Transmitting high rate data within a MIMO WLAN

1. A method for transmitting high rate data within a multiple input multiple output (MIMO) wireless local area network (WLAN), the method comprises:

selecting one of a plurality of predetermined data rates for a data transmission rate;

when the selected data transmission rate is between a first predetermined data rate and a second predetermined data rate of the plurality of predetermined data rates, enabling two transmission paths and activating two antennas for use in the two transmission paths;

when the data transmission rate is greater than the second predetermined data rate, enabling four transmission paths and activating four antennas for use in the four transmission paths;

for each of the enabled transmission paths, determining the following to provide the data transmission rate over the enabled transmission paths: channel bandwidth; level of constellation; number of data subcarriers; rate code; and cyclic prefix duration; and

operating a MIMO WLAN transceiver to transmit at the data transmission rate over the enabled transmission paths according to the determined channel bandwidth; level of constellation, number of data subcarriers, rate code, and cyclic prefix duration.

2. The method of claim 1 , wherein the enabling the two transmission paths comprises at least one of:

activating two antennas for a 20 MHz channel; and

activating two antennas for a 40 MHz channel.

3. The method of claim 1 , wherein the level of constellation comprises at least one of:

64 Quadrature Amplitude Modulation (QAM);

128 QAM; and

256 QAM.

4. The method of claim 3 , wherein the determining the number of data subcarriers when the level of constellation is 64 QAM comprises at least one of:

selecting 52 subcarriers of 64 subcarriers for carrying data; and

selecting 54 subcarriers of 64 subcarriers for carrying data.

5. The method of claim 4 comprises, when 52 subcarriers are selected:

utilizing alternating two pilot subcarriers per each of the two transmission paths; and

selecting a rate 5/6 code.

6. The method of claim 4 comprises, when 54 subcarriers are selected:

utilizing alternating two pilot subcarriers per each of the two transmission paths; and

utilizing subcarriers +27 and −27 for carrying data.

7. The method of claim 4 comprises, when 52 subcarriers are selected:

reducing cyclic prefix; and

selecting a rate 3/4 code.

8. The method of claim 4 further comprises:

adjusting a spectral mask based on the number of subcarriers selected.

9. The method of claim 1 further comprises:

when the data transmission rate is less than the first predetermined data rate due to distance, enabling the two transmission paths to utilize a 20 MHz channel with code rates less than 3/4 for 12, 24, or 48 Mbps (Mega bits per second) data rates or enabling the two transmission paths to utilize a 40 MHz with code rates less than 3/4 for 27 or 54 Mbps data rates.

10. The method of claim 1 further comprises:

when the data transmission rate is greater than the second predetermined data rate, enabling four transmission paths utilizing a 20 MHz channel and a code rate of 3/4 for 192 Mbps data rate or enabling the four transmission paths utilizing a 40 MHz channel and a code rate of 3/4 for 486 Mbps data rate.

11. A transmitter comprises:

baseband processing module; and

a plurality of radio frequency (RF) transmitters, wherein the processing module functions to:

select one of a plurality of predetermined data rates for a data transmission rate;

when the selected data transmission rate is between a first predetermined data rate and a second predetermined data rate of the plurality of predetermined data rates, enable two transmission paths and activate two antennas for use in the two transmission paths;

when the data transmission rate is greater than the second predetermined data rate, enable four transmission paths and activate four antennas for use in the four transmission paths;

for each of the enabled transmission paths, determine the following to provide the data transmission rate over the enabled transmission paths: channel bandwidth; level of constellation; number of data subcarriers; rate code; and cyclic prefix duration; and

operate a MIMO WLAN transceiver to transmit at the data transmission rate over the enabled transmission paths according to the determined channel bandwidth; level of constellation, number of data subcarriers, rate code, and cyclic prefix duration.

12. The transmitter of claim 11 , wherein the baseband processing module functions to enable the two of the plurality of RF transmitters by at least one of:

activating the two of the plurality of RF transmitters for a 20 MHz channel; and

activating the two of the plurality of RF transmitters for a 40 MHz channel.

13. The transmitter of claim 11 , wherein the level of constellation comprises at least one of:

64 Quadrature Amplitude Modulation (QAM);

128 QAM; and

256 QAM.

14. The transmitter of claim 13 , wherein the determining the number of data subcarriers when the level of constellation is 64 QAM comprises at least one of:

selecting 52 subcarriers of 64 subcarriers for carrying data; and

selecting 54 subcarriers of 64 subcarriers for carrying data.

15. The transmitter of claim 14 , wherein the baseband processing module further functions to, when 52 subcarriers are selected:

utilize alternating two pilot subcarriers per frame for each of the two of the plurality of RF transmitters; and

select a rate 5/6 code.

16. The transmitter of claim 14 , wherein the baseband processing module further functions to, when 54 subcarriers are selected:

utilize alternating two pilot subcarriers per frame for each of the two of the plurality of RF transmitters; and

utilize subcarriers +27 and −27 per frame for carrying data.

17. The transmitter of claim 14 , wherein the baseband processing module further functions to, when 52 subcarriers are selected:

reduce cyclic prefix of a frame; and

select a rate 3/4 code.

18. The transmitter of claim 14 , wherein the baseband processing module further functions to:

adjust a spectral mask based on the number of subcarriers selected.

19. The transmitter of claim 11 , wherein the baseband processing module further functions to:

when the data transmission rate is less than the first predetermined data rate due to distance, enable the two of the plurality of RF transmitters to utilize a 20 MHz channel with code rates less than 3/4 for 12, 24, or 48 Mbps (Mega bits per second) data rates or enabling the two of the plurality of RF transmitters to utilize a 40 MHz with code rates less than 3/4 for 27 or 54 Mbps data rates.

20. The transmitter of claim 11 , wherein the baseband processing module further functions to:

when the data transmission rate is greater than the second predetermined data rate, enable four of the plurality of RF transmitters utilizing a 20 MHz channel and a code rate of 3/4 for 192 Mbps data rate or enabling the four of the plurality of RF transmitters utilizing a 40 MHz channel and a code rate of 3/4 for 486 Mbps data rate.