The Investigation On 40Gb/s/? WDM-PON Transmission System And Colorless ONU

With the rapid spread of the Internet, represented by high-definition video, IPTV, P2P, the services of high rate and high quality develop rapidly,and the data flow in the network increases rapidly, which brings huge bearing pressure to the access network system, which is kown as "the last kilometer" of the telecommunication network. Wavelength division multiplexing passive optical network (WDM-PON) will become one of the next generation access network boosters, due to the advantages of high bandwidth capacity, wide coverage, transparent protocol, compatibility with existing network. 40Gb/s/ ? WDM-PON is one of the important developing directions of optical access technology.In this paper, some 40Gb/s/? WDM-PON system solutions are studied, such as the uplink and downlink modulation formats of high spectrum efficiency and relating generating schemes, colorless ONU, and receiver equalization algorithms. The research is carried out mainly from the following aspects.Firstly, analysis and comparison modulation formats of high spectrum efficiency and the relating generating schemes which are suitable for 40Gb/s/ ? WDM-PON system, such as half-cycle subcarrier 16QAM,4PAM, PM-DQPSK. Compare their spectrum efficiency, dispersion tolerance performance and receivers' performance, and analyze the system performance and cost of different transmission systems. PM-DQPSK based on coherent detection is suitable for downlink transmission. A 16QAM modulation schenme based on intensity modulation coherent detection is proposed, which is suitable for uplink transmission. The analysis and simulation results show that compared with coherent detection,direct detection has the advantages of simplicity and low-cost, but is limited in transmission performance, which is a good uplink transmission scheme.Secondly, study of colorless ONU schemes based on SOA-REAM uplink modulation and tunable laser. The scheme based on SOA-REAM is simulated, which can effectively improve the uplink modulation rate. For the colorless ONU schemes based on tuable laser, an adaptive tunable laser wavelength tuning method which is suited for subcarrier modulation scheme is proposed. In this scenario, the low frequency signal which carry uplink wavelength information is generated in the OLT. Simulation results show that the proposed method can reduce the system complexity and improve the accuracy of adaptive wavelength tuning.Lastly, to compensate the transimission impairments in 40Gb/s/ ?WDM-PON system, off-line receiver equalization is studied in two aspects:the domain and the frequency. Apply RDE domain algorithm to equalize multilevel modulation, such as 16QAM. Simulation results show that RDE algorithm can improve the system performance and has good convergence speed. In order to reduce the computational and hardware complexity, a parallel processing scheme is adopted. Then, it shows the effectiveness of the proposed method in simulation. Among domain equalization algorithm,overlapping frequency domain equalization algorithm is studied, and its effectiveness is verified in the simulation of 16QAM transmission system.Last, bitrate flexible transceiver based on IMDD half-cycle subcarrier M-QAM is proposed, and the receiver uses OFDE algorithm to compensate impairments. Simulations show that the proposed transceiver has good performance.