Patent ID: 8565432

Claim:
A method performed by a mobile communications node at a setup or a reconfiguration of a radio bearer, the method comprising: receiving a radio bearer setup message from a network communications node, the radio bearer setup message being applied in configuring the radio bearer within the mobile communications node to be able to communicate data with said network communications node; identifying an activation time value within the received radio bearer setup message; activating the radio bearer at the identified activation time; transmitting a radio bearer setup complete message confirming that the radio bearer has been setup and of communicating new cipher data for use in determining values of a cipher input parameter to be used for ciphering and deciphering data communicated with the network communications node; obtaining an uplink cipher activation time after the radio bearer setup message including a data rate defined for the radio bearer; before said transmitting the radio bearer setup complete message, starting to perform ciphering data to be transmitted by the radio bearer or deciphering data received by the radio bearer using values of said cipher input parameter determined using existing cipher data; and after said transmitting the radio bearer setup complete message, ciphering data to be transmitted by the radio bearer or deciphering data received by the radio bearer using second values of said cipher input parameter determined using said new cipher data.