Carrier Phase Recovery And Frequency Offset Estimation For High Speed Optical Transmission System

The high-speed optical communication system is developing from10or40Gb/s to100Gb/s. The laser phase noise and the frequency offset are the main factors that affectthe performance of100G PDM-16QAM or PDM-QPSK systems, in addition to factorssuch as fiber loss, CD and polarization mode dispersion. In order to make better use ofwavelength resource and increase the flexibility of WDM network, optical burstswitching network is often considered for dynamic configuration and switching ofsub-wavelength. In the optical burst switching network, optical-signals appear in theform of burst, thus burst-mode receivers are needed. The large capacity coherent opticalcommunication system is studied for both the traditional high speed coherent opticalcommunication system and the high speed burst-mode coherent optical communicationsystem in this paper:First, the high-speed coherent optical communication system is studied with afocus on the CD equalization technology and the carrier phase estimator. Blind phasesearch algorithm for the carrier phase estimator is studied. Considering the limit ofhardware speed, the BPS algorithm is designed in parallel form with simplifiedcomputing process. Fixed-point simulation of the algorithm is also carried out tovalidate the feasibility of parallel design based on performance comparison withsimulation results of floating-point.Second, the burst-mode receiver is designed for the high speed burst coherentoptical communication system. In order to meet the needs of fast channel equalizationrequirements for the optical burst-mode coherent receiver, this paper proposes a methodthat combines electric channel equalization with frequency offset estimation. The outputfrom the frequency offset estimation module is used in both tap coefficient updating ofthe equalizer and frequency offset compensation. Simulation results show that thecombination of the two modules in the optical burst-mode coherent receiver is able torealize channel equalization and frequency offset estimation and compensationeffectively, even under the case witch there exists significant transient frequency offsetin the optical burst-mode coherent receiver.