Xiao-Wen CHANG

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• COMP 350
Numerical Computing
• COMP 540
Matrix Computations
• COMP 642
Numerical Estimation
•  Publications J. Wen and X.-W. Chang. Sharper Bounds on Four Lattice Constants, Designs, Codes and Cryptography, to appear. X.-W. Chang, Z. Chen and J. Wen. An extended Babai method for estimating linear model based integer parameters, Econometrics and Statistics, to appear. J. Wen and X.-W. Chang. On the Success Probability of Three Detectors for the Box-Constrained Integer Linear Model, IEEE Transactions on Communications, 69 (2021), pp. 7180-7191 H. Li, X.-W. Chang and B. Champagne. Success-Probability-Based Power Allocation for Downlink PNC in Multi-way Relay Channels, Proc. IEEE VTC-Spring, Helsinki, Finland, April 2021, 6 pages. X.-W. Chang, C.C. Paige and D. Titley-Peloquin. Structure in Loss of Orthogonality, Linear Algebra and Its Applications, 623 (2021), pp. 149-167. S. S. Hosseini, B. Champagne and X.-W. Chang. Power Allocation Scheme for Cell-Free Massive MIMO Systems, IEEE Access, 9 (2020), pp. 6498-6512. X.-W. Chang and D. Titley-Peloquin. An Improved Algorithm for Generalized Least Squares Estimation, Numerical Algebra, Control and Optimization, 10 (2020), pp. 451-461. X.-W. Chang, Z. Chen and Y. Xu. On the Randomized Babai Point, Proceedings of The 2020 IEEE International Symposium on Information Theory (ISIT), pp. 1195-1200. M. Zhao, S. Luan, I. Porada, X.-W. Chang, and D. Precup. META-Learning State-based Eligibility Traces for MoreSample-Efficient Policy Evaluation, Proceedings of the 19th International Conference on Autonomous Agents and MultiAgent Systems (AAMAS), May 2020, pp. 1647-1655. S. S. Hosseini, J. Abouei, B. Champagne and X.-W. Chang. A Novel Cooperative HARQ Protocol for Free-Space Optical Broadcasting Systems, IEEE/OSA Journal of Lightwave Technology, 38 (2020), pp. 1789-1799. X.-W. Chang, P. Kang, and D. Titley-Peloquin. Error Bounds for Computed Least Squares Estimators, Linear Algebra and Its Applications, 586 (2020), pp. 28-42. S. Luan, M. Zhao, X.-W. Chang and D. Precup. Break the Ceiling: Stronger Multi-scale Deep Graph Convolutional Networks, Proceedings of Thirty-third Conference on Neural Information Processing Systems (NeurIPS 2019), pp. 10943--10953. H. Li, X.-W. Chang, B. Champagne and Y. Cai. Efficient Detection Scheme for Physical-layer Network Coding in Multiway Relay Channels, IEEE Access, 7 (2019), pp.167639-167652. J. Wen, X.-W. Chang and J. Weng. Improved Upper Bounds on the Hermite and KZ Constants, Proceedings of The 2019 IEEE International Symposium on Information Theory (ISIT), pp. 1742-1746. A. Morsali, S. S. Hosseini, B. Champagne and X.-W. Chang. Design Criteria for Omnidirectional STBC in Massive MIMO Systems, IEEE Wireless Communications Letters, 8 (2019), pp.1435-1439. J. Wen and X.-W. Chang. On the KZ Reduction, IEEE Transactions on Information Theory, 65 (2019), pp. 1921-1935. X.-W. Chang and V.J. Prevost. Success Probability of a Suboptimal Solution to the Sparse MAP Detection, Proceedings of The 2018 IEEE International Symposium on Information Theory (ISIT), pp. 66-70. S. Yousefi, X.-W. Chang, H. Wymeersch, B. Champagne and G. Toussaint. A Novel Approach for Ellipsoidal Outer-Approximation of the Intersection Region of Ellipses in the Plane, Computational Optimization and Applications, 69 (2018), pp. 383-402. X. Lin, Y. Chen, X.-W. Chang, X. Liu and X. Wang. SHOW: Smart Handwriting on Watches, Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies, 1 (2017), Issue 4, Article No. 151. J. Wen, X.-W. Chang and C. Tellambura. On the Success Probability of the Box-Constrained Rounding and Babai Detectors, Proceedings of The 2017 IEEE International Symposium on Information Theory (ISIT), pp. 526-530. J. Wen and X.-W. Chang. GfcLLL: A Greedy Selection Based Approach for Fixed-Complexity LLL Reduction, IEEE Communications Letters, 21 (2017), pp. 1965-1968. X. Lin, X.-W. Chang and X. Liu. LocMe: Human Locomotion and Map Exploration based Indoor Localization, Proceedings of The 2017 IEEE International Conference on Pervasive Computing and Communications (PerCom), pp. 131-140. J. Wen and X.-W. Chang. Success Probability of the Babai Estimators for Box-constrained Integer Linear Models, IEEE Transactions on Information Theory, 63 (2017), pp. 631-648. J. Wen and X.-W. Chang. A Linearithmic Time Algorithm for a Shortest Vector Problem in Compute-and-Forward Design, Proceedings of The 2016 IEEE International Symposium on Information Theory (ISIT), pp. 2344-2348. J. Wen, B. Zhou, W. Mow, and X.-W. Chang. An Efficient Algorithm for Optimally Solving a Shortest Vector Problem in Compute-and-Forward Design, IEEE Transactions on Wireless Communications, 15 (2016), pp. 6541-6555. S. Yousefi, H. Wymeersch, X.-W. Chang, and B. Champagne. Tight 2-Dimensional Outer-approximations of Feasible Sets in Wireless Sensor Networks , IEEE Communication Letters, 20 (2016), pp. 570-573. J. Wen and X.-W. Chang. A Modified KZ Reduction Algorithm, Proceedings of The 2015 IEEE International Symposium on Information Theory (ISIT 2015), pp. 451-455. J. Wen, B. Zhou, W. Mow, and X.-W. Chang. Compute-and-Forward Protocol Design Based on Improved Sphere Decoding, Proceedings of IEEE International Conference on Communications 2015, pp. 1631-1636. S. Yousefi, R. Vaghefi, X.-W. Chang, B. Champagne, and M. Buehrer. Sensor Localization in NLOS Environments with Anchor Uncertainty and Unknown Clock Parameters, Proceedings of IEEE International Conference on Communications 2015 - Workshop on Advances in Network Localization and Navigation, pp. 742-747. S. Yousefi, X.-W. Chang, and B. Champagne. Mobile Localization in Non-Line-of-Sight Using Constrained Square-Root Unscented Kalman Filter, IEEE Transactions on Vehicular Technology, 64 (2015), pp. 2071-2083. M.F. Anjos, X.-W. Chang, and W.-Y. Ku. Lattice Preconditioning for the Real Relaxation Branch-and-Bound Approach for Integer Least Squares Problems, Journal of Global Optimization, 59 (2014), pp. 227-242. M. Al Borno, X.-W. Chang, and X. Xie. On "Decorrelation" in Solving Integer Least-Squares Problems for Ambiguity Determination, Survey Review, 46 (2014), pp. 37-49. S. Yousefi, X.-W. Chang, and B. Champagne. Cooperative Localization of Mobile Nodes in NLOS, Proceedings of IEEE International Symposium on Personal, Indoor and Mobile Radio Communications 2014 (PIMRC'14), pp. 275-279. S. Yousefi, X.-W. Chang, and B. Champagne. Distributed Cooperative Localization in Wireless Sensor Networks without NLOS Identification, Proceedings of The 11th Workshop on Positioning, Navigation and Communication 2014 (WPNC'14), 6 pages. S. Yousefi, X.-W. Chang, and B. Champagne. A Joint Localization and Synchronization Technique Using Time of Arrival at Multiple Antenna Receivers, Proceedings of 47th Annual Asilomar Conference on Signals, Systems, and Computers (Asilomar 2013), pp. 2017-2021. S. Yousefi, X.-W. Chang, and B. Champagne. An Improved Extended Kalman Filter for Localization of a Mobile Node with NLOS Anchors, Proceedings of The Ninth International Conference on Wireless and Mobile Communications (ICWMC 2013), pp. 25-30. (Best paper award) X.-W. Chang, J. Wen, and X. Xie. Effects of the LLL Reduction on the Success Probability of the Babai Point and on the Complexity of Sphere Decoding, IEEE Transactions on Information Theory, 59 (2013), pp. 4915-4926. X. Chen, X.-W. Chang, and X. Liu. SyRaFa: Synchronous Rate and Frequency Adjustment for Utilization Control in Distributed Real-Time Embedded Systems (main document, supplementary document) IEEE Transactions on Parallel and Distributed Systems, 24 (2013), pp. 1052-1061. X. Chen, X. Liu, S. Wang, and X.-W. Chang. TailCon: Power-Minimizing Tail Percentile Control of Response Time in Server Clusters, Proceedings of IEEE 31st Symposium on Reliable Distributed Systems (SRDS'12), pp. 61-70. X.-W. Chang, D. Stehle, and G. Villard. Perturbation Analysis of the QR Factor R in the Context of LLL Lattice Basis Reduction, Mathematics of Computation, 81 (2012), pp. 1487-1511. X.-W. Chang. Perturbation of the Q-factor of the QR Factorization, Numerical Linear Algebra with Applications, 19 (2012), pp. 607-619. S. Breen and X.-W. Chang. Column Reordering for Box-Constrained Integer Least Squares Problems, Proceedings of IEEE GLOBECOM 2011, 6 pages. X. Xie, X.-W. Chang, and M. Al Borno. Partial LLL reduction, Proceedings of IEEE GLOBECOM 2011, 5 pages. X.-W. Chang and R.-C. Li. Multiplicative Perturbation Analysis for QR Factorizations, Numerical Algebra, Control and Optimization, 1 (2011), pp. 301-316. X.-W. Chang and D. Stehle. Rigorous Perturbation Bounds of Some Matrix Factorizations, SIAM J. Matrix Anal. Appl. 31 (2010), pp. 2841-2859. X.-W. Chang and G.H. Golub. Solving Ellipsoid-Constrained Integer Least Squares Problems, SIAM J. Matrix Anal. Appl., 31 (2009), pp. 1071-1089. X.-W. Chang, C.C. Paige and D. Titley-Peloquin. Stopping Criteria for the Iterative Solution of Linear Least Squares Problems, SIAM J. Matrix Anal. Appl., 31 (2009), pp. 831-852. X.-W. Chang and D. Titley-Peloquin. Backward Perturbation Analysis for Scaled Total Least Squares Problems, Numerical Linear Algebra with Applications, 16 (2009), pp. 627-648. X.-W. Chang, X. Yang, T. Le-Ngoc, and P. Wang. Partial Regularization Approach for Detection Problems in Underdetermined Linear Systems, IET Communications, 3 (2009), pp. 17-24. X.-W. Chang, C.C. Paige and D. Titley-Peloquin. Characterizing Matrices that are Consistent with Given Solutions, SIAM J. Matrix Anal. Appl., 30 (2008), pp. 1406-1420. X.-W. Chang, G.H. Golub and C.C. Paige. Towards a Backward Perturbation Analysis for Data Least Squares Problems, SIAM J. Matrix Anal. Appl., 30 (2008), pp. 1281-1301. X.-W. Chang and Q. Han, Solving Box-Constrained Integer Least Squares Problems, IEEE Transactions on Wireless Communications, 7 (2008), pp. 277-287. X.-W. Chang and T. Zhou, MILES: MATLAB package for solving Mixed Integer LEast Squares problems, GPS Solutions, 11 (2007), pp. 289-294. X.-W. Chang and C.C. Paige, Euclidean Distances and Least Squares Problems for a Given Set of Vectors, Applied Numerical Mathematics, 57 (2007), pp. 1240-1244. X.-W. Chang and X. Yang, An Efficient Tree Search Decoder for Underdetermined MIMO Systems, in Proceedings of the IEEE GLOBECOM 2007, Washington, DC, Nov 26-30, 2007, pp. 4375 - 4379. X.-W. Chang and X. Yang, An Efficient Regularization Approach for Underdetermined MIMO System Decoding, in Proceedings of the 2007 International Wireless Communications and Mobile Computing Conference, Honolulu, Hawaii, August 12-16, 2007, pp. 349-353. X.-W. Chang and X. Yang, A New Fast Generalized Sphere Decoding Algorithm for Under-determined MIMO Systems, in Proceedings of 23rd Biennial Symposium on Communications, Kingston, Ontario, Canada, May 30 - June 1, 2006, pp. 18-21. X.-W. Chang, Computation of Huber's M-estimates for a Block-angular Regression Problem, Computational Statistics & Data Analysis, Special Issue on Matrix Computations and Statistics, 50 (2006), pp. 5-20. X.-W. Chang, X. Yang, and T. Zhou, MLAMBDA: A Modified LAMBDA Method for Integer Least-squares Estimation, Journal of Geodesy, 79 (2005), pp. 552-565. Erratum: In Algorithm 3.2 on page 558, PERMUTE(L,D,i,\bar D(k+1,k+1),\hat a,Z) should be changed to PERMUTE(L,D,i,\bar D(i+1,i+1),\hat a,Z). X.-W. Chang and Y. Guo, Huber's M-estimation in Relative GPS Positioning: Computational Aspects, Journal of Geodesy, 79 (2005), pp. 351-362. X.-W. Chang, C.C. Paige, and C.C.J.M. Tiberius, Computation of a Test Statistic in Data Quality Control , SIAM J. Sci. Comp., 26 (2005), pp. 1916-1931. X.-W. Chang, M.J. Gander and S. Karaa, Asymptotic Properties of the QR Factorization of Banded Hessenberg-Toeplitz Matrices, Numerical Linear Algebra with Applications, 12 (2005), pp. 659-682. J. Zhu, R. Santerre, and X.-W. Chang, A Bayesian Method for Linear Inequality Constrained Adjustment and Its application to GPS Positioning, Journal of Geodesy, 78 (2005), pp. 528-534. X.-W. Chang and M. Huang, Kinematic Relative GPS Positioning Using State-Space Models: Computational Aspects, Proceedings of ION 61st Annual Meeting, Cambridge, Massachusetts, June 27-29, 2005, pp. 937-948. X.-W. Chang and L. Qu, Wavelet Estimation of Partially Linear Models , Computational Statistics & Data Analysis, 47 (2004), pp. 31-48. X.-W. Chang, C.C. Paige, and L. Yin, Code and Carrier Phase Based Short Baseline GPS Positioning: Computational Aspects, GPS Solutions, 7 (2004), pp. 230-240. (Note: There are errors in the printed version due to the production editor's faults. The version here should be error free) M.J.D. Hayes, T. Luu, and X.-W. Chang, Kinematic Mapping Application to Approximate Type and Dimension Synthesis of Planar Mechanisms , 9th Advances in Robotic Kinematics, J. Lenarcic and C. Galletti (eds), Kluwer Academic Publishers, Dordrecht, The Netherlands. Sestri Levante, Italy, June 28 - July 1, 2004, pp. 41-48. X.-W. Chang and C.C. Paige, An Algorithm for Combined Code and Carrier Phase Based GPS Positioning, BIT Numerical Mathematics, 43 (2003), pp. 915-927. X.-W. Chang and C.C. Paige, An Orthogonal Transformation Algorithm for GPS Positioning, SIAM J. Sci. Comp., 24 (2003), pp. 1710-1732. Householder XV talk An Efficient Algorithm for GPS Based Positioning X.-W. Chang and C.C. Paige, Numerical Linear Algebra in the Integrity Theory of the Global Positioning System, Computational Statistics & Data Analysis, Special Issue on Matrix Computations and Statistics, 41 (2002), pp. 123-142. X.-W. Chang, Some Features of Gaussian Elimination with Rook Pivoting , BIT Numerical Mathematics, 42 (2002), pp. 66--83. X.-W. Chang and C.C. Paige, Componentwise Perturbation Analyses for the QR Factorization, Numerische Mathematik, 88 (2001), pp. 319-345. X.-W. Chang, C.C. Paige, and L. Qiu, A Recursive Least Squares Approach for Carrier Phase Based Positioning, Proceedings of ION GPS-2001, Salt Lake City, Utah, 11-14 September 2001, pp. 1039-1047. X.-W. Chang, C.C. Paige, and V. Pereptchai, Integrity Methods Using Carrier Phase, Proceedings of International Symposium on Kinematic Systems in Geodesy, Geomatics and Navigation (KIS 2001), Banff, Alberta, Canada June 5-8, 2001, pp. 235-245. X.-W. Chang, C.C. Paige, and J. Studenny, Two Carrier Phase Based Approaches for Autonomous Fault Detection and Exclusion , Proceedings of ION GPS-2000, Salt Lake City, Utah, 19-22 September 2000, pp. 1895-1905. X.-W. Chang and C.C. Paige, Sensitivity Analyses for Factorizations of Sparse or Structured Matrices, Linear Algebra and Appl., 284 (1998), pp. 53-71. X.-W. Chang, On the Sensitivity of the SR Decomposition, Linear Algebra and Appl., 282 (1998), pp. 297-310. X.-W. Chang and C.C. Paige, On the Sensitivity of the LU Factorization, BIT, 38 (1998), pp. 486--501. X.-W. Chang and C.C. Paige, Perturbation Analyses for the Cholesky Downdating Problem, SIAM J. Matrix Anal. Appl., 19 (1998) pp. 429-443. X.-W. Chang, C.C. Paige, and G.W. Stewart, Perturbation Analyses for the QR Factorization, SIAM J. Matrix Anal. Appl., 18 (1997) pp. 775-791. H. Xu and X.-W. Chang, Approximate Newton Methods for Nonsmooth Equations, J. Opt. Theory and Appl., 93 (1997), pp. 373-394. X.-W. Chang, Perturbation Analyses for the Cholesky Factorization with Backward Rounding Errors, Scientific Computing: Proceedings of the Workshop, 10-12 March 1997, Hong Kong, ed. G. Golub, F. Luc and R. Plemmons, Springer, Singapore, pp. 180-187, 1997. X.-W. Chang, C.C. Paige, and G.W. Stewart, New Perturbation Analyses for the Cholesky Factorization, IMA J. Numer. Anal., 16 (1996), pp. 457-484. X.-W. Chang and C.C. Paige, A Perturbation Analysis for R in the QR Factorization, Technical Report, SOCS-95.7, McGill University, School of Computer Science. X.-W. Chang and J. Wang, The Symmetric Solutions of the Matrix Equations $AX+YA=C$, $AXA^T+BYB^T=C$ and $(A^TXA,B^TXB)=(C,D)$, Linear Algebra and Appl., 179 (1993), pp. 171-189. J. Wang and X.-W. Chang, The Best Approximation of Symmetric Positive Semidefinite Matrices with Spectral Constraints, Numerical Math.,J. Chinese Universities., 14 (1992), pp. 78-86. X.-W. Chang and J. Wang, The Best Approximation of Matrices with Two Kinds of Linear Constraint, J. Nanjing Univ. Math. Biqu. 9 (1992), pp. 166-177. J. Wang and X.-W. Chang, An Efficient Method for Solving the Minimum $L_1$ Norm Solution of $Ar=b$, Comm.on Appl.Math.and Comput., 5 (1991), pp. 40-49. J. Wang, X.-W. Chang, and Z. Chen, An Algorithm of Seismic Inversion, Geophysical Prospecting for Petroleum, 29 (1990), pp. 85-97. J. Wang and X.-W. Chang, Symmetric Solution of a Linear Matrix Equation, J.Nanjing Univ. Math. Biqu., 7 (1990), pp. 125-129. J. Wang and X.-W. Chang, Some Notes on the Generalized Inverse under $L_1$ Norm, J.Nanjing Univ. Math. Biqu., 7 (1990), pp. 228-237. W. Sun and X.-W. Chang, An Unconstrained Minimization Method Based on Homogeneous Function(I)---Greville's Method, J. Nanjing Univ.(Natural Sci. Ed.), 25 (1989), pp. 577-583. W. Sun and X.-W. Chang, An Unconstrained Minimization Method Based on Homogeneous Function(II)---Orthogonal Factorization, Comm. on Appl. Math. and Comput., 3 (1989), pp. 81-88. J. Wang, X.-W. Chang, and Z. Chen, Algorithms of Certain Seismic Inverse Problem, Proc. of International Symposium on Geophysical Exploration, Beijing, 1989, pp. 454-458.