Performance Analysis Of Jitter Of Delay In CSMA/CA Wireless Access Networks

Various wireless access networks with unique advantages emerge one after another.Owing to the distributed features and flexibility,CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance)mechanisms have been widely adopted in wireless networks.With the development of wireless communication technology,all kinds of services in wireless networks have different Qo S(Quality of Service)requirements.According to the tolerance for the delay,the services can be divided into two categories: real-time services and non-real-time services.The jitter of delay is an important Qo S metric for the real-time services.Traditional voice services have requirements for delay jitter,while the emerging VR(Virtual Reality)services and industrial control information in the new generation of industrial Internet of things have stricter requirements for delay jitter.Therefore,the research on the delay jitter performance of real-time services in CSMA/CA wireless networks is of great significance for performance evaluation.In this paper,we aim to analyze the delay jitter of real-time services for the CSMA/CA networks under homogeneous and heterogeneous scenarios.And we analyze the impact of packet arrival,CSMA/CA networks parameters on the delay jitter performance of real-time services.The contributions of this paper are concluded as follows.(1)In this paper,we aim to analyze the access delay and delay jitter of packets for the CSMA/CA mechanism with inactive period under the homogeneous scenarios.The Energy Efficient Carrier Sense Multiple Access with Collision Avoidance(EE-CSMA/CA)mechanism introduces the inactive period in the frame structure.Nodes don't transmit packets during the inactive period.To analyze the access delay and delay jitter of CSMA/CA mechanism,we model the service process.Due to the stochastic nature of the CSMA/CA mechanism,it is difficult to analyze the service process and the service time of a packet.For the CSMA/CA mechanism with inactive period,how to quantify the effect of inactive period on the service time is still an unexploited problem.The randomness of service time makes the delay analysis difficult.The delay jitter is defined as the difference of delay experienced by two successive packets,and the difficulty of delay analysis complicates the analysis of delay jitter.Firstly,based on the Markov theory,we model the mechanism of EE-CSMA/CA as a four-dimensional Markov chain,and the fourth variable of Markov chain differentiates the active period and the inactive period of EE-CSMA/CA.Secondly,in probability generationdomain,we obtain the probability distribution of service time and the access delay.Thirdly,the queue in a node is decoupled,and two queues with different states of empty and non-empty are configured logically,which helps to enable the complex analysis of delay jitter.Based on the probability theory,the probability distribution of delay jitter is obtained.The proportion of active period in the whole frame structure is closely related to Qo S and energy consumption.In order to guarantee Qo S and save energy,we estimate the minimum durations of active period by the dichotomy under the access delay and delay jitter constraints,respectively.In the simulation,we analyze the effects of different frame structure,access parameters and the number of node on the service time and delay jitter performance of packets.The results show that different frame structure will make service time and delay jitter different.The access parameters also have influence on service time and delay jitter.(2)Considering that wireless networks will support various services in the future,we analyze the performance of delay jitter of real-time services for the CSMA/CA networks with heterogeneous services in this paper.The existence of non-real-time services in the networks is bound to affect the services of real-time services,and it further affects the performance of delay jitter of real-time services.The inter-arrival time of real-time services packets is random,and the number of non-real-time services packets arriving at the inter-arrival time of real-time services is stochastic.Besides,the service time of two types services is random,which makes it difficult to determine the departure moment of the packets.The threefold stochastic characteristic makes the analysis of delay of real-time services difficult.In order to overcome the difficulty caused by these three random variables,we analyze the delay of the real-time services packets when they arrive at the queue;During the inter-arrival time of real-time services packets,we derive the delay of the packets at every slot;Through queue analysis,we obtain the delay expression of the real-time services packet.Since the expression of delay is the algebraic operation of random variables,the analysis is complicated in the time domain.Hence,we will use the nature of the generation function to solve the probability generation function of delay jitter of the real-time services packets in the probability generation domain.Finally,the probability distribution of delay jitter is obtained by inverse transform.In the simulation,we explore the factors that affect delay jitter.The results show that different arrival models lead to different probability distributions of delay jitter.The networks access parameters also have impact on the delay jitter.