Research And Design Of Internet Of Things Random Access Scheme Based On 3GPP R13 Standard

In recent years,artificial intelligence has received more and more attention.In order to make people's lives more convenient,various smart devices have emerged.The future market for smart devices is large,and the society's demand for Internet of Things devices will also increase dramatically.Among various communication technologies used in the Internet of Things,the Narrow-band Internet of Things(NB-IoT)stands out for its large connection and wide coverage.NB-IoT is a new cellular technology proposed for the new Internet of Things business.It is inherited from Long Term Evolution(LTE)and has many similarities with LTE,but it is also very different.In NB-IoT,random access is the first step to achieve uplink synchronization and plays a vital role in the entire communication process.Only after successful random access can subsequent data transmission be performed.Based on 3GPP R13,this thesis first studies the characteristics of the NB-IoT,and studies the random access process of NB-IoT.The main content is the random access process of the first layer,including the repeated transmission of the Preamble on the Narrow-band physical random access channel(NPRACH)and the random access response(RAR).The thesis proposes a mathematical model based on random geometry,analyzes the factors that affect the success rate of random access and the impact of repeated Preamble on random access performance,and at the same time simulates and verifies the correctness of the model.Simulation results show that increasing the number of repetitions can increase the random access success rate in various situations,and at the same time can reduce the transmission power,thereby achieving power savings;but it will lead to a reduction in the utilization of data transmission channel resources,making data transmission efficiency lower.Therefore,the parameters can be adjusted through model simulation to find the appropriate number of repetitions to maximize resource utilization.In addition,the thesis establishes a mathematical model for the random access process of the two access traffic arrival models,derives the formulas of random access success rate and random access conflict rate,and through the computer to simulate the access situation of different access time and the number of UEs,and the simulation results verified the correctness of the proposed mathematical model,and can improve the random access success rate of the system and reduce the random access collision rate of the system according to the simulation results.This thesis proposes a mathematical model based on random geometry for the random access process of NB-IoT.In addition,two different access traffic arrival models are mathematically modeled,and verified the correctness of the mathematical model proposed in this thesis by computer.And give advice on how to improve the success rate of random access.In practice,the random access performance of NB-IoT can be optimized according to the simulation results of the mathematical model.