Uplink transmissions in unlicensed cells with additional transmission timing offsets

The invention relates to a radio base station or user equipment for scheduling respectively performing uplink transmissions via an unlicensed cell configured between the user equipment and the radio base station. The UE can perform an uplink transmission via the unlicensed cell according to at least the following types. A first type spans a complete subframe duration and starts and ends at subframe boundaries followed by the UE. A second type spans a complete subframe duration and includes an additional time offset with respect to the subframe boundaries followed by the UE. A third type spans less than a complete subframe duration and includes an additional time offset with respect to the subframe boundaries followed by the UE. The UEs perform uplink transmissions according to one of the types in such a manner that at least between two directly-subsequent uplink transmissions a time gap with no uplink transmission occurs.