Unraveling the potential of Wireless Sensors in the age of Industry 4.0
Abstract: Human civilization is now staring at the fourth industrial revolution, where wireless technologies will play a pivotal role in its success. Wireless sensors’ role is also becoming more significant in the present day to facilitate industrial automation and manufacturing processes and address health, safety, and environmental concerns. However, wireless communication is primarily unreliable due to noise, interference, and channel fading. Several factors, like hardware quality of the sensors, imperfect calibration, harsh environment, and deployment locations, can also affect the sensors’ observation, which throws further challenges for information reliability and latency. These challenges must be addressed urgently for the success of Industry 4.0.The scope of this Ph.D. research works is broadly divided into two research problems. The first research problem, this dissertation investigates, is how to retrieve and process the local detection of wireless sensors in critical industrial applications. Diversity techniques are known to improve the reliability of wireless communication. Therefore, various spatial diversity techniques using an antenna array with a large number of elements at the receiver are investigated first to find out the suitability of wireless communication for critical industrial applications. Moreover, in order to improve sensors’ detection performance, distributed detection methods are popularly used. This Ph.D.thesis proposes techniques and algorithms to transmit and fuse local decisions from non-identical wireless sensors, e.g., sensors with different detection capabilities. The fusion center utilizes the spatial diversity or spatial multiplexing based scheme to retrieve the sensors’ local decisions.In order to design a reliable wireless communication system, it is highly desirable to understand the channel characteristics of the wireless medium. The second research problem this dissertation address is to characterize the radio propagation channel in one of the millimeter wave frequency bands. Millimeter wave wireless technologies bring several benefits, which can further revolutionize the industrial manufacturing and automation processes. In this.D. research work, the radio channel measurements were carried out at the24 GHz ISM band in various industrial environments within Gävle, Sweden, with the help of highly competent in-house assembled affordable testbeds. Several radio propagation aspects, like, the large scale fading, small scale fading, multipath propagation, and Doppler effect, are studied.
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