Enhanced SDU discard procedure for a special data segmentation in a wireless communications system

A method for handling discarding of a sequence of service data units in a communications system, the sequence of service data units comprising at least a last discarded service data unit (SDU), the method comprising the following steps:

• when a protocol data unit (PDU) containing a length indicator of the last discarded SDU contains no new SDUs:
• creating a move receiving window super field (MRW SUFI);
• setting a NLENGTH field of the MRW SUFI to 0;
• setting a last sequence number move receiving window field (SN_MRWLENGTH) to a sum of one plus a sequence number (SN) of the PDU containing the length indicator of the last discarded SDU;
• and
• issuing the MRW SUFI;
• wherein the length indicator indicates an end position of the last discarded SDU;
• the SN_MRWLENGTH indicates a sequence number of a PDU that contains a data segment of a SDU right after the last discarded SDU;
• setting the NLENGTH field of the MRW SUFI to 0 indicates that the last SDU discarded ended in a PDU with sequence number SN_MRWLENGTH-1 and that the first data octet in a PDU with sequence number SN_MRWLENGTH is the first data octet of the SDU right after the last discarded SDU;
• and the MRW SUFI is used to signal the information of discarded SDUs.