Joint Estimation Method of Sampling Frequency Offset and Carrier Frequency Offset Based on Maximum Likelihood Estimation

A technique of maximum likelihood estimation and sampling frequency offset, applied in multi-frequency code systems and other directions, it can solve the problems of error leveling estimation accuracy, high computational complexity, and inability to continue to converge, and achieves reduced computational complexity and high precision. Effect

Inactive Publication Date: 2018-01-05
NAT UNIV OF DEFENSE TECH
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Problems solved by technology

[0012] The technical problem to be solved by the present invention is: Aiming at the high computational complexity caused by the two-dimensional global search in the existing SFO and CFO joint estimation method, and the problem that the error flat estimation accuracy cannot continue to converge when the SNR is high, a method is proposed A Joint Estimation Method of SFO and CFO Based on Maximum Likelihood Estimation
The proposed joint estimation method does not require two-dimensional global search, so the computational complexity is greatly reduced, and at the same time, the existing estimation method has the problem of error flat when the SNR is high, and the estimation accuracy is improved.

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  • Joint Estimation Method of Sampling Frequency Offset and Carrier Frequency Offset Based on Maximum Likelihood Estimation
  • Joint Estimation Method of Sampling Frequency Offset and Carrier Frequency Offset Based on Maximum Likelihood Estimation
  • Joint Estimation Method of Sampling Frequency Offset and Carrier Frequency Offset Based on Maximum Likelihood Estimation

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Embodiment Construction

[0035] figure 2 It is a flowchart of the present invention, and the present invention comprises the following steps:

[0036] Step 1: In the IEEE 802.11a protocol, the typical error tolerance range of SFO is [-20×10 -6 ,+20×10 -6 ], so when performing first-order Legendre polynomial approximation, set the value range of SFO as η∈[-2β×10 -5 ,2β×10 -5 ] is sufficient to meet the range of η values ​​in the actual system;

[0037] The second step: Let t=(10 5 / 2β)η, then t∈[-1,1], so we know:

[0038] Since the independent variable of the approximated function needs to be in the interval [-1,1] when the Legendre polynomial is approximated in the third step, it is necessary to multiply η by 10 5 / 2β transforms it to t, performing a Legendre polynomial approximation to a function with variable t.

[0039] Step 3: Right Perform first-order Legendre polynomial approximation in the interval t∈[-1,1];

[0040] 3.1 Let p 0 (t)=1,p 1 (t) = t;

[0041] Among them, p 0 (t) ...

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Abstract

The invention discloses an SFO and CFO combined estimation method based on maximum likelihood estimation, and aims to solve the problems that the computational complexity is high due to two-dimensional global search, and the high-SNR (Signal Noise Ratio) error floor estimation accuracy cannot continue to converge in the existing SFO and CFO combined estimation method. The technical solution is that the method comprises the following steps: determining a range of SFO, transforming the range of SFO into a range of variable t, using first-order Legendre polynomial to approximate a formula I shown in the description to obtain first-order Legendre polynomial approximant, substituting the approximant into a formula II shown in the description to obtain t; transforming a final estimation value eta' of SFO by t; obtaining an estimation value epsilon' of CFO by the eta'. The SFO and CFO combined estimation method based on maximum likelihood estimation does not require the two-dimensional global search, so that the computational complexity is reduced greatly, meanwhile, the problem of error floor in high SNR in the existing estimation method is eliminated, and the estimation accuracy is improved.

Description

technical field [0001] The present invention mainly relates to the field of synchronization estimation in baseband signal processing of a wireless communication system, and aims to provide a method for jointly estimating sampling frequency offset (SFO) and carrier frequency offset (CFO) with low computational complexity and high estimation accuracy. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) technology is widely used in modern wireless communication systems due to its high spectrum efficiency, and has been adopted by multiple communication protocols such as IEEE 802.11a, IEEE 802.16a, DVB-T and DRM. However, OFDM technology is very sensitive to synchronization errors, resulting in a significant decrease in the performance of its receiver. Both SFO and CFO are the most important synchronization errors in OFDM systems. In order to improve the performance of the receiver, it is necessary to estimate the values ​​of SFO and CFO in the receiv...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/26
Inventor 邢座程刘苍唐川张洋原略超王锋汤先拓王庆林吕朝危乐董永旺
Owner NAT UNIV OF DEFENSE TECH
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