Simulation And Optimization Of 802.11ax Wireless Control Network For Large-scale AGV Scheduling

With the rapid development of IoT and WSN,Wireless control networks play an increasingly important role in the Internet.The wireless control network is self-organizing,simple to deploy and densely distributed so that it can be applied to almost all areas of social and economic activities.Intelligent logistics warehousing,as a typical application of wireless control networks,has received continuous attention in recent years.For traditional logistics and warehousing,it is not enough to rely on manual operation.The inefficiency caused by the unclear classification of the goods,the unreasonable goods stacking,the damage of the goods and the safety of personnel will bring huge additional costs to the enterprise.In this case,the intelligent automated unmanned storage system can solve this problem well.This paper analyzes and extracts the demands of the wireless control network under the intelligent logistics warehousing scenario and designs a total solution for this network based on the latest generation of Wi-Fi standard,IEEE 802.11 ax,for large-scale,lowlatency,high-throughput requirements.In the PHY layer,this paper establishes a bandwidth segmentation model based on the characteristics of 802.11ax—OFDMA and constructs an end-to-end delay model by analyzing the data transmission process in the network.Based on this,a delay-oriented optimization model for user resource scheduling is proposed.Using this optimization model,a recursive user resource scheduling algorithm and an efficient user grouping algorithm under MU-MIMO are proposed.In order to deal with the bad effects of high user intensification on the network,this paper implements and evaluates the network expansion technology in the IEEE 802.11 ax standard.It mainly reduces the data conflict or interference and increases network capacity by identifying the basic service set(BSS)color bits and the network allocation vector(NAV)and dynamically adjusting the sensitivity threshold and the transmit power to ignore the traffic from the nodes in overlapping basic service set(OBSS).In addition,since the NS-3 simulator used in this paper does not fully support certain features of the PHY layer and MAC layer of IEEE 802.11 ax,another work of this paper is to adjust and extend the relevant functional modules of this network simulation platform.The simulation results show that the recursive-based scheduling algorithm proposed in this paper is 25% and 33% higher than the traditional Best-effort and greedy algorithms respectively.Compared with the 802.11 ac network with the default configuration,the throughput of the 802.11 ax network applying the above network expansion technology is improved a lot.Meanwhile,the data collision and interference caused by user increasing are greatly reduced so that the throughput of all BSSs in the network is more balanced.