Methods and apparatus for packet data convergence protocol (pdcp) transmit buffer handling

A wireless transmit/receive unit (WTRU) comprising:

• a processor;
• and
• a transceiver in communication with the processor,
• wherein the processor and the transceiver are configured to receive packet data convergence protocol (PDCP) configuration information for a split bearer, wherein the PDCP configuration information includes information about a first discard time period and information about a second discard time period,
• wherein the processor is further configured to store a first packet and a second packet in a PDCP transmit buffer,
• wherein the processor and the transceiver are further configured to:
• start the first discard time period and transmit the first packet over a primary path,
• start the second discard time period and transmit the second packet over a secondary path,
• discard the first packet stored in the PDCP transmit buffer based on a first one of expiry of the first discard time period or reception of an acknowledgement (ACK) for the first packet,
• discard the second packet stored in the PDCP transmit buffer based on a first one of expiry of the second discard time period or reception of an ACK for the second packet, and
• reduce or extend at least one of the first discard time period or the second discard time period based on at least one parameter.