Research On The Multi-Service Adaptive Wireless Communication Protocol For Industrial Networks

Recently,as the key technology in the industrial field,the industrial Internet makes industrial automation possible for all production enterprises in the future.Compared with wired networks,wireless networks have many advantages such as low cost and high flexibility,so wireless communication has become the best choice for users in complex industrial situation.Generally,traditional industrial networks only undertake the transmission of industrial control information,which are suitable for applications of low speed and delay.However,with the upgrading of industrial wireless networks,more and more applications appear in the industrial networks,but these different kinds of applications have different Quality of Service(QoS)requirements.Thus,the traditional wireless communication protocols need to be modified or extended to make them more adaptable in the upgraded industrial networks.This paper introduces the detail of the wireless LAN IEEE802.11 standard.It is well known that IEEE 802.11 MAC layer provides two kinds of medium access mechanism,named Distributed Coordination Function(DCF)and Point Coordination Function(PCF),respectively.Since the DCF and PCF mechanism cannot meet the QoS performance of the coexistence of various kinds of applications simultaneously,for this purpose,based on the access mechanism of IEEE802.11 MAC layer,this paper proposes a multi-service adaptive wireless network communication protocol(MSA-MAC).In this paper,according to the different QoS demands of a variety of services,the industrial applications are divided into three categories,namely control business,audio and video business and general data business.The application is differentiated by the Type of Service(ToS)in the IP packet encapsulated into the MAC Protocol Data Unit(MPDU).Besides,the calculation formulas and models of these applications are specifically given.In the polling algorithm of the MSA-MAC mechanism,the Access Point(AP)decides whether the clients need to be polled by defining the MAC management frame.At the same time,the AP prioritizes eachpolled client dynamically based on business requirements and the number of successful and missed polls,which determines the polling time slots from the AP.The higher the priority,the more polling slots the client will get.On the basis of the real-time of applications,the polling interval allocation algorithm for the MSA-MAC mechanism assigns the time required during CFP.By designing the mobile node model on the simulation software ns-2,the traditional DCF mechanism,the PCF mechanism and the proposed adaptive mechanism are verified in different application scenarios,respectively.Finally,the simulation results show that the MSA-MAC adaptive mechanism exhibits better network performance than DCF and PCF mechanism,which meets the QoS requirements of various services.