A method in a transmitting radio node for scheduling service data flows within a radio bearer towards a receiving radio node in a radio communications network is provided. The transmitting radio node maps data packets of at least two service data flows within the radio bearer to a respective pre-scheduling queue at a PDCP layer, wherein each pre-scheduling queue is associated with a service or a service quality requirement of the respective service data flow. The transmitting radio node further pre-schedules the data packets of the respective pre-scheduling queue down to a scheduling queue at a RLC or a MAC layer. The transmitting radio node further schedules the data packets in the scheduling queue towards the receiving radio node. The transmitting radio node takes a prebuffer time of a data packet queued in the pre-scheduling queue into account when pre-scheduling and/or scheduling the data packets.