A communication device receives an uplink grant from a node of a cellular network. The uplink grant indicates uplink radio resources allocated to the communication device in reoccurring time intervals. For each of these time intervals, the communication device selects between an active mode and an inactive mode. In the active mode the communication device performs an uplink transmission in the allocated uplink radio resources. In the inactive mode the communication device performs no uplink transmission in the allocated uplink radio resources.