Research On Access Congestion Control For M2M Communication In LTE

With the rapid development of M2M(Machine to Machine) communication, the existing mobile network has been unable to meet the development of M2 M communication. Especially the "tidal effect" of M2 M flow, namely the sudden large-scale accesses of M2 M equipments, which will have huge impact on other normal communication, especially H2H(Human to Human) communication which should be guaranteed with priority. Besides, M2 M communication is commonly divided into many classes with different priorities, so the M2 M communication with high priority should be guaranteed with priority as well. As a result, it is of great importance to design an access control strategy which can avoid excessive access of M2 M communication and guarantee H2 H communication or M2 M communication with high priority to access the network with priority at the same time.An adaptive resource separation algorithm is proposed in this thesis to ease the network congestion leaded by M2 M communication. First, a kind of dynamic ACB(Access Class Barring) mechanism based on the ACB mechanism which can adjust the access barring factor dynamically according to the real-time load is proposed, it can optimize the throughput of the network. Then, to solve the main problem of obtaining the real-time load, the load tracking algorithm is proposed, in this algorithm, the estimation of the number of the RApreamble is used to approximate the real-time load estimation. After setting the statistic frame, by running the steady state estimation and the statistic frame estimation at the same time in this algorithm, it can estimate the steady state load effectively and judge the jump of load accurately and timely with the given performance requirements. In that way, it can provide accurate and timely parameter for the access control strategy afterwards.Then, aiming at the problem of the congestion leaded by M2 M when coexists with H2 H communication, how the backoff mechanism dose influence on arrival rate is analyzed at first. Then the optimal resource separation method in different situation is discussed combing with the dynamic ACB mechanism. Finally, the adaptive resource separation algorithm is proposed combining with dynamic ACB mechanism and dynamic resourceseparation, which can realizes the optimization of network throughput and the discrimination for different communication priorities, making it possible to alleviate network congestion effectively, improve the network performance and optimize the income function.Finally, the adaptive resource separation algorithm is generalized to multi-priority M2 M communication by adapting the dynamic ACB mechanism and dynamic resource separation to this situation and theoretical analysis of optimal resource separation method in this situation, so that it can behave a good performance with multi-priority M2 M communication as well.