  In this paper, we derive the error vector magnitude (EVM) in a selection
combining (SC) system experiencing co-channel interference, for arbitrary
number of antennas and interferers when all the channels experience Rayleigh
fading. We use a novel approach that uses the CCDF of SIR to derive EVM as
using the conventional approach to derive EVM for a SC system is difficult.
Considering two selection rules based on (a) maximum signal power (b) maximum
signal to interference ratio, we observe that EVM is worse when maximum signal
power based rule is used. Further, EVM is also derived considering (a) all the
channels to be independent and (b) channels to be correlated due to
insufficient antenna spacing at receiver. For some special cases, EVM is also
derived when the desired channels experience Nakagami-m fading.
