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Frequency Offset Estimation Method of OFDM System Based on Multipath Separation

A technology of frequency offset estimation and maximum likelihood estimation, which is applied in the field of frequency offset estimation of OFDM systems based on multipath separation, can solve the problems of frequency offset estimation accuracy reduction and frequency offset estimation accuracy impact, and achieve good estimation performance and complex operations low degree of effect

Active Publication Date: 2018-11-06
CHONGQING UNIV
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Problems solved by technology

[0004] This application provides a frequency offset estimation method for OFDM systems based on multipath separation to solve the technical problem that the frequency offset estimation accuracy of traditional frequency synchronization algorithms is affected by scattering paths in multipath fading channels, resulting in reduced frequency offset estimation accuracy.

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  • Frequency Offset Estimation Method of OFDM System Based on Multipath Separation
  • Frequency Offset Estimation Method of OFDM System Based on Multipath Separation
  • Frequency Offset Estimation Method of OFDM System Based on Multipath Separation

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Embodiment

[0026] A frequency offset estimation method for OFDM systems based on multipath separation, such as figure 1 shown, including the following steps:

[0027] First, the local CAZAC sequence is given by Generate, where j is the imaginary unit, N FFT It is the number of FFT transformation points for OFDM, r is a positive integer, r and N FFT Reciprocal prime, in this embodiment, r=3.

[0028] For the CAZAC sequence, its autocorrelation function is:

[0029]

[0030] In the formula, mod means modulo.

[0031] S1: Two sets of training symbols TS1 and TS2 with the same structure are used to form a training sequence according to [TS1, TS2]. Among them, TS1 and TS2 both use a CAZAC sequence with a quarter cyclic prefix. The schematic diagram of its structure is as follows figure 2 shown.

[0032] S2: Calculate the channel impulse response h from TS1 and TS2 respectively 1 and h 2 , that is: according to the maximum likelihood estimation of the channel impulse response Ca...

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Abstract

The present invention provides a method for estimating the frequency offset of an OFDM system based on multipath separation, which belongs to the technical field of wireless communication. The estimation accuracy of the frequency offset of the traditional frequency synchronization algorithm is affected by the scattering path in a multipath fading channel, resulting in a reduction in the accuracy of the estimation of the frequency offset. To solve the problem, make full use of the separable impulse responses of each path, complete the frequency offset estimation of each path in the time domain, and combine the estimated frequency offset values ​​of each path according to the principle of maximum ratio, which can realize the OFDM system in the multipath fading channel environment Fractional frequency synchronization has good estimation performance in the multipath fading channel environment, and all operations are completed in the time domain without time-frequency transformation, and the computational complexity is low.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to a multipath separation-based OFDM system frequency offset estimation method. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) technology improves the system's ability to resist multipath fading by converting frequency-selective fading channels into flat fading channels, and can provide higher data transmission rates and spectrum utilization. It is a new generation of broadband mobile The core technology of communication system. Frequency synchronization is the key technology of OFDM system. In order to ensure the demodulation performance of the system, it is generally required that the frequency deviation should be less than 4% of the subcarrier spacing in Gaussian channels, and less than 2% of the subcarrier spacing in multipath fading channels. Therefore, the research on the frequency offset estimation scheme has important practica...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/26H04L27/00
CPCH04L27/0014H04L27/2655H04L27/2672H04L2027/0026
Inventor 吴玉成李晓朱鹏程夏扬吴钒刘统
Owner CHONGQING UNIV
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