| The Internet-of-Things(IoTs)technology has been considered as the core component of the next-generation information technology,which has drawn more and more attentions for countries all over the world.IoT technology has been widely adopted in smart traffic,smart city,intelligent medical care,and intelligent industries,where a great amount of innovative and demonstrative applications and industries have been developed.In particular,wireless industrial control network(WICN)utilizes wireless communication technologies to monitor and control physical devices in an industrial production environment.As an emerging industrial communication technology,WICN enables IoT to be adaptively used in the industrial production with theoretical and technological foundations.Compared with the traditional wireless control networks based on the wired communication,WICN has various advantages including low installation and maintenance cost,high scalability and mobility.Therefore,WICN becomes a promising design choice in the intelligent industrial production systems.Due to the restrictions on the node size and deployment environment,wireless nodes are typically battery-powered.Energy consumption has direct impact on the operation and maintenance cost,lifetime and transmission reliability of the network.Therefore,it has become one of the most important research issues in the field of wireless networks.Unlike traditional wireless sensor networks,which are mainly used for environmental data acquisition and monitoring,the contemporary wireless industrial control network has been widely used in closed-loop control tasks of field equipment in industrial production environment.The real-time constraints determine whether the collection of key information and the transmission of control instructions in the process of industrial automation control can be completed in a predictable time.Real-time network systems need to provide upper bound guarantee for end-to-end communication delay between nodes in the milliseconds granularity,which leads to new challenges for the design of architecture and protocols in data link layer and network layer.However,traditional wireless network energy optimization technologies often do not take real-time as the core design constraints,therefore cannot be directly applied to the wireless industrial control network with real-time acquisition and control tasks as the main design considerationsTaking the standard WirelessHART protocol as an example,in order to ensure the reliability and real-time transmission,it usually chooses the path based on link quality as the key consideration,which potentially causes the problems of node energy black hole and scheduling congestion.Aiming at the above problems,this work aims at the design and multi-objective optimization of real-time,reliability and low power consumption in the design of routing protocols for wireless industrial control networks.On the basis of guaranteeing the real-time transmission delay,the network communication protocols with high reliability and low power consumption are studied in order to design networks with high reliability and low power consumption which provides theoretical basis and technical support for real-time wireless industrial control network system.Given the above research objectives,this work study the routing protocol design of WirelessHART network.The main research work and contributions include the following contents.The standard WirelessHART routing selection only considers channel quality as the input factor,which potentially leads to high energy consumption and low reliability in the network communication.In this work,we propose to integrate layer levels and residual energy of forwarding nodes into the process of link selection.On this basis,a reliable graph routing construction algorithm and an energy efficient graph routing algorithm are proposed.Energy efficient link selection algorithm improves network robustness and prolongs network lifetime.Firstly,in the process of constructing the routing graph,this paper proposes to add a forwarding link to a node at the same layer when a node has only one upper forwarding node,so as to ensure that each node has enough choice when selecting the uploading links.Furthermore,the paper puts forward an optimal link selection scheme by considering link quality,energy consumption,hop number and other factors in the process of link selection,and using comprehensive analysis method to determine the weight coefficient.By adding redundant links and choosing links reasonably,the success rate of transmission is greatly increased and the number of retransmissions is reduced,thus enhancing the robustness of the network and prolonging the network lifetime.Finally,in the simulation experiment the proposed algorithm is compared with the existing JRMNL and RUG WirelessHART routing protocols.The experimental results show that the algorithm proposed in this work has obvious advantages in prolonging network life and improving data transmission reliability.Data fusion has become a widely recognized energy-saving technology in wireless sensor networks by reducing the number of data transmission in the whole network to reduce network energy consumption.However,the existing data fusion methods often fail to consider the real-time requirements of network communication.In the process of data forwarding,data packets need to wait at some nodes to be aggregated with packets from other nodes,which potentially leads to some data packets missing the end-to-end communication deadline constraints.To the best of our knowledge,this paper proposes the first data fusion framework for real-time communication in industrial wireless networks.It combines the data fusion method with the link selection and superframe scheduling stage of WirelessHART network routing algorithm.The proposed framework reduces the transmission times of data packets through data fusion,and guarantees the real-time and reliability requirements of the network.In the link selection of uploading path,the key factors such as link quality,energy consumption,residual energy and fusion factors are fully considered.Under the influence of fusion factors,the link pointing to the parent node with higher transmission frequency is chosen as the uploading link,so that more data packets in the network can be aggregated.On this basis,this work reconstructs the superframe based on the greedy heuristic method,so that at the intermediate routing node,the data packets that can be fused into a single packet can be allocated to similar slots,thus reducing the waiting time overhead of data fusion,so that the network using data fusion still maintains the real-time characteristics.The experimental results show that the framework proposed in this chapter satisfies the real-time requirements of network communication at the cost of a certain fusion waiting time.Meanwhile,the energy consumption of a single node and the overall lifetime of the network are substantially improved.Clustering-based routing protocol is also one of the well-established technologies for energy consumption optimization in wireless sensor networks.By periodically selecting cluster head nodes to be responsible for data forwarding within the cluster,clustering-based routing balances the residual energy of the network nodes and improves the network life cycle.At the same time,clustering routing intuitively makes data fusion easier when the cluster head forwards data,which further reduces the network communication overhead.In this paper,for the first time,cluster routing and superframe scheduling algorithm based on node frequency are introduced into WirelessHART network.Firstly,the cluster head selection process is introduced into the uploading link selection phase of WirelessHART protocol.The weights are calculated comprehensively from the aspects of node communication energy consumption,residual energy,frequency of data generated by field devices themselves to determine the selection of the upload link,so as to meet the real-time constraints of the superframe scheduling phase with the best efforts.Furthermore,the superframe scheduling phase of WirelessHART communication protocol is redesigned,which combines superframe scheduling with clustering-based data fusion.Meanwhile,the size of the packet and the frequency of the node are optimized to ensure the end-to-end delay of the packet.The experimental results show that,compared with the existing WirelessHART communication protocols,the clustering-based routing algorithm proposed in this paper can improve the average network life by 40%under end-to-end real-time constraints.The above-mentioned research work primarily considers the combination of subjective and objective based comprehensive analysis method for link selection,which to a certain extent depends on the subjective judgment in the process of network design.In addition.the above methods determine the next hop link selection scheme according to the local network state,ignoring the global end-to-end path energy consumption status and real-time performance.In order to solve the above problems,we further propose a node energy consumption prediction algorithm based on LSTM(Long-Short Term Memory).The link loss between nodes is analyzed by using link transmission loss and time information over the past period of time.Then,using the link transmission loss obtained from the analysis,the link selection problem from field devices to the gateway in the network system can be modelled.We further propose an end-to-end path selection and scheduling algorithm based on ant colony algorithm for WirelessHART,which reduces the data transmission delay in the equipment network and balance the energy consumption of the transmission nodes in the network.Link selection method based on LSTM puts forward some requirements for computing power of the gateway.At the same time,compared with the previous methods,the global prediction of network end-to-end paths makes the residual energy of network nodes more balanced,and further improves the network lifetime while guaranteeing real-time performance. |
