This Article 
 Bibliographic References 
 Add to: 
Non-Line-of-Sight Localization in Multipath Environments
May 2008 (vol. 7 no. 5)
pp. 647-660
This paper presents a comprehensive Non Line of Sight (NLOS) localization scheme and a least square estimator that leverages on the bi-directional estimation of the Angle of Arrival (AOA) and Time of Arrival (TOA) of signals exchanged between mobile and reference devices. The proposed localization scheme requires two or more signal paths which can be either Line of Sight (LOS) signals or Non-line of Sight (NLOS) multipath signals that undergo one bound scattering. Our multipath selection scheme is shown to be able to discard multiple bound scattering paths with a high degree accuracy. We used empirical data obtained through experimentation in a real environment to analyse the performance of our proposed localization scheme, and to compare it to the existing methods. The results of this experiment show that the proposed localization scheme that just uses two signal paths, is able to outperform the existing localization schemes in both LOS and extreme NLOS situations where all reference devices are in NLOS with the mobile device. This localization approach is very useful in multipath environments where it may not always be possible to have at least three reference devices in LOS with the mobile device.

[1] J.H. Reed, K.J. Krizman, B.D. Woerner, and T.S. Rappaport, “AnOverview of the Challenges and Progress in Meeting the E-911 Requirement for Location Service,” IEEE Comm. Magazine, pp. 30-37, Apr. 1998.
[2] A.H. Sayed, A. Tarighat, and N. Khajehnouri, “Network-Based Wireless Location: Challenges Faced in Developing Techniques for Accurate Wireless Location Information,” IEEE Signal ProcessingMagazine, vol. 22, pp. 24-40, July 2005.
[3] N. Patwari, J.N. Ash, S. Kyperountas, A.O. Hero III, R.L. Moses, and N.S. Correal, “Locating the Nodes: Cooperative Localization in Wireless Sensor Networks,” IEEE Signal Processing Magazine, vol. 22, pp. 54-69, July 2005.
[4] T.P. Deasy and W.G. Scanlon, “Stepwise Algorithms for Improvingthe Accuracy of Both Deterministic and Probabilistic Methods in WLAN-Based Indoor User Localization,” Int'l J. Wireless Information Networks, vol. 11, Oct. 2004.
[5] J.Y. Lee and R.A. Scholtz, “Ranging in a Dense Multipath Environment Using an UWB Radio Link,” IEEE J. Selected Areas in Comm., vol. 20, pp. 1677-1683, Dec. 2002.
[6] X. Wang, Z.X. Wang, and B.O'. Dea, “A TOA-Based Location Algorithmm Reducing the Errors Due to Non-Line-of-Sight (NLOS) Propagation,” IEEE Trans. Vehicular Technology, vol. 52, pp. 112-116, Jan. 2003.
[7] Y.T. Chan and K.C. Ho, “A Simple and Efficient Estimator for Hyperbolic Location,” IEEE Trans. Signal Processing, vol. 42, pp.1905-1915, Aug. 1994.
[8] P.Z. Alba, V. Josep, and D.H. Brooks, “Closed-Form Solution for Positioning Based on Angle of Arrival Measurements,” Proc. 13thIEEE Int'l Symp. Personal Indoor Mobile Radio Comm. (PIMRC'02), vol. 4, pp. 1522-1526, 2002.
[9] L. Cong and W.H. Zhuang, “Hybrid TDOA/AOA Mobile Users Location for Wideband CDMA Cellular Systems,” IEEE Trans. Wireless Comm., vol. 1, pp. 439-447, July 2002.
[10] T. Roos, P. Myllymaki, and H. Tirri, “A Statistical Modeling Approach to Location Estimation,” IEEE Trans. Mobile Computing, vol. 1, no. 1, pp. 59-69, Jan.-Mar. 2002.
[11] Z.L. Wu, C.H. Li, J.K.Y. Ng, and K.R.P.H. Leung, “Location Estimation via Support Vector Regression,” IEEE Trans. Mobile Computing, vol. 6, no. 3, pp. 311-321, Mar. 2007.
[12] T. Ross, P. Myllymaki, H. Tirri, P. Misikangas, and J. Sievanen, “AProbabilistic Approach to WLAN User Location Estimation,” Int'l J. Wireless Information Networks, vol. 9, no. 3, July 2002.
[13] P.C. Chen, “A Non-Line-of-Sight Error Mitigation Algorithm in Location Estimation,” Proc. IEEE Wireless Comm. Networking Conf. (WCNC '99), vol. 1, pp. 316-320, 1999.
[14] S. Venkatraman, J. Caffery, and H.R. You, “Location Using LOSRange Estimation in NLOS Environments,” Proc. 55th IEEE Vehicular Technology Conf. (VTC Spring '02), vol. 2, pp. 856-860, May 2002.
[15] N. Khajehnouri and A.H. Sayed, “A Non-Line-of-Sight Equalization Scheme for Wireless Cellular Location,” Proc. IEEE Int'l Conf.Acoustics, Speech, and Signal Processing (ICASSP '03), vol. 6, pp. 549-552, Apr. 2003.
[16] J. Borras, P. Hatrack, and N.B. Mandayam, “Decision Theoretic Framework for NLOS Identification,” Proc. 48th IEEE Vehicular Technology Conf. (VTC '98), vol. 2, pp. 1583-1587, 1998.
[17] L. Xiong, “A Selective Model to Suppress NLOS Signals in Angle of Arrival (AOA) Location Estimation,” Proc. Ninth IEEE Int'l Symp. Personal, Indoor, and Mobile Radio Comm. (PIMRC '98), vol. 1, pp. 461-465, 1998.
[18] L. Cong and W.H. Zhuang, “Nonline-of-Sight Error Mitigation in Mobile Location,” IEEE Trans. Wireless Comm., vol. 4, pp. 560-572, Mar. 2005.
[19] Y.T. Chan, W.Y. Tsui, H.C. So, and P.C. Ching, “Time-of-Arrival Based Localization under NLOS Conditions,” IEEE Trans. Vehicular Technology, vol. 55, pp. 17-24, Jan. 2006.
[20] J. Li, J. Conan, and S. Pierre, “Mobile Station Location Estimation for MIMO Communication Systems,” Proc. Third Int'l Symp. Wireless Comm. Systems (ISWCS '06), Sept. 2006.
[21] H.L. Miao, K. Yu, and M.J. Juntti, “Positioning for NLOSPropagation: Algorithm Derivations and Cramer-Rao Bounds,” Proc. IEEE Int'l Conf. Acoustics, Speech, and Signal Processing (ICASSP '06), vol. 4, pp. 1045-1048, June 2006.
[22] K. Pahlavan, X.R. Li, and J.P. Makela, “Indoor Geolocation Scienceand Technology,” IEEE Comm. Magazine, vol. 40, pp.112-118, Feb. 2002.
[23] Q.H. Spencer, B.D. Jeffs, M.A. Jensen, and A.L. Swindlehurst, “Modeling the Statistical Time and Angle of Arrival Characteristicsof an Indoor Multipath Channel,” IEEE J. Selected Areas in Comm., vol. 18, pp. 347-360, Mar. 2000.
[24] R.J.-M. Cramer, R.A. Scholtz, and M.Z. Win, “Evaluation of an Ultra-Wide-Band Propagation Channel,” IEEE Trans. Antennas and Propagation, vol. 50, pp. 561-570, May 2002.
[25] Y.H. Qi, H. Kobayashi, and H. Suda, “Analysis of Wireless Geolocation in a Non line of Sight Environment,” IEEE Trans. Wireless Comm., vol. 5, pp. 672-681, Mar. 2006.
[26] A. Alexiou and M. Haardt, “Smart Antenna Technologies for Future Wireless Systems: Trends and Challenges,” IEEE Comm. Magazine, vol. 42, pp. 90-97, Sept. 2004.
[27] T. Kaiser, “When Will Smart Antennas Be Ready for the Market?” IEEE Signal Processing Magazine, vol. 22, pp. 87-92, Mar. 2005.
[28] P. Grover, R. Agarwal, and A.K. Chaturvedi, “Geolocation Using Transmit and Receive Diversity,” Proc. IEEE Global Telecommunications Conf. (GLOBECOM '04), vol. 6, pp. 3681-3684, 2004.
[29] G. Caire and S. Shamai, “On the Achievable Throughput of aMultiantenna Gaussian Broadcast Channel,” IEEE Trans. Information Theory, vol. 49, pp. 1691-1706, July 2003.
[30] A.B. Gershman and N.D. Sidiropoulous, Space-Time Processing for MIMO Communications. John Wiley & Sons, 2005.
[31] T. Kaiser, A. Bourdoux, H. Boche, J.R. Fonollosa, J.B. Anderson, and W. Utschick, “Smart Antennas State of the Art,” EURASIP Book Series on Signal Processing and Communications. Hindawi, 2005.
[32] Q. Sun, S.Y. Tan, and K.C. Teh, “Analytical Formulae for Path Loss Prediction in Urban Street Grid Microcellular Environments,” IEEE Trans. Vehicular Technology, vol. 54, pp. 1251-1258, July 2005.
[33] S.Y. Tan and H.S. Tan, “Improved Three Dimensional Ray Tracing Technique for Microcellular Propagation Models,” IEE Electronics Letters, vol. 31, no. 17, pp. 1503-1505, Aug. 1995.
[34] S.Y. Tan and H.S. Tan, “A Microcellular Communications Propagation Model Based on the Uniform Theory of Diffraction and Multiple Image Theory,” IEEE Trans. Antennas and Propagation, vol. 44, no. 10, pp. 1317-1326, Oct. 1996.
[35] C. Trevor F, An Introduction to Multivariate Data Analysis. Ar nold, 2005.
[36] S.M. Kay, Fundamentals of Statistical Signal Processing: Estimation Theory, vol. 1, Prentice Hall, 1993.

Index Terms:
Location-dependent and sensitive, Pervasive computing, Mobile environments
Chee Kiat Seow, Soon Yim Tan, "Non-Line-of-Sight Localization in Multipath Environments," IEEE Transactions on Mobile Computing, vol. 7, no. 5, pp. 647-660, May 2008, doi:10.1109/TMC.2007.70780
Usage of this product signifies your acceptance of the Terms of Use.