Date Added: May 2009
In this paper the authors describe the effect of imperfections in the Radio Environment Map (REM) information on the performance of Cognitive Radio (CR) systems. Via simulations they explore the relationship between the required precision of the REM and various channel/system properties. For example, the degree of spatial correlation in the shadow fading is a key factor as is the interference constraint employed by the primary user. Based on the CR interferers obtained from the simulations, they characterize the temporal behavior of such systems by computing the Level Crossing Rates (LCRs) of the cumulative interference represented by these CRs. This evaluates the effect of short term fluctuations above acceptable interference levels due to the fast fading.