Patent ID: 8588181

Claim:
A communication method performed in a mobile communication device of a telecommunication system, the method comprising: receiving Service Data Units, SDUs, for transmission to a source node of the telecommunication system; storing a copy of the SDUs in an SDU management buffer; passing the SDUs to a concatenation and segmentation unit to generate Protocol Data Units, PDUs; storing the PDUs in a transmit buffer for transmission to the source node; sending a feedback message to the SDU management buffer identifying an SDU that can be removed from the SDU management buffer when, for Unacknowledge Mode, UM, data, the PDUs corresponding to that SDU have been forwarded from the transmission buffer or when, for Acknowledge Mode, AM, data, receipt of the PDUs corresponding to that SDU have been acknowledged by the source node; in response to the receipt of the feedback message, allowing removal of the identified SDU from the SDU management buffer; receiving a status report from the source node; receiving a handover command from the source node after receiving the status report; and after completing handover to a target node, using the received status report to control which SDUs are passed to the concatenation and segmentation unit to form PDUs for transmission to the target node.