Free-space model and two-ray ground reflection model have been widely used in the literatures as the propagation models to investigate the performance of an ad hoc network. But these two models are too simple to represent a real world scenario. A more realistic model namely shadowing propagation model has been used in this paper to investigate the performances of ad hoc network. In shadowing propagation model a mobile node may receive a packet at a signal level that is below a required threshold level. This low signal level affects the routing protocol as well as the medium access control scheme of a network. In this paper, the effects of shadowing on the performance of an ad hoc network have been investigated. Two solutions have also been suggested in this paper to overcome the effects of shadowing. \textcopyright 2011 IEEE.