Patent ID: 8073012

Claim:
A method for handling, service data unit, called SDU hereinafter, discard in a transmitter of a wireless communications system, the wireless communications system comprising the transmitter and a receiver, the method comprising: activating a mode of â€œuse of a special value of a header extension fieldâ€, wherein the mode represents that, in a protocol data unit, called PDU hereinafter, a header extension field with a special value indicates both that a succeeding octet following the header extension field contains data and that a last octet of the PDU is a last octet of a SDU; forming a first PDU, wherein the first PDU contains a last SDU and a header extension field with the special value in the first PDU is used instead of a length indicator for indicating that the last octet of the last SDU is the last octet of the first PDU and that the succeeding octet following the header extension field contains data; discarding a plurality of SDUs including the last SDU; and setting a value of a field to be a sequence number of a second PDU, wherein the field is utilized for indicating the receiver to discard all not yet successfully received SDUs that have segments with sequence number being less than the value of the field, and the second PDU is next to the first PDU.