| Mobile Internet of Things(IoT)is a network system composed of radio frequency identification,wireless data communication,wireless Internet technology and other technologies.It is also the result of collision and integration of mobile communications,mobile terminals and IoT,and it is an important mode and way for the development of IoT.In recent years,the number of intelligent access devices continues to increase sharply,especially the rapid popularization of mobile intelligent terminals,which provides more opportunities for malicious nodes to attack the network.In addition,the non-cooperative behavior of selfish users,the frequent movement of terminals or the loss of limited energy on terminals,unpredictable network size and other characteristics,bring enormous challenges for the continuity,reliability and energy-saving effects of current mobile IoT services.Therefore,based on the network architecture of mobile IoT,focusing on the data forwarding and routing problems in mobile IoT bussiness which are greatly affected by mobile terminals,this paper makes a deep research on the trustworthiness forwarding model of mobile access network,the trustworthiness forwarding model fusing multi-layer networks and the energy-saving routing mechanism based on mobile Ad Hoc network(MANET).The work includes the following three aspects:(1)To solve the problem of privacy leak or service interruption caused by malicious or selfish nodes destroying or not forwarding data,a trustworthiness forwarding model of mobile access network based on multivariate social relationships between nodes is proposed.First,according to the unequal trust relationships between objects in the actual scenarios,this model first defines the local unidirectional trustworthiness relationships between nodes by using the contact probability,service degree and recency between objects.Then,combining the degree of nodes,the social similarity between nodes and the individual centrality of nodes are measured respectively by using the product of vectors and the adjustment factor,so as to the global two-way trustworthiness relationships between nodes.Finally,the law of universal gravitation is used to integrate the two-way trustworthiness factors to evaluate the forwarding capability of nodes.Experiments on two real data sets show that the proposed model has high stability and reduces the average delivery delay and average network cost while taking into account the cumulative delivery rate of data.(2)To deal with the problem of reliable data transmission across space in large-scale mobile IoT when there are many types of network nodes and the complete network structure information can not be known beforehand,a trustworthiness forwarding model of hybrid network based on fog computing is proposed.First,the model establishes the unidirectional trustworthiness relationships between nodes in a hybrid network composed of mobile terminal nodes and fog infrastructure nodes,and constructs a dynamic trustworthiness overlapping community detection model by using seed expansion and random walk optimization algorithm,which can dynamically segment large-scale mobile IoT based on communities;Second,considering the long-distance communication function of fog infrastructure nodes,all connected fog infrastructure nodes are partitioned according to certain rules and form multiple sub-connected components.Third,based on the distribution of sub-connected components,the communities obtained in the first step are re-united according to the set rules to form logical joint edge community structures.Finally,on the basis of the logical joint edge community structures,the corresponding forwarding capability metrics and the corresponding forwarding rules are established for mobile nodes and fog infrastructure nodes,respectively.Experiments on two real data sets show that the proposed model surpasses some popular forwarding modes in terms of cumulative data delivery rate,average delivery delay and average network cost.(3)To solve the problem of increasing energy consumption caused by re-searching and re-routing services while link breakages between mobile terminals in MANET,a dynamic cloudlet-assisted energy-saving routing mechanism is proposed.First,the mechanism establishes temporary files for each mobile device to record its ID and routing information in a certain period,and considers using D2D(Device-to-Device)as the main communication mode between mobile terminals.Second,it uses a cloudlet as a small data center,creates a service sharing table for all cloudlets and establishes a cooperative mechanism between cloudlets.Finally,no matter how mobile terminals change their locations,relying on the above-mentioned settings,they can always re-search and re-route the lost services quickly through other routes.The experimental results show that the proposed scheme greatly reduces the energy consumption of re-searching and re-routing services for mobile terminals in MANET compared with not using the proposed mechanism.The trustworthiness forwarding model constructed for mobile access network based on multi-social attributes of nodes can avoid the adverse effects of malicious or selfish nodes on forwarding by enhancing the credibility of interaction between nodes,and has good scalability.In the case of unpredictable network size,the trustworthiness forwarding model of hybrid network based on fog computing combines dynamic community structure with trans-space long-distance forwarding ability of fixed facilities on network edge,and effectively completes the reliable transmission of mobile IoT data in local scope and long-distance.Using the dynamic cooperation mechanism between Cloudlets can greatly shorten the time of re-routing or re-search service for mobile terminals in MANET,and improve the efficiency of service operation,but also save a lot of system energy.In a word,the application of the above three mechanisms can achieve high efficiency,low energy consumption,safe and reliable transmission of data,and provide the most basic guarantee for the sustainable development of mobile IoT applications. |
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