A first base station transmits, to a second base station, a handover request message for a wireless device. The handover request message includes an identity of a candidate cell of the second base station, and an early timing advance acquisition (ETA) parameter of the wireless device. The ETA parameter indicates a request for a configuration parameter, of the candidate cell, for an ETA. The first base station receives, from the second base station, a handover request acknowledge message including the configuration parameter, where the configuration parameter includes a random access channel (RACH) configuration.