Research On Peak-to-average Power Ratio Reduction Of OFDM System In Low Voltage Power Line Communication

Low-voltage Power Line Carrier Communication is a kind of technology of informationtransmission and exchange using existing low voltage power network. The technology hasunique advantages and great market potential in the field of intelligent home network andbroadband access, so it has been paid more and more attention. However, the low-voltagepower line channel has many defects, such as time-varying characteristics, strong selectivefading, and serious interference. These problems restrict its development.Orthogonal Frequency Division Multiplexing (OFDM) technology has many advantages,including higher band utilization, fast transmission rate, resistance to multipath time delay andstrong anti-interference ability, easier hardware implementation, and so on. OFDM can beused as a modulation method of low-voltage power line communication to realize high speeddata transmission. In the application processing, OFDM signals exist higher Peak-to-AveragePower Ratio(PAPR), which directly affects the performance of the system.Through analysis of low-voltage power line channel characteristics, the channel modelsof low-voltage power line communication system are provide. The thesis introduces the basicprinciple of OFDM technology, as well as the application of OFDM in low voltage power linecommunication system, and summarized the key technologies of OFDM.. Then the PAPR ofOFDM signals is defined, the main reasons of the higher PAPR are analyzed, and its influenceon the system. The thesis simulate several classical reduction PAPR algorithms, including theClipping algorithm, Selection Mapping (SLM) and Partial Transmit Sequences(PTS). Theirrespective advantages and disadvantages are analyzed. On this basis, an improved algorithmof SLM, namely the scaled SLM is discussed in detail, including its advantages and its mainproblems. Then the scaled SLM and clipping method are combined in order to further reduce the PAPR. In addition, aiming at the problem of high computational complexity of PTSalgorithm, the ideas of the tabu search is used in the phase search of PTS. The new algorithmhas the lower calculation complexity than the classical PTS algorithm. Furthermore, the newalgorithm is compared with iterative PTS algorithm. In the case of the calculation complexityis almost equal, the new algorithm can more effectively reduce the PAPR.