A Study of Quota-Based Dynamic Network Selection for Multimode Terminal Users

Due to the fact that existing cellular data cards usually select networks with the highest physical data rate as their priority choices, network radio resources may not be efficiently and equally utilized in a multiple network environment, even when the network with the highest data rate is already congested. In this paper, we present a dynamic network selection algorithm via a quota-based admission control design for accommodating access requests in a multiple heterogeneous and orthogonal network environment, which may become common for today's third-generation cellular operators. Under today's flat rate charging schemes, a few extremely heavy users may degrade the performance and the fairness of the whole network. Therefore, we propose an algorithm called quota-based utilization balance algorithm (QUBA) designed to settle such a problem and also maximize the overall utility of all users. The design philosophy of QUBA is to let system utilization in the fastest networks be statistically balanced and sufficiently utilized. In addition, the time complexity analysis for the proposed scheme is included and the order of operations is shown relatively low compared with that of existing schemes. Performance metrics in terms of the overall system utility (i.e., the satisfaction index), the blocking probability, and the system utilization are investigated. From simulation results, it is shown that QUBA has significantly improved the performance of the overall system compared to existing approaches.