Patent ID: 8027294
Filing Date: 2011-09-27
Classification: H04L

Abstract:
1. An apparatus for transmitting an orthogonal frequency division multiplexing access (OFDMA) symbol in an OFDMA system, comprising: a transceiver to monitor a received signal quality of a receiver; and a controller to adaptively determine a bandwidth limit parameter based on the monitored received signal quality of the receiver, wherein the controller determines whether a value to limit bandwidth less than a previous bandwidth limit parameter violates bandwidth limit requirements for the OFDMA system when a currently received signal quality of the receiver is less than a previously received signal quality of the receiver, and when the value to limit bandwidth less than the previous bandwidth limit parameter does not violate the bandwidth limit requirements, the controller determines the bandwidth limit parameter as the value to limit bandwidth less than the previous bandwidth limit parameter, and when the value to limit bandwidth less than the previous bandwidth limit parameter violates the bandwidth limit requirements, the controller determines a modulation scheme that includes a low data rate and determines the bandwidth limit parameter based on the determined modulation scheme that includes the low data rate, and the controller determines whether a value to limit bandwidth more than the previous bandwidth limit parameter violates the bandwidth limit requirements for the OFDMA system when the currently received signal quality of the receiver is better than the previously received signal quality of the receiver, and when the value to limit bandwidth more than the previous bandwidth limit parameter does not violate the bandwidth limit requirements, the controller determines 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, the controller determines a modulation scheme that includes a high data rate and determines the bandwidth limit parameter based on the determined modulation scheme that includes the high data rate, and wherein the transceiver generates an OFDMA symbol based on the determined bandwidth limit parameter to transmit to the receiver.