engleski

Reduction of impulse noise caused errors in OFDM system

Orthogonal frequency division multiplexing (OFDM) divides the available spectrum into several narrowband subchannels. To obtain a high spectral efficiency, the frequency responses of the subchannels are overlapping and orthogonal. However, to avoid interchannel interference, guard interval in frequency domain is used. We will show how this guard space in frequency domain can be used to reduce the impact of impulse noise, which is one of the major reasons of false symbol detection in power line communication system. To be able to correct samples corrupted by impulse noise the receiver has to detect the position of the impulse within the OFDM symbol. The proposed receiver combines power calculation in time and frequency domain to detect the presence and the position of the impulse. Samples corrupted by impulse noise are set to zero, and restored with the help of known signal power in frequency band corresponding to guard interval in frequency domain. If the maximal length of impulse is 2L, the needed length of the guard interval corresponds to L subcarriers.

impulse noise cancellation; OFDM

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