A Time-Frequency Interleaving Preprocessing Combined Method Against Narrowband Interference and Impulse Noise in OFDM System

Abstract

The invention provides a time-frequency interleaving preprocessing combined method for resisting narrowband interference and impulse noise in an OFDM system. The method specifically comprises the following steps of carrying out LDPC coding and corresponding constellation labeling on a signal in the OFDM system, optimizing parameters of a time domain interleaver, and fully whitening the noise; after OFDM modulation is carried out at a sending end, utilizing cyclic shift operation of a sub-matrix of a block interleaver in a frequency domain to carry out frequency domain interleaving on OFDM sub-carriers; and carrying out noise preprocessing through an amplitude limiting method of a receiving end, and nonlinearly removing the noise and the interference which are still higher than thresholds after full interleaving. According to the method, the characteristics of the interleaver and the advantages of noise processing of a nonlinear method are fully combined, the resistance performance of the OFDM system to the narrowband interference and the impulse noise can be effectively enhanced, and compared with a traditional block interleaving method, the system transmission performance is further improved.

Description

technical field [0001] The invention relates to an anti-jamming and noise method in an OFDM system, in particular to a time-frequency interleaving preprocessing joint method for fighting narrow-band interference and impulse noise in an OFDM system. Background technique [0002] Orthogonal frequency division multiplexing (OFDM) is an efficient multi-carrier modulation technology. Because it has the characteristics of orthogonal multiplexing between subcarrier frequencies and long duration, it has high spectrum utilization and anti-multipath Effect and other advantages, so it is widely promoted and applied in various digital communication systems, such as wireless area network (WLAN), PLC power line standard communication IEEE1901.2 and digital broadcast audio (DAB), etc., which is the core representative of 4G communication. [0003] OFDM is continuously developed through the FDM system. In a traditional FDM system, a certain interval needs to be left in the spectrum to ensu...

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Problems solved by technology

[0007] However, the existing traditional interleaving technology has many deficiencies, such as poor flexibility, and the interleaver needs to be redesigned for different coding and modulation parameters; traditional block interleaving in the frequency domain cannot avoid joint errors in the time domain and frequency domain at the same time. The performance improvement of interleaving is not large, etc.

On the other hand, since the interleaving technology can only reduce the impact of the impulse noise probabilistically, it cannot be absolutely guaranteed to eliminate it, so when the noise power is too high, the interleaving technology has certain limitations

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