A wireless device receives a radio resource control message comprising uplink periodic resource allocation configuration parameters. The uplink periodic resource allocation configuration parameters indicate: a hybrid automatic repeat request (HARQ) process identifier offset; and a number of uplink semi-persistent HARQ processes. Aa HARQ process identifier for a current transmission time interval is determined as a sum of the HARQ process identifier offset and a value determined based on: the current transmission time interval; and the number of uplink semi-persistent HARQ processes. A transport block associated with a HARQ process identified by the HARQ process identifier is transmitted.