Wireless Transmission Method And Design Based On Dynamic QoS In Real-time Wireless Control System

In 5G,ultra-reliable and low-latency communication(URLLC)can effectively reduce the packet loss rate and time delay in real-time wireless control systems to meet the high-performance requirements of real-time and reliability in industrial interconnection and automation.However,in order to meet the strict Quality of Service(QoS),URLLC consumes a lot of wireless resources,which seriously hinders the implementation and massive deployment of this technology.First,a clear relationship between the performance of the control system and the characteristics of the wireless network is deduced in order to carry out an communication and control integrated design.Then,with the goal of improving resource utilization,wireless transmission and resource allocation methods are designed.Finally,we ensure the excellent performance of both the control system and the communication system.The main research works are as follows:(1)Random access and resource allocation based on channel state.Considering the multi-control loop real-time wireless control system with distributed access mechanism,multiple sensors independently and randomly decide whether to access the shared wireless medium.In order to reduce the packet collision caused by simultaneous transmission of sensors and the resource loss caused by the extremely high QoS of URLLC,we propose a channel state-based sensor random access and resource allocation method.First,we established an optimization problem that minimizes energy consumption under the constraint of control convergence rate.In order to solve this problem,we derive the relationship between the control subsystem constraints and URLLC QoS requirements,and the control convergence speed,which is the performance constraint of control,is transformed into communication reliability.Then the Lagrangian dual subgradient method in the convex optimization method is used to solve this optimization problem,and we obtain a schedule strategy and a dynamic power allocation method based on the channel state.The simulation verifies that this method can significantly reduce power consumption and ensure the control performance requirements.(2)Power allocation strategy of real-time wireless control system based on Uplink Multi-user Multiple Input Multiple Output(UL-MU-MIMO)antenna technology.Under the premise of ensuring control performance,we obtain the optimal transmission power by optimizing energy efficiency.First,we constructed the UL-MU-MIMO wireless communication model and control system model.Then,the energy efficiency of system is defined,which assumes that all users consume a fixed amount of circuit power in addition to radio frequency power.Next,we established an optimal problem for maximizing energy efficiency,in which both control constraints and QoS requirements in URLLC are considered.Then,from the perspective of joint design of communication and control,the coordination problem is transformed into a conventional communication resource allocation problem through the connection of communication reliability and control constraints.Finally,we propose an exhaustive search method to obtain the optimal power allocation scheme.The simulation results verify that the method can significantly improve the energy efficiency of the system.