Code design and implementation improvements for low density parity check codes for wireless routers using 802.11N protocol

1. A method for implementing Low Density Parity Check (LDPC) codes in an IEEE 802.11 standard system configured to operate in a Multiple-Input, Multiple-Output (MIMO) schema, comprising:

a) defining a base LDPC code, having a length equal to an integer number of data carriers in an Orthogonal Frequency Division Multiplexing (OFDM) symbol;

b) receiving the base LDPC code on a plurality of sub-carriers, wherein the base LDPC code is transmitted at an expected phase on sub-carriers specified by the IEEE 802.11 standard system, and

c) receiving the base LDPC code on sub-carriers other than those specified by the IEEE 802.11 standard system, wherein the base LDPC code on the other sub-carriers is transmitted offset in phase from the base LDPC code on the specified sub-carriers.

2. The method of claim 1 , wherein the base LDPC code is 192 bits long.

3. The method of claim 1 , further comprising using a longer LDPC code, wherein a length of the longer LDPC code is an integer multiple of the base LDPC code.

4. The method of claim 3 , further comprising transmitting bits of the longer LDPC code sequentially on the specified sub-carriers and the other sub-carriers.

5. The method of claim 1 , wherein the specified sub-carriers are transmitted by a first transmission antenna and the other sub-carriers are transmitted by at least one other antenna.

6. A Low Density Parity Check (LDPC) coded, IEEE 802.11 compatible Multiple-Input, Multiple-Output (MIMO) broadcast system, comprising:

a receiver for receiving a signal on a plurality of receive antennas, the signal encoded with a base LDPC code having a length equal to an integer number of data carriers in an Orthogonal Frequency Division Multiplexing (OFDM) symbol, and for decoding information bits using the base LDPC code;

a demodulator, coupled to the receiver, for demodulating the signals; and

a decoder, coupled to the demodulator, for decoding the demodulated signals into information bits, wherein the demodulated decoded information bits are transmitted to the receiver on sub-carriers specified by an IEEE 802.11 standard system and on sub-carriers other than those specified by the IEEE 802.11 standard system, wherein transmissions on the sub-carriers other than those specified by the IEEE 802.11 standard system are offset in phase from transmissions on the sub-carriers specified by the IEEE 802.11 standard system.

7. The LDPC coded, IEEE 802.11 compatible MIMO broadcast system of claim 6 , wherein the base LDPC code is 192 bits long.

8. The LDPC coded, IEEE 802.11 compatible MIMO broadcast system of claim 6 , further comprising using a longer LDPC code, wherein a length of the longer LDPC code is an integer multiple of the base LDPC code.

9. The LDPC coded, IEEE 802.11 compatible MIMO broadcast system of claim 8 , further comprising bits of the longer LDPC code being sequentially received on the specified sub-carriers and other sub-carriers.

10. The LDPC coded, IEEE 802.11 compatible MIMO broadcast system of claim 6 , wherein the specified sub-carriers are transmitted by a first antenna and other sub-carriers are transmitted by at least one other antenna.

11. A method for implementing Low Density Parity Check (LDPC) codes in a Multiple-Input, Multiple-Output (MIMO) system, comprising:

a) transmitting a base LDPC code of length equal to an integer number of data carriers over a plurality of sub-carriers at an expected phase on sub-carriers specified by the IEEE 802.11 standard system, and

b) transmitting the base LDPC code on sub-carriers other than those specified by the IEEE 802.11 standard system offset in phase from the base LDPC code on the specified sub-carriers.

12. The method of claim 11 , wherein the base LDPC code is 192 bits long.

13. The method of claim 11 , further comprising transmitting a longer LDPC code, wherein a length of the longer LDPC code is an integer multiple of the base LDPC code.

14. The method of claim 13 , further comprising transmitting bits of the longer LDPC code sequentially on the IEEE 802.11 standard sub-carriers and the other sub-carriers.

15. The method of claim 11 , wherein the IEEE 802.11 standard sub-carriers are transmitted by a first antenna and the other sub-carriers are transmitted by at least one other antenna.

16. A broadcast system, comprising:

an encoder, for encoding a signal in the broadcast system using a base Low Density Parity Check (LDPC) code having a length equal to an integer number of data carriers in the broadcast system,

a modulator, coupled to the encoder, for modulating the LDPC encoded signal; and

a transmitter, coupled to the modulator, for transmitting the modulated LDPC encoded signal on a plurality of transmit antennas, wherein the modulated LDPC encoded signal is transmitted on IEEE 802.11 standard sub-carriers in an expected phase and on other sub-carriers at a phase offset from the expected phase.

17. The broadcast system of claim 16 , wherein the base LDPC code is 192 bits long.

18. The broadcast system of claim 16 , wherein the encoder further encodes the signal using a longer LDPC code, wherein a length of the longer LDPC code is an integer multiple of the base LDPC code.

19. The broadcast system of claim 18 , wherein bits of the longer LDPC code are sequentially transmitted on the IEEE 802.11 standard sub-carriers and the other sub-carriers.

20. The broadcast system of claim 16 , wherein the IEEE 802.11 standard sub-carriers are transmitted by a first antenna and other sub-carriers are transmitted by at least one other antenna.