| Orthogonal Frequency Division Multiplexing(OFDM)technology has been widely used in modern information communication because of its high spec-trum utilization,strong inter-symbol interference(ISI)capability,and easy-to-implement frequency domain equalization.To most wireless communication stan-dards,it is the key physical layer technology of 4G,and it is also one of the im-portant alternative technologies of 5G.In the process of wireless communication research and commercialization,OFDM technology has been a research hotspot for experts and scholars.Among them,the peak-to-average power ratio is one of the key factors affecting system performance.Solving the high PAPR prob-lem of OFDM system is especially important in practical communication system applications.This paper analyzes and studies the proposed PAPR reduction algorithms,and considers the computational complexity,redundant information and the im-pact on the BER of OFDM system in view of the high bit redundancy existing in the current PAPR research.After that,a new PAPR reduction algorithm was proposed.This method is mainly based on the GreenOFDM algorithm and is an improved algorithm based on the selection mapping method(SLM).The general selection mapping method selects a candidate symbol sequence with the lowest PAPR for transmission by generating a different candidate symbol sequence of the M group.The new algorithm is based on the GreenOFDM algorithm:using the M group phase rotation factor sequence to generate a M~2/4 group of candidate symbol sequences.This allows more candidate symbol sequences to be generated with fewer IFFT operations.Therefore,in the case that the redundant infor-mation of the transmitted signal is consistent,the computational complexity is greatly reduced,and the purpose of reducing the system PAPR is better achieved.In addition,in the process of generating the M~2/4 group candidate symbols,in order to ensure the same transmit power,a weighting factorαis introduced to select the best combination of two sets of symbols to obtain the optimal PAPR suppression effect.Under the condition that the signal transmission power is kept constant in the Green OFDM algorithm.The main contributions of this paper are as follows:1.By introducing the factorαand selecting the bestαvalue,the best combination of the two sequences is obtained,and the computational complexity remains un-changed.The effect of reducing PAPR is improved.2.We have further designed an improved idea.By taking P values ofα,the number of candidate symbols is further increased,so that the effect of reducing PAPR is more significant,but will increase.Certain sidebands have redundant information.This has important theoretical guiding significance and practical value for the application of OFDM technology. |
