Method and apparatus for implementing bearer specific changes as part of a connection reconfiguration that impacts the security keys being used

A user equipment configured to communicate with two cell groups including a first cell group and a second cell group, communication with the two cell groups comprising establishment of a first medium access control (MAC) entity and a second MAC entity, the first MAC entity associated with the first cell group and the second MAC entity associated with the second cell group, the user equipment comprising:

• a transceiver that receives a first connection reconfiguration message to configure at least one split bearer with a first logicalchannelidentity, terminated in the second cell group;
• and
• a controller that applies a first security key for communication with the first cell group and a second security key for communication with the second cell group;
• wherein a second connection reconfiguration message is received by the transceiver, the second connection reconfiguration message including a counter having a count value for deriving a third security key for communication with the second cell group, wherein the third security key that was derived for communication with the second cell group is based on the count value of the received counter;
• and
• wherein the third security key for communication with the second cell group is applied by the controller, while continuing to use the first security key and the first MAC entity for communication with the first cell group, where continuing to use the first MAC entity includes not resetting the first MAC entity.