Data transmission apparatus with a data transmission amount controllable and a method therefor

A data transmission apparatus for transmitting a transmission request to transmit a data signal to a receiver unit and for, upon receiving a data transmission permission from the receiver unit, transmitting the data signal to the receiver unit, comprising:

• a data transmission circuit outputting a received data signal to the receiver unit;
• a control circuit controlling a maximum transmission amount of the data signal to be transmitted at a time;
• and
• a transmission amount storing circuit storing therein an average transmission amount value,
• said control circuit comprising:
• a first management circuit adding up the average transmission amount value each time the data signal is transmitted and storing therein the added-up value as a first management value, the average transmission amount value being stored in said transmission amount storing circuit;
• a second management circuit adding up a transmission amount of the data signal transmitted from said data transmission circuit each time the data signal is transmitted and storing therein the added-up amount value as a second management value;
• and
• a maximum amount determination circuit determining, based on the first and second management values, the maximum data amount of the data signal to be transmitted next from said data transmission circuit, and
• wherein, with the maximum as a threshold, said data transmission circuit determines an amount of the data signal to be transmitted next and transmitting the transmission request to transmit the amount of the data signal to the receiver unit.