Research On Reducing The PAPR Of OFDM Based On Active Constellation Extension Algorithm

With the fast development of our society,we have a higher demand on the rate and reliability of the transmission of text,image,voice,and video.OFDM technique has become an important technology in wireless communication systems since its great spectrum effectiveness,capability to eliminate the adverse effect of ISI,and anti-multipath fading ability.However,its development and application are limited by the critical practical problem of high PAPR of OFDM signal due to the use of multi-carrier modulation.For this reason,PAPR is an important matter that could not be neglected in OFDM.Therefore,how to effectively reduce PAPR of input OFDM signal becomes an important research topic.In this paper,we researched on reducing the PAPR of OFDM based on ACE algorithm.The rest of our research is formed as follows:(1)We introduce the three techniques for reducing PAPR of OFDM system:coding method,amplitude limit method,and probability method.Then,theoretical analysis and simulation results show that the probability technology is widely considered to be the most promising technology to solve the highPAPR of OFDM system.(2)The ACE approach is followed by a detailed discussion of three improved algorithms: ACE-POCS,ACE-SGP,and ACE-BD.In order to accelerate the convergence of three improved algorithms and reduce the complexity due to the high number of iterations,we propose here a fast convergence ACE-POCS based on the LSA algorithm called LSA-POCS-ACE.The proposed LSA-POCS-ACE algorithm calculates the optimization factor? using the LSA approximation.The main goal is to rapidly make the amplitude of the peak cancelling signal close to that of the original clipping noise.The results of simulation performs that in comparison to that of traditional ACE-POCS method,the proposed scheme achieves good performances from the first iteration without degradation in BER,and results in a significant reduction in complexity,suggesting that the algorithm for reducing PAPR is very competitive.(3)The ACE-POCS algorithm and PTS algorithm are combined in four possible ways to reduce the PAPR: PTS-ACE-POCS,Interlaced ACE-POCS-PTS,Half-to-Half ACE-POCS-PTS,and ACE-POCS-PTS.Results show that the proposed algorithm ACE-POCS-PTS has the best performance.In addition,ACE-POCS-PTS scheme can be used to achieve a better performance with more number of subcarriers,especially in low order modulation schemes.