Research On Routing Protocols In IOV

Internet of Vehicle(IOV) applies communication technologies to the traffic system. Utilizing the vehicle-to-vehicle, vehicle-to-infrastructure and infrastructure-to-infrastructure communications, IOV provides lots of applications related to safety, convenience and entertainment.Therefore, IOV attracts a extensive attention, which inspires the development of Intelligent Transportation System. Among all, the routing protocol is one of the most crucial technologies due to its responsibility for the route selection. Currently, the geographic routing is one of the most attractive protocols, in which a node acquires the location information of itself, its neighbors and the destination using the GPS device, hello algorithm and location service system respectively. Furthermore, the transmitter makes the routing decision only according to the local information. Without the route construction and maintenance phases,the geographic routing protocol is suitable for and widely adopted in IOV.However, most of the existing geographic routing protocols are based on two-dimensional(2D) scenarios, while the realistic traffic environment contains three-dimensional(3D) scenarios, such as the viaduct and tunnel. The existence of the 3D scenario generates the multilevel distribution instead of the planer distribution of vehicles. The transmission range degrades and the communication model changes in the 3D IOV. Moreover, the existing mobility and system model addressing the 2D scenario are not suitable in the 3D IOV. Finally,all impacts of the 3D scenario deteriorate the performance of existing geographic routing protocols in IOV.To address the issue, we make research on the geographic routing protocol in 3D scenarios of IOV. We first exact the basic traffic scenarios and build the fundamental analysis model.Based on the model, we design an adaptive hello algorithm for the tradeoff between the accuracy of the neighbor table and the overhead of the hello algorithm. In the classic scenarios,we design the stochastic analysis for the traditional geographic routing protocol. Motivated by the analysis results, we propose a three-dimensional oriented geographic routing protocol in IOV. The main work and contributions of this dissertation contains the following four parts.(1) On the analysis model of the 3D scenario of IOV. To address the issue that the existing analysis model is not suitable in the 3D scenario of IOV, we build the fundamental analysis model by analyzing the basic features of the traffic environment. Specifically, we give the impacts of the road-width on the performance of the routing, and calculate a threshold for ignoring the width. Based on the results, we propose the basic road model. Utilizing an outdoor transmission experiment, we reveal the impacts of the multilevel feature on the transmission range and give the basic communication model. In addition, a 3D oriented accident drive mobility model is designed based on the mobility model generator Vanet Mobi Sim.(2) On the location discovery of the neighbor in IOV. To address the issue that existing hello algorithms cannot deal the tradeoff between the accuracy of the neighbor table and the overhead, we first derive the relation between the key factors impacting on the accuracy of the neighbor table, i.e., the hello interval and timeout interval, and the variation of the neighbor table. Depending on the derivation results, an effective local information-based adaptive hello scheme is proposed, in which the local information, i.e., the variation of the neighbor table, is used to adaptively adjust the hello interval and timeout interval to accommodate the mobility of the network. Furthermore, we conduct simulations for the proposed hello algorithm and three existing algorithms. Results show that the proposed algorithm can handle the tradeoff better than other algorithms, which is more suitable in IOV.(3) On the performance analysis of the existing geographic routing protocol in IOV. Based on the extracted basic scenarios, i.e., the 2D single lane, 2D multi-lane and 3D multi-level scenarios, we analyze the performance of the existing geographic routing protocol by the renewal theory. We prove the relationship of each hop routing progress, and give one sufficient condition that ensures these increments are approximately i.i.d. Then, we calculate the routing length in all three scenarios. Moreover, we discuss the impacts of 3D scenarios on the performance of the geographic routing protocol, and give the advice for the design of routing protocols.(4) On design of the geographic routing protocol in the 3D scenario of IOV. To address the issue that existing geographic routing protocol suffers the issue of hop count increase and delivery ratio decrease in the network, we proposed a 3D oriented geographic routing protocol. In the proposed protocol, we present a calculation method for the connectivity probability for routing at the intersection. Furthermore, we deign a greedy opportunity forwarding algorithm to ensure the performance of routing on the road segment in 3D scenarios.Simulation results from both the network layer and system level show that the proposed protocol performs better than existing geographic routing protocols in terms of the hop count and delivery ratio.