Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Wireless network positioning as a convex feasibility problem | Gholami et al. EURASIP Journal on Wireless Communications and Networking 2011 2011 161 EURASIP Journal on . http content 2011 1 i6i Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Wireless network positioning as a convex feasibility problem Mohammad Reza Gholami Henk Wymeersch Erik G Strom and Mats Rydstrom Abstract In this semi-tutorial paper the positioning problem is formulated as a convex feasibility problem CFP . To solve the CFP for non-cooperative networks we consider the well-known projection onto convex sets POCS technique and study its properties for positioning. We also study outer-approximation OA methods to solve CFP problems. We then show how the POCS estimate can be upper bounded by solving a non-convex optimization problem. Moreover we introduce two techniques based on OA and POCS to solve the CFP for cooperative networks and obtain two new distributed algorithms. Simulation results show that the proposed algorithms are robust against non-line-of-sight conditions. Keywords wireless sensor network positioning algorithm convex feasibility problem projection onto convex sets outer approximation 1 Introduction Wireless sensor networks WSNs have been considered for both civil and military applications. In every WSN position information is a vital requirement for the network to be able to perform in practical applications. Due to drawbacks of using GPS in practical networks mainly cost and lack of access to satellite signals in some scenarios position extraction by the network itself has been extensively studied during the last few years. The position information is derived using fixed sensor nodes also called reference nodes with known positions and some type of measurements between different nodes 1-7 . From one point of view WSNs can be divided into two groups based on collaboration between targets cooperative networks and non-cooperative networks. In cooperative networks the measurements .
