An apparatus for a terminal device, the apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device to: determine first information characterizing a difference between a first timing advance value associated with a first radio cell that is at least temporarily provided to the terminal device by a first device and a second timing advance value associated with a second radio cell that is at least temporarily provided to the terminal device by a second device, and to transmit the first information to a network device associated at least with the first radio cell.