Hanif, M.F.Smith, P.Shafi, M.2010-01-122010-01-122009Hanif, M.F., Smith, P., Shafi, M. (2009) Performance of Cognitive Radio Systems with Imperfect Radio Environment Map Information. Sydney, Australia: Australian Communications Theory Workshop 2009, 4-6 Feb 2009.http://hdl.handle.net/10092/3360In this paper we describe the effect of imperfections in the radio environment map (REM) information on the performance of cognitive radio (CR) systems. Via simulations we 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, we 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. We derive analytical formulae for the LCRs in Rayleigh and Rician fast fading conditions. The analytical results are verified by Monte Carlo simulations.en"©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE."Conference Contributions - PublishedFields of Research::290000 Engineering and Technology::291700 Communications Technologies::291710 Radio communications and broadcasting not elsewhere classified