Research On M2M Random Access In LTE-A

M2M(Machine to Machine)needs to communicate with the eNodeB through the existing network.But the simultaneous access of mass M2 M devices may cause the signaling congestion of RAN(Radio Access Network),and severely affect the original H2H(Human to Human)users in the network.Therefore,in order to guarantee the performance of RAN,it is very important to lay out an effective access control strategy that considers the characteristics of M2 M service.Aiming at the possible problem of congestion leaded by M2 M devices which connect the network,the access control methods of M2 M communications are investigated in this dissertation.Firstly,aiming at determining and adjusting the parameters of ACB mechanisms in RAN congestion control methods,a load feedback algorithm is proposed.It can estimate the current load and predict the load of the next access slot,and then the access control parameters of M2 M devices can be dynamically adjusted based on the load change.In this way,the proposed algorithm reduces the undesirable impact on traditional H2 H devices for massive synchronous accesses of M2 M devices,decreases the retransmission number and improves the access success rate.Then,according to the slotted access scheme in RAN congestion control methods,a dynamic frame length algorithm is presented in the article.Through monitoring the real-time access load of the network,this proposed algorithm can realize the dynamic selection of frame length in slotted access scheme,which makes the optimized access frame length more suitable for the current access load.This raised algorithm ensures a higher success rate of access,eliminates the unnecessary access delay,and also decreases the number of preamble transmission to a certain extent.Finally,the two proposed schemes above are compared from the aspects of success rate and channel utilization rate,then a suggestion of scheme selection is provided subsequently.