Patent Document ID: 20160352361
Application ID: 14545588
Patent Flag: 0

Claim One:
1. A communications apparatus, comprising: an outer encoder configured to transform a sequence of input bits to a sequence of outer encoded bits, wherein the sequence of outer-encoded bits is encoded in accordance with an outer code that is a member of the group consisting of a block code and a non-recursive convolutional code; a constrained interleaver that is configured to implement a permutation function to permute the order of the outer-encoded bits to produce a constrained-interleaved sequence of outer-encoded bits, wherein the permutation function implements a pseudo-random reordering of the outer-encoded bits subject to the at least one SRCI constraint; an inner encoder configured to transform the constrained-interleaved sequence of outer-encoded bits to a sequence of inner-encoded bits, wherein the sequence of inner-encoded bits is encoded in accordance with an inner code; and whereby the sequence of inner-encoded bits constitutes a serially-concatenated sequence of bits that incorporates coding from both the inner code and the outer code in accordance with a serially-concatenated code that achieves a target minimum distance of d t ; wherein the constrained interleaver implements at least one SRCI (single row constrained interleaver) constraint that prevents one or more low-distance error sequences from occurring in the serially-concatenated code; wherein the outer code has a minimum distance of d 0 and the inner code has a minimum distance of d i ; wherein the permutation function implemented by the constrained interleaver is configured to implement the at least one SRCI constraint in order to enforce d t >d 0 d i ; and wherein the at least one SRCI constraint includes at least one first SRCI constraint that ensures that the permutation function does not place any respective index from the integer ring [0,K−1] into any position in a permuted integer ring π[0,K−1] that corresponds to any identified respective restricted zone, where each identified respective restricted zone corresponds to a subset of one or more adjacent positions in π[0,K−1] that, if the respective index were to be placed into any one of the identified respective restricted zones, at least one error sequence of weight less than d t would become possible in the serially-concatenated code.