Methods and apparatuses for re-establishing a radio resource control (RRC) connection

A User Equipment (UE) for re-establishing a Radio Resource Control (RRC) connection between the UE and a target evolved NodeB (eNB), the UE comprising:

• a processor;
• and
• a computer program product storing instructions that, when executed by the processor, causes the UE to:
• process an RRC Connection Reestablishment message transmitted by the target eNB and received at the UE, the RRC Connection Reestablishment message including a downlink (DL) authentication token which was calculated by a Mobility Management Entity (MME) using an integrity algorithm and a set of input parameters, wherein the set of input parameters includes a Non Access Stratum (NAS) integrity key;
• and
• compare the received DL authentication token to a token calculated by the UE using said integrity algorithm and said set of input parameters to authenticate the received DL authentication.

A target evolved Node B (eNB), for re-establishing a Radio Resource Control (RRC) connection between a User Equipment (UE) and the target eNB, the target eNB comprising:

• a processor;
• and
• a computer program product storing instructions that, when executed by the processor, causes the target eNB to:
• process a message transmitted by a Mobility Management Entity (MME) and received at the target eNB, the message including a downlink (DL) authentication token that was calculated by the MME using an integrity algorithm and a set of input parameters, wherein the set of input parameters includes a Non Access Stratum (NAS) integrity key;
• and
• send an RRC Connection Reestablishment message to the UE, the RRC Connection Reestablishment message including the DL authentication token.

A Mobility Management Entity (MME) for re-establishing a Radio Resource Control (RRC) connection between a User Equipment (UE) and a target evolved NodeB (eNB), the MME comprising:

• a processor;
• and
• a computer program product storing instructions that, when executed by the processor, causes the MME to:
• calculate a downlink (DL) authentication token using an integrity algorithm and a set of input parameters, wherein the set of input parameters includes a Non Access Stratum (NAS) integrity key as input;
• and
• send a message including the generated calculated DL authentication token to the target eNB.