The Research On Peak-to-Average Power Ratio Reduction In OFDM Systems

As mobile technology develop swift, the people are also getting higher and higher to the correspondence request, high ability, the high speed's mobile multimedia transmits into the pursue goal. Orthogonal Frequency Division Multiplexing (OFDM) is an effective transmission scheme to cope with much impairments, such as transmits high rate data, high spectral efficiency, combating inter symbol interference (ISI) and multi-path delay. It was considered as one of next generation mobile communication core technologies.However, many key problems of an OFDM system have not been solved yet, such as sensitivity of frequency offsets and high PAPR (Peak-To-Average Power Ratio), which limit wide application of OFDM technique. This thesis mainly focuses on the techniques of PAPR reduction and use MATLAB software to achieve simulation. We have achieved the following work:(1) This thesis first analyzes the basic theory of OFDM signal and key technique.(2) Then, the definition add distribution of PAPR is presented in detail. On the basis, the paper makes deep analysis on simulation, and summarizes the most popular three kinds of PAPR reducing techniques, including non-distorting technology, pre-distorting technology and coding technology. Also, the paper makes thorough compare of these methods, and draws conclusions. Particularly, strong emphasis is cast on Partial Transmit Sequences (PTS), which belongs to the non-distorting technology. Though, the PTS method possesses the advantages of anti distortion, not being limited by the number of carriers, less loss of frequency spectrum. However, the most serious flaw of PTS is the heavy complexity of computation, which strongly restricts the application of PTS method.(3) Harasses the high operation order of complexity question which in view of the signal in the pre-distorting technology Partial Transmit Sequences (PTS) exists to conduct the dissect, first introduce two kinds of low complexity algorithms based on the PTS (Cimini iterative method, and Dual Layered Phase Sequencing). Then, proposes a new algorithm based on the PTS, Introduce in detail the new algorithm's basic philosophy, and how to realize specifically. Simulate it with MATLAB, Analyzes the new algorithm's performance and algorithm' order of complexity.Compare the new algorithm with the two algorithms (Cimini iterative method and Dual Layered Phase Sequencing) and the PTS, confirm that the new algorithm not only can reduce the PAPR of the OFDM system, but also can large scale reduce the complexity of computation.