection(IM/DD) such as PAM4 (4-pulse amplitude modulation) has become a hotspot of research all over the world in order to achieve higher transmission rate, since the standard of 400GbE has been developed.The major problem of MPAM(M-ary pulse amplitude modulation) is that with the increasing of M, it's resistance to Inter Symbol Interference(ISI) will decrease rapidly, which leads to higher bit error rate and affects the transmission reliability. Therefore, many applications with MPAM need to be paired with channel coding such as forward error correction, and as the 5G eMBB(enhanced mobile broadband) channel coding scheme, LDPC(low density parity check code) and Polar code are centainly the hot spots of research.Modulation and coding of channel are important parts of the information transmission system, which play significant roles in the validity and reliability of the information transmission. Therefore, after doing some research on the relevant knowledge of FEC and modulation in Metropolitan Area Network, we focus on the research on LDPC, Polar code and the optical pulse position modulation based on double-circle iteration(DCI-PPM) proposed in this paper. The main research of this paper are as follows:(1) Under the research of FEC, and the construction of LDPC, we design a 50GS/s optical communication system based on LDPC-TC-32QAM.We do some research on its BER performance and the influence of times of decoding iteration, and compare with LDPC-16QAM.(2) Under the research of the construction of Polar Code, simulate and analyse the performance of Polar Code in different length, different rate in AWGN and BEC channel.(3) Under the research of the requirement of MAN and the performance of MPAM, we do some research on MPAM and the PAM4 modulation based on Gray code, simulate and analyse its performance of BER.We propose an optical pulse position modulation based on double-circle iteration(DCI-PPM). This paper designs its modulation model, mapping principle and the related demodulation model. Simulating and analyzing its performance of bandwidth utilization, bit error rate and tolerance of chromatic dispersion , and comparing them to PAM4.