A base transceiver station for a mobile communications system is disclosed, which is divided into a plurality of functional units that enables the signal processing resources to be flexibly allocated and cost-effectively implemented in hardware. A flexible communications interface is created between the base transceiver station units which allows the signal processing resources within the units to be used more efficiently. Essentially, the base transceiver station hardware is dimensioned to statistically distribute the signal processing resources among the different radio transmission services available. Consequently, the allocated base transceiver station hardware can be used more efficiently, which minimizes the overall size and weight of the base station.