Reliable Access-based Efficient Data Transfer Mechanism For IoVs

The Internet of Vehicles (IoVs) refers to an open network system composed of human, vehicles, and their surroundings, which is expected to be controllable, operable and reliable. It collects and processes the massive static and dynamic interaction information among human, vehicles, and traffic infrastructures with the aid of advanced technologies, thereby solving the problems in heterogeneous converged mobile network, such as the computability, scalability, and sustainability of intelligent management and information services. The deep integration of human, vehicles and their environments provided by IoVs eventually enriches personal automobile life, enhances the traffic participants’ travel efficiency, promotes city services and reduces the social cost of system operation. As an important research problem in IoVs, data are transferred among people, vehicles, other devices (sensors, networks) via heterogeneous wireless networks. However, due to the dynamic and complex environment, traditional data transmission technologies don’t work well in the IoVs environment. The demand for a data transmission method, which can transfer data efficiently, reliably and steadily, is urgent. Therefore, how to ensure the reliability and effective of data transmission in IoVs has become a hot research problem. Although the problem has been widely studied, there are still some limitations:1) Although current data transmission oriented location technology can improve the efficiency of network access and clustering routing, the technology is largely dependent on GPS. Hence, it cannot take full advantages of different type of location technologies in different environments.2) Data transmission oriented network handoff strategy can provide support for data transmission in IoVs environment, but the single handoff strategy cannot meet the needs of IoVs and IoVs users. Therefore, current handover strategy doesn’t take full consideration of the network state and the terminate state. What’s more, the strategy ignores the negative impact of the motive terminate to the quality of vehicle, resulting in a sharp decrease in the network stability.3) The security of access points can affect the reliability of data transmission. Because of the openness of IoVs, there are many unfamiliar points. The existing security policies are difficult to support the large-scale points effectively, which makes the security and reliability of data transmission difficult to be guaranteed.4) The multi-path based transmission scheme renders a low efficiency of data transmission. This is because in a multi-path communication environment, the cache capability of each node, bandwidth and distance varies, leading to the disorder of data packages. Furthermore, the retransmission mechanism in link layer could fail due to the misjudgement of the correlation of data packets. Inefficient retransmission, on the other hand, might waste network bandwidth and thus increase end-to-end delay. In IoVs, the end-to-end data is transmitted among many asymmetric networks, which, to a great extent, limits the transmission efficiency. Specifically, even a small data error can be magnified in IoVs, which significantly reduces the overall efficiency as an outcome. To address these problems, this paper aims to improve the network access quality from three aspects:real-time positioning, vertical network handover, secure access. These three breakthrough points are integrated, presenting a clustered collaborated communication scheme. We intensively study a mechanism of efficient data transmission on IoVs, and the achievements are summarized as follows:1) A real-time positioning method based on alterable importance in IoVs is proposed. Some circumstances such as the lack of positioning base stations, multipath fading and shadow effect will cause a low positioning resolution. This paper proposed a composite positioning method based on the alterable importance. Firstly, positioning data of several vehicle positioning technologies could be obtained, and the corresponding error could determine the location coverage areas. Secondly, the importance method of knowledge base was used to calculate the importance of each location coverage area. The variations of importance were as feedback to optimize errors of positioning. Finally, the importance of each location coverage area was as the weighting of each composite area. The target location could be obtained through the weighted average algorithm. Simulation results showed that the method could meet the real-time and improve the positioning accuracy.2) A user-self decision-making tree for switching networks based on their own preferences is proposed. Specific to low network stability and low service quality, which are caused by network choice diversity. So, a vertical handoff method based on cognitive self-selection decision tree was proposed. Firstly, according to the location information of vehicles, the respective handoff probability distribution of them is established and the decisions through the self-selection decision tree are made. Simulation results show that the proposed user-self decision-making tree can meet both the needs of vehicle network switching and the users.3) A secure authentication method is proposed for the consideration of me non-secure network access points and reliability of data transmission. Firstly, identity authentication of each car is implemented through hash-encryption based radio-frequency identification (RFID). A trust evaluation for vehicles is then conducted after completing the identity authentication. The trust evaluation has two types and they are direct and indirect. The direct trust evaluation for a car is determined by its record of the degree of safety, whereas the indirect one is assessed based on the recommendation trust from the other nodes in the same network. The proposed authentication model includes identity authentication, access network authentication and network acceptance authentication. Simulation experiments show that the suggested model can effectively distinguish unsafe vehicles and thus ensure the network security.4) A new data transmission method on account of the clustering routing in IoVs is proposed. Because the frequent interruptions of wireless links between the vehicles cause data retransmission, the whole IoVs performance fell sharply. A cluster partition model is built based on the vehicle’s moving tendency. And the digraph is adopted to find out the optima path between clusters, ensuring multi-path efficiency and network robustness. In order to enhance data delivery efficiency, we propose a solution which is based on network coding. In this solution, data are coded, recoded, and decoded in different stages. Simulation results show that the method could effectively improve the stability of clusters and reach a high productiveness of data delivery.