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HiLoc: Sub-Meter Level Indoor Localization Using a Single Access Point With Distributed Antennas in Wireless Sensor Networks

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SOFT MATTER 2014年第13期10卷 4869-4881页

作者： Liu, Kaikai Tian, Zengshan Li, Ze Wang, Jiacheng Zhou, Mu Chongqing Univ Posts & Telecommun Sch Commun & Informat Engn Chongqing 400065 Peoples R China

Indoor localization as one of the visions of the Internet of Things (IoTs) receives much attention in Wireless Sensor Networks (WSNs). Many prior indoor localization technologies concentrated on multiple Access Points (APs), so developing a system that uses a single AP with high accuracy is indispensable, especially for households or small businesses. To this end, we present HiLoc, a single AP-based indoor localization system with sub-meter accuracy. The key insight of HiLoc is to estimate the relative Time of Flight (ToF) between the target and the distributed antennas and localize the target using the convex optimization accurately. Specifically, HiLoc utilizes the combination of Orthogonal Matching Pursuit (OMP) and Maximum Likelihood (ML) to estimate relative ToF. Then, by applying the semi-definite relaxation technique, the localization process can be transformed into an SDP problem. Unlike the methods that use the iterative least-square, in which an accurate guess of the target location is required, we can find the target location accurately without any initializations. Furthermore, we design the prototype AP using Software-Defined Radio (SDR) platform with Orthogonal Frequency Division Multiplexing (OFDM) signals. Our implementation in extensive indoor environments shows that HiLoc achieves a median localization error of 0.72m at 100MHz signal bandwidth, comparable to the state-of-the-art prior systems.

关键词： Location awareness Antennas Wireless sensor networks Antenna arrays Sensors Bandwidth OFDM Indoor localization single access point semi-definite programming software-defined radio

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Filtering approaches to accelerated consensus in diffusion sensor networks

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INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 2014年第11期27卷 3266-3279页

作者： Abd-Elrady, Emad Mulgrew, Bernard Abu Dhabi Womens Coll Higher Colleges Technol Abu Dhabi U Arab Emirates Univ Edinburgh Inst Digital Commun Sch Engn Edinburgh EH9 3JL Midlothian Scotland

The main objective in distributed sensor networks is to reach agreement or consensus on values acquired by the sensors. A common methodology to approach this problem is using the iterative and weighted linear combination of those values to which each sensor has access. Different methods to compute appropriate weights have been extensively studied, but the resulting iterative algorithm still requires many iterations to provide a fairly good estimate of the consensus value. In this paper, different accelerating consensus approaches based on adaptive and non-adaptive filtering techniques are studied and applied on the problem of acoustic source localization using the adaptive projected subgradient method. A comparative simulation study shows that the non-adaptive polynomial filters based on Newton's interpolating polynomials and semi-definite programming can provide more accelerated consensus and better estimation accuracy than adaptive filters evaluated using constrained affine projection algorithm or stochastic gradient algorithm provided that the network topology is known beforehand. Copyright (c) 2013 John Wiley & Sons, Ltd.

关键词： adaptive filtering adaptive projected subgradient method consensus diffusion networks distributed algorithms optimization methods semi-definite programming

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Linear Pre-coding in MIMO-CDMA Relay Networks

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WIRELESS PERSONAL COMMUNICATIONS 2014年第2期79卷 1321-1341页

作者： Golbon-Haghighi, Mohammad-Hossein Mahboobi, Behrad Ardebilipour, Mehrdad KN Toosi Univ Technol Tehran Iran

Our aim in this paper is to define a novel beamforming approach in wireless multiple-input-multiple-output (MIMO) code-division-multiple-access (CDMA) relay networks, which involves communication between multiple source-destination pairs. It is assumed that full channel state information of source-relay and relay-destination channels are available. Our design consists of a two-step amplify-and-forward protocol. The first step includes signal transmission from the sources to the MIMO relay, and the second step contains transmitting a version of the linear precoded signal to the destinations. Beamforming is investigated only in MIMO-relay node to reduce end user's hardware complexity and save the computational power. Accordingly, the optimization problem is defined to find the MIMO relay beamforming coefficients that minimize total relay transmit power by keeping the signal-to-interference-plus-noise ratio (SINR) of all destinations above a certain threshold value. It is shown that such optimization problem is a non-convex quadratically constrained quadratic programming, which is NP-hard in general. However, by relaxing this problem to a semi-definite programming problem, the problem can be solved efficiently. Simulation results verify the performance gain implied by MIMO-CDMA relay system compared to the non-CDMA coded system.

关键词： semi-definite programming MIMO CDMA Relay networks Power allocation Beamforming MIMO-relay

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Optimal design of multi-response experiments using semi-definite programming

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OPTIMIZATION AND ENGINEERING 2009年第1期10卷 75-90页

作者： Atashgah, Ali Babapour Seifi, Abbas Amirkabir Univ Technol Dept Ind Engn Tehran Iran

Optimal design of multi-response experiments for estimating the parameters of multi-response linear models is a challenging problem. The main drawback of the existing algorithms is that they require the solution of many optimization problems in the process of generating an optimal design that involve cumbersome manual operations. Furthermore, all the existing methods generate approximate design and no method for multi-response n-exact design has been cited in the literature. This paper presents a unified formulation for multi-response optimal design problem using semi-definite programming (SDP) that can generate D-, A- and E-optimal designs. The proposed method alleviates the difficulties associated with the existing methods. It solves a one-shot optimization model whose solution selects the optimal design points among all possible points in the design space. We generate both approximate and n-exact designs for multi-response models by solving SDP models with integer variables. Another advantage of the proposed method lies in the amount of computation time taken to generate an optimal design for multi-response models. Several test problems have been solved using an existing interior-point based SDP solver. Numerical results show the potentials and efficiency of the proposed formulation as compared with those of other existing methods. The robustness of the generated designs with respect to the variance-covariance matrix is also investigated.

关键词： Optimal design of experiment n-exact design Multi-response linear models semi-definite programming

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Shape-Constrained Estimation Using Nonnegative Splines

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JOURNAL OF COMPUTATIONAL AND GRAPHICAL STATISTICS 2014年第1期23卷 211-231页

作者： Papp, David Alizadeh, Farid Northwestern Univ Dept Ind Engn & Management Sci Evanston IL 60208 USA Rutgers State Univ Piscataway NJ 08854 USA

We consider the problem of nonparametric estimation of unknown smooth functions in the presence of restrictions on the shape of the estimator and on its support using polynomial splines. We provide a general computational framework that treats these estimation problems in a unified manner, without the limitations of the existing methods. Applications of our approach include computing optimal spline estimators for regression, density estimation, and arrival rate estimation problems in the presence of various shape constraints. Our approach can also handle multiple simultaneous shape constraints. The approach is based on a characterization of nonnegative polynomials that leads to semidefinite programming (SDP) and second-order cone programming (SOCP) formulations of the problems. These formulations extend and generalize a number of previous approaches in the literature, including those with piecewise linear and B-spline estimators. We also consider a simpler approach in which nonnegative splines are approximated by splines whose pieces are polynomials with nonnegative coefficients in a nonnegative basis. A condition is presented to test whether a given nonnegative basis gives rise to a spline cone that is dense in the space of nonnegative continuous functions. The optimization models formulated in the article are solvable with minimal running time using off-the-shelf software. We provide numerical illustrations for density estimation and regression problems. These examples show that the proposed approach requires minimal computational time, and that the estimators obtained using our approach often match and frequently outperform kernel methods and spline smoothing without shape constraints. Supplementary materials for this article are provided online.

关键词： Bernstein polynomials Density estimation Nonnegative polynomials Regression Second-order programming semi-definite programming Splines

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Sum Secrecy Rate in Multicarrier DF Relay Beamforming 10

Sum Secrecy Rate in Multicarrier DF Relay Beamforming

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International Conference on Signal Processing and Communications (SPCOM)

作者： Vishwakarma, Sanjay Chockalingam, A. Indian Inst Sci Dept ECE Bangalore 560012 Karnataka India

ISBN: (纸本)9781479946655

In this paper, we study sum secrecy rate in multicarrier decode-and-forward relay beamforming. We obtain the optimal source power and relay weights on each subcarrier which maximize the sum secrecy rate. For a given total power on a given subcarrier k, P-0(k), we reformulate the optimization problem by relaxing the rank-1 constraint on the complex positive semidefinite relay weight matrix, and solve using semidefinite programming. We analytically prove that the solution to the relaxed optimization problem is indeed rank 1. We show that the subcarrier secrecy rate, R-s (P-0(k)), is a concave function in total power P-0(k) if R-s (P-0(k)) > 0 for any P-0(k) > 0. Numerical results show that the sum secrecy rate with optimal power allocation across subcarriers is more than the sum secrecy rate with equal power allocation. We also propose a low complexity suboptimal power allocation scheme which outperforms equal power allocation scheme.

关键词： Cooperative relaying physical layer security sum secrecy rate multicarrier multiple eavesdroppers semi-definite programming

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Optimal Beamforming Design for Two-Way Relaying with Simultaneous Energy Harvesting

Optimal Beamforming Design for Two-Way Relaying with Simulta...

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6th International Symposium on Communications, Control and Signal Processing (ISCCSP)

作者： Wang, Feng Wang, Xin Fang, Zhaoxi Zhang, Rui Fudan Univ Dept Commun Sci & Engn Yangpu Peoples R China Zhejiang Wanli Univ Fac Elec & Inf Engnr Hangzhou Zhejiang Peoples R China Natl Univ Singapore Dept Elect & Comp Engn Singapore 117548 Singapore

ISBN: (纸本)9781479928903

We consider the beamforming design in non-regenerative multiuser two-way relaying (TWR) system where the multi-antenna relay performs simultaneous energy harvesting and information processing. Based on a power splitting receiver architecture at the relay, we develop the optimal beamforming scheme that maximizes the minimum of users' signal-to-interference-plus-noise-ratios (SINRs). Given the power splitting ratios, it is shown that the optimal max-min SINR value can be obtained by a semi-definite programming (SDP) based Dinkelbach-type algorithm with fast convergence. Specifically, when all the antennas at the relay use the same power splitting ratio, the jointly optimal power splitting and beamforming design reduces to a one-dimension search for the optimal max-min SINR value;while when the antennas at the relay are allowed to employ different power splitting ratios, a more complex search is required to find the solution. Numerical results demonstrate that simultaneous energy harvesting and information processing have the potential to significantly enhance the performance of multiuser TWR.

关键词： Two-way relaying beamforming energy harvesting power splitting semi-definite programming

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Robust Linear Estimation Fusion with Allowable Unknown Cross-Covariance 17

Robust Linear Estimation Fusion with Allowable Unknown Cross...

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17th International Conference on Information Fusion (FUSION)

作者： Gao, Yongxin Li, X. Rong Song, Enbin Xi An Jiao Tong Univ CIESR Xian 710049 Shaanxi Peoples R China Univ New Orleans Dept Elect Engn New Orleans LA 70148 USA Sichuan Univ Dept Math Chengdu 610064 Sichuan Peoples R China

ISBN: (纸本)9781479916344

This paper deals with distributed estimation fusion under unknown cross-covariance between errors of local estimates. We propose a constraint to restrict the set of possible cross-covariance matrices first. Then this constraint, named allowance degree of cross-covariance, is used to derive a fusion method. Based on the allowance degree, we present an optimal robust fusion method in the minimax sense via semi-definite programming and also a suboptimal fusion. We analyze the properties of the proposed fusion methods and describe the relationship between the suboptimal fusion and some existing fusion methods. Numerical examples are given to illustrate their performance compared with the traditional covariance intersection method.

关键词： Estimation fusion robust fusion minimax semi-definite programming covariance intersection

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A STUDY ON THE STATISTICAL MODELING OF FADING AND ITS EFFECTS ON SYSTEM PERFORMANCE USING SIRP AND SDP METHODS

A STUDY ON THE STATISTICAL MODELING OF FADING AND ITS EFFECT...

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IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

作者： Yang, Cheng-An Yao, Kung Biglieri, Ezio Univ Calif Los Angeles Dept Elect Engn Los Angeles CA 90095 USA

ISBN: (纸本)9781479928934

Many statistical models (mainly due to physical propagation studies and field measurements) have been proposed to characterize the statistics of the NLOS flat-fading wireless communication channel. There appears to have no known statistical theory on the formation of many of these fading envelope statistics. We offer the statistical modeling of fading envelope statistics under the NLOS assumption based on the SIRP representation. In practice, these channel statistics cannot be modeled with certainty. We advocated the use of moment-bound theory to obtain bounds on the system performance metrics. In this paper, we combine the theory of moment bounds with that of SIRP, and the use of the SDP optimization method to show how sharper bounds of the error rate and ergodic channel capacity of a communication system can be computed.

关键词： Fading distribution Spherically-invariant random process semi-definite programming Moment bound theory performance bounds of BPSK systems

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Worst Case SINR Guarantees for Secrecy using Relay Beamforming with Imperfect CSI

Worst Case SINR Guarantees for Secrecy using Relay Beamformi...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Sujana, Agepati Vishwakarma, Sanjay Chockalingarn, A. Indian Inst Sci Dept ECE Bangalore 560012 Karnataka India

ISBN: (纸本)9781479930838

In this paper, we study beamforming techniques for secrecy with worst case signal-to-interference-plus-noise ratio (SINR) guarantees in cooperative communications with imperfect channel state information (CSI). The worst case SINRs are the minimum SINR at the intended destination and the maximum SINR at the eavesdroppers. We consider a norm bounded CSI error model. With the available imperfect channel estimates, we design beamformers such that the minimum SINR receivable by the intended destination is above a certain threshold, while the maximum value of SINRs receivable at the eavesdroppers are below another lower threshold. We consider amplify-and-forward (AF) and decode-and-forward (DF) relaying schemes. The relays do the worst case transmit beamforming and injection of artificial noise (AN). We jointly optimize the beamformers and the AN for the AI;and DF schemes subject to the worst case SINR constraints at the destination and the eavesdroppers. We solve the corresponding optimization problems as semi-definite programming (SDP) problems by rank relaxation and S-procedure. Numerical results show that AN injection at the relays significantly reduces the average total transmit power required to meet the worst case SINR constraints, and improves the solution feasibility of the optimization problems.

关键词： Physical layer security cooperative communication artificial noise imperfect CSI semi-definite programming S-procedure

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