  Small cells deployed in licensed spectrum and unlicensed access via WiFi
provide different ways of expanding wireless services to low mobility users.
That reduces the demand for conventional macro-cellular networks, which are
better suited for wide-area mobile coverage. The mix of these technologies seen
in practice depends in part on the decisions made by wireless service providers
that seek to maximize revenue, and allocations of licensed and unlicensed
spectrum by regulators. To understand these interactions we present a model in
which a service provider allocates available licensed spectrum across two
separate bands, one for macro- and one for small-cells, in order to serve two
types of users: mobile and fixed. We assume a service model in which the
providers can charge a (different) price per unit rate for each type of service
(macro- or small-cell); unlicensed access is free. With this setup we study how
the addition of unlicensed spectrum affects prices and the optimal allocation
of bandwidth across macro-/small-cells. We also characterize the optimal
fraction of unlicensed spectrum when new bandwidth becomes available.
