Signal Design and Error Rate of an Impulse Noise Channel

An optimal signal design of the classical smeardesmear technique for combating impulse noise is demonstrated. The signal design makes use of calculus of variations to derive an integral equation to which several solutions are given, along with a technique for generating additional solutions. A computer simulation and an evaluation of Rice´s triple integral pdf for impulse noise are used to analyze the error probability of a smear-desmear data channel and a standard data channel. This is the first known publication of a general evaluation of Rice´s integral for the intermediate repetition rate case. The error rates show that the smeardesmear channel is superior only for the lower repetition rate and/or lower level impulse noise cases. An analysis is then made of a clipper before the receiving filter. It is shown that this improves the system error rate to a degree, depending on the clipping level and the preclipper bandwidth-with the wider bandwidth giving greater improvement. The smear-desmear channel experienced a greater improvement than the conventional channel, so that the smear-desmear channel can be considered superior except for very high noise levels or repetition rates; practical considerations in the preclipper bandwidth and clipping level are the limiting factors.