Apparatus and method for mobility procedure involving mobility management entity relocation

A method operational at a wireless device, the method comprising:

• identifying entry of the wireless device into a new service area of a network;
• transmitting a service area update request to a radio access node associated with the network;
• receiving a control plane message from a target control plane device indicating control plane device relocation or a key refresh due to a service area change, the control plane message received in response to transmitting the service area update request, the control plane message including a target control plane device identifier that identifies the target control plane device, and wherein the target control plane device is a different control plane device from a source control plane device currently serving or having previously served the wireless device;
• and
• deriving a first key based in part on the target control plane device identifier included in the control plane message received and a second key shared between the wireless device and a key management device that maintains the second key, the key management device associated with the network, wherein the radio access node and the target control plane device are separate from the key management device.

A wireless device comprising:

• means for identifying entry of the wireless device into a new service area of a network;
• means for transmitting a service area update request to a radio access node associated with the network;
• means for receiving a control plane message from a target control plane device indicating control plane device relocation or a key refresh due to a service area change, the control plane message received in response to transmitting the service area update request, the control plane message including a target control plane device identifier that identifies the target control plane device, and wherein the target control plane device is a different control plane device from a source control plane device currently serving or having previously served the wireless device;
• and
• means for deriving a first key based in part on the target control plane device identifier included in the control plane message received and a second key shared between the wireless device and a key management device that maintains the second key, the key management device associated with the network, wherein the radio access node and the target control plane device are separate from the key management device.

A non-transitory computer-readable storage medium having instructions stored thereon, the instructions when executed by at least one processor causes the processor to:

• identify entry of the wireless device into a new service area of a network;
• transmit a service area update request to a radio access node associated with the network;
• receive a control plane message from a target control plane device indicating control plane device relocation or a key refresh due to a service area change, the control plane message received in response to transmitting the service area update request, the control plane message including a target control plane device identifier that identifies the target control plane device, and wherein the target control plane device is a different control plane device from a source control plane device currently serving or having previously served the wireless device;
• and
• derive a first key based in part on the target control plane device identifier included in the control plane message received and a second key shared between the wireless device and a key management device that maintains the second key, the key management device associated with the network, wherein the radio access node and the target control plane device are separate from the key management device.