Peak-to-average ratio restraining method and device in multi-carrier orthogonal frequency division multiplexing system

Abstract

The invention discloses a method for peak-to-average ratio suppression in a multi-carrier orthogonal frequency division multiplexing OFDM system. The system comprises that: baseband frequency-domain signals of each carrier are combined into a time-domain multi-carrier combination channel signal on each OFDM symbol; clipping noise corresponding to each carrier is obtained from the multi-carrier combination channel signal, the length of the clipping noise is a symbol length; a frequency-domain response of the clipping noise corresponding to each carrier and symbol length is obtained, is reversely superposed to a baseband frequency-domain signal after the corresponding carrier has a time delay on an OFDM symbol to make a peak-to-average ratio suppression. The invention also discloses a device for peak-to-average ratio suppression in a multi-carrier OFDM system. The invention can make an effective suppression to the peak-to-average ratio in the multi-carrier OFDM system.

Description

technical field [0001] The present invention relates to Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) technology, in particular to a method and device for peak-to-average ratio suppression in a multi-carrier OFDM system. Background technique [0002] Among the existing communication technologies, OFDM technology has become the key to the fourth generation of mobile communication due to its high frequency utilization rate, strong anti-intersymbol interference (ISI, Inter Symbol Interference) and carrier interference (ICI, Inter Carrier Interference) capabilities. technology. [0003] For the single-carrier technology, at the transmitting end of the OFDM signal, if the single carrier includes N sub-carriers, the high-speed data stream is divided into N parallel sub-data streams after serial-to-parallel conversion, and the inverse Fourier transform (IFFT, Inverse Fast Fourier Transform), which converts the frequency domain signal...

AI Technical Summary

Problems solved by technology

If directly figure 1 The scheme shown is applied to an OFDM system. Since the modulation and coding methods and carrier power of subcarriers on different OFDM symbols may be different, the allowable performance loss will also be different. If the same filter is used for each OFDM symbol For example, if filter coefficients are designed in a high-order modulation mode, the clipping capability of the matched filter will be very limited. After the matched filter, the peak-to-average ratio of the multi-carrier OFDM system is still high. EVM (Error Vector Magnitude) loss to select filter coefficients will inevitably lead to subcarriers of high-order modulation methods that cannot meet the EVM requirements specified in the protocol, seriously affecting the link performance of the system

[0008] even if right figure 1 Appropriate improvement of the matched filtering in , such as using different filter coefficients on each OFDM symbol, will also cause serious distortion of some sampling points between two OFDM symbols, resulting in serious out-of-band leakage and inter-symbol interference, This significantly deteriorates the EVM of the high-order modulated subcarriers in the OFDM carrier, and the out-of-band leakage will also make the channel signal after the peak-to-average ratio suppression unable to meet the spectrum template specified in the protocol

[0009] From the above analysis, it can be seen that, figure 1 The shown clipping scheme using matched filtering cannot be directly applied to multi-carrier OFDM systems, and there is no effective peak-to-average ratio suppression scheme for multi-carrier OFDM systems

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