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

Claim 0:
1. A method comprising:
establishing, in a mobility management entity (MME), a security key for protecting Radio Resource Control/User Plane traffic between a User Equipment (UE) and a radio base station serving the UE, wherein establishing the security key comprises:
Receiving a Non access Stratum (NAS) message containing a NAS service request from the UE, the NAS message indicating a NAS uplink sequence number;
Deriving 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;
Sending said derived security key to the radio base station serving said UE.