Patent ID: 7519018

Claim:
A method for adjusting data modulation at a subscriber unit, comprising: receiving data at a physical layer transmitter for transmission, wherein the received data is received in data blocks from a higher layer ARQ mechanism; formatting the received data into packets for transmission, wherein the packets are smaller in size than the data blocks, and each packet having a forward error correction (FEC) encoding/data modulation, and wherein the packets are transmitted using an orthogonal frequency division multiple access (OFDMA) air interface; appending an error check sequence for each packet; transmitting the packets; storing the packets for retransmission in a buffer memory incorporated into the physical layer transmitter; monitoring a return channel for receipt of an acknowledgment for each packet that packet has been received; limiting the number of retransmissions to an operator-defined integer value; clearing the buffer memory after the integer value is reached; retransmitting an original or selectively modified packet at the physical layer transmitter, if an acknowledgment for that packet has not been received within a predetermined period of time; and wherein the physical layer ARQ mechanism and physical layer transmitter operate transparently with respect to the higher layer ARO mechanism; receiving and demodulating received packets at a physical layer receiver; transmitting a corresponding acknowledgment in an acknowledgment generator for a given packet at the physical layer receiver, wherein a mechanism configured to receive the corresponding acknowledgment for the given packet operates transparently with respect to the higher layer ARQ mechanism; collecting retransmission statistics; adjusting the particular encoding/data modulation of each packet using the collected retransmission statistics; wherein if the collected retransmission statistics indicate a low number of retransmissions, a higher capacity encoding/data modulation scheme is selected as the particular encoding/data modulation and if the collected retransmission statistics indicate a high number of retransmissions, a lower capacity encoding/data modulation scheme is selected as the particular encoding/data modulation; combining the retransmitted original or selectively modified packet with the transmitted packets; and selectively nulling subchannels from an OFDM frequency set wherein the use of a poor quality subchannel is precluded for a predetermined period and adding a previously nulled subchannel back into the OFDM frequency set where a retransmission rate or link quality indicates a high quality for the previously nulled subchannel.