Studies On Network Performances Of Multiple Fading Channels Based On VANET

With the accelerated development of the automobile and transportation industry,people's daily lives are increasingly dependent on cars.While bringing convenience to people,it also caused many problems such as road congestion and environmental degradation.Under this circumstance,Vehicular Ad Hoc Network(VANET),as an indispensable part of intelligent transportation,plays a very important role in greatly improving the timeliness and effectiveness of information transmission between vehicles.Therefore,this paper will focus on the network performance of VANET.The main research work of this paper is as follows(1)Analyzing a variety of wireless fading channel models and related theoretical knowledge.Firstly,the common wireless channel models,such as Rayleigh fading channel,Rician fading channel,Nakagami-m fading channel and Weibull fading channel are briefly introduced,At the same time,the Probability Distribution Function(PDF)of the above fading channel models is presented.Secondly,the random graph theory based on Wireless Sensor Networks(WSNs)is briefly described,and the derivation and proof of the node isolation probability and conditional connectivity probability based on the theory are given.The subsequent chapters will use the isolation probability and conditional connectivity probability to analyze the network connectivity probability.Finally,the definition of outage probability and network throughput are elaborately given.(2)Contrasting and analyzing the network connectivity probability obtained from the approximate and accurate expressions of the lower bound of the conditional connectivity probability under WSNs.Firstly,based on WSNs,the node deployment model is defined.Secondly,according to the link connection condition,the node isolation probability,the approximate and exact expressions of the lower bound of the conditional connectivity probability and the network connectivity probability are derived.Finally,the influences of parameters such as node density,path loss and area of region on the connectivity probability under Rayleigh fading channel model are discussed respectively.In addition,compared with the exact expression,the simulation proves that the approximate expression proposed in this paper greatly simplifies the calculation process.so the approximate expression has certain simplicity.(3)Studying and discussing the network connectivity probability under Rayleigh and Nakagami-m fading channel model.Firstly,the isolation probability and network connectivity probability under Nakagami-w and Rayleigh fading channel models are calculated respectively.In addition,this paper also studies the performance of connectivity probability under different parameter settings,such as different node density,different path loss,and different threshold power.Finally,the simulation results prove that the connectivity probability under Nakagami-w fading channel is better than that of Rayleigh fading channel under the same node density.(4)Analyzing the outage probability,packet error probability,average packet loss probability,throughput and average delay of Nakagami-m fading,Weibull fading,Rician fading and Rayleigh fading.Furthermore,this paper also discusses and simulates the effects of different parameters on the above of the probability,such as different contention window sizes,different packet sizes,different vehicle numbers,different vehicle speeds,and different packet arrival rates.Finally,combined with the actual situation in the road driving,the factor of the safety distance between vehicles is added,which makes the research on the network performance in the VANET environment more realistic.