Patent ID: 7142608

Claim:
A method of transmitting digital data by radio signals in orthogonal frequency division multiplex, the method comprising: dividing the digital data into frames at an transmission end, the digital data in the frames being divided into error protection classes; modulating the digital data to OFDM cells, the OFDM cells being converted in an OFDM cell multiplex, and each of the OFDM cells being assigned to an OFDM subcarrier; transmitting the OFDM cells at a power level corresponding to one of the error protection classes; transmitting error protection class data in a logic channel separate from the digital data; and demodulating the OFDM cells to digital data at a reception end as a function of the error protection class data; wherein the error protection class data is generated by using a number, length and transmission reliability of the error protection classes and by using transmission parameters.