Research On M2M Random Access Procedure With Spatial Group Based On LTE Network

LTE/LTE-A technology is designed for H2H communications.It is one of the best choices when applied to Internet of Things,since it has huge number of base station and is stable in technical framework.It is important to solve access problem in a massive amount of devices scenarios,and random access process is the key point in the procedure.Therefore,the optimization of random access scheme for M2M scenarios is of great significance.Firstly,the paper studies various improved schemes in the field,and proposes a new random access scheme named spatial grouping based scheme.A system model is presented in the paper.The workflow and the key steps are analyzed as well.Secondly,spatial grouping based scheme proposes two new mechanisms,improving the fairness of the timing advance based scheme.The two mechanisms are polling grouping mechanism and double restriction mechanism.The former provides good fairness for the system,and the latter gives the system outstanding performances in access and device quantity restriction.What is more,the paper has done many works on theoretical analysis,proving excellent performance of the scheme in collision probability.Finally,a simulation system is built based on the proposed system model.The paper gives rich analysis and comparison about traditional random access procedure,timing advance based scheme and the proposed scheme.The paper gives the simulation results on collision probability,access rate and fairness.Besides,the paper illustrates that the grouping number and the timing advance interval width have influences on system performance.Therefore,simulations had been done with the two parameters in the collision probability,access rate and fairness.Phenomenons in simulations have been explained with corresponding theories.By adjusting grouping number,the system can have a best access rate with a certain device number.By adjusting timing advance interval width,the system can improve the uplink channel resource usage rate.With the optimization of the two parameters,the random access procedure can perform better than the traditional scheme.