Aiming at the problem of multi-hop data transmission among mobile vehicles in Vehicular Ad Hoc Network(VANET),combining the moving features of vehicle in cities,this paper proposes a Data Forwarding mechanism based on Distributed Learning(DFDL) by improving the existing BubbleRap routing mechanisms.Based on the “store-carry-and forward” message transmission mode,DFDL determines the vehicles’ community tags by using the time interval and frequency of enwunter,and calculates the centrality of nodes by the mobile entropy of vehicle movement.During data forwarding,DFDL selects appropriate relay nodes for data packet messages by comprehensively judging the community tags and centrality of nodes.This mechanism achieves multi-hop message forwarding among moving vehicles in long distance.Experimental results show that,for moving vehicles in cities,DFDL significantly improves the message delivery ratio and the average delivery delay performance than the BubbleRap routing mechanism.

For the problem of network congestion caused by using table driven routing protocol in urban traffic,this paper proposes a modified Zone Routing Protocol(ZRP).It takes bus’s characteristics of constant speed and fixed rate into consideration,builds cluster by the rule that considering bus node as the head node of the cluster and ordinary car node as the intra-node of the cluster.On the basis,it establishes bus backbone network,and uses ZRP to promote the communication among the vehicle nodes by using active routing mode and on-demand routing mode.Simulation results show,compared with Ad Hoc On-demand Distance Vector Routing(AODV) protocol and Destination-sequenced Distance Vector(DSDV) protocol,the routing protocol has great improvement in transmission delay,packet loss rate and routing overhead.

Communication links are easily affected by speed and irregular location distribution due to high-speed movement of cars in Vehicular Ad hoc Network(VANET).A routing optimization scheme based on link reliability is proposed after analyzing the characteristic of car driving.Links reliability optimization is realized by dividing stable communication distance,calculating available connecting time and the handling mechanism of max multiple value of links.Experimental results show that,compared with AODV and other schemes,this scheme has a better performance on link reliability,data transport efficiency and the disconnecting number of link.

Vehicle identity is the vehicle’s exclusive user legitimate identification stored in trusted centre,which is directly related to the vehicle user’s information,so that its anonymous authentication reflects the protection of user privacy.Based on a certificateless signature scheme,this paper proposes an anonymous authentication protocol without the management of certificate or the problem of key escrow.The security and performance of the proposed protocol are analyzed.Result shows that the protocol has higher efficiency than the certificate-based authentication protocol and the identity-based authentication protocol.It is anonymous,undeniable,mutually authenticated,privacy preserving and anti-attack.

In order to study the influence of node movement direction and movement speed on the dynamism of Vehicular Ad Hoc Network(VANET),a link dynamic analysis model is established by limiting the path width and node propagation range in the actual VANET environment.The theoretical expression of link duration and its Cumulative Distribution Function(CDF) are derived.The theoretical results are verified by the simulation experiment,and the results show that the theoretical analysis results are in good agreement with the simulation data,and node movement speed,road width and node transmission range have a certain impact on the results,however the node transmission range on the VANET link duration is relatively large.

In order to solve the problem that multi-dimensional non-functional properties are not taken into consideration during the design of Controller Area Network(CAN),such as real-time,security and reliability,this paper proposes an integration optimization model.The scalability and bandwidth utilization ratio are used as the optimization objectives of the model.Under the premise of meeting the requirement of real-time,reliability and safety,by means of increasing the weight of scalability and bandwidth utilization,the unified optimization of both is realized.Then different objectives are normalized to get the balance optimization within the range.On this basis,integrating signal packaging ideas,it presents the multi-dimensional non-functional properties integration optimization algorithm in CAN system based on Simulated Annealing(SA).Experimental results on real signal set and simulated signal set show that compared with the situation of integration optimization without considering multi-dimensional non-functional attributes,this algorithm can obtain higher objective optimization rate.