Reach On The Improved Algorithm Of PAPR Reduction Techniques Of OFDM System

Today， Orthogonal Frequency Division(OFDM) has been used much in thecommunication system of high speed wireless data and it is also adopted by the standard ofnext mobile communication. OFDM can withstand the multipath interference of wirelesschannel, it has higher spectrum efficiency when compared with single-carrier modulation atthe same time. But one of the greatest disadvantages of OFDM system is the high PeakAverage Power Radio (PAPA), which limits the further application of the technologyseverely.The paper research the issue of high PAPR in the OFDM system, and introduce theproblem systematically about high PAPR of OFDM system from aspect of basic OFDMsystem correlation theory, PAPR correlation theory, and the technology of PAPR withstandand so on, it also introduce the current basic way of solving the problem. The paper proposean improved arithmetic that is called select-union arithmetic, it aims especially at theadvantage and disadvantage about no signal distortion, and high complexity among thecurrent method of withstanding PAPR. Select-union arithmetic combine computationalcomplexity to the three arithmetic with different improvement effect which contains PartialTransmit Sequence(PTS), Multiple phase factor PTS, selected mapping(SLM). The basic ideaof select-union arithmetic is base on group data of traditional PTS arithmetic, use groupeddata as a unit selecting arithmetic. The principle of arithmetic selection is that send the groupwhich occur with big probability to the PTS arithmetic with relative low complexity, send thegroup with smaller occur probability to multiple phase factor PTS with lower complexity, andsend the group with minimum probability to the SML arithmetic with highest complexity. Thebasic process as follows: grouping the raw data, then select appropriate arithmetic for thegrouped data, adopting arithmetic corresponded to the grouped data which selected byarithmetic. Result of experiment simulation proves that union arithmetic can reduce PAPR byaround4dB, compared with PTS arithmetic with same amount of packet, when lessmodulation number, the improvement degree of PAPR is superior to PTS arithmetic, whenmore modulation number, the improvement degree of PAPR is same with PTS arithmeticeven slightly better.