UKF-based channel and carrier frequency deviation estimating method in the OFDM system

Abstract

An UKF based channel and carrier wave frequency shift estimation method in OFDM system is applied in the technique field of wireless transmission. Said channel estimation method starts from a frequency domain, to get cursory estimated values at pilot channels firstly by using a LS method, and then to get accurate estimated values by utilizing path capturing method and UKF method in time domain. According to the UKF based carrier wave frequency shift estimation method in OFDM system in accordance with the present invention, wave frequency shift is estimated in time domain through UKF filtering method, and then ICI is eliminated through carrier wave frequency shift correction. Aiming at OFDM system in which disturbances between sub-carriers exist and which passes through time-varying wireless channel, the present invention further provides an UKF based channel and carrier wave frequency combination estimation method which is capable of eliminating ICI and improving veracity of channel estimation and exhibits excellent astringency and robustness by utilizing specific pilot frequency structure and convolutional change forms of a matrix.

Description

technical field [0001] The invention relates to a method for channel and frequency offset estimation in the technical field of wireless communication, in particular to a method for estimating channel and carrier frequency offset based on UKF (unscented Kalman filter) in an OFDM system. Background technique [0002] In wireless communication, the signal is affected by factors such as channel attenuation, multipath delay spread, and Doppler frequency spread during the propagation process. In order to better recover the sent signal at the receiving end, coherent demodulation is usually used, and coherent demodulation requires Channel parameter information, which is obtained through channel estimation, so the performance of the channel estimator directly affects the system performance. The Orthogonal Frequency Division Multiplexing (OFDM) system can effectively resist the inter-symbol interference caused by multipath spreading, making it possible to carry out data transmission u...

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Problems solved by technology

[0004] After searching the literature of the prior art, it was found that Dieter Schafhuber et al. published an article "Dual Selectivity in Wireless MIMO-OFDM System" in the 2003 IEEE International Wireless Communication Signal Processing Academic Conference (IEEE Workshop on Signal Processing Advances in Wireless Communication). Adaptive Identification and Tracking of Doubly Selective Fading Channels for Wireless MIMO-OFDM Systems”, this paper proposes an adaptive filter based on least mean square (LMS) suitable for multi-antenna OFDM systems The channel estimation method uses pilot symbols and LMS filters to track and estimate the time-varying channel without knowing the channel statistical information, but this method has an obvious shortcoming that the estimation accuracy is not very high, especially in In the environment of medium and low signal-to-noise ratio, it is far less than the channel estimation method based on the two-dimensional minimum mean square error criterion

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