To obtain an easy and efficient method for reducing interference and optimizing the use of radio resources by executing transmission at a transmitting speed being lower than a permission transmitting speed after the latter speed is received in a user device.

When a perfect frame is received from a new user, the average of reception power is obtained until the last frame or certain preceding frames in order to calculate the estimation of an interference level. Then a network calculates the permission transmitting speed SFmin concerning the new user on the basis of the calculated level of the interference and on the number of active state users and transmits SFmin to new UE. When the calculated speed SFmin is received from UTRAN, the UE sets new TFC on DPDCH to respect the limit of SFmin concerning the transmitting speed. Besides, signalling is executed at a low transmitting speed on DPCCH and a transmission frame is prepared.