Data transmission device and data transmission method capable of minimizing delay of fast data both in normal conditions and noisy conditions

Abstract

A multiplexing/synchronization control section receives data (in which the ratio between fast data and interleave data is fixed) which are supplied from an upper layer device at a prespecified data rate, and separates the data into fast data and interleave data. An interleaving section executes interleaving to the interleave data. The fast data and the interleave data, whose data rates have been controlled by a fast data rate converter and an interleave data rate converter respectively, are supplied to a tone ordering section to be assigned to carriers of a symbol (frame). In the case where the amount of data which can be assigned to each NEXT symbol is larger than or equal to a “specific amount” which corresponds to the fixed data rate of the fast data supplied from the upper layer device, the tone ordering section assigns fast data of the “specific amount” to each symbol regardless of whether the symbol is a FEXT symbol or a NEXT symbol. In the case where the amount of data which can be assigned to each NEXT symbol is smaller than the “specific amount”, the tone ordering section assigns fast data only to each NEXT symbol and assigns fast data of an amount larger than the “specific amount” to each FEXT symbol. Thereby, delay of fast data (such as video data, voice data, data for real-time application software, etc. to which delay is harmful) is minimized both in normal conditions and in noisy conditions.