摘要 |
A method of transmitting digital data by radio signals in orthogonal frequency division multiplex (OFDM). Digital data is divided into error protection classes and the power level of the digital data is altered according to the particular error protection class. In addition to the data thus altered, error protection class data is transmitted in a separate logic channel. By using this error protection class data, a reception device is able to reverse this change in power level and perform a correct demodulation. The error protection class data is generated on the basis of the number, length and transmission reliability of the error protection classes and on the basis of transmission parameters. The digital data, divided into frames, is first assigned to services, and then these services are assigned to a corresponding error protection class.
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