Method and apparatus for seamless handover in a wireless communication network

摘要

In a wireless communication network where base stations receive protocol data units (PDUs) from mobile stations for decompression and deciphering for ordered, sequential transfer as service data units (SDUs) to an associated core network, the teachings presented herein provide a method of supporting seamless handover of a mobile station from a source base station to a target base station. By way of example, the teachings herein apply to a network based on the E-UTRA specifications, as promulgated by the 3GPP. However, that example is non-limiting, as the teachings herein apply to any network that employs in-sequence data delivery and duplicate data detection at handover. Broadly, the source base station forwards out-of-sequence SDUs and corresponding sequence number information to the target base station in support of seamless handover, and the target base station uses that information to request retransmissions as needed for packet reordering.

主权项

1. A method of supporting seamless handover of a mobile station from a source base station to a target base station in a wireless communication network in which base stations receive Packet Data Convergence Protocol (PDCP) protocol data units from mobile stations for ordered, sequential transfer as PDCP service data units to an associated core network, the method comprising:
during handover execution, receiving at the target base station PDCP service data units and sequence number information forwarded from the source base station, wherein:
the forwarded PDCP service data units comprise PDCP service data units being held at the source base station for sequential transfer to the associated core network; andthe forwarded sequence number information indicates sequence numbers corresponding to the forwarded PDCP service data units; reordering the forwarded PDCP service data units as needed at the target base station for sequential transfer from the target base station to the associated core network, the reordering comprising:
identifying missing PDCP service data units based on the forwarded sequence number information, andrequesting retransmission by the mobile station of PDCP protocol data units regenerated from the missing PDCP service data units using a new ciphering state.