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