A wireless device may receive one or more messages comprising configuration parameters of a cell. A reference duration for contention window adjustment may be determined based on the configuration parameters. The reference duration may be from a beginning of a channel occupancy of a first transmission burst and until an end of a first slot. The at least one physical uplink shared channel (PUSCH) may be transmitted. A contention window value may be determined based on a plurality of new data indicators (NDIs) received in a plurality of uplink grants corresponding to a plurality of first transport blocks transmitted by the wireless device during the reference duration. The wireless device may perform a listen before talk procedure based on the contention window value. One or more second transport blocks may be transmitted based on the listen before talk procedure indicating a clear channel.