Distributed Cooperative Frequency Management Schemes For Industrial Wireless Sensor Networks

Industrial wireless technology, regarded as special wireless sensor systems, will be robust, reliable, cost-efficient, totally secure, and in many cases, integral to the measurement device. It will be the obvious choice for monitoring and controlling industrial processes to optimize resource efficiency and productivity. Although wireless technology has taken a major leap forward with the boom in wireless personal communications, applications to industrial sensor systems must meet some significant different challenges. One of these critical issues is reliability. Industrial applications require absolute sustained performance in harsh environments.This paper principally deals with problems in reliable wireless communication for industrial application. Different from today's networking standards, dynamic spectrum management is brought in industrial wireless system with a distributed architecture for enhancing system reliability and robustness, in collaboration with hybrid direct sequence spread spectrum and frequency hopping spread spectrum technology.This thesis covers spectrum management algorithms commonly used in short range communication for industrial networks, including operational principle, key technology and architecture. A well-designed wireless network architecture will transparently allowing effective allocation, schedule and management for frequency resources. Thus, a dynamic spectrum management scheme will be provided for distributed industrial wireless network architecture.Wireless sensor systems must demonstrate that they can communicate effectively even in areas with high electromagnetic noise or radio frequency interference, and other harsh environments typical of industrial operations. System operations must remain unaffected by such common industrial equipment as moving metal vehicles, storage tanks, arc welders, and banks of variable-speed drives that can affect transmission characteristics. The performance reliability of wireless systems will be sufficiently high that they can be depended upon to perform essential functions, such as managing electromagnetic spectrum. The physical layer is primarily addressed in distributed wireless sensor systems mentioned above. By spreading data transmissions across the available frequency band in a prearranged scheme, spread spectrum encoding technology makes the signal less vulnerable to noise, interference, and snooping. Although there are three spread-spectrum schemes suitable for industrial wireless systems, the two most common are frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS). And a combination of FHSS and DSSS provides both interference rejection (FHSS) and the coding gain (DSSS). There are two key components of this dynamic channel assignment that contribute to end-to-end network reliability: direct sequence spread spectrum and slow frequency hopping. Some of the performance metrics are discussed subsequently. Finally matlab simulation method and channel model are discussed. In conclusion, by defining how a wireless node utilizes radio spectra, joins a network and communicates with neighbors, an implementation of distributed cooperative dynamic frequency management shows a reliable performance for industrial wireless transmission.Beyond above solution, adaptive mechanism is employed in radio communication to protect against notoriously variable and unpredictable point-to-point wireless link. This could be done by utilizing a wideband frequency hopping scheme that would avoid known interference. Such a distributed wireless sensor system, an adaptive frequency hopping (AFH) technology is proposed and analyzed. Results show that a distributed cooperative adaptive system has the advantage of surviving in extremely congested industrial environments.