Today’s mobile communication systems use sophisticated signal processing to achieve high transmission rates. Therefore a high complexity in the digital system part as well as very accurate signal processing in the analog RF subsystem is needed. So far analog and digital part are developed separately. The increased performance requirements demand now a common verification of the complete system including analog and digital parts. At the design of an IEEE 802.11a wireless LAN receiver it is demonstrated, how the RF receiver part is tested in the system level simulation. Different simulation tools are used. The simulation results show the impact of properties of the RF part on the system performance. Experiences from the tool evaluation are presented.