A necessary condition on the location of pilot tones for impulse noise cancellation in OFDM system and its applications in Hiperlan2

The similarity between Reed Solomon codes in the complex field and multicarrier (OFDM) systems can be useful to correct impulse noise. This similarity is best seen when the input of the IFFT in the OFDM modulator has some consecutive zeros. However, this case is merely of theoretical interest, since consecutive zeros, in the OFDM modulator, do not correspond to real subcarriers. However in many cases, pilot tones are generally scattered among the information subcarriers. Our approach is to use these pilot tones as syndromes in order to correct impulse noise. This paper presents a number of interesting results relating on the distribution of pilot tones in the emitted sequence, where we have a necessary condition under which a maximal correction capacity is guaranteed. This necessary condition is also sufficient in the two simple cases, where the correction capacity is 2 or 3. Efficiency of this technique is illustrated by simulations in the practical context of Hiperlan2.