Patent ID: 11917055
Assignee: TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 8:
9. A mobility management entity (MME), the mobility management entity comprising:
processing circuitry;
wherein:
the mobility management entity is arranged to establish a security key for protection of Radio Resource Control/User Plane traffic between a user equipment (UE) and a radio base station serving the UE; and
the processing circuitry is configured to:
receive a Non access Stratum (NAS) message containing a NAS Service Request from the UE, the NAS message indicating a NAS uplink sequence number;
derive the security key from at least said indicated NAS uplink sequence number and from a stored access security management entity-key shared with said UE, using a key derivation function taking the NAS uplink sequence number and the stored access security management entity-key as inputs; and
send the derived security key to the radio base station serving said UE.