Realization of optimum interleavers

Abstract

Four realizations of interleavers that reorder a sequence of symbols so that no contiguous sequence ofn_2symbols in the reordered sequence contains any pair of symbols that were separated by fewer thann_1, symbols in the original ordering are introduced. For anyn_1andn_2that satisfy an appropriate relative primeness condition, these interleavers are optimum in the sense that of all possible interleavers providing the indicated symbol separation, one of these four realizations achieves both the minimum possible encoding delay and the minimum possible combined storage capacity for the interleaver and its unscrambler.