Simulation models are key factors in evaluating the performance of any current communication systems. In addition, evaluating the improvements carried out along the optimization of a system requires access to information about behavioural changes induced on it. For Wimax and other wireless standards simulation results depend on many particular aspects regarding to link level models. This work summarizes the characteristics of a Wimax channel and their implementation on a simulator. In addition, limitations on existing models for simulating fixed Wimax channels are identified and an approach to extend those models to a mobile scenario is proposed. Finally, a comparison is drawn amongst the results taken out from the proposed modified models against the fixed wireless application ones.