Wireless Resource Pre-allocation Technology For Low Delay And High Reliability Communication

Ultra-reliable and low-latency communication?URLLC?as one of the three major application scenarios of 5G,is widely considered as the technical basis of new applications such as industrial automation and automatic driving.URLLC has very stringent requirements for quality of service?QoS?:the user-side delay does not exceed1 millisecond,and the reliability of 32-byte packets is 1¹0^-5.According to the development strategy of 5G,the main bearer services of 5G in the medium term are enhanced mobile broadband?eMBB?and URLLC service reuse.Based on the arrival characteristics of URLLC packets,this text mainly studies the resource pre-allocation problem of users in competitive random access channels.Firstly,URLLC uplink?UL?transmission control plane resource pre-allocation strategy:for UE initial access channel scenarios,when eMBB and URLLC users access cellular systems randomly based on competition at each random access opportunity?RAO?,this paper studies how to ensure that URLLC user control plane delay does not exceed 10 milliseconds.In order to reduce the probability of conflict among users,the Neyman-Pearson?N-P?criterion is introduced to classify the transmission states of URLLC users,and different resource pre-allocation strategies are designed for URLLC users with different transmission states.In order to analyze the access success probability of different resource pre-allocation strategies,a probability analysis model is established,and a nonlinear recursive function of random access delay is obtained by taking the random access delay of control plane as an optimization index.In order to study the properties of the objective function,the random access delay is transformed into the cumulative distribution function?CDF?of RAO.The simulation results show that the resource pre-allocation strategy proposed in this paper can guarantee the delay requirement of URLLC control layer with a probability of about 95%.Through simulation,the effects of the parameters such as the number of eMBB users,URLLC users and preamble reserved number on the system performance are also analyzed.Secondly,URLLC service UL transmission user plane resource pre-allocation strategy:for the system is in radio resource control?RRC?connection state,when eMBB and URLLC are based on competitive random access,how to optimize the performance of the system through reasonable resource pre-allocation schemes under the QoS constraints of URLLC is studied.In order to reduce the collision probability between users,slotted ALOHA protocol is introduced.Since the improvement of communication system reliability is not obvious by retransmitting,the mechanism of retransmitting is abandoned to ensure the millisecond delay of UL transmission.In order to further reduce the communication delay,a short frame with frame length of0.125 milliseconds is used for data transmission.In order to guarantee the quality of service of URLLC,a"two-state"transmission model is designed,and for the sake of simplicity,it is assumed that the instantaneous channel gain of all channels is greater than the threshold value.Finally,a resource pre-allocation strategy is designed with the constraints of URLLC users'QoS requirements and the number of accessible URLLC users as the optimization objective.The simulation results show that the proposed resource pre-allocation strategy is superior to the traditional resource pre-allocation strategy.In order to further reduce the probability of user-to-user conflict,diversity transmission technology is introduced.Through simulation,the influence of data packet arrival rate and diversity times on system performance is analyzed.