Spectrum sensing is the key enabling technology for cognitive radio networks. The main objective of spectrum sensing is to provide more spectrum access opportunities to cognitive radio users without interfering with the operations of the licensed network. Spectrum sensing decisions can lead to erroneous sensing due to fading, shadowing and other interferences caused by either terrain inconsistency or dense urban structure. In order to improve spectrum sensing decisions, in this paper a cooperative spectrum sensing scheme is proposed, which takes the propagation conditions such as the variance and intensity of terrain and urban structure between two points with respect to signal propagation into consideration. We have also derived the optimum fusion rule which takes location reliability into consideration. The analytical results show that the proposed scheme outperform the conventional cooperative spectrum sensing approaches.