دانلود رایگان مقاله مدل انتخاب جریان و زمان فعال مشترک برای بازیابی محتوا خودکار از طریق ITS

Abstract

Operators need to address increased data demands to meet subscribers’ growing requirements by offloading a portion of cellular traffic onto other types of networks. In this paper, we investigate the possibility of using vehicular ad hoc networks (VANETs) for this purpose. We study joint data flow selection and contention resolution in a hybrid VANET-cellular system. We formulate the problem as an optimization problem called FOSAA, which considers vehicle-to-vehicle and vehicle-to-infrastructure link quality, channel access, inter-nodal interference and node active time. The problem is solved through an iterative approach. FOSAA is compared to other proposed schemes. The performance results show that offloading fraction is significantly affected by the data volume, vehicle density and number of hops from the infrastructure to the downloader vehicles.

8. Conclusions

In this work, we presented FOSAA, an analytical model that determines the potential of using vehicular nodes for cellular traf- fic offloading. We studied joint data flow selection and contention resolution in a hybrid VANET and cellular infrastructure system, where the objective is to maximize the set of data flows offloaded through the vehicular nodes. The evaluation results show that FOSAA prioritizes the offloading of 1- and 2-hop flows and that the adequate node time activity assignment ensures a higher offloading fraction. FOSAA also obtains a higher offloading fraction compared to the Greedy and Cont-A approaches and converges after a maximum of 4 iterations. We concluded that the node active times are closely related to the number of active neighbor and son nodes and to the vehicular environment. The Nei-A scheme was proposed to approximate the FOSAA scheme. The simulations results show hat the FOSAA and Nei-A schemes present similar performances and that they are adaptable to both light and heavy load cases.