Cooperative Internet access using heterogeneous wireless networks

Abstract

The forthcoming generation of mobile communication systems is widely perceived as a convergence platform, which encompasses both multiple heterogeneous wireless access technologies and diverse cooperative networking paradigms. Great efforts have been devoted to build a flexible architecture capable of managing them as a whole.

Meanwhile, wireless user devices become more intelligent. They not only participate in the radio resource allocation process by feeding back their channel states, but also can choose to contribute to the resource provision process by forwarding data for each other. Opportunities bring new challenges. As mobile devices become smarter, a rational user can adapt its behavior in order to benefit more from the network, even if doing so may affect other users and the system¿s overall performance.

Thus, the design of resource management schemes for this new era of mobile communication should explore the cooperation possibility among heterogeneous wireless networks and their users, while taking the selfish nature of users and their strategic interactions into consideration. This thesis studies the problem of how to deliver Internet access service cooperatively to (selfish) users using heterogeneous wireless networks, in an efficient, fair, and incentive-compatible manner.

Firstly, this thesis addresses the coordinated radio resource allocation problem for users which are simultaneously covered by multiple overlapping heterogeneous wireless networks. We propose the coordinated proportional fairness (CPF) criterion, based on which a globally fair and efficient allocation decision can be easily computed. As CPF decision depends on the input from users, a selfish user may manipulate its channel state report if doing so can increase its gain from the network. We prove that CPF allocation is incentive compatible, i.e., a user¿s dominant strategy is to honestly report its channel state. In practice, the single-association setting, where amobile station is only associated with one base station, is often desirable. We show that the solution using the same fairness criterion in single-association setting is both computationally expensive and prone to user-manipulation. Alternatively, we propose the Selfish Load Balancing (SLB) allocation scheme, which always converges to a Nash equilibrium, and often achieves performance near to CPF allocation.

Next, the thesis studies the cooperative resource provision problem for highly mobile users in areas where high-bandwidth connection is only available intermittently. We show that user-contributed mobile forwarding can greatly enhance users¿ Internet access experience. We design MobTorrent, a cooperative, on-demand framework, which uses the ubiquitous low-bandwidth cellular network as a control channel while forwarding data through high-bandwidth contacts using a Delay Tolerant Networking (DTN) approach. MobTorrent makes use of the semi-deterministic knowledge about future contacts, so that the user-contributed mobile forwarding process can be efficiently orchestrated.

To foster cooperation among selfish participants in a DTN environment (e.g., as required by MobTorrent), we propose MobiCent, a credit-based incentive system designed using the algorithmic mechanism design approach. We prove that the proposed scheme is incentive compatible, in the sense that rational nodes will not strategically waste any transfer opportunity or cheat by creating non-existing contacts. MobiCent also provides different pricing mechanisms to cater to client that wants to minimize either payment or data delivery delay.