  With the increasing interest in the use of millimeter wave bands for 5G
cellular systems comes renewed interest in resource sharing. Properties of
millimeter wave bands such as massive bandwidth, highly directional antennas,
high penetration loss, and susceptibility to shadowing, suggest technical
advantages to spectrum and infrastructure sharing in millimeter wave cellular
networks. However, technical advantages do not necessarily translate to
increased profit for service providers, or increased consumer surplus. In this
paper, detailed network simulations are used to better understand the economic
implications of resource sharing in a vertically differentiated duopoly market
for cellular service. The results suggest that resource sharing is less often
profitable for millimeter wave service providers compared to microwave cellular
service providers, and does not necessarily increase consumer surplus.
