A Method of Impulse Interference Suppression in OFDM System Based on Compressed Sensing

Abstract

The invention discloses an OFDM system impulse interference restraining method based on compression sensing. The situation that both impulse noise and background noise obey Gaussian distribution is assumed, then an estimated value of unknown hyper-parameters of the Gaussian distribution is obtained by maximizing a conditional expectation function, a posterior mean value of the impulse noise is obtained by combining the estimated value of the hyper-parameters and the projection, on known pilot frequency in an OFDM symbol, of the impulse noise, then an estimated value of the impulse noise is obtained, and finally the purpose of restraining impulse noise interference is achieved through a DFT conversion mode that the estimated value of the impulse noise is subtracted from a receipt signal vector quantity. The OFDM system impulse interference restraining method based on compression sensing has the advantages that the impulse noise is estimated by using the projection, on the known pilot frequency in the OFDM symbol, of the impulse noise, and sampling rate needed in the process of signal processing is reduced; in the iteration and estimation processes of the hyper-parameters, an alternating and updating process of the hyper-parameters is utilized, the rate of convergence is accelerated, the maximization solution process of the conditional expectation function is simplified, and finally the performance of restraining the impulse noise interference is improved obviously.

Description

technical field [0001] The invention relates to an interference suppression method in the communication field, in particular to a compressed sensing-based OFDM system pulse interference suppression method. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) technology is widely used in various communication standards due to its high spectral efficiency and anti-multipath interference ability, such as power line communication standards, Long Term Evolution (Long Term Evolution, LTE) standards and terrestrial digital TV broadcasting standards, etc. However, in many communication systems (such as dense cellular network communication systems and power line communication systems), traditional OFDM receivers face severe performance degradation due to the serious interference of impulse noise, so how to suppress impulse interference in OFDM systems has been It has become a research hotspot in the field of communication in recent years. [0003] At pres...

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Problems solved by technology

However, since the SBL algorithm directly uses ExpectationMaximization (EM) to update all the hyperparameters to be estimated in each iteration when solving the hyperparameters through the maximum likelihood method, which makes the convergence of the entire SBL algorithm slow, And it will make the conditional expectation maximization step difficult to realize; in addition, since the SBL algorithm directly solves the posterior expectation and the posterior mean after obtaining the hyperparameter estimation value, it will make the calculation more difficult when the signal dimension is large, and the influence on the impulse noise estimate is not accurate enough

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