The present invention concerns a method of processing traffic data in Layer 2 of a wireless communications system, whereby the MAC layer is arranged, after receipt of a traffic data volume report from the RLC layer, to process said data volume report and to then issue an acknowledgement message to the RLC layer. The method ensures that the RLC and MAC layers are synchronized with respect to traffic data processing. The MAC layer may be arranged to issue an acknowledgement to the RLC layer only where it determines from processing a data volume report that the RLC layer is not permitted to transmit data in a next or subsequent corresponding TTI. The present invention also concerns a process for data discard in a Radio Link Control (RLC) layer of a Wideband Code Division Multiple Access (WCDMA) wireless communications system such as a Universal Mobile Telecommunications System (UMTS). The process involves, responsive to thetriggering of a data discard operation, determining whether the RLC layer is permitted to transmit data. Where it is determined that the RLC layer is not permitted to transmit data in a next or subsequent TTI, the method includes the step of informing the RLC layer that data is not required.