Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Communicate > Data communication > Data transmission technology

Research on the Reduction of Peak to Average Power Ratio in SLM OFDM Systems

Author ZhaoChengLong
Tutor YaoJianGuo
School Nanjing University of Posts and Telecommunications
Course Communication and Information System
Keywords Orthogonal Frequency Division Multiplexing Fourier transform PAPR Selective Mapping Computational complexity Chaotic sequence
CLC TN919.3
Type Master's thesis
Year 2012
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Orthogonal frequency division multiplexing (OFDM) technology , due to having a higher spectral efficiency can be achieved through the use of Fourier transform , anti - multipath fading and inter-symbol interference , and so on , in the wireless communication system has a wide range of application . However , OFDM also has some bottlenecks , such as the OFDM signal peak to average power ratio (APR) is relatively large . If the range of linearity of the amplifier is less than the range of variation of the signal , it will make the signal distortion occurs, thus destroying the orthogonality between the individual subchannels and will generate interference between the respective channels , the performance of the system will deteriorate . Increase the linear range of the amplifier will make problem solving , but the cost will be too high . To this end , reducing the PAPR of the need to solve the problem in the OFDM signal . This paper focuses on peak reduced OFDM system average power than this issue focus on research . Under normal circumstances , to reduce PAPR main limiters coding class probability class in three ways . This paper focuses on the probability class selective mapping (SLM) . Selective mapping mode to use the IFFT operation of the additional U-1 group , makes the high computational complexity of the system , then the paper from the IFFT operation to proceed, the IFFT operation process is split into two parts , after a split after computing complexity will be reduced to varying degrees , but before the performance and the split complexity compared to no significant decrease. Chaotic sequence of papers will be an improved application of selective mapping , in order to reduce the peak-to-average ratio of the system . Autocorrelation properties of chaotic sequence , cross-correlation properties are very good , and easy to generate , can produce any number of phase , etc. , with a good performance , but finite precision calculation so that it will appear periodically when the autocorrelation function the peak . In this regard, this sequence can be improved, its segmentation measures, and the new chaotic sequence applied to the system . Improved chaotic sequence is better than the common phase sequence , its performance is superior .

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