Patent ID: 8208498

Claim:
A method used for synchronization between base stations during handoff in a Long Term Evolution (LTE) wireless communication system, the method comprising: generating a message comprising a plurality of sequential counts and a next packet data convergence protocol (PDCP) sequence number (SN) for handover continuity, each count comprising an aggregate of a Hyper-Frame Number (HFN) and a PDCP SN; sending the message from a source base station to a target base station; and performing a count maintenance at the target base station based upon at least a latest ciphering HFN and PDCP SN and latest deciphering HFN and PDCP SN by using a backward offset from a count value received by the target base station, the backward offset extending a time for expiration of a security key associated with at least one of the latest ciphering HFN and PDCP SN and the latest deciphering HFN and PDCP SN.