Research On Routing Protocols For Wireless Ad Hoc Networks And Information Propagation On Social Networks

The sixth-generation mobile communication network(6G)provides personalized and deterministic network connectivity and services through self-organization,autonomous collaboration,autonomous deployment,and self-healing optimization.Wireless ad hoc networks without the need for fixed infrastructures have extensive applications in various application fields,such as Vehicular Ad Hoc Network(VANET),Wireless Sensor Network,and Flying Ad Hoc Network(FANET).Routing is the core of network self-organization and the key factor to determine network performance.Therefore,it is of great theoretical and practical value to study the routing protocols and analyze the transmission performance of wireless ad hoc networks.However,there are great challenges for routing establishment and maintenance in wireless ad hoc networks,such as threedimensional(3D)characteristics of node movement space,wireless transmission channels fading,and interference.While predicting the service adaptive routes by considering the distribution and change of the network service load can reduce the delay of route establishment and improve the successful ratio of packet transmission.Therefore,we will study the law of information propagation in social networks to predict the distributions of services,which lay a foundation for the research on the service adaptive routing strategy.This thesis studies two classical practical application scenarios of wireless ad hoc networks with nodes moving in 3D space,i.e.,VANET based on vehicles and FANET based on unmanned aerial vehicles(UAVs).The information propagation in social network based on nodes with individual characteristics and social attributes also is studied.According to the network’s characteristics and services requirements,we establish system models based on practical application scenarios.Then we analyze the connectivity,data forwarding performance,and information propagation characteristics of the network by using stochastic geometry and complex network theory.Based on the analysis results,the evolution of the network,information transmission performance,and routing strategies are intensively studied.The main research contents and contributions of this thesis are summarized as follows:Firstly,we study the communication problem in land 3D space scenes such as viaducts and tunnels.To solve the problems of link connectivity and packet forwarding caused by complex road environment and wireless transmission environment of two-layer VANET,the connectivity of VANET is analyzed by using stochastic geometry theory.Two distance measures are put forward,i.e.,single-hop distance and time-varying effective transmission range.Their closed-form solutions are obtained.Then,a data forwarding strategy for the two-layer VANET is proposed.Furthermore,the simulation results verify the advantage of the theoretical analysis results and show that the effective transmission range constrains the next-hop relay selection area.The data forwarding strategy proposed can effectively improve the reliability of packet transmission.Secondly,focusing on the 3D space in the air,to solve the problems of link quality and highly dynamic topology between UAVs caused by the high-speed flight fully autonomously,the link connectivity and packet forwarding performance are analyzed by using stochastic geometry theory.The effective transmission range in 3D space is proposed.Furthermore,the next-hop best-link forwarding strategy is proposed under the constraints of the 3D relay selection area by utilizing a link utility function as the metric.Moreover,a cone model is established to study the packet forwarding problem,and a 3D perimeter forwarding strategy is proposed.Simulation results show that the proposed routing strategy composed of the best-link forwarding strategy and 3D perimeter strategy can effectively reduce the packet loss rate and improve the network throughput.Thirdly,for the social network composed of nodes with strong individual characteristics and social attributes,to solve the problems of the influence of population heterogeneity and individual intimacy heterogeneity on information propagation,individuals are classified according to their population heterogeneity.Then the individual intimacy heterogeneity between individuals is modeled as the weight of links in the network.Next,an adoption threshold model of population heterogeneity is constructed in weighted social networks,and a partition theory based on edge-weight and population heterogeneity is proposed.The theoretical analyses are matched with the simulation results,which point out that fashion individuals can accelerate information propagation,and the weak weight distribution heterogeneity can also accelerate information dissemination.Single-layer social networks cannot accurately draw individual behavior characteristics when individuals use multiple social networks at the same time.Finally,focusing on the multi-dimensional intimacy and the individual fashion-passion trend characteristic in multi-layer social networks,a multi-layer weighted social network is constructed,and an adoption threshold model with a tent-like probability function is built.Next,a partition theory based on edge-weight and individual fashion-passion trend thresholds is utilized to quantify and analyze individual information propagation mechanisms in the multi-layer social network.The theoretical analyses and simulation results point out that the strong individual fashion-passion trend can accelerate information propagation and weight distribution heterogeneity also accelerates information propagation.They also point out that a maximum final information acceptance and behavior adoption size can be obtained at an optimal individual fashion-passion trend value.