Block interleaving scheme with configurable size to achieve time and frequency diversity

1. An apparatus comprising:

a demultiplexer to demultiplex an input packet having N bits into L sub-packets on L branches;

M flipping blocks coupled to the demultiplexer to flip M of the L sub-packets, M being smaller than L;

L sub-interleaves coupled to the demultiplexer and the M flipping blocks to interleave the (L-M) sub-packets and the M flipped sub-packets; and

a concatenate coupled to the L sub-interleaves to concatenate the interleaved sub-packets to form an output packet; wherein L and M are integers greater than or equal to one.

2. The apparatus of claim 1 wherein the demultiplexer operates in a normal mode and a robust mode.

3. The apparatus of claim 2 wherein in the normal mode the input packet is switched at a rate of every L bits for each of the L branches.

4. The apparatus of claim 2 wherein in the robust mode the input packet is repeated L times.

5. The apparatus of claim 4 wherein in K of the L branches the input packet is read from bit N 0 of the N bits in a wrap-around manner.

6. The apparatus of claim 1 wherein each of the M flipping blocks reverses a bit order of one of the L sub-packets from end to beginning.

7. The apparatus of claim 1 wherein each of the L sub-interleavers writes the sub-packet row-by-row in a matrix having R rows and C columns and reads the sub-packet from the matrix in a helical scan manner.

8. The apparatus of claim 7 wherein C is equal to a product of number of symbols and number of carriers divided by a constant.

9. The apparatus of claim 8 wherein R is equal to 10 and the constant is equal to 40.

10. The apparatus of claim 1 wherein the concatenator concatenates the L sub-packets on a sub-packet basis.

11. A method comprising: demultiplexing an input packet having N bits into L sub-packets on L branches; flipping M of the L sub-packets, M being smaller than L; interleaving the (L-M) sub-packets and the M flipped sub-packets; and concatenating the interleaved sub-packets to form an output packet; wherein L and M are integers greater than or equal to one.

12. The method of claim 11 wherein demultiplexing comprises operating in a normal mode and a robust mode.

13. The method of claim 12 wherein in the normal mode the input packet is switched at a rate of every L bits for each of the L branches.

14. The method of claim 12 wherein in the robust mode the input packet is repeated L times.

15. The method of claim 14 wherein in K of the L branches the input packet is read from bit N 0 of the N bits in a wrap-around manner.

16. The method of claim 11 wherein flipping comprises reversing a bit order of one of the L sub-packets from end to beginning.

17. The method of claim 11 wherein interleaving comprises:

writing the sub-packet row-by-row in a matrix having R rows and C columns; and

reading the sub-packet from the matrix in a helical scan manner.

18. The method of claim 17 wherein C is equal to a product of number of symbols and number of carriers divided by a constant.

19. The method of claim 18 wherein R is equal to 10 and the constant is equal to 40.

20. The method of claim 11 wherein concatenating comprises concatenating the L sub-packets on a sub-packet basis.

21. A system comprising:

a forward error correction (FEC) encoder to encode an input data stream, the FEC encoder comprising an interleaver to interleave an input packet from the input data stream, the interleaver comprising:

a demultiplexer to demultiplex the input packet having N bits into L sub-packets on L branches;

M flipping blocks coupled to the demultiplexer to flip M of the L sub-packets, M being smaller than L;

L sub-interleaves coupled to the demultiplexer and the M flipping blocks to interleave the (L-M) sub-packets and the M flipped sub-packets; and

a concatenate coupled to the L sub-interleaves to concatenate the interleaved sub-packets to form an output packet;

a modulator coupled to the FEC encoder to modulate the output packet; and

a power spectral density (PSD) shaping module coupled to the modulator to spectrally shape the modulated output packet; wherein L and M are integers greater than or equal to one.

22. The system of claim 21 wherein the modulator is an orthogonal frequency division multiplexing (OFDM) modulator.