Patent ID: 7151934

Claim:
A radio data communications method in which at least one of a first radio network controller and a second radio network controller performs a soft handover process for allowing soft handover of a mobile terminal, when the mobile terminal is performing the soft handover, the method including steps of: changing radio network controllers that perform the soft handover process; and transmitting data as part of the soft handover process in downlink radio data communications in which the first radio network controller transmits data to the mobile terminal via the second radio network controller and a base station, the soft handover processing including the steps of: determining a first transmission timing of transmitting the data to all base stations to which the mobile terminal is connected when performing the soft handover, determining a second transmission timing of transmitting the data to the second radio network controller, dividing the data and providing a sequence number to each of the data fragments based on a sequence number providing status, transmitting the data fragments to all the base stations at the first transmission timing, transmitting at least a data fragment to the second radio network controller wherein said data fragment is added with information requesting the sequence number providing status, and transmitting the sequence number providing status from the second radio network controller to the first radio network controller, wherein the sequence number providing status includes the number of data fragments having been transmitted since the data fragment added with information requesting the sequence number providing status.