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Joint estimation method of frequency offset, DC (Direct Current) and imbalance of orthogonal frequency division multiplexing system

A technique of orthogonal frequency division and joint estimation, applied in the field of joint estimation

Inactive Publication Date: 2013-06-12
UNIV OF SCI & TECH BEIJING
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Problems solved by technology

[0005] However, for the more general problem of joint estimation of CFO, DCO, and I / Q imbalance, only a small amount of work has focused on estimation methods based on pilots and preambles.

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  • Joint estimation method of frequency offset, DC (Direct Current) and imbalance of orthogonal frequency division multiplexing system
  • Joint estimation method of frequency offset, DC (Direct Current) and imbalance of orthogonal frequency division multiplexing system
  • Joint estimation method of frequency offset, DC (Direct Current) and imbalance of orthogonal frequency division multiplexing system

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Embodiment Construction

[0040] In the specific implementation process, the estimated OFDM system is a WLAN system, where N=64, K=48, using QPSK modulation, and setting the power delay distribution of Ruili frequency selective fading channel as e -p / 5 , P=0,...,9. Use normalized mean square error (NMSE) to compare the estimation results, namely with In order to record the changes of CFO, DCO and I / Q imbalance as quickly as possible, only one OFDM symbol is used for estimation. Compare the estimation results of CFO and DCO with the two methods of the present invention and TD-CPE and TD-MUE. The specific results are as attached respectively. figure 2 And image 3 Shown. TD-CPE and TD-MUE both estimate and compensate DCO based on time-averaged methods, and estimate CFO based on preamble and MUSIC-like algorithms, respectively. It can be seen from the figure that the estimation results based on TD-CPE and TD-MUE have error leveling under high SNR, while the estimation result of the present invention has...

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Abstract

The invention relates to a joint estimation method of frequency offset, DC (Direct Current) and imbalance of an orthogonal frequency division multiplexing system, is suitable for the field of digital signal processing, especially the joint estimation of carrier frequency offset (CFO), DC offset (DCO) and I / Q imbalance (I / Q imbalance) of the orthogonal frequency division multiplexing (OFDM) system of a direct conversion receiver. The invention provides an estimation method of CFO, DCO and I / Q imbalance of an eigen-decomposition based estimator (EDE). Compared with the previous estimation method, the estimation method provided by the invention does not depend on specific lead code and pilot frequency, and is suitable for more general situations in the OFDM system, the bandwidth is not occupied, and the estimation efficiency is higher.

Description

Technical field [0001] The invention relates to the joint estimation of carrier frequency offset (CFO), direct current offset (DCO) and I / Q imbalance (I / Q imbalance) in an orthogonal frequency division multiplexing (OFDM) system based on a direct conversion receiver . Background technique [0002] Orthogonal frequency division multiplexing system has become one of the most promising wireless communication technologies due to its robustness to frequency fading channels, high spectral efficiency, and efficient implementation based on fast Fourier (inverse) transform. However, the OFDM system is very sensitive to carrier frequency offset. Because the carrier frequency offset will destroy the orthogonality between subcarriers and introduce interference between subcarriers, these will greatly reduce the system performance. In order to reduce the negative impact of carrier frequency offset, OFDM systems must have accurate carrier frequency offset estimation methods. On the other han...

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Application Information

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IPC IPC(8): H04L27/26H04L25/02H04L25/03
Inventor 刘涛王程
Owner UNIV OF SCI & TECH BEIJING
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