The Research On PAPR Reduction For OOFDM System With IPTS Clipping Algorithm

As a novel multi-carrier modulation technology, optical orthogonal frequency division multiplexing(OOFDM) has become a popular research in optical communication field in recent years because of special advantages. Coherent optical orthogonal frequency division multiplexing(CO-OFDM) system is considered as the important solution for large-capacity high-speed, and long- haul fiber communications for its superior perfo rmance in spectral efficiency, receiver sensitivity, and polarization-dispersion resilience.High peak-to-average power ratio(PAPR) is one of the major drawbacks, which will increase the complexity and cost of system, and affect the non- linearity of fiber. Therefore, how to reduce the PAPR effectively is the key for OOFDM system to become practical. The research emphasis in this thesis is to reduce the PAPR of CO-OFDM and polarization division multiplexing coherent optical orthogonal frequency division multiplexing(PDM-CO-OFDM) system, with iterative partial transmit sequence(IPTS) clipping algorithm. The thesis is organized as follows:1. Firstly, the research background, development situation, and problems of OOFDM system are introduced. The basic princ iple and key technology of CO-OFDM system are depicted. Then the reasons why PAPR is high and the negative influences of PAPR on the performance of system are discussed. In addition, CO-OFDM and PDM-CO-OFDM system are built with matlab and optisystem software.2. The classification, merits, and demerits of traditional PAPR reduction algorithms are introduced, especially the PTS and clipping technique. IPTS algorithm with low computation complexity is proposed on the basis of PTS algorithm. The PAPR of OOFDM system is reduced with the novel PAPR reduction algorithm called IPTS clipping algorithm, which is the combination of IPTS and clipping algorithm.3. The PAPR of 20Gbit/s CO-OFDM system is reduced with IPTS clipping algorithm. The PAPR reduction performance of PTS, IPTS, clipping, clipping IPTS, and IPTS clipping algorithm are compared by use of complementary cumulative distribution function(CCDF) curves and signal power figures in optical domain. Furthermore, the influences of clipping and IPTS clipping algorithm on the bit error rate(BER) performance of system are analyzed.4. The IPTS clipping algorithm is used to reduce the PAPR of 100Gbit/s PDM-CO-OFDM system. The influences o f IPTS clipping algorithm and clipping algorithm on the BER and non- linearity performance of system are analyzed. The BER of system in different directions is researched. In addition, the influences of different transmission distances on the BER and non-linearity performances of system are discussed.