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Method, apparatus, and data packet format to implement transmit diversity in a multicarrier environment is disclosed. For diversity transmission operations, space frequency encoding techniques are employed creating distinguishable first and second time domain signals from a multicarrier frequency do

Method, apparatus, and data packet format to implement transmit diversity in a multicarrier environment is disclosed. For diversity transmission operations, space frequency encoding techniques are employed creating distinguishable first and second time domain signals from a multicarrier frequency domain symbol bearing data of interest, which are then broadcast in parallel over first and second transmission units respectively. For diversity reception operations, complementary space frequency decoding is used to recover a corrected multicarrier frequency domain symbol from a time domain signal containing either this symbol, a space frequency modified symbol based on the multicarrier symbol, or a possible partial/complete combination of both. The data packet format includes portions defining a transmission diversity semaphore, a preamble enabling training of a receiver receiving the data packet, and a payload.

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1. A communication device, comprising: a symbol encoder configured to encode information bits into frequency domain data corresponding to multicarrier frequency domain symbols (MFDSs);an encoder configured to generate modified frequency domain data when the communication device is operating in a div

1. A communication device, comprising: a symbol encoder configured to encode information bits into frequency domain data corresponding to multicarrier frequency domain symbols (MFDSs);an encoder configured to generate modified frequency domain data when the communication device is operating in a diversity transmission mode, the modified frequency domain data comprising re-ordered complex conjugate data corresponding to the frequency domain data;a converter configured to i) convert the frequency domain data to a first time domain signal, and ii) convert the modified frequency domain data to a second time domain signal when the communication device is operating in the diversity transmission mode;a first radio frequency (RF) transmitter configured to transmit the first time domain signal;a second RF transmitter configured to i) transmit the second time domain signal when the communication device is operating in the diversity transmission mode, and ii) not transmit the second time domain signal when the communication device is operating in a legacy mode; andlogic circuitry configured to control operation of the communication device according to one of a plurality of transmission modes comprising the diversity transmission mode and the legacy mode. 2. The communication device of claim 1, wherein the symbol encoder is configured to encode the information bits into orthogonal frequency division multiplexing (OFDM) symbols. 3. The communication device of claim 1, wherein the legacy mode corresponds to compliance with at least one of the IEEE Standard 802.11a and the IEEE Standard 802.11g supplements to the IEEE Standard 802.11 (1999). 4. The communication device of claim 1, wherein the converter comprises: a first converter device configured to convert the frequency domain data to the first time domain signal; anda second converter device configured to convert the modified frequency domain data to the second time domain signal when the communication device is operating in the diversity transmission mode. 5. The communication device of claim 1, wherein the logic circuitry is further configured to: generate a physical layer control protocol (PLCP) header of a PLCP frame that includes the MFDSs in a payload of the PLCP frame, including formatting the PLCP header to indicate that the payload of the PLCP frame is being transmitted according to the diversity transmission mode when the communication device is operating in the diversity transmission mode. 6. The communication device of claim 5, wherein the logic circuitry is further configured to: set a bit in the PLCP header to indicate that the payload of the PLCP frame is being transmitted according to the diversity transmission mode when the communication device is operating in the diversity transmission mode. 7. A method, comprising: controlling a transmission operation of a communication device according to one of a plurality of transmission modes comprising at least a diversity transmission mode and a legacy mode;encoding, at the communication device, information bits into frequency domain data corresponding to multicarrier frequency domain symbols (MFDSs);generating, at the communication device, modified frequency domain data when the communication device is operating in the diversity transmission mode;converting, at the communication device, the frequency domain data to a first time domain signal;converting, at the communication device, the modified frequency domain data to a second time domain signal when the communication device is operating in the diversity transmission mode;transmitting, with the communication device, the first time domain signal;transmitting, with the communication device, the second time domain signal when the communication device is operating in the diversity transmission mode; andnot transmitting, with the communication device, the second time domain signal when the communication device is operating in a legacy mode. 8. The method of claim 7, wherein encoding the information bits into frequency domain data corresponding to MFDSs comprises encoding the information bits into frequency domain data corresponding to orthogonal frequency division multiplexing (OFDM) symbols. 9. The method of claim 7, wherein the legacy mode corresponds to compliance with at least one of the IEEE Standard 802.11a and the IEEE Standard 802.11g supplements to the IEEE Standard 802.11 (1999). 10. The method of claim 7, wherein generating the modified frequency domain data comprises generating re-ordered subcarrier complex conjugates of the frequency domain data. 11. The method of claim 7, further comprising: generating a physical layer control protocol (PLCP) header of a PLCP frame that includes the MFDSs in a payload of the PLCP frame, including formatting the PLCP header to indicate that the payload of the PLCP frame is being transmitted according to the diversity transmission mode when the communication device is operating in the diversity transmission mode. 12. The method of claim 11, wherein formatting the PLCP header includes: setting a bit in the PLCP header to indicate that the payload of the PLCP frame is being transmitted according to the diversity transmission mode when the communication device is operating in the diversity transmission mode. 13. A communication device, comprising: logic circuitry configured to control operation of the communication device according to one of a plurality of reception modes comprising a diversity mode and a legacy mode;a radio frequency (RF) receiver configured to downconvert a received RF signal to a time domain signal;a converter configured to convert the time domain signal to first frequency domain data corresponding to multicarrier frequency domain symbols (MFDSs);a decoder configured to, when the communication device is operating in the diversity mode: treat the first frequency domain data as composite data corresponding to a plurality of transmit signals having been transmitted in a transmit diversity mode, including treating the first frequency domain data as a composite of original frequency domain data and re-ordered subcarrier complex conjugates of the original frequency domain data, anddecode the composite data to generate corrected second frequency data; anda symbol decoder configured to i) decode the first frequency domain data to generate information bits when the communication device is operating in the legacy mode, and ii) decode the corrected second frequency domain data to generate information bits when the communication device is operating in the diversity mode. 14. The communication device of claim 13, wherein the first frequency domain data corresponds to orthogonal frequency division multiplexing (OFDM) symbols. 15. The communication device of claim 13, wherein legacy mode corresponds to at least one of the IEEE Standard 802.11a and the IEEE Standard 802.11g supplements to the IEEE Standard 802.11 (1999). 16. The communication device of claim 13, wherein the diversity decoder is configured to pass through the first frequency domain data without modification when the communication device is operating in the legacy mode. 17. The communication device of claim 13, wherein the logic circuitry is further configured to: process a physical layer control protocol (PLCP) header of a PLCP frame that includes the MFDSs in a payload of the PLCP frame to determine whether the PLCP header is formatted to signal that the payload of the PLCP frame was transmitted according to a diversity transmission mode, andcontrol operation of the communication device according to the diversity mode when the PLCP frame is determined to be formatted to signal that the payload of the PLCP frame was transmitted according to a diversity transmission mode. 18. The communication device of claim 17, wherein the logic circuitry is further configured to: determine whether a bit in the PLCP header was set to indicate that the payload of the PLCP frame was transmitted according to the diversity transmission mode. 19. A method, comprising: controlling operation of a communication device according to one of a plurality of reception modes comprising a diversity mode and a legacy mode;downconverting, at the communication device, a received radio frequency (RF) signal to a time domain signal;converting, at the communication device, the time domain signal to first frequency domain data corresponding to multicarrier frequency domain symbols (MFDSs);treating, at the communication device, the first frequency domain data as composite data corresponding to a plurality of transmit signals having been transmitted in a transmit diversity mode when the communication device is operating in the diversity mode;decoding, at the communication device, the composite data to generate corrected second frequency data when the communication device is operating in the diversity mode;decoding the first frequency domain data to generate information bits when the communication device is operating in the legacy mode; anddecoding the corrected second frequency domain data to generate information bits when the communication device is operating in the diversity mode. 20. The method of claim 19, wherein the first frequency domain data corresponds to orthogonal frequency division multiplexing (OFDM) symbols. 21. The method of claim 19, wherein legacy mode corresponds to at least one of the IEEE Standard 802.11a and the IEEE Standard 802.11g supplements to the IEEE Standard 802.11 (1999). 22. The method of claim 19, wherein: treating the first frequency domain data as composite data comprises treating the first frequency domain data as a composite of original frequency domain data and re-ordered subcarrier complex conjugates of the original frequency domain data; anddecoding, at the communication device, the composite of original frequency domain data and re-ordered subcarrier complex conjugates of the original frequency domain data to generate the corrected second frequency data. 23. The method of claim 19, further comprising: passing the first frequency domain data through a decoder of the communication device without modification when the communication device is operating in the legacy mode, wherein the decoder is configured to decode the composite data to generate corrected second frequency data when the communication device is operating in the diversity mode. 24. The method of claim 19, further comprising: processing, at the communication device, a physical layer control protocol (PLCP) header of a PLCP frame that includes the MFDSs in a payload of the PLCP frame to determine whether the PLCP header is formatted to signal that the payload of the PLCP frame was transmitted according to a diversity transmission mode; andcontrolling operation of the communication device according to the diversity mode when the PLCP frame is determined to be formatted to signal that the payload of the PLCP frame was transmitted according to a diversity transmission mode. 25. The method of claim 24, wherein processing the PLCP header to determine whether the PLCP header is formatted to signal that the payload of the PLCP frame was transmitted according to a diversity transmission mode comprises: determining, at the communication device, whether a bit in the PLCP header was set to indicate that the payload of the PLCP frame was transmitted according to the diversity transmission mode.