Network Layer Software Design And Key Management Research For WirelessHART

Industrial wireless technology is a research focus in industrial control field in 21st century following the fieldbus. It is a revolutionary technology which can reduce costs of the industrial measurement and control system and improve the range of industrial measurement and control system applications. WirelessHART is the first wireless mesh network communications protocol designed to meet the needs for process automation applications. It solves the problem of traditional wired HART industrial applications' limitations and adds the ability of wireless communication. WirelessHART is backward compatible with existing HART devices and applications. It has the advantages of simple, reliable and secure. Existing HART applications can utilize WirelessHART without software upgrades. Based on the WirelessHART protocol stack, the network manager can configure and manage the WirelessHART network and the gateway can collect data from the field device. So it is very meaningful to design and implement a proprietary protocol stack software for WirelessHART. A secure and efficient key management scheme can ensure the WirelessHART secure applications in industrial process automation.At the beginning of the paper, the research significance and status of WirelessHART protocol stack software and network key management are described. WirelessHART architecture is also analyzed. Secondly, after building the fundamental development environment on CC2430 chip, the protocol stack software's architecture is designed based on the hierarchical communication model of the protocol stack. The no operating system mode can make code execution more efficient and ensure the memory resource meet the requirement of the follow-up software development. The designed protocol stack software's architecture provides good guidance for the detailed design of each protocol layer. Thirdly, the WirelessHART network layer software is designed based on the protocol stack software's architecture. The detailed design includes network layer state machine design, network layer initialization design, network layer primitive task processing design and network layer background task processing design. The task processing mechanism that primitive is prior to state can benefit the expansion of the protocol stack. Also the primitive task processing scheme can improve the utilization rate of the embedded system's memory and the efficiency of the software development. A brief WirelessHART application layer software is designed to realize device's joining and data transmission. Fourthly, a one-way hash function-based key management scheme for WirelessHART networks is proposed. In the proposed key management scheme, double hash key chains are used to realize broadcast authentication for key renewal and to solve the problem that the renewal times of the whole network share keys are limited. Broadcast and unicast communications are combined to enforce the reliability of key renewal in WirelessHART networks. Compared with the existing key management scheme for WirelessHART networks, the proposed scheme improves the network's security and reduces the network's communication energy consumption without increasing the computing energy consumption and memory overhead. At last, the designed WirelessHART network layer software is tested, and the test results show that the designed network layer software can complete the required functions of the network layer.