Signaling of security information for mobility

Abstract

A method can include transmitting, by a first base station to a wireless device, a radio resource control (RRC) message including a layer 1/layer 2 triggered mobility (LTM) configuration of a cell of a second base station. The method can also include receiving, by a distributed unit (DU) of the first base station from a central unit (CU) of the first base station, a message indicating a next hop chaining count (NCC) for deriving a key of the second base station and an identifier of the cell. The method can further include determining to execute the LTM, of the wireless device, to the cell. The method can additionally include transmitting, to the wireless device, an LTM cell switch medium access control (MAC) control element (CE) for the LTM, indicating the NCC, wherein the LTM cell switch MAC CE comprises an identifier of an LTM candidate configuration of the cell.