Research On Key Technologies Of Massive Access In M2M Communication

The fifth generation mobile communication systems(5G)is expected to be commercialized in 2020,and millions of devices will connect to the network to realize"Internet of Everything." Machine to Machine(M2M)communication is an important component of the Internet of Things(IoT).Efficient access to network is the prerequisite for interconnecting all things.When a large amount of terminals initiate random access requests at the same time,huge access load will be exerted on the existing networks and serious congestion may occur.Consequently,the transmitted data may be lost and the quality of service(QoS)of network is decreased.Therefore,it is necessary and imperative to study the efficient access scheme for massive access to prevent the congestion.In order to solve the issue of M2M massive access,a new traffic flow control scheme should be designed by considering the delay tolerance and the group feature of M2M.In this thesis,a novel traffic flow control method of M2M is proposed and the main points and contributions of our works are given as follows:(1)Random access control method based on the priority of M2M traffic.When massive terminals with diverse M2M applications initiate random access request at the same time,we firstly divide the access request into groups according to the delay tolerance of respective application.Then,a dynamic allocation method for random access channel resources is proposed based on the properties of the groups.Suppose the total number of terminals is known,the partition ratio of preamble resources and the random access barring factors for respective application are obtained through optimization theory analysis.Based on this and after theoretical derivation,we obtain three performance expressions,i.e.,access success probability,preamble collision probability,and average access delay.Finally,the numeric simulation is conducted and the results have shown that the overall performance of the proposed method is better than the traditional ACB scheme.(2)Random access control scheme for M2M based on double buffer queue.Since the existing network architecture can not meet the massive M2M access scenarios,a new M2M communication architecture with three-tier is proposed.Considering the characteristics of M2M massive access,a novel access control algorithm is proposed,which allocates the access requests to the corresponding buffer queue according to the delay tolerance of arriving M2M data flows.Then,the stochastic network calculus is adopted to construct a reasonable arriving model for M2M data flow,as well as network service model.The data flow arriving curve and service curve are obtained through theoretical analysis.The minimum delay boundary under different scheduling conditions is also derived.Finally,simulation results validates the correctness and effectiveness of the proposed scheme.