Method and apparatus to switch uplink transmission on uplink split bearer

A user equipment (UE) configured for dual connectivity with a split bearer configuration may transmit uplink data packets to one or both a master cell group (MCG) and a secondary cell group (SCG). The UE may transmit an uplink transmission from a packet data convergence protocol (PDCP) entity over one or both of a first radio link control (RLC) entity associated with the MCG and a second RLC entity associated with the SCG. The configuration including a transmit buffer threshold. The UE may receive, at the PDCP entity, an uplink switch start indication. The UE may activate the second RLC entity in response to receiving the uplink switch start indication. The UE may transmit a buffer status report according to a current transmit buffer level plus the transmit buffer threshold. Accordingly, the UE may communicate with the SCG based on the uplink switch start indication.