Dual radio operation between access systems using 3GPP radio access technology

An apparatus of a base station, the apparatus comprising:

• a memory;
• and
• processing circuitry in communication with the memory and arranged to:
• decode from a user equipment (UE) an Attach Request that comprises a Request Type that is selectable by the UE between a Handover Attach and a non-Handover Attach, the Handover Attach being an indication of Internet Protocol (IP) address retention during handover;
• and
• encode the Attach Request for transmission to a mobility management entity (MME) to complete handover with the UE based on the Attach Request.

A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors, the one or more processors to:

• establish simultaneous operation between a user equipment (UE) and both a Long Term Evolution (LTE) access system and a 5th generation (5G) access system, the LTE access system comprising an evolved packet core (EPC), the 5G access system comprising a 5G core network,
• wherein the UE is configured to operate in an LTE mobility management state and a 5G mobility management state, the LTE mobility management state and the 5G mobility management state independent of each other,
• wherein the EPC and the 5G core network share a Home Subscriber Storage (HSS) node and an Internet Protocol (IP) anchor, and
• wherein the instructions further configure the one or more processors to retain an IP address of the UE during handover of the UE between the 5G and LTE access systems using the IP anchor and the HSS in response to the UE using an Attach Request comprising a Request Type that indicates a Handover Attach.