A Short-Coding Error Parameter for Channels with Block Interference

For a class of channels, called block interference channels, a paradoxical situation prevails, namely, the capacity increases but the cutoff rate decreases with an increase of the block interference length. Also, despite the large capacity, there is a degradation in the performance of practical coding schemes when the block interference length is excessive. We introduce a short-coding error parameter (SCEP), whereby a bound on the average probability of decoding error is expressed for codes with length shorter than the block interference length. This bound is tighter than the bound based on the (conventional) cutoff rate. The SCEP is independent of the block interference length.