The invention relates to packet transmission scheduling and specifically to UMTS packet transmission scheduling.It is an object of the invention to provide an improved method for packet transmission scheduling, especially on downlink shared channels and an improved packet transmission scheduling system, both the improved method and the system especially adapted to be used for UMTS systems.The invention proposes a quality of service scheduling of multiple data flows in a CDMA system, wherein a priority order of protocol data units (PDU) of multiple data flows with regard to predefined flow's quality of service requirements is determined and a serving of the protocol data units (PDU) is performed by dynamically creating transport block sets (TBS) to be transmitted to the physical layer (PHY-layer) with regard to the defined priority order and in dependence of allocated radio resource constraints.