TECHNICAL FIELD

The present disclosure relates to wireless communications, and specifically relates to session management with interworking between fifth generation system (5GS) and evolved packet system (EPS).

BACKGROUND

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Geographical coverage of 5G New Radio (NR) access network connected to a 5G core (5GC) network is limited when 5G system (5GS) is newly introduced. A mobile device moves out of a coverage of the NR access network served by the 5GC network can rely on another radio access technology (e.g., evolved universal terrestrial radio access (E-UTRA)) connected to an evolved packet core (EPC) network in an evolved packet system (EPS). Interworking between the 5GC and the EPC enables a mobile device user to have wide-area mobility while retaining a stable IP address.

SUMMARY

Aspects of the disclosure provide a method. The method can include receiving a “create new evolved packet system (EPS) bearer” operation code in a mapped EPS bearer contexts information element (IE) in a first protocol data unit (PDU) session modification command message for creating a mapped EPS bearer context at a user equipment (UE) in a wireless communication system, and when there is neither a quality of service (QoS) flow descriptions IE in the first PDU session modification command message indicating a QoS flow description corresponding to an EPS bearer identity (EBI) in the mapped EPS bearer context, nor an existing QoS flow description at the UE corresponding to the EBI included in the mapped EPS bearer context, sending a PDU session modification request message including a mapped EPS bearer contexts IE to delete the mapped EPS bearer context.

In an embodiment, a PDU session modification complete message is sent in response to receiving the PDU session modification command message. In an embodiment, it is determined whether there is the QoS flow descriptions IE in the first PDU session modification command message indicating the QoS flow description corresponding to the EBI in the mapped EPS bearer context. In an embodiment, it is determined whether there is the existing QoS flow description at the UE corresponding to the EBI included in the mapped EPS bearer context.

In an embodiment, the method can further include processing one or more QoS rules in a QoS rules IE or one or more QoS flow descriptions in a QoS flow descriptions IE included in the PDU session modification command message. In an embodiment, a second PDU session modification command message including a mapped EPS bearer contexts IE to delete the mapped EPS bearer context is received, and the mapped EPS bearer context is deleted. In an embodiment, the method further includes deleting the mapped EPS bearer context locally without receiving a second PDU session modification command message including a mapped EPS bearer contexts IE to delete the mapped EPS bearer context.

Aspects of the disclosure provide an apparatus including circuitry. The circuitry can be configured to receive a “create new evolved packet system (EPS) bearer” operation code in a mapped EPS bearer contexts IE in a first PDU session modification command message for creating a mapped EPS bearer, and when there is neither a QoS flow descriptions IE in the first PDU session modification command message indicating a QoS flow description corresponding to an EBI in the mapped EPS bearer context, nor an existing QoS flow description corresponding to the EBI included in the mapped EPS bearer context, send a PDU session modification request message including a mapped EPS bearer contexts IE to delete the mapped EPS bearer context.

