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 the scheme shown in Figure 1 is directly applied to the 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 each OFDM symbol Both use the same filter coefficients for matched filtering. For example, if the filter coefficients are designed in a high-order modulation mode, the clipping capability of the matched filtering will be very limited. After the matched filtering, the peak-to-average ratio of the multi-carrier OFDM system is still high, while Larger error vector magnitude (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 the matched filtering in Figure 1 is properly improved, such as using different filter coefficients on each OFDM symbol, it will cause serious distortion of some sampling points between two OFDM symbols, resulting in serious out-of-band leakage and Intersymbol interference, which significantly deteriorates the EVM of the high-order modulation subcarriers in the OFDM carrier, and the out-of-band leakage will also make the channel signal after 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 the clipping scheme implemented by matched filtering shown in Figure 1 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.

Images