Obtaining system frame number of target cell during handover

摘要

A method of obtaining system frame number for handover is provided. A UE receives a handover command from a serving base station in a serving cell. The UE performs downlink synchronization with a target base station. Upon synchronization, the UE determines a radio frame boundary of a target cell. The UE then obtains a system frame number of the target cell based on the radio frame boundary. The UE performs a handover procedure with the target cell by transmitting a RACH preamble to the target base station. The RACH preamble is transmitted over a PRACH resource determined from the system frame number without reading SFN information from a PBCH/BCH broadcasted from the target base station. Finally, the UE establishes data connection with the target base station. Handover interruption time is reduced by obtaining SFN before PBCH reading and decoding.

主权项

1. A method for handover in an LTE/LTE-A wireless communication system, the method comprising:
receiving a handover command from a serving base station by a user equipment (UE), wherein the UE is served in a serving cell of the serving base station; performing downlink synchronization with a target base station, wherein the UE determines a first radio frame boundary of a target cell of the target base station; obtaining a system frame number (SFN) of the target cell by comparing the first radio frame boundary of the target cell and a second radio frame boundary of the serving cell and thereby deducing the SFN of the target cell from a time difference between the second radio frame boundary of the serving cell and the first radio frame boundary of the target cell before receiving additional SFN and timing information from the serving or the target base station; and performing a handover procedure with the target cell based on the deduced system frame number before reading SFN information in a broadcast channel broadcasted by the target base station.