Method and apparatus for handling out-of-order packets during handover in a wireless communication system

Techniques for sending packets and maintaining synchronization during handover is described. A user equipment (UE) may be handed over from a source base station to a target base station. The source base station may forward packets for the UE to the target base station, which may receive the packets out of order. In one design, the target base station may determine whether each packet can be sent in order to the UE, send the packet if it can be sent in order, and discard the packet otherwise. In another design, the target base station may re-order packets received within a re-ordering window and may send the re-ordered packets to the UE. In yet another design, the target base station may process each packet received out of order as if the packet is in order, e.g., by incrementing a hyper-frame number (HFN) or re-assigning the packet with a later sequence number.