PDCP key flow management for lower-layer mobility failures to ensure data security and integrity

Abstract

A user equipment, a base station, and a handover method are provided for LTM cell switching and LTM cell recovery; for example, the user equipment comprises: a transceiver, which, in operation, receives from a source cell an indication to switch from the source cell to a target cell, wherein the source cell and the target cell are operated by a first base station; the user equipment further comprises circuitry, which, in operation, makes an attempt to switch from the source cell to the target cell, the switch attempt including: changing a count variable to a first value; and controlling the transceiver to transmit, through the target cell, to the first base station an encrypted switch completion message using the first value of the count variable;After determining a failure in the attempt to switch, the circuit makes an attempt to recover a candidate cell from a set of preconfigured candidate cells operated by the first base station, the recovery attempt including: setting the count variable to a second value different from the first value; and controlling the transceiver to transmit, through the candidate cell, to the first base station an encrypted recovery completion message that uses the second value of the count variable.