Modeling And Performance Analysis Of Operation Mechanisms For IEEE 802.11p And NOMA Technology In Internet Of Vehicles

Vehicular Ad Hoc Network(VANET)can provide secure,convenient,and efficient services for new vehicular applications such as anti-collision applications,security and surveillance applications,and multimedia streaming.On the one hand,IEEE 802.11p supports communication in dynamic vehicle environments and improves the comfort of the vehicular environment,but is prone to network congestion under error-prone channel conditions.On the other hand,the scarcity of spectrum resources remains a great challenge for the explosive growth of service flows in vehicular networks.From the perspective of improving vehicular comfort and spectral efficiency,the following were studied.Firstly,we discuss the IEEE802.11p and Non-Orthogonal Multiple Access(NOMA)technologies.Based in the introduce the physical layer and media layer of IEEE802.11p protocol,this paper focuses on the basic theoretical basis and key technologies of Cognitive Radio-NOMA(CR-NOMA)network architecture and the theoretical basis of queueing in the modeling of vehicle networking system.Secondly,the quality of service of the four access categories of IEEE 802.11p enhanced distributed channel access(EDCA)was investigated with channel errors considered.To address the error-prone characteristics of the channel and unsaturated traffic conditions,a three-dimensional Markov model is developed first,followed by an analysis of the characteristics and mutual transition probabilities of the seven classes of states in the model,and then,the steady-state equations of the system are developed to derive the steady-state distribution.According to the steady-state probability,the initial transmission probability,transmission collision probability and transmission error probability of the system are derived,and then the system throughput and delay performance are derived and analyzed.Numerical simulation results show that the increase in BER will seriously decrease the performance of highpriority ACs.Finally,a hybrid collaborative spectrum sharing protocol based on Orthogonal Multiple Access(OMA)and NOMA is proposed to meet the service demand of massive service streams in internet of vehicles(IoV)and to ensure that high priority is given to service streams to be served first.Specifically,the system can switch between noncognitive transmission mode,Underlay OMA mode,and Overlay OMA/NOMA mode,according to the automatic repeat request(ARQ)feedback of PU.In order to describe the switching between these three switching modes,a Markov model is developed to analyze the corresponding steady state probabilities and end-to-end outage probabilities.So,we derive closed-form expressions for the throughput of primary and secondary users to investigate the spectrum utilization.Numerical and simulation results show that the proposed hybrid cooperative cognitive protocol outperforms the pure OMA hybrid cooperative cognitive protocol.