Method for reducing PAPR of OFDM system

Abstract

The present invention discloses a method for reducing PAPR of OFDM system. The method replaces traditional Mu law companding function by hyperbolic tangent function, to ensure the value obtained after companding the data of the original signal be within a certain range, the concrete process is that as follows: in transmission terminal, to calculate the time field OFDM signal after IFFT so as to obtain average amplitude, and confirm companding parameter k and amplitude modulation parameter Alpha based on the demand of OFDM system; according to the average amplitude and Alpha as well as k, to implement companding transformation to the OFDM signal with hyperbolic tangent function mode, then to transmit to the channel after parallel-serial conversion and filtering; in the receiving terminal, to calculate the received OFDM signal so as to obtain the average amplitude of the received signal, and to limit the amplitude of the OFDM signal based on threshold; according to average amplitude and alpha as well as k, to implement companding inverse transformation to the OFDM signal with hyperbolic tangent companding inverse transformation function mode, so as to resume the original signal. The present invention has the advantage of reducing PAPR well, and can be used to treat the PAPR in the fourth generation OFDM radio communication system.

Description

technical field [0001] The invention belongs to the technical field of communication, and relates to the problem of peak-to-average power ratio (PAPR) in an OFDM communication system, in particular to a non-linear companding method for effectively reducing the peak-to-average power ratio of an OFDM system. Background technique [0002] Orthogonal frequency division multiplexing OFDM technology is considered to be one of the core technologies of the fourth generation mobile communication 4G because of its efficient spectrum utilization and good anti-multipath fading performance. At present, OFDM technology has been used in asymmetric digital subscriber line ADSL , digital audio broadcasting DAB and digital TV broadcasting DVB, IEEE 802.11, IEEE 802.16 and power line broadband data communication have been widely used. [0003] The basic principle of OFDM is to distribute high-speed data streams to several sub-channels with relatively low transmission rates for transmission thr...

AI Technical Summary

Problems solved by technology

As μ increases, this improvement becomes more and more obvious, but due to the companding curve characteristics of the traditional companding transformation function, it is not enough for the compression of very large signals and the expansion of very small signals, so the data symbols after companding transformation cannot presents a uniform and tight distribution

Although the inverse companding transform can basically restore the received signal, because the average power of OFDM symbols will be slightly different, there will be some differences between the signal after companding and inverse transforming and the original signal, that is, the companding transform will cause certain BER

[0023] It can be seen that although the companding transformation is more flexible than the clipping, the companding transformation needs to be further improved in reducing PAPR, improving OFDM symbol distribution and improving bit error rate

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