Research Of Power Control Strategy For Industrial Wireless Network

With the rapid development of wireless sensor network technology and increasingly sophisticated wireless technology into the field of industrial control systems, and has become a hot research of industrial control systems. Industrial wireless technology has many advantages of low cost, low power consumption, simple to deploy, extensive application prospects. Countries and companies have added to the research and development of industrial wireless network technology, and developed the internationally recognized protocol standard, WIA-PA standard has our own intellectual property, industrial wireless networking standard approved by the the leading industry of China in the field of industrial wireless network technology which has been in the leading technology.Industrial wireless network WIA-PA as an emerging technology, with high real-time, high reliability, low power and low cost, in all aspects of research continued to mature at the same time, there are also traditional wireless network technology problems, such as network energy conservation issues. WIA-PA protocol stack hierarchy, the physical layer and MAC layer is compatible with IEEE802.15.4 protocol, using the design of TDMA and save network energy consumption, however, inconvenient to adopt to bring their own battery-powered, and replace the battery WIA-PA network nodes, the nodes energy is very limited, the need to save all you can save energy, remove all unnecessary energy expenditure.The author participated in researchiong and developing WIA-PA network, studied in-depthly about sensor node energy consumption issues and found that the energy of the uniform transmission power to send messages will cause significant waste, which would affect the life cycle of the network. Combined with characteristics and network energy consumption needs of WIA-PA industrial wireless network and based on PCSMAC power control protocol,the paper provided a new power control algorithm PCWIA (Power Control Protocol for the WIA-PA, based on the RSSI and of SIR),which determined the optimal transmit power according to the RSSI and SIR. The algorithm taked into account external factors such as channel interference and asymmetric characteristics of the wireless link, by dynamically adjusting the transmission power, and the nodes sended packets to minimize the required transmit power to reduce node energy consumption, and ultimately extended the network lifetime and improve the energy efficiency of the network; and reduced the range of each source node sending a signal when the interference, which will reduce mutual interference between the communication nodes,and improve network reliability.This article first analyzes the current study of network-level power control, neighbor node level power control and independent node-level power control protocol, and point out that these agreements or policy applied to the shortcomings of WIA-PA. The study found that the the only PCSMAC agreement to calculate the minimum transmission power of thinking is closest to the WIA-PA application requirements and network characteristics. Therefore, the author based on the PCSMAC WIA-PA network of the wireless link characteristics and the requirements for power control protocol proposed a power control strategy based on the asymmetric link PCWIA. Single link metrics used in the calculation of the minimum transmit power for PCSMAC calculate the minimum transmit power accuracy is not enough and did not respond to link quality changes; the proposal of the agreement based on the symmetry properties of the wireless link is not established, combined with the WIA-characteristics of the PA network, PCWIA calculate the optimal transmission power is taken into account link quality RSSI and signal to interference ratio of SIR, the power control strategy can make the appropriate response to network link quality is good or bad, enhanced power control strategy effectiveness and robustness; in PCWIA in the asymmetric characteristics of the wireless link power control strategy to prevent the power control of the wireless link asymmetry caused by packet loss, thereby affecting network performance and energy-saving effect of the network. Finally, in the network environment using NS2 simulation software configuration, in theory, using the power control strategy PCWIA WIA-PA network average than WIA-PA network does not use power control to 13% energy savings, the simulation results show that did not use the power control of the WIA-PA network energy consumption using PCWIA than a decrease of 15.3%. Theoretical analysis and experimental results show that, relative to PCSMAC terms of PCWIA more saving network energy consumption, a more robust and better scalability, in order to verify the effectiveness of the PCWIA WIA-PA.