Research On High-timeliness Routing Algorithm For Vanets

Vehicular Ad hoc Networks(VANETs),with the development of communication technology and the growth of vehicle holdings,is becoming increasingly important and is considered to be one of the most promising and market-valuable IoT scenarios.In VANETs,Vehicles can use sensors,cameras and other equipments to collect the information from the surrounding environment.The information collected can be transmit to the access point(AP)and the required users,and will be used to achieve intelligent driving decision,real-time route planning,vehicle positioning and tracking,and other intelligent transportation applications.However,it is a great challenge to develop the information updating strategy and design the routing algorithm,due to the limited network resources,high-speed node movement and frequent topology changes.This thesis focuses on the scenario of information updating in VANETs,and studies the formulation of information updating strategy and the design of routing algorithm.Aiming at the VANETs in urban scenarios,we propose a Greedy Traffic Light and Queue aware Routing protocol.After that,we jointly optimize the information collection strategy and routing algorithm,and propose a distributed information collection strategy and routing algorithm in VANETs.The specific research contents and main innovations of this thesis are summarized as follows.(1).In this thesis,a Greedy Traffic Light and Queue aware Routing protocol is proposed.In order to achieve reliable data transmission with low delay and high reliability,this algorithm improves the traditional location-based routing algorithm by taking into account many factors such as traffic conditions and load balancing.Firstly,in order to solve the problem of topology hole,considering traffic lights and vehicle driving direction,the street connectivity is calculated more accurately.Secondly,in order to reduce delay and increase reliability,the priority of neighbor vehicles is calculated based on vehicle speed,vehicle direction,vehicle location,channel quality and queue length.Then,the most suitable relay node is selected according to the street connectivity and priority.Finally,the proposed routing algorithm is simulated at the system level based on Simulation of Urban Mobility(SUMO)and Network Simulator version 2(NS2).The effects of vehicle speed,vehicle density and network load are simulated.The simulation results show that the proposed method,compared with the existing methods,has been optimized in terms of both packet delivery rate and end-to-end delay.(2).A distributed updating strategy and routing algorithm based on information timeliness is proposed.Jointly considering the information updating and multi-hop information transmission in VANETs,the system is modeled to minimize the age of information.The distributed information updating strategy and routing algorithm are deduced using Lyapunov stability theory.Only local information is needed to decide whether to collect or not,which greatly reduces the complexity of the algorithm.After that,this thesis optimizes the routing algorithm,and proposes an improved back-pressure algorithms based on Q-learning algorithm,to increase the destination driving force and solve the uncertainties beyond multi-hop caused by node movement.Finally,the information collection strategy and routing algorithm are simulated with real scenarios.The simulation results show that the information collection strategy and routing algorithm designed in this thesis can effectively improve the timeliness of information and increase the system stability.