Abstract :
Impulsive Noise Cancellation in Multicarrier Transmission A parallel between Reed–Solomon codes in the complex field and multicarrier transmission using orthogonal frequency-division multiplexing (OFDM) is first presented. This shows that when the signal is sent over some channel composed of Gaussian plus impulse noise, the impulse noise can be removed by a procedure similar to channel coding decoding, using information carried by the “syndrome.” The result is first derived in a simple situation (oversampled discrete multitone, additive channel), which is merely of theoretical interest. In any case, consecutive zeros, in the output of the OFDM modulator, do not correspond to real subcarriers. Pilot tones are emitted for synchronization or channel-estimation purposes. These pilot tones are generally scattered among the information ones. Our approach is to see these pilot tones as syndromes, in order to correct impulse noise. We show that the correction capacity is conditioned by the position of these pilot tones in the emitted sequence. A protection subsystem is introduced after the decoding operation in order to detect malfunction of this decoder. Efficiency of this technique is corroborated with simulations in the slightly modified Hiperlan2 context. Other extensions are then provided in order to increase the practical usefulness of the method.
