Methods, apparatus, and systems for wireless communication are described. In one example aspect, a method includes performing, by a communication node, a handover procedure from a source base station to a target base station based on information associated with a Protocol Data Unit (PDU) session. The information indicates that at least one tunnel in a list of tunnels that carry user data has a one-to-one correspondence with a Quality of Service (QoS) flow. The method also includes transmitting, for the handover procedure, downlink data to both the source base station and the target base station by the communication node.