Methods and apparatus for backwards compatible communication in a multiple input multiple output communication system with lower order receivers

A receiver in a multiple antenna communication system having at least one transmitter having a plurality of transmit antennas, comprising:

• at least one receive antenna for receiving an indication of a duration to defer until a subsequent transmission, said indication transmitted such that said indication is capable of being interpreted by a lower order receiver by diagonally loading a SIGNAL field across said plurality of antennas;
• and by transmitting, on each of said plurality of transmit antennas, said SIGNAL field on a distinct set of subcarriers while setting the remaining subcarriers to a null value;
• and means for deferring for said indicated duration.

A method for transmitting data by a transmitter having a plurality of transmit antennas in a multiple antenna communication system, said method comprising the step of:

• determining an indication of a duration to defer until a subsequent transmission;
• and transmitting said indication of said duration to defer until said subsequent transmission, said indication transmitted such that said indication is capable of being interpreted by a lower order receiver by diagonally loading a SIGNAL field across said plurality of transmit antennas and by transmitting, on each of said plurality of transmit antennas, said SIGNAL field on a distinct set of subcarriers while setting the remaining subcarriers to a null value.

A transmitter in a multiple antenna communication system, comprising:

• N transmit antennas for transmitting at least one training symbol using at least one of said N transmit antennas and transmitting an indication of a duration to defer until a subsequent transmission, said indication transmitted such that said indication is capable of being interpreted by a lower order receiver by diagonally loading a SIGNAL field across said plurality of transmit antennas;
• and by transmitting, on each of said plurality of transmit antennas, said SIGNAL field on a distinct set of subcarriers while setting the remaining subcarriers to a null value.