Analysis And Optimization Of Jitter In IEEE 802.15.4 WSN And IP Concatenated Networks

With the influx of M2M(Machine to Machine,Man to Machine,Machine to Mobile network)services,the terminal present heterogeneity in the network.For real-time services,the jitter is the most one of the key factors of Qo S(Quality of Service).The structure of the network presents the diversification,the service in one network unit affects it in another network unit.Therefore,under the background of mixed services,the characteristic of the jitter of real-time services in the multiple network is very significant for the performance evaluation of the network and the Qo S optimization.This paper mainly formulated and analyzed the jitter distribution of real-time services incurred by non-real-time services in the IEEE 802.15.4 WSN(Wireless Sensor Network)and IP core Network concatenated networks.This article provides a general method for solving the probability distribution of end-to-end jitter.The investigation for the influence factor of the jitter of real-time services provides a reliable theoretical basis for the design of future networks.The main work is discussed as follows:(1)Under the heterogeneous services arrival,this paper established the queuing model of IEEE 802.15.4 WSN and IP core network concatenated network.In the IEEE 802.15.4 WSN,this paper modeled the mixed access model of the CAP(Contention Access Period)and CFP(Contention Free Period).Based on Markov theory,we modeled the processes of the random access during CAP stage with heterogeneous services and the dynamic resource allocation during CFP stage.We modeled the GTS allocation process by using a one-dimensional Markov chain.By analyzing the number of access successfully GTS request during CAP,we established the relationship between the CAP and CFP.Consequently,we got a complete model of IEEE 802.15.4 mixed access mechanism.In addition,we obtained the departure processes of real-time services and non-real-time services in the wireless access network,namely,the arrival processes in the IP core network.(2)In the IP core network,it is difficult to analyze the length of queue because the queue changes transiently.Creatively,we analyzed the jitter by observing the dynamic queue length at every moment when the real-time service arrives.There exist four folded random variables when we analyze the dynamic changes of queue,namely: 1)the inter-arrival time of real-time services is stochastic;2)the number of arrived non-real-time services packets is random during the real-time service packet inter-arrival time;3)in the IP core network,the service rate of real-time services packet is variable due to the retransmission mechanism;4)theservice time of non-real-time service packet is no longer fixed.These four folded random processes make the analysis of the length of queue become harder.In order to overcome above-mentioned difficulties,we analyzed the dynamic changes of the queue during the inter-arrival time of real-time services slot by slot.We obtained the relational expression between the length of the queue at the moment of real-time services arrived.For the service time of both two types of services packet are variable,we mapped the service time of real-time services packet and non-real-time services packet to the service time of an equivalent services packet.We can only get the add or subtract relations between random variables,which mates it very difficult to analyze the length of queue in the time domain.Therefore,we transformed these relationships in the time domain into the relations in the generating function domain.We took advantage of some properties of the generating function for further analysis.According to the relationship between the length of queue and jitter,we got the jitter distribution of real-time services at the first router.Further,we analyzed the departure processes of real-time services.We know that the output of previous router is the input of next router.According to the principle of recursion,we can get the end-to-end probability distribution of the jitter of real-time services in concatenated networks.(3)This paper explored the influence factor of the jitter of real-time services in concatenated networks,such as the number of real-time terminal and non-real-time terminal,the arrival rate of the two types of services,the set of mac Min BE and mac Max Frame Retries in the IEEE 802.15.4,the optimal ratio of CAP slots and CFP slots and the service rates of the two types of services in the IP network.Mastering these influence factors is very important for the control of traffic,the estimation of the number of terminals and the design of hops.