Methods, apparatus, and systems for coding with constrained interleaving

A communications apparatus comprising:

• a constrained interleaver configured to rearrange an ordering of a sequence of N=rm input bits in accordance with a permutation function in order to produce a permuted sequence of output bits, wherein N, r, and m are positive integers, m>1, and the rearrangement of the ordering in accordance with the permutation function is equivalent to performing the following operations:
• applying a word-level pseudo-random permutation function to pseudo-randomly rearrange an ordering of a plurality of multi-bit words embedded in the sequence of N=rm input bits;
• loading the N=rm number of input bits into a r×m array of bits, wherein the array has r rows and m columns, and the bits are serially loaded into the r×m array of bits along rows,
• applying an ith pseudo-random row permutation function to each row i, for i=1, 2, . . . r, wherein the ith pseudo-random row permutation function pseudo-randomly rearranges an ordering of m bits in the ith row, wherein a number of ways that the ith respective pseudo-random permutation function can pseudo-randomly rearrange the m bits in the ith row is restricted in accordance with at least one inter-row constraint;
• and
• reading bits out of the r×m array along r-bit columns to form the permuted sequence of output bits.

A method for use in a communications apparatus that includes a constrained interleaver operative to rearrange an ordering of a sequence of N=rm input bits in accordance with a permutation function in order to produce a permuted sequence of output bits, wherein N and m are positive integers, m>1, the method comprising

• rearranging the sequence of N=rm input bits in accordance with the permutation function, wherein the permutation function is equivalent to performing the following operations:
• applying a word-level pseudo-random permutation function to pseudo-randomly rearrange an ordering of a set of multi-bit words embedded in the sequence of N=rm input bits;
• loading the N r=rm number of input bits into a r×m array of bits, wherein the r×m array has r rows and m columns, and the bits are serially loaded into the r×m array of bits along rows,
• applying an ith pseudo-random row permutation function to each row i, for i=1, 2, . . . r, wherein the ith pseudo-random row permutation function pseudo-randomly rearranges an ordering of m bits in the row, wherein a number of ways that the ith respective pseudo-random permutation function can pseudo-randomly rearrange the m bits in the ith row is restricted in accordance with at least one inter-row constraint;
• and
• reading bits out of the r×m array along r-bit columns to form the permuted sequence of output bits.