US Patent 7936880 Method, apparatus and system for key derivation

A method, an apparatus and a system for key derivation are disclosed. The method includes the following steps: a target base station) receives multiple keys derived by a source base station, where the keys correspond to cells under control of the target base station; the target base station selects a key corresponding to the target cell after knowing a target cell that a user equipment (UE) wants to access. An apparatus for key derivation and a communications system are also provided.