  An operator-assisted user-provided network (UPN) has the potential to achieve
a low cost ubiquitous Internet connectivity, without significantly increasing
the network infrastructure investment. In this paper, we consider such a
network where the network operator encourages some of her subscribers to
operate as mobile Wi-Fi hotspots (hosts), providing Internet connectivity for
other subscribers (clients). We formulate the interaction between the operator
and mobile users as a two-stage game. In Stage I, the operator determines the
usage-based pricing and quota-based incentive mechanism for the data usage. In
Stage II, the mobile users make their decisions about whether to be a host, or
a client, or not a subscriber at all. We characterize how the users' membership
choices will affect each other's payoffs in Stage II, and how the operator
optimizes her decision in Stage I to maximize her profit. Our theoretical and
numerical results show that the operator's maximum profit increases with the
user density under the proposed hybrid pricing mechanism, and the profit gain
can be up to 50\% in a dense network comparing with a pricing-only approach
with no incentives.
