Single-carrier fractional order Fourier domain equalizing technology

Abstract

The invention relates to the single carrier fractional order Fourier domain equalization technology, which belongs to the broadband wireless digital communication field. In order to reduce the intersymobl interference (ISI) caused by deep fading points responded by channel frequency and control the noise power after the equalization, fractional order Fourier transform is adopted at a receiving end to replace the Fourier transform in the traditional single carrier frequency domain equalization system. Firstly, the optimum fractional order Fourier order selection is performed, time domain receiving signals are transformed to the optimum order for equalization by using discrete fractional order Fourier transform (DFRFT), the equalized data blocks are changed back into time domain signals through discrete fractional order Inverse Fourier transform, and the noise cannot be magnified when the intersymobl interference is completely eliminated, and the system performance is improved. At the same time, the method has fast algorithm because of the discrete fractional order Fourier transform, therefore, the system realization is simple, and the computational complexity is low.

Description

A Single Carrier Fractional Fourier Domain Equalization Technique Technical field The invention relates to a single carrier equalization technology, which belongs to the field of broadband wireless digital communication. It can be used to improve the anti-interference performance of the system. Background technique Single Carrier Frequency Domain Equalization (Single Carrier Frequency Domain Equalization, SC-FDE) system is similar to Orthogonal Frequency Division Multiplexing (OFDM) system, and it is also a block transmission technology. According to the characteristics of Fourier transform, frequency domain equalization technology is used to eliminate multipath Intra-symbol interference caused by propagation. Compared with OFDM technology, it has similar anti-multipath interference ability and has a small peak-to-average power ratio (PeaktoAveragePowerRatio, PAPR), which overcomes the need for expensive large linear dynamic range due to the large PAPR of OFDM signals Th...

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Problems solved by technology

(1) When frequency-domain linear equalizer is used, the ZF equalizer based on zero-forcing criterion can completely eliminate the intersymbol interference generated by the channel, but in the frequency-selective channel, especially when the channel has a deep fading pole in the frequency domain , it will increase the noise, reduce the signal-to-noise ratio of the system, and lead to a decrease in system performance; while the MMSE equalizer based on the minimum mean square error criterion can be regarded as a compromise between channel noise and residual intersymbol interference. The performance is better than the ZF equalizer when the deep fading pole is on, but the MMSE equalization cannot completely eliminate the intersymbol interference

(2) Aiming at the shortcomings of frequency-domain linear equalizers, Benvenuto.Nevio and Zhu.Yu proposed two decision feedback equalization methods, FD-DFE and FDE-NP, in 2002 and 2006, respectively, which can further eliminate residual code gaps. However, its performance depends on the order of the decision feedback filter. The higher the order, the better the performance, but the higher the computational complexity

Currently, there are several different types of fast algorithms for DFRFT, with different accuracies and computational complexities

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