Wireless communications for selecting an uplink carrier for a random access procedure are described. A base station may configure a wireless device with one or more uplink carriers associated with a downlink carrier of a cell. The one or more uplink carriers may comprise at least a normal uplink (NUL) carrier and a supplemental uplink (SUL) carrier. The wireless device may measure one or more downlink reference signals and channel occupancy level(s) of an NUL and/or an SUL. The wireless device may select one of an NUL or an SUL for a random access procedure, for example, based on a signal strength of the one or more downlink reference signals and/or the channel occupancy level(s).