Extraction of two wire Loop topology using Hybrid Single Ended Loop Testing

Bharathi M, Amsaveni A, Ravishankar S


Performance estimation of a digital subscriber line (DSL) is critical for an operator to commit on the quality of service (QoS) requirements. The performance of the subscriber line depends on the line topology and the noise power spectral density (PSD).  Single ended loop testing (SELT) is the preferred and economical method for identifying the loop topology. In this paper SELT based on a combination of Correlation Time Domain Reflectometry (CTDR) and Frequency Domain Reflectometry (FDR) is proposed to identify the topology of a two wire line. The proposed CTDR and FDR use the existing modem for probing the line. In CTDR, complementary codes are used to probe the line and the reflections are correlated with the probe signal. This correlated signal is then analyzed to predict the loop. The prediction accuracy of the CTDR is limited but the main advantage is, it does not need any prior knowledge of the loop.  FDR uses the CTDR prediction as an initial estimate and employs optimization algorithm to accurately predict the loop. So the combined method has the advantage of predicting the loop accurately without any prior knowledge of the loop. As the SELT measurements are done online, the effect of cross talk and AWGN is considered. The developed algorithm is tested for standard ANSI loops and the results shows good prediction capability of this algorithm. 



Full Text:



. Kenneth J.Kerpez, David L.Waring, Stefano Galli, James Dixon, Phiroz Madon, “Advanced DSL Management,” IEEE Communications Magazine, pp. 116-123, September 2003

. Stefano Galli , David L.Waring ,”Loop Makeup Identification Via Single Ended Testing :Beyond Mere Loop Qualification,” IEEE Journal on Selected Areas in Communication, Vol. 20, No. 5, pp. 923-935, June 2002.

. Stefano Galli, Kenneth J.Kerpez, “Single-Ended Loop Make-up Identification –Part I:A method of analyzing TDR Measurements,” IEEE Transactions on Instrumentation and Measurement, Vol. 55, No. 2, pp. 528-537, April 2006.

. Stefano Galli , Kenneth J. Kerpez, “Signal Processing For Single-Ended Loop Make-Up Identification,” in proceedings IEEE 6th Workshop on Signal Processing Advances in WireIess Communications, pp. 368-374, 2005.

. Kenneth J.Kerpez, Stefano Galli, “Single-Ended Loop Make-up Identification –Part II: Improved Algorithms and Performance Results,” IEEE Transactions on Instrumentation and Measurement, Vol. 55, No. 2, pp. 538-548, April 2006.

. Tom Bostoen,PatrickBoets, Mohamed Zekri,Leo Van Biesen, DaanRabijns, ”Estimation of the Transfer function of a Subscriber Loop by means of a One-port Scattering Parameter Measurement at the Central Office,” IEEE Journal on Selected Areas in Communciations, Vol. 20, No. 5, pp. 936-948, June 2002.

. Carine Neus,PatrickBoets and Leo Van Biesen, “Transfer Function Estimation of Digital Subscriber Lines with Single Ended Line Testing,” in proceedings Instrumentation and Measurement Technology Conference 2007.

. David E. Dodds, “Single Ended FDR to Locate and Specifically Identify DSL Loop Impairments,” in proceedings IEEE ICC 2007, pp. 6413- 6418.

. David E. Dodds, Timothy Fretz, “Parametric Analysis of Frequency Domain Reflectometry Measurements,” in proceedings Canadian Conference on Electrical and Computer Engineering 2007, pp. 1034-1037, 2007.

. V. D. Lima, A. Klautau, J. Costa, K. Ericson, A. Fertner and C. Sales, “A wavelet-based expert system for digital subscriber line topology identification,” INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS , 2014.

. Claudomiro Sales, Roberto M.Rodrigues ,Fredrik Lindqvist, Joao Costa,Aldebaro Klautau,Klas Ericson,Jaume Rius I Riu and Per Ola Borjesson “Line Topology Identification Using Multiobjective Evolutionary Computation,” IEEE Transaction on Instrumentation and Measurement, Vol 59, No3,pp.715-729, March 2010.

. Single-ended line testing for digital subscriber lines (DSL), Telecommunication standardization sector of ITU std. G.996.2, 05/2009.

. Test Procedure for Digital Subscriber Line Transceivers, Telecommunication standardization sector of ITU std. G.996.1, 02/2001

. M. Bharathi, S. Ravishankar, “Single Ended Loop Topology Estimation using FDR and Correlation TDR in a DSL Modem,” Cyber Journals: Multidisciplinary Journals in Science and Technology, Journal of Selected Areas in Telecommunications (JSAT), June 2012, pp.40-48.

. M. Bharathi and S. Ravishankar, “A Combined correlation TDR and FDR procedure for single ended loop topology estimation in DSL,” in proceedings IEEE International conference on Signal Processing, Communication and Computing, Xi’an, China,14-16, Sep 2011.

. M.A.Luersen, R.Le Riche, F.Guyon, “A constrained, globalized, and bounded Nelder–Mead method for engineering optimization,” Structural and Multidisciplinary optimization journal, Springer, Volume 27, Issue 1-2, pp. 43-54, May 2004.

. T.Starr, J.M.Cioffi, and P. J. Silverman,Eds., Understanding Digital Subscriber Line Technology, New York: Prentice Hall,1999.

. S Ravishankar, R Arjun, “A hybrid method for physical and power line loop topology estimation using a broadband modem” IEEE Symposium on Radio and Wireless Symposium (RWS),2016, 24-27 Jan. 2016, Austin, TX, USA

. A Ravishankar, S Ravishankar , “Extraction of two wire and power line loop topology using customized genetic algorithms,” Sixth International Symposium on Embedded Computing and System Design (ISED), 2016 , 15-17 Dec. 2016.


  • There are currently no refbacks.

Copyright (c) 2018 Informacije MIDEM