  Mobile Collaborative Internet Access (MCA) enables mobile users to share
their Internet through flexible tethering arrangements. This can potentially
make better use of network resources. However, from a mobile network operator's
(MNO's) viewpoint, it can either reduce revenue or increase congestion, and
thus has been blocked by some MNOs in practice. We propose a hybrid pricing
framework for MNOs who charge users separately for access and tethering. This
scheme serves to coordinate the tethering decisions of mobile users with MNO
network management objectives. We analyze the MNOs' equilibrium pricing
strategies in both cooperative and competitive scenarios. In the cooperative
scenario, at the equilibrium, each user's cost is independent of any chosen
tethering links. We then characterize the optimal hybrid pricing strategies of
MNOs in this scenario. For the competitive scenario, we formulate the MNOs'
competitive interactions as a pricing game, and we show that MNO competition
leads to equalized prices for users if an equilibrium exists but does not
guarantee its existence. Both insights motivate a quantity competition game,
which is shown to guarantee an equilibrium. Simulation results show that in
scenarios of interest the proposed hybrid pricing schemes can double both MNOs'
profit and users' payoff and such improvements increase with the degree of
network heterogeneity.
