  This paper studies the impact of co-channel interferences (CCIs) on the
system performance of multi-hop amplify-and-forward (AF) relaying, in a simple
and explicit way. For generality, the desired channels along consecutive
relaying hops and the CCIs at all nodes are subject to Nakagami-$m$ fading with
different shape factors. This study reveals that the diversity gain is
determined only by the fading shape factor of the desired channels, regardless
of the interference and the number of relaying hops. On the other hand,
although the coding gain is in general a complex function of various system
parameters, if the desired channels are subject to Rayleigh fading, the coding
gain is inversely proportional to the accumulated interference at the
destination, i.e. the product of the number of relaying hops and the average
interference-to-noise ratio, irrespective of the fading distribution of the
CCIs.
