Radio link recovery for user equipment

A user equipment (UE) comprising:

• at least one processor;
• and
• at least one memory storing instructions thereon that, when executed by the at least one processor, cause the UE to perform at least:
• during a data transfer operation over a control plane between a mobility management entity (MME) of a communication system and the UE, in response to a radio link failure occurring between the apparatus and a source access node, generating a first message indicating that the radio link failure has occurred between the UE and the source access node of the communication system, the first message being protected using a first key associated with a non-access stratum (NAS) security context previously established between the UE and the MME of the communication system, the message indicating that the radio link failure has occurred;
• transmitting, to the MME, via a target access node, the first message indicating that the radio link failure has occurred between the UE and the source access node to initiate recovery of a radio link for the UE, the target access node being different than the source access node;
• and
• receiving, in response to the first message, from the MME, via the target access node, a second message protected using a second key associated with the NAS security context previously established between the UE and the MME, the second message comprising data that previously failed to be delivered to the UE when the radio link failure occurred during the data transfer operation over the control plane between the MME and the UE.

A Cellular Internet-of-Things (CIoT) user equipment configured for receiving data in a Narrow Band IoT (NB-IoT) network via a radio link, the CIoT user equipment comprising:

• at least one processor;
• and
• at least one memory storing instructions thereon that, when executed by the at least one processor, cause the CIoT user equipment to perform at least:
• requesting establishment of a non-access stratum (NAS) security context between the user equipment and a mobility management entity (MME) of the communication system;
• receiving, from the MME, with an indication that the NAS security context has been established between the user equipment and the MME, an integrity key or information regarding the integrity key, the integrity key being created during establishment of the NAS security context between the user equipment and the MME;
• in response to a radio link failure (RLF) occurring between the user equipment and a source access node of the communication system during a data transfer operation over a control plane between the MME and the user equipment, initiating recovery of the radio link by sending a first message to the MME through a target access node of the communication system, without using the source access node to relay the first message, while maintaining the NAS security context previously established between the user equipment and the MME, wherein the first message is integrity protected using the integrity key created during establishment of the NAS security context between the user equipment and the MME, and wherein the target access node is different from the source access node;
• and
• receiving, from the target access node, a second message protected using the integrity key associated with the NAS security context previously established between the user equipment and the MME, the second message comprising data that previously failed to be delivered to the user equipment when the RLF occurred during the data transfer operation over the control plane between the MME and the user equipment.