Handover method and user equipment

A user equipment, UE, for performing handover from a next-generation, NG, system to a 4G system, wherein the UE is configured to connect to the NG system with multiple protocol data unit, PDU, sessions for a same data network, DN, including a primary PDU session and a secondary PDU session, the UE comprising,

• a radio frequency, RF, unit, and
• a processor configured to control the RF unit,
• wherein the processor is configured to:
• control the RF unit to receive a command for handover to the 4G system;
• control the RF unit to transmit first session information regarding the primary PDU session to a network, wherein the first session information informs a quality of service, QoS, level of the primary PDU session;
• establish a packet data network, PDN, connection with the 4G system based on the first session information and map the primary PDU session to a first bearer of the PDN connection which satisfies the QoS level of the primary PDU session;
• and
• determine whether to create a second bearer for the secondary PDU session,
• wherein, determining whether to create the second bearer comprises:
• based on the first bearer not satisfying a QoS level demanded by traffic of the secondary PDU session, trigger creation of the second bearer by transmitting a bearer resource allocation request to a PDN Gateway, P-GW;
• and
• based on the first bearer satisfying the QoS level demanded by the traffic of the secondary PDU session, transmit the traffic of the secondary PDU session to the first bearer without triggering the creation of the second bearer.