An ultra-small cell base station for a vehicle is coupleable, for signal exchange, to a first antenna assembly, which is configured to receive radio signals of a cellular radio user device situated inside the vehicle and to emit radio signals to be received by the user device. The ultra-small cell base station is also coupleable to a second antenna assembly, configured to receive radio signals of a further cellular radio user device situated outside the vehicle and to emit radio signals to be received by the further user device. The ultra-small cell base station is also coupleable to a network-side antenna assembly of the vehicle configured to receive radio signals emitted by a pre-defined static cellular radio base station and to emit radio signals to be received by the static base station. The ultra-small cell base station is configured to operate a first and a second small cell.