Access Algorithm Design For Large-scale Devices And Platform Implementation In Cellular Based Internet Of Things Networks

With the rapid development of communication technology,mobile communications are converting from human connections to machine connections.Especially in recent years,the rapid development of the low power wide-area communication technologies represented by Narrow Band Internet of Things(NB-IoT),which are used in Cellular based Internet of Things(C-IoT),brings a new opportunity to IoT.Compared to the short distance communication technology such as WiFi,bluetooth,the IoT technologies based on cellular have features such as wide coverage,mobility and large connection supporting and so on,which can bring more and richer application scenarios.However,how to offer better service for massive IoT devices under the condition of limited cellular network resources is a problem should be solved in C-IoT.Directly applying the resource management and allocation of technology in traditional IoT or cellular network to C-IoT is often unable to achieve the desired effect.In this paper,according to the characteristics of C-IoT,IoT devices and cellular network resources information,combined with the idea of data analysis,an access scheme with massive equipments in the cellular is proposed.And simulation verifies the performance through the MATLAB.In addition,this paper also sets up a NB-IoT system platform based on NS3,and a large number of source code in LTE module is modified.The main work summarized as follows:Firstly,the IoT technology are summarized.We summarize and introduce the short distance communication technology,the wide area communication technology and the resource management technology in the IoT.Then,combined with the idea of data analysis,an access scheme is proposed under the scene of C-IoT cellular,taking the characteristics such as big number of IoT devices,high power consumption demand and the size of sending and receiving packets are mainly small into account.The algorithm can be divided into three steps:Firstly,according to the transmission power of devices and length of transmission packets,the K-means algorithm is used to cluster grouping the equipments;Secondly,the free network resources are assigned to the equipment group according to the result of grouping and the free resource state information;Thirdly,according to the time needed for information transmission equipment as well as the maximum tolerance value of transmission time delay,sort within each group of IoT equipment and then connect to the base station in turn.The simulation results show that the algorithm can ensure the success access rate of IoT equipment,improve the system throughput and reduce the energy consumption of system.Finally,based on NS3,we establish the C-IoT system simulation platform.NB-IoT technology is used and functional entities,which include User Equipment,Evolved Node B,Mobility Management Entity,Serving Gateway,Packet Data Network Gateway and the forth,are modified to support NB-IoT equipments on the basis of LTE module.And the adhesion process of NB-IoT equipment,MO and MT control surface data transmission process are achieved by amending and optimizing the interfaces of functional entities mentioned above.