An apparatus, method and computer program for determining one or more radio resources to be used for performing a wireless communication over a sidelink of a mobile communication system. The method includes determining whether a transportation vehicle executing the method is in coverage or out of coverage of a base station of the mobile communication system, selecting one or more methods or mechanisms for improving a transmission reliability of the wireless communication over the sidelink from a group of methods or mechanisms for improving the transmission reliability in response to the transportation vehicle being out of coverage, and determining the one or more radio resources to be used for performing the wireless communication over the sidelink of the mobile communication system using the selected method or mechanism.