Method and system for lowering peak-average-ratio of information symbol in OFDM system

Abstract

The invention discloses a method and a system for reducing peak-to-average ratio of information symbols in an OFDM system. The method comprises the following steps: changing the values of pilot sequences in OFDM symbols to obtain a pilot sequence set; subjecting each pilot sequence in the pilot sequence set to inverse Fourier transformation to obtain a corresponding pilot sequence set in a time domain; subjecting a coded and interlaced data sequence to inverse Fourier transformation to obtain a corresponding data sequence in the time domain; adding the data sequence in the time domain to each pilot sequence of the pilot sequence set in the time domain to obtain a new sequence set; respectively calculating the peak-to-average ratio of each sequence in the new sequence set; and selecting the pilot sequence corresponding to the sequence with the least peak-to-average ratio in the new sequence set as the emission pilot sequence. In the method, the pilot sequence can be used for reducing the peak-to-average ratio of the information symbols, thereby saving the system overhead and improving the system capacity.

Description

technical field [0001] The present invention relates to the technical field of Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing), in particular to a method and system for reducing the peak-to-average ratio of information symbols in an OFDM system. Background technique [0002] In the OFDM system, each information symbol is superimposed by multiple independently modulated subcarrier signals. When the phases of each subcarrier are the same or similar, the superimposed signals may generate a large peak power. This will bring a high peak-to-average power ratio (PAPR, Peak-to-Average PowerRatio), peak-to-average power ratio, referred to as peak-to-average ratio (PAR). The peak-to-average ratio is relatively high, which means that when the signal passes through nonlinear devices such as power amplifiers, the power amplifier is required to have a large dynamic range, otherwise nonlinear distortion will occur, and the generated harmonics w...

AI Technical Summary

Problems solved by technology

[0009] First of all, it is necessary to reserve a large number of subcarriers in order to achieve better performance in reducing PAR, but this will reduce the spectral efficiency of the system, thereby reducing the system capacity;

[0010] Secondly, since the position of the reserved subcarriers will affect the performance of reducing the peak-to-average ratio, in order to obtain the optimal performance, the positions of the reserved subcarriers should be randomly distributed, and at the same time should be allocated at equal intervals. Other subcarrier allocation methods have the same effect. Not very good, it can be seen that this method has particularly high requirements on the location of reserved subcarriers, which will seriously affect the flexibility of resource scheduling;

[0011] In addition, these reserved subcarriers will cause neighbor cell interference to neighboring cells, and it is difficult to eliminate

[0012] In summary, due to the high requirements on the number and location of reserved subcarriers, it will not be conducive to practical applications

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