The paper introduces a model of wireless sensor network (WSN) nodes with SystemC-AMS, a C++ based language for system-level description, then presents model refinements and simulation improvements of the system. Firstly the paper details the components of a WSN node : a sensor, an ADC, a microcontroller and a RF transceiver with some introduced impairements. Secondly, it presents the implementation of RF components refinements, for a designer closer model specifications, such as power gain, noise figure, IIP3 specifications. Finally, the third part shows the simulation improvements introduced by a baseband equivalent implementation made easier with a C++ based language.