Apparatus and method for transmitting OFDMA symbols

A method of transmitting an orthogonal frequency division multiplexing access (OFDMA) symbol in an OFDMA system, comprising:

• monitoring a received signal quality of a receiver;
• determining a bandwidth limit parameter adaptively based on the monitored received signal quality of the receiver,
• wherein determining the bandwidth limit parameter adaptively includes:
• determining when the currently received signal quality of the receiver is less than a previously received signal quality of the receiver;
• when the currently received signal quality of the receiver is less than the previously received signal quality of the receiver determining whether a value to limit bandwidth less than a previous bandwidth limit parameter violates bandwidth limit requirements for the OFDMA system;
• when the value to limit bandwidth less than the previous bandwidth limit parameter does not violate the bandwidth limit requirements, determining the bandwidth limit parameter as the value to limit bandwidth less than the previous bandwidth limit parameter,
• when the value to limit bandwidth less than the previous bandwidth limit parameter violates the bandwidth limit requirements, determining a modulation scheme that includes a low data rate, and the bandwidth limit parameter based on the determined modulation scheme that includes the low data rate,
• when the currently received signal quality of the receiver is better than the previously received signal quality of the receiver, determining whether a value to limit bandwidth more than the previous bandwidth limit parameter violates the bandwidth limit requirements for the OFDMA system,
• when the value to limit bandwidth more than the previous bandwidth limit parameter does not violate the bandwidth limit requirements, determining the bandwidth limit parameter as the value to limit bandwidth more than the previous bandwidth limit parameter, and
• when the value to limit bandwidth more than the previous bandwidth limit parameter violates the bandwidth limit requirements, determining a modulation scheme that includes a high data rate, and the bandwidth limit parameter based on the determined modulation scheme that includes the high data rate;
• and
• generating an OFDMA symbol based on the determined bandwidth limit parameter to transmit to the receiver.

A non-transitory computer readable medium storing computer executable instructions thereon, the computer executable instructions, when executed in a computer, executing a method of transmitting an orthogonal frequency division multiplexing access (OFDMA) symbol in an OFDMA system, comprising:

• monitoring a received signal quality of a receiver;
• determining a bandwidth limit parameter adaptively based on the monitored received signal quality of the receiver,
• wherein determining the bandwidth limit parameter adaptively includes:
• determining when the currently received signal quality of the receiver is less than a previously received signal quality of the receiver;
• when the currently received signal quality of the receiver is less than the previously received signal quality of the receiver, determining whether a value to limit bandwidth less than a previous bandwidth limit parameter violates bandwidth limit requirements for the OFDMA system;
• when the value to limit bandwidth less than the previous bandwidth limit parameter does not violate the bandwidth limit requirements, determining the bandwidth limit parameter as the value to limit bandwidth less than the previous bandwidth limit parameter,
• when the value to limit bandwidth less than the previous bandwidth limit parameter violates the bandwidth limit requirements, determining a modulation scheme that includes a low data rate, and the bandwidth limit parameter based on the determined modulation scheme that includes the low data rate,
• when the current received signal quality of the receiver is better than the previously received signal quality of the receiver, determining whether a value to limit bandwidth more than the previous bandwidth limit parameter violates the bandwidth limit requirements for the OFDMA system,
• when the value to limit bandwidth more than the previous bandwidth limit parameter does not violate the bandwidth limit requirements, determining the bandwidth limit parameter as the value to limit bandwidth more than the previous bandwidth limit parameter, and
• when the value to limit bandwidth more than the previous bandwidth limit parameter violates the bandwidth limit requirements, determining a modulation scheme that includes a high data rate, and the bandwidth limit parameter based on the determined modulation scheme that includes the high data rate;
• and
• generating an OFDMA symbol based on the determined bandwidth limit parameter to transmit to the receiver.