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Study on Reliability of Industrial Wireless Networks and Testbed Design

Author: LiYunHuan
Tutor: ChenCaiLian
School: Shanghai Jiaotong University
Course: Control Theory and Control Engineering
Keywords: Industrial wireless network Reliability Wireless HART Cognitive radio technology Collaboration transmission technology
CLC: TP273
Type: Master's thesis
Year: 2012
Downloads: 59
Quote: 0
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Abstract

With the development of wireless sensor network technology, industrial wireless technology has become a new research focus in the field of industrial control has been widespread concern in academia and industry. Industrial wireless technology can be extended to the industrial control network can not reach the areas of the actual conditions or economic reasons, such as rolled steel industrial process monitoring and control many \longer barriers to access to information. Wireless technology, however, in order to be successfully used in the field of industrial control, you first need to ensure the high reliability of the transmission. Industrial field wireless link reliability than the cable channel many influencing factors mainly come from two aspects: on the one hand, due to the noise complex and volatile, on-site use of electronic devices such as WiFi and Bluetooth cause severe co-channel industrial wireless network interference; random industrial site and humid environment and metal equipment caused by reflections wireless signal fading quite serious. Industrial wireless network reliability problem is the focus of attention required for its application. The papers for a typical industrial wireless networking standard ━ ━ Wireless HART, analysis of the reliability of technical features and outstanding problems, propose methods to improve the anti-jamming and anti-fading industrial wireless network, improve reliability. The wireless HART mainly using Direct Sequence Spread Spectrum / blind hopping mechanism for processing high-power two methods to improve the reliability of wireless transmission. The key to the former method is a frequency hopping channel for the network to provide the most reliable collection the continuous skip disturbed channel will still cause the link transmission interruption. The latter method only overcome mist absorption, diffraction fading due to signal fading is more effective, but resistance to signal fading caused by multipath transmission is not very obvious, but will also cause serious interference within the network, and the power consumption. To solve the above problem, this paper carried out the research work of the following: 1 for the wireless HART direct sequence spread spectrum / blind hopping mechanisms are inadequate, the use of cognitive radio technology to optimize the frequency hopping channel set to optimize the industrial anti-jamming capability of the wireless network. We use spectrum sensing method based on the fast Fourier transform, the establishment of a collection based cognitive radio hopping channel optimization model, based on the optimal level traversal algorithm to solve the optimization problem. The advantage of the proposed method: (1) maximize the spreading gain, that achieve the hopping channel set of channel capacity and maximize; (2) maximize hopping gain, ie, to maximize the number of channel frequency hopping channel collection . Therefore, you can achieve the purpose of the maximization of industrial wireless network anti-jamming capability. 2, to increase the transmit power for wireless HART anti-fading interfere with this deficiency is likely to cause internal network, cooperative transmission diversity gain access to space and time to overcome multipath fading. The principle of the method is the link on each radio the device listens link approached the several hops radio equipment signal, using the maximum ratio combining and then demodulated to achieve. Firstly, given the relationship between the link reliability is the number of nodes involved in collaborative m path loss coefficient, the simulation results show that when m = 2 can be obtained a significant reliability gain, as m increases, reliable sexual gain saturation. Sites In this paper, a non-orthogonal transmission mode to compensate for a decline in throughput of the link, and simulation analysis of the number m of the cooperative nodes the maximum symbol deviation and the path loss coefficient of the influence of non-orthogonal cooperative diversity gain. Existing wireless test node existence of the physical layer reconfiguration constrained the reassortant long time and not easy to achieve synchronization configuration shortcomings difficult loop simulation of cognitive radio and cooperative transmission technology. In order to achieve the test of the ability of anti-interference and fading industrial wireless network, the paper based on existing software radio architecture using programmable RF front-end programmable IF processing chip DSP baseband processor design reconfigurable physical layer. In order to achieve the parameters of the physical layer synchronization reassortant, we developed a high-precision synchronization based on GPS clock source and the AD9548 chip clock source. In order to reduce the reconfiguration delay, using SCM configure the internal registers of the programmable chip, theoretical calculations show that the configuration of the delay can be controlled in about 100 s, and can reach the needs of industrial wireless frequency hopping.

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