In LWA, eNodeB sends few PDCP PDUs over the LTE network and others over the Wi-Fi link. While sending PDCP PDUs over the Wi-Fi link, eNodeB adds DRB ID to the packet and forms LWA-AP PDU.
When LWA-AP of the UE side receives the packet, it comes to know which packets belong to which DRB. After getting these PDCP PDUs over both LTE and Wi-Fi link, PDCP at the UE does re-ordering if required and then rest of things are same as it does for LTE network.
