Data transmission device and data transmission method capable of minimizing delay of fast data

Abstract

A data transmission device for executing data transmission in environments where the noise level changes periodically minimizes delay of fast data. 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. The fast data is supplied to a tone ordering section without changing its data rate. Meanwhile, an interleaving section executes interleaving to the interleave data, and a rate converter controls the data rate of the interleave data and supplies the interleave data to the tone ordering section. The tone ordering section assigns the fast data and the interleave data to each carrier of a symbol (frame) to be transmitted, based on preobtained bit distribution with respect to low noise periods or high noise periods, depending on whether the symbol is transmitted in the low noise periods or in periods including the high noise periods. In the data assignment, the amount of fast data included in each symbol is set constant regardless of whether the symbol is transmitted in the low noise periods or in periods including the high noise periods, thereby the amount of fast data transmitted in a fixed time period is made constant, and thus delay of fast data is minimized.