LTE-Advanced (LTE-A) proposed by the 3rd Generation Partnership Project (3GPP) has been accepted by the International Telecommunication Union (ITU) in 2010 as an IMT-Advanced (IMT-A) compliant 4G mobile radio system. As part of this application 3GPP has provided LTE-A system level simulation results for cell spectral efficiency and cell edge user spectral efficiency. In this work we analytically derive the spectral efficiency, throughput distribution, and cell edge user spectral efficiency for LTE-A in an IMT-A scenario and validate it by comparison to system level simulation results gained from the openWNS simulator. The method used can also be applied to estimate performance gains of protocol improvements.