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ABSTRACT: In order to improve the efficiency of paging management, various paging strategies have been proposed for tracking single mobile user in the wireless cellular network. However, most of the schemes have ignored the important problem of efficient search for multiple mobile users under delay and bandwidth constraints. Given the condition that the search is over only after all the users in the group are found, this problem is defined as the Conference Call Search (CCS) problem. As opposed to the single user tracking, for which one can always reduce the expected search cost, for a multicast search the dependency between the delay and the search cost is NP-hard. In this paper, we propose a non-optimal search method that yields a low search delay as well as a low search cost. The 2D Markov walk is used as the mobility model which describes a broad class of mobility patterns. The Weighted Bipartite Graph Matching is used to allocate paging bandwidth which keeps a total maximum location probability at each paging round. Experimental results show that our paging scheme also achieves a low paging cost and delay compared to other schemes proposed in the literature.
Global Telecommunications Conference, 2009. GLOBECOM 2009. IEEE; 01/2010
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ABSTRACT: This paper presents an adaptive multigrid method used in both the forward and inverse problems. The proposed method combines adaptive mesh and multigrid solution strategy to resolve the forward problem. The accuracy and efficiency of the former forward solver are improved by incorporating the above two procedures. For image reconstruction the regularized Gauss-Newton method combined with adaptive multigrid method can improve the spatial resolution of reconstructed images. Both experimental and simulated results are presented.
Instrumentation and Measurement Technology Conference Proceedings, 2007. IMTC 2007. IEEE; 06/2007
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ABSTRACT: Electrical impedance tomography (EIT) is a technique for reconstructing the conductivity distribution inside an inhomogeneous distribution by injecting currents at the boundary of a subject and measuring the resulting changes in voltage. A hybrid method is proposed for solving the inverse problem for EIT, which combines the Krylov subspace and the Tikhonov regularization for double levels of regularization to the ill-posed problem. Numerical simulation results using the hybrid method are presented and compared to those from truncated singular value decomposition (TSVD) regularization and the Tikhonov regularization. Experimental results with the hybrid method are also presented, indicating that the hybrid method can reduce the computation time, and improve the resolution of reconstructed images with the regularization parameter automatically chosen by the L-curve method.
Measurement Science and Technology 01/2007; 18(3):813. · 1.49 Impact Factor
