Infrastructure and Spectrum Sharing Trade-offs in Mobile Networks

We assess the fundamental trade-offs between spectrum and radio access infrastructure sharing. Specifically, we analyze three mobile network sharing scenarios: radio access infrastructure sharing, spectrum sharing, and the combination of the two, which we term full sharing. We perform our analysis employing stochastic geometry models, such as the homogeneous Poisson point process and the Gauss-Poisson process, which allow us to vary the spatial correlation in base station placements of different mobile operators. Our major contributions can be summarized as follows. We derive analytical expressions for the coverage probability and the average user data rate for a shared network created as a union of independently distributed networks for each of the three sharing scenarios. For the general base station placement model, we show that infrastructure and spectrum sharing cannot be simply substituted for each other, as there exists a trade-off in the coverage and data rate performance between the two. Moreover, the combination of the two approaches does not simply produce linearly scaling gains, as the increase in the data rate is traded for a minor reduction in the coverage (when compared to infrastructure sharing performed in isolation). We show that the spatial distributions of the networks of the sharing operators have a significant impact on the performance of sharing. We show that respective density of the networks of the two operators influences how the two operators perceive sharing gains. In particular, it is often the case that a larger operator has more to gain from sharing due to disproportionally lower interference suffered from the smaller operator.