  With more and more demand from devices to use wireless communication
networks, there has been an increased interest in resource sharing among
operators, to give a better link quality. However, in the analysis of the
benefits of resource sharing among these operators, the important factor of
co-location is often overlooked. Indeed, often in wireless communication
networks, different operators co-locate: they place their base stations at the
same locations due to cost efficiency. We therefore use stochastic geometry to
investigate the effect of co-location on the benefits of resource sharing. We
develop an intricate relation between the co-location factor and the optimal
radius to operate the network, which shows that indeed co-location is an
important factor to take into account. We also investigate the limiting
behavior of the expected gains of sharing, and find that for unequal operators,
sharing may not always be beneficial when taking co-location into account.
