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

A data transmission device which executes data transmission in environments where the noise level changes periodically, wherein data transmission is executed setting an amount of fast data which are assigned to each frame at a constant non-zero amount when fast data are being transmitted even if an amount of data assigned to each frame changes due to the periodic change of the noise level,

• wherein the data transmission device is a device which executes data transmission using multi-carrier, comprising:
• a separation means for receiving data which are supplied from an upper layer device at a fixed data rate including fast data and interleave data at a prespecified ratio, and separating the data into the fast data and the interleave data;
• an interleaving means for executing interleaving to the interleave data which have been separated by the separation means;
• an interleave data rate control means for controlling the data rate of the interleave data according to the periodic change of the noise level;
• a tone ordering means for assigning the fast data to the carriers of the frame starting from a carrier that can carry the smallest number of bits so that the amount of the fast data included in the frame will be the constant amount and assigning the interleave data to the carriers of the frame starting from a carrier than can carry the largest number of bits, based on preobtained bit distribution of the multi-carrier with respect to low noise periods or with respect to high noise periods depending on whether the frame is a frame that is transmitted in the low noise periods or a frame that is transmitted in periods including the high noise periods;
• a coefficient conversion means for converting data which have been assigned by the tone ordering means to each carrier of the frame into corresponding coefficients, based on the preobtained bit distribution and preobtained gain distribution of the multi-carrier with respect to the low noise periods or with respect to the high noise periods depending on whether the frame is a frame that is transmitted in the low noise periods or a frame that is transmitted in periods including the high noise periods;
• and
• a transform means for transforming the coefficients with respect to the carriers of the frame into a signal which varies in time.

A data transmission method for transmitting data in environments where the noise level changes periodically, comprising the step, when transmitting fast data, of setting an amount of the fast data which are assigned to each frame at a constant non-zero amount even if an amount of data assigned to each frame changes due to the periodic change of the noise level,

• wherein the data transmission is executed using multi-carrier and the data transmission method comprises the steps of:
• a separation step in which data, which are supplied from an upper layer device at a fixed data rate including fast data and interleave data at a prespecified ratio, are separated into the fast data and the interleave data;
• an interleaving step in which interleaving is executed to the interleave data which have been separated in the separation step;
• an interleave data rate control step in which the data rate of the interleave data is controlled according to the periodic change of the noise level;
• a tone ordering step in which the fast data are assigned to the carriers of the frame starting from a carrier that can carry the smallest number of bits so that the amount of the fast data included in the frame will be the constant amount, and the interleave data are assigned to the carriers of the frame starting from a carrier that can carry the largest number of bits, based on preobtained bit distribution of the multi-carrier with respect to low noise periods or with respect to high noise periods depending on whether the frame is a frame that is transmitted in the low noise periods or a frame that is transmitted in periods including the high noise periods;
• a coefficient conversion step in which data which have been assigned to each carrier of the frame in the tone ordering step are converted into corresponding coefficients, based on the preobtained bit distribution and preobtained gain distribution of the multi-carrier with respect to the low noise periods or with respect to the high noise periods depending on whether the frame is a frame that is transmitted in the low noise periods or a frame that is transmitted in periods including the high noise periods;
• and
• a transform step in which the coefficients with respect to the carriers of the frame are transformed into a signal which varies in time.

A computer-readable record medium storing a program for instructing a computer or a DSP (Digital Signal Processor) of a data transmission device to execute a process for transmitting data, wherein data transmission is executed setting an amount of fast data which are assigned to each frame at a constant non-zero amount when fast data are being transmitted even if an amount of data assigned to each frame changes due to a periodic change of the noise level,

• wherein the data transmission is executed in the process using multi-carrier, and the process comprises the steps of:
• a separation step in which data, which are supplied from an upper layer device at a fixed data rate including fast data and interleave data at a prespecified ratio, are separated into the fast data and the interleave data;
• an interleaving step in which interleaving is executed to the interleave data which have been separated in the separation step;
• an interleave data rate control step in which the data rate of the interleave data is controlled according to the periodic change of the noise level;
• a tone ordering step in which the fast data are assigned to the carriers of the frame starting from a carrier that can carry the smallest number of bits so that the amount of the fast data included in the frame will be the constant amount, and the interleave data are assigned to the carriers of the frame starting from a carrier that can carry the largest number of bits, based on preobtained bit distribution of the multi-carrier with respect to low noise periods or with respect to high noise periods depending on whether the frame is a frame that is transmitted in the low noise periods or a frame that is transmitted in periods including the high noise periods;
• a coefficient conversion step in which data which have been assigned to each carrier of the frame in the tone ordering step are converted into corresponding coefficients, based on the preobtained bit distribution and preobtained gain distribution of the multi-carrier with respect to the low noise periods or with respect to the high noise periods depending on whether the frame is a frame that is transmitted in the low noise periods or a frame that is transmitted in periods including the high noise periods;
• and
• a transform step in which the coefficients with respect to the carriers of the frame are transformed into a signal which varies in time.