Embodiments provide an apparatus, a vehicle, a method, and a computer program for setting a transmission power. The apparatus (10) is operable to set a transmission power of a vehicular relay transceiver (100) in a mobile communication system (400). The relay transceiver (100) is operable in a vehicle (500) to relay information between a mobile transceiver (200) associated with the relay transceiver (100) and a base station transceiver (300) of the mobile communication system (400). The apparatus (10) comprises a transceiver module (12) which is operable to transmit a common signal using a transmission power. The transmission power influences a coverage area of the relay transceiver (100). The relay apparatus (10) further comprises a controller module (14) operable to determine information related to a quality of a radio link between the relay transceiver (100) and the base station transceiver (300) and information on a state of the vehicle (500). The controller module (14) is further operable to set the transmission power based on the information related to the quality of the radio link and based on the information on the state of the vehicle (500).