A Frequency Offset Estimation and Analysis Method of Ofdm System Based on Null Carrier

Abstract

The invention belongs to the field of wireless communication, and relates to a method for estimating and analyzing the frequency offset of an OFDM system based on an empty carrier. The mean square error of frequency offset estimation is calculated by using the statistical properties of Rayleigh channel and noise. The theoretical value of the mean square error of frequency offset estimation is directly calculated using the statistical properties of two random variables including the Rayleigh channel response coefficient and channel noise, combined with the statistical properties of the detected inactive subcarriers and additive complex Gaussian white noise; When calculating the theoretical value of the mean square error of frequency offset estimation, the Taylor series expansion is used to obtain a more accurate expression of the mean square error of frequency offset estimation. The invention utilizes the statistical characteristics of the Rayleigh channel to obtain the theoretical value of the mean square error of frequency offset estimation, and takes its high-order approximation as a result, thereby effectively improving the versatility and accuracy of the estimation analysis method.

Description

technical field [0001] The invention belongs to the field of wireless communication, and relates to an OFDM system frequency offset estimation and analysis method based on an empty carrier. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) has become one of the most critical technologies in wireless communication systems due to its high spectrum utilization rate and strong anti-multipath fading performance. Many common wireless communication systems use OFDM technology. In addition to high spectral efficiency and anti-multipath fading capability, OFDM technology can also effectively overcome intersymbol interference (ISI), and can use IFFT / FFT fast algorithm for modulation and demodulation. In an OFDM practical system, due to factors such as the Doppler effect, it often causes a carrier frequency offset (Carrier Frequency Offset, CFO), resulting in spectral overlap between adjacent subcarriers, resulting in the destruction of orthogonality, res...

AI Technical Summary

Problems solved by technology

Due to the complexity of the objective function, this algorithm does not involve the theoretical calculation method of the mean square error of the estimated value of CFO under the Rayleigh channel, that is, it cannot well verify the correctness of the estimation method

[0004] In 2018, some researchers proposed a CFO estimation and compensation method for OFDM-IM systems in wireless fixed channels (see South China University of Technology's Chinese invention patent application "A Method for Estimating Frequency Offset of OFDM-IM Systems", the publication date is August 2018 On April 17th, the publication number is CN108418772A), but the fixed channel has great limitations, and this method is not general in the complex and changeable channel environment, and it is difficult to be popularized and applied.

Images