Investigation On Coherent Reception DSP Algorithm For 100G Upstream Passive Optical Networks

With the explosive development of the Internet business,IP traffic is raising rapidly,people's demand for information business enhances unceasingly."The last kilometer" becomes increasingly concerned about the focus of the solution.Access network,what gives priority to passive optical network,is becoming a hot spot of network application and construction.In order to meet demand for network bandwidth,users put forward more requirements on optical access network technology at present which could provide large capacity,higher branching ratio and longer transmission distance to meet the application requirement of large capacity and wide coverage and reduce the operating costs with ODN passive.The technology which combines the coherent detection,polarization multiplexing and digital signal processing has improved the spectrum efficiency and power budget of the system.Therefore 100G coherent passive optical networks(PON)becomes one of the trend of the future development.Meanwhile,with the increase of transmission rate and transmission distance,the impairment of fiber link,such as CD?PMD and polarization crosstalk,gradually becomes the main factors to affect the system performance.The dissertation mainly deeply researches on the key problems such as fast convergence in coherent reception DSP algorithm for 100G upstream passive optical networks.The main work of the dissertation is sketched as follows:1.Since the optical bursts of different ONU may go through different optical paths,the impairment they experience may differ greatly and change over time.We design a method of digital signal process aided by control signal for burst-mode coherent receiver in order to compensate the optical butst respectively and reduce the convergence time to improve delay and throughput performance.The method use the tap coefficients of the last optical burst aided by control signal to initialize the tap coefficient of the present optical burst sent by the same ONU.he simulation of 100Gbps PM-QPSK burst-mode coherent reception results show that the proposed method could reduce the 70%convergence time.The 128Gbps PM-QPSK experiment shows the proposed method could reduce two thirds convergence time.2.According to the demand of large capacity and wider coverage,we design 100G PON upstream PM-QPSK burst-mode coherent reception system scheme.ONU which is based on four MZ modulators produce PM-QPSK signal.OLT based on burst-mode coherent receiver to recover the optical burst of ONU with fast tunable laser.The scheme can both improve the spectrum efficiency,power budget and transmission distance to meet the large capacity and wider coverage application.The simulation results show that This system can meet the power budget of 1:128 splitting ratio under 60km transmission distance without EDFA in channel,and the burst-mode coherent receiver can be used to receive and restore the signal which can reduce two thirds of the overhead of system.3.According to the demand of large bandwidth in future enterprise users(>1Gbps),we design 100G PON upstream PM-4PAM intensity modulator and burst-mode coherent reception system scheme based on electro absorption modulator.ONU which is based on two EA modulators produce PM-QPSK signal.OLT based on burst-mode coherent receiver to recover the optical burst of ONU with fast tunable laser.The simulation results show that this system can meet the power budget of 1:16 splitting ratio without EDFAs in the channel under 60km transmission distance,the cost is about 50%of PM-QPSK scheme and the burst-mode coherent receiver can be used to receive and restore the signal and reduce the complexity to one percent of PM-QPSK scheme.