advertisement

Telecommunications Industry Association (TIA) TR-30.1/99-08-025 Quebec City, Quebec, 19 August 1999 COMMITTEE CONTRIBUTION Technical Committee TR-30 Meetings SOURCE1: Texas Instruments CONTRIBUTORS: Name: Phone: Fax: E-mail: Rohit Gaikwad Murtaza Ali1 972-997-5290 972-997-5693 mali@ti.com TITLE: Crosstalk analysis models for G.PNT and G.VDSL spectral compatibility experiments PROJECT: PN-4643 DISTRIBUTION: Members of TR-30.1 and meeting attendees ABSTRACT The analysis models used in computing crosstalk interference and line attenuation in the original paper [1] were not provided in the document. The purpose of this document is to clarify this by specifying the FEXT, NEXT, and line attenuation models. The analysis models provided herein are consistent with those models agreed upon at the Nuremberg SG15/Q4 meeting on August 6, 1999 [4], [5]. These models will be used by all ITU-T SG15/Q4 participants who perform G.pnt – VDSL crosstalk analyses. This will facilitate the generation of uniform and consistent results. Copyright Statement The contributor grants a free, irrevocable license to the Telecommunications Industry Association (TIA) to incorporate text contained in this contribution and any modifications thereof in the creation of a TIA standards publication; to copyright in TIA’s name any TIA standards publication even though it may include portions of this contribution; and at TIA's sole discretion to permit others to reproduce in whole or in part the resulting TIA standards publication. 1. 1 Introduction: Texas Instruments Inc. Dallas, Texas 1 The equations used in computing crosstalk interference and line attenuation in the original paper [1] were not provided in the document. The purpose of this document is to clarify this by specifying the FEXT, NEXT, and line attenuation models. The analysis models provided here are consistent with those models agreed upon at the Nuremberg SG15/Q4 meeting on August 6, 1999 [4], [5]. These models will be used by all ITU-T SG15/Q4 participants who perform G.pnt – VDSL crosstalk analyses. This will facilitate the generation of uniform and consistent results. 2. Crosstalk combining models and line attenuation model The PSD of G.PNT NEXT is expressed as: PSDPNT NEXT ( f ) PSDPNT Disturber( f ) xn f 3 2 where xn = 8.818 n/49)0.6 or equivalently, xn = 0.8536 n0.6 for n<50. The FEXT loss model is: H FEXT f klf 2 H channel f 2 2 where H channel f is the channel transfer function, k is the coupling constant and is 8 10-20 (n/49)0.6 for n<50 or 3.083 10-20 for 10, 1% worst-case disturbers, l is the coupling path length in feet, f is in Hz. The FEXT noise PSD is therefore: PSDPNT FEXT ( f ) PSDPNT Disturber( f ) H FEXT f 2 Alternately, VDSL NEXT and FEXT noise interference into G.PNT use the same equations. In the presence of both VDSL and HPNA disturbers, the combined NEXT PSD is expressed according to the crosstalk combining model in [4] PSDNEXT ( f ) PSDPNT Disturber ( f ) X N f 3 2 0.6 1 n 1 / 0.6 PSDVDSL Disturber ( f ) X n f 3 2 n 0.6 2 1 / 0.6 0.6 where n1 and n2 are the number of G.PNT and VDSL disturbers respectively and XN = 8.536 10-15. Similarly, the combined FEXT PSD due to VDSL and HPNA disturbers is expressed as 2 PSDFEXT ( f ) PSDPNT Disturber ( f ) H 1 ( f ) X F f 2 l1 n10.6 1 / 0.6 PSDVDSL Disturber ( f ) H 2 ( f ) X F f 2 l 2 n20.6 2 where n1 and n2 are the number of G.PNT and VDSL disturbers respectively with coupling path lengths l1 and l2, and XF = 7.7441 10-21. |H1(f)| and |H2(f)| are the channel transfer functions of the loop over lengths l1 and l2. In [1], the coupling path lengths l1 and l2 are equal. The total crosstalk power is obtained by summing the individual NEXT and FEXT powers. We use G.VDSL loops with no bridged taps having lengths of 300 m, 900 m, 1200 m, and 4500 ft (all of 26 AWG). The R, L, C, G paremeters for the loops were obtained from [3, Table 3.4]. A 3 dBm/Hz exit loss was assumed on the G.PNT transmit spectra while computing the crosstalk powers. The point of injection of NEXT and FEXT is assumed to be at the network interface device (NID) end. 2 1 / 0.6 0.6 3. Conclusions: The models used to generate the data are based on well accepted models published previously [2], [3], [4]. 4. Summary This contribution is provided for information only. 5. References [1] ITU-T Temporary Document NG-102, Q4/15, G.PNT: Spectral compatibility of home phoneline network transceivers (G.PNT) with xDSL and other existing in-home services, Nuremberg, Germany 2 –6 August 1999 [2] ITU-T Temporary Document MA-055, Q4/15, G.gen: HomePNA 1.0 Spectral Compatibility, Australia 29 March – 2 April 1999 [3] Walter Y. Chen, DSL Simulation Techniques and Standards Development for Digital Subscriber Line Technology, MacMillan Technology Series, 1998 [4] ANSI T1E1.4/99-002R4, Spectrum Management for Loop Transmission Systems [5] ITU-T Temporary Document NG-118R1, Q4/15, G.PNT: G.pnt: Ad hoc group report, Nuremberg, Germany 2 – 6 August 1999 3