Decentralized Detection in IEEE 802.15.4 Wireless Sensor Networks
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Research Article Decentralized Detection in IEEE 802.15.4 Wireless Sensor Networks ` 1 Chiara Buratti,2 Gianluigi Ferrari,1 and Roberto Verdone2 Marco Martalo, 1 Wireless
Ad hoc and Sensor Networks (WASN) Laboratory, Department of Information Engineering, University of Parma, Viale G. P. Usberti 181/A, I, 43100 Parma, Italy 2 Wireless Communication Laboratory (WiLab), Department of Electronics, Computer Sciences, and Systems, University of Bologna, Viale Risorgimento 2, I, 40136 Bologna, Italy ` [email protected] Correspondence should be addressed to Marco Martalo, Received 18 February 2010; Revised 11 June 2010; Accepted 23 August 2010 Academic Editor: Carles Anton-Haro Copyright © 2010 Marco Martalo` et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We present a mathematical model to study decentralized detection in clustered wireless sensor networks (WSNs). Sensors and fusion centers (FCs) are distributed with the aim of detecting an event of interest. Sensors are organized in clusters, with FCs acting as cluster heads, and are supposed to observe the same common binary phenomenon. A query-based application is accounted for; FCs periodically send queries and wait for replies coming from sensors. After reception of data, FCs perform data fusion with a majority-like fusion rule and send their decisions to an access point (AP), where a final data fusion is carried out and an estimate of the phenomenon is obtained. We assume that sensors are IEEE 802.15.4-compliant devices and use the medium access control (MAC) protocol defined by the standard, based on carrier-sense multiple access with collision avoidance. Decentralized detection and MAC issues are jointly investigated through analytical modelling. The proposed framework allows the derivation of the probability of decision error at the AP, when accounting for packets’ losses due to possible collisions. Our results show that MAC losses strongly affect system performance. The impact of different clustering configurations and of noisy communications is also investigated.
1. Introduction and Related Work Wireless sensor networks (WSNs) have become an interesting research topic, both in military and civilian scenarios [1]. Remote environmental monitoring, such as surveillance of reserved areas, are important fields of application of WSNs. These applications often require very low-power consumption, low-cost hardware [2], and clustering has been proposed as a possible approach for saving energy. As an example, when contention-based medium access control (MAC) protocols are used, splitting nodes in small clusters not interfering among them allows to decrease the time needed for accessing the channel and, therefore, the energy consumed. In fact, the smaller is the number of nodes competing for the channel, the lower will be the probability to find the channel busy and to delay transmissions. The i
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