For a given blocklength we determine the number of interleavers which have
spread equal to two. Using this, we find out the probability that a randomly
chosen interleaver has spread two. We show that as blocklength increases, this
probability increases but very quickly converges to the value 1βeβ2β0.8647. Subsequently, we determine a lower bound on the probability of an
interleaver having spread at least s. We show that this lower bound converges
to the value eβ2(sβ2)2, as the blocklength increases.Comment: 5 pages, published in Proceedings of IEEE International Symposium on
Information Theory 2005, Adelaide, Australi