Research Of Constellation Recovery Method For Reducing Papr In MIMO-OFDM System

The MIMO-OFDM technology is the organic combine of Orthogonal frequencydivision multiplexing and multi-input multi-output technology, is one of the mostrepresentative options now to achieve the wireless high-speed large-capacitytransmission. This paper researches the problem how to reduce the MIMO-OFDMsystem peak to average power ratio. At present, the PAPR reduction algorithm include:signal pre-distortion class algorithm, coding class algorithms and probabilistic algorithms.Various algorithms has its own advantages and disadvantages, the ability to reduce thePAPR and the computational complexity of the system introduced by various algorithmsis not the same. Signal pre-distortion class of algorithms, the advantages is simplestructure, easy to implement, and needn’t to add redundant code; the drawback is thedistortion of the signal and the system BER performance is poor. Class encodingalgorithm, theoretically allow peak to average ratio is very small, and there is no signaldistortion, but the drawback is that the more sub-carriers, the lower coding efficiency,and the codec is very complex. The probability class algorithms can greatly reduce thelarge signal the probability, thus significantly improve the PAPR performance; theshortcomings of the algorithm is more complicated, send additional information neededto take up additional channels.This paper first introduces the basic principles and system architecture of theMIMO-OFDM systems, elaborated on the criteria and classification of space-time codecompilation, analyses and describes the definition of the PAPR in MIMO-OFDMsystems and related issues detailedly. Finally, analysis and interprets the constellationRecovery Act principles detailedly. Constellation Recovery Act, it is proposed on thebasis of existing algorithms, the basic principle is: in the transmitter, using softwareclipping limiter to reduce the PAPR of the system, its system structure is simple, and canflexibility to change the PAPR value according to the system design requires, In thereceiver, using the constellation features of the modulated signal to recovery the actualvalue of limiting data, thus reduce the signal distortion, and improve the errorperformance. This paper designs the MIMO-OFDM system based on the constellation ofthe Recovery Act, and applies MATLAB for the simulation analysis. The simulationresults show that MIMO-OFDM system based on the constellation of the Recovery Act,the PAPR performance has been significantly improved, the average output power of thesystem increases, and bit error rate is descendant. Compared to the SLM method, whichthe weight vector coefficient is8, in the conditions of the best PAPR, the BERperformance is similar, but the constellation Recovery Act needs no additional channel to send additional information and the amount of computation required greatly reduced.