Pdu set handling during mobility

A method performed by a source base station for a wireless transmit/receive unit (WTRU), the method comprising:

• transmitting, to a target base station, a handover request message including protocol data unit (PDU) set context information for the WTRU;
• receiving, from the target base station, a handover request acknowledge message;
• transmitting, to the WTRU, an radio resource control (RRC) reconfiguration message;
• receiving, from a network node comprising a user plane function (UPF), at least one PDU of a PDU set intended for the WTRU;
• determining to relay the at least one PDU to the target base station based on the PDU set context information and monitoring of the PDU set performed by the source base station;
• transmitting, to the target base station, the at least one PDU;
• receiving, from the target base station, a context release message for the WTRU;
• and
• releasing a context for the WTRU in response to the received context release message.

A target base station for a wireless transmit/receive unit (WTRU), the target base station comprising:

• a transceiver;
• and
• a processor, wherein the transceiver and the processor are configured to:
• receive, from a source base station, a handover request message including protocol data unit (PDU) set context information for the WTRU;
• determine to accept a handover of the WTRU based on the received PDU set context information for the WTRU;
• transmit, to the source base station, a handover request acknowledge message;
• receive, from the source base station, at least one PDU of a PDU set intended for the WTRU;
• and
• transmit, to the source base station, a context release message for the WTRU.