摘要 |
A mechanism for encrypting transmission of frames in a telecommunications network comprising a mobile station (MS), a radio network controller (SRNC) and at least one base station (BS1, BS2). The mobile station (MS) and each base station (BS1,BS2) have a corresponding timing reference (MSFN,BS1FN,BS2FN). The mechanism comprises the step of establishing a connection-specific timing reference which is common to all nodes (MS,BS1,BS2,RNC) involved in the connection and which comprises a common frame numbering scheme agreed between the mobile station (MS) and the radio network controller (SRNC) while establishing the connection, wherein said reference comprises a connection-specific frame number (CFN) and a frame number extension (HFN); the mobile station (MS) and the radio network controller (SRNC) use the CFN and the HFN for ciphering and deciphering the frames. |