Wireless Communication Packet Management For Real-time Wireless Control System

The wireless control system has received more and more attention due to its many advantages.In the fifth generation(5G)cellular network,as a mission-critical scenario,ultra-reliable and low-latency communications(URLLC)can be used as the promoter of real-time wireless control systems.Considering the strict requirements of quality of service(QoS)of URLLC,it is necessary to design suitable scheduling management strategies to meet the communication performance requirements and optimize the control performance according to different control scenarios.Based on two different research scenarios,this text mainly studies how to schedule and manage wireless communication data packets to meet the performance requirements in all levels of the system.1.Design of URLLC packet discarding of real-time wireless control system.In order to maintain ultra-high QoS in the URLLC of the real-time control system under the condition of limited resources,the wireless communication data packets of some remote control devices are inevitably discarded.Since the control constraints of the communication data packets in each time slot of each device are different,the packet loss strategy has a non-negligible impact on the performance of the control system.That is,when designing the scheme of dropping packets,not only the constraints from the communication level but also the requirements of control performance needs to be taken into account.Consequently the integrated design of communication and control is considered to meet the overall performance requirements of the system.In this text,firstly,the system model is established and then an optimization problem is formulated.Next an algorithm is proposed to solve the optimization problem and the optimal strategy of discarding packets is found.Finally,the performance is compared under several different conditions.The simulation results show that the strategy of dropping packets proposed in this text has better performance than the traditional two strategies in terms of control performance.2.An optimal caching method based on cost control in device-to-device(D2D)network.Based on D2 D communication,when the predictive control instructions of the control device in the predictive control system becomes the cache object of the D2 D caching network,the performance requirements of the cache and the control level must be comprehensively considered.From the perspective of predictive control systems,the communication between the controller and the actuator is lossy.As protection against these losses,the controller sends a series of prediction commands in each packet.The received predicted commands are placed in the cache of the actuator.In the absence of a new control packet,the executor reads the current predicted control commands from the cache and sends it to the device.Once the cache is empty and the device does not receive new control commands,the control cost will be incurred.Considering that control constraints of each device are not the same,different caching strategies will cause different control costs.Therefore,a problem with the goal of optimizing system caching performance is be established under the scenario of D2 D communication based predictive control system,and an algorithm is proposed to solve the problem and obtain the best strategy.The simulation results show that the algorithm proposed in this text optimizes the caching performance while optimizing the control performance and minimizing the control cost of the predictive control system.