| Summary: | 博士 === 國立臺灣大學 === 電機工程學研究所 === 88 === Several issues on the design and performance analysis of differential polarization modulation fiber-optic systems are addressed. To reduce the system complexity and the phase-noise sensitive property of the conventional 4-Quadrature (4Q) system, we design a differential 4Q system which possesses simpler system structure and does not need the absolute phase information of the received signals at the receiver. On the other hand, we solve the performance analysis problem in the conventional Double Differential Polarization Shift Keying (DDPolSK) system. The exact distribution of the received information parameters is derived first time. The saddle point method is applied to obtain the approximated Bit Error Rate (BER) values which agree with simulation data very well. Furthermore, the Gram-Schmidt Differential Polarization Shift Keying (GDPolSK), which generalizes the constellation design concept of the conventional DDPolSK, is proposed to construct the reference frame based on the Gram-Schmidt algorithm. The idea is to take the relative position of consecutive three symbols as an information symbol and design the constellation of the information symbol directly instead of applying the conventional n-vertex polyhedron method. This system not only provides more design flexibility in the symbol constellation but also performs much better than the conventional DDPolSK. At last, a novel differential coding method is proposed to further improve the performance of Differential Polarization Shift Keying (DPolSK) systems. The optimal constellation for the system is symmetric and easy to find. So it is named Symmetrically DPolSK (SDPolSK). The SDPolSK system constructs the noisy reference frame at the receiver more accurately than the Gram-Schmidt algorithm such that it has the best performance among all DPolSK systems presented so far.
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