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TopNetwork Controlled Systems are feedback control systems wherein the control loops are closed through a real-time network. Some research papers such as (Yang, T. C. 2006, Yang, T. C et al., 2005 & Yu, H et al., 2005) present discussions of design issues and some brief studies for NCS. Other papers such as in (Pavon, et al., 2004) study the effects of the Medium Access Control (MAC) protocol on the performance of the NCSs and consider a joint performance index of all the systems sharing the wireless channel. In Li, and Li (2010), network controlled loops are considered and real time character is the common request of the distributed control system. Other works of the literature deal with secure systems that allow access to privileged data, when the medium access is a wireless network based on IEEE 802.11 standard (Mejía-Nogales, J et al., 2009). Suzuki, T et al., (2001) proposed priority scheduling schemes for multimedia transmission with the PCF (Point Coordination Function) of the IEEE 802.11 standard MAC protocol where the Access Point controls all transmissions based on a polling mechanism. In Siwaruk, S (2008), author evaluated the throughput performance of the 802.11e MAC HCF (Hybrid Coordination Function) and compared it with the 802.11 legacy MAC. The HCF provides a virtually collision-free WLAN environment and can support a desirable QoS requirement as in PCF while maintaining simplicity and on-demand medium access nature as in DCF.
Considerable efforts have also been invested toward reducing the power consumption in networks using clustering technique. In Ketki Ram, B et al. (2012), a grid based clustering algorithm for minimizing energy consumption is proposed where clustering is formed depending upon the interest of nodes. Authors in Tipsuwan, et al., (2009) studied the design of a new sensor network platform for reliably detecting, classifying, and quickly reporting rare, random, and ephemeral events in a large-scale, long lived and retaskable manner. This new mote was designed for the ExScal project which seeks to demonstrate a 10 000 node network capability of discriminating civilians, soldiers and vehicles, spread over a large area, with node lifetimes approaching 1000 hours. Many other works aim at reporting an overview of WSNs technologies, main applications and standards, features in WSNs design, and evolutions. In particular, some peculiar applications, such as those based on environmental monitoring are discussed and design strategies highlighted.