1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T G.995.2 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2015) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Metallic access networks Enhanced common mode
2、 limits and measurement methods for customer premises equipment operating on copper pairs Recommendation ITU-T G.995.2 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMO
3、N TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.
4、400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 General G.900G.909 Parameters for optical fib
5、re cable systems G.910G.919 Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s G.920G.929 Digital line transmission systems on cable at non-hierarchical bit rates G.930G.939 Digital line systems provided by FDM transmission bearers G.940G.949 Digital line systems G.950G.95
6、9 Digital section and digital transmission systems for customer access to ISDN G.960G.969 Optical fibre submarine cable systems G.970G.979 Optical line systems for local and access networks G.980G.989 Metallic access networks G.990G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-
7、RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.995.2 (08/2015) i
8、 Recommendation ITU-T G.995.2 Enhanced common mode limits and measurement methods for customer premises equipment operating on copper pairs Summary To achieve optimal performance for VDSL2 lines making use of vectoring, Recommendation ITU-T G.995.2 specifies common mode (CM) voltage limits up to 30
9、MHz on the digital subscriber line (DSL) that provide additional radio protection relative to what is currently specified in CISPR22. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.995.2 2015-08-29 15 11.1002/1000/12565 _ * To access the Recommendation, type the URL http:
10、/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.995.2 (08/2015) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the fiel
11、d of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizi
12、ng telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered
13、by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate
14、both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved wh
15、en all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPER
16、TY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted
17、by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that
18、this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2015 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. I
19、TU-T G.995.2 (08/2015) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 1 5 CPE common mode voltage limits . 2 6 Common mode voltage measurement method . 2 Annex A ITU-T G.9
20、93.2 CPE common mode voltage limits and measurement method . 3 A.1 CM voltage limits in frequency band 2.208 MHz to 30 MHz 3 A.2 CM voltage limits in the frequency band 138 kHz to 2.208 MHz . 3 A.3 CM measurement method . 4 Bibliography. 5 Rec. ITU-T G.995.2 (08/2015) 1 Recommendation ITU-T G.995.2
21、Enhanced common mode limits and measurement methods for customer premises equipment operating on copper pairs 1 Scope To achieve optimal performance for VDSL2 lines making use of vectoring, this Recommendation specifies common mode (CM) voltage limits up to 30 MHz on the DSL line that provide additi
22、onal radio protection relative to what is currently specified in IEC CISPR 22. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indica
23、ted were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Rec
24、ommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.993.2 Recommendation ITU-T G.993.2 (2015), Very high speed digital subscriber line transceivers 2 (VDSL2). IEC CISPR 22 IEC
25、 CISPR 22 (2008), Information Technology Equipment Radio Disturbance Characteristics Limits and Methods of Measurement. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following term defined elsewhere: 3.1.1 vectoring b-ITU-T G.993.5: The coordinated transmission and/or coordi
26、nated reception of signals of multiple DSL transceivers using techniques to mitigate the adverse effects of crosstalk to improve performance. 3.2 Terms defined in this Recommendation This Recommendation defines the following term: 3.2.1 customer premises equipment (CPE): Equipment located at the cus
27、tomer premises, including the network termination (NT) equipment, as shown in Figure 5-4 of ITU-T G.993.2. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ADSL Asymmetric Digital Subscriber Line CM Common Mode CPE Customer Premises Equipment ISN Impeda
28、nce Stabilization Network DSL Digital Subscriber Line LCL Longitudinal Conversion Loss SHDSL Single-pair High-speed Digital Subscriber Line 2 Rec. ITU-T G.995.2 (08/2015) VDSL Very high speed Digital Subscriber Line 5 CPE common mode voltage limits The common mode voltage limits for VDSL2 CPE are de
29、fined in Annex A, clauses A.1 and A.2. 6 Common mode voltage measurement method The common mode voltage measurement method for VDSL2 CPE is defined in Annex A, clause A.3. Rec. ITU-T G.995.2 (08/2015) 3 Annex A ITU-T G.993.2 CPE common mode voltage limits and measurement method (This annex forms an
30、integral part of this Recommendation.) To achieve optimal performance for VDSL2 lines making use of vectoring, this annex specifies common mode (CM) voltage limits up to 30 MHz on the DSL line that provide additional radio protection relative to what is currently specified in IEC CISPR 22. A.1 CM vo
31、ltage limits in frequency band 2.208 MHz to 30 MHz At the U-R2 reference point (see Figure 5-4 of ITU-T G.993.2), and for frequencies in the frequency band from 2.208 MHz to 30 MHz, the CM voltage (UCM) shall comply with the CM voltage limit and the CM power in a 1 MHz sliding window (PCM) shall com
32、ply with the CM power limit, as listed in Table A.1. Table A.1 CM voltage and power limits Frequency (MHz) CM voltage limit Average detector (dBV) CM power limit in a 1 MHz sliding window (dBm) 2.208-30 40 60 NOTE 1 For an efficient operation of vectored VDSL2, a low quiet line noise of approximatel
33、y 140 dBm/Hz in this frequency band is required. A general UCM voltage limit of 40 dBV together with PCM power limit in a 1 MHz sliding window of 60 dBm seems to be appropriate to ensure such a low noise level even in environments with a concentrated deployment of DSL equipment. On customer side, th
34、e combination of a power supply unit with low CM emissions and a CM choke (nominal value between 0.5 and 2 mH) in the line interface should enable CPEs to fulfil the limits. NOTE 2 With UCM measured with 9 kHz bandwidth into a 150 Ohms impedance, and PCM measured with 1 MHz bandwidth, a PCM level of
35、 60 dBm corresponds with a UCM level of 6010log(1000000)+10log(9000)+(90+10log(150) = 31.3 dBV. A.2 CM voltage limits in the frequency band 138 kHz to 2.208 MHz For frequencies in the frequency band from 138 kHz to 2.208 MHz, the common mode voltage (UCM) at the U-R2 reference point shall satisfy: 0
36、10/lo g /lo g2363 ff ffU CM dBV, with: f0 = 138 kHz and f1 = 2.208 MHz. NOTE 1 The limit for UCM decreases linearly with the logarithm of the frequency from 63 dBV at 138 kHz to 40 dBV at 2.208 MHz. The slope of the limit curve in this frequency interval has been chosen identical to CISPR22 limit sl
37、ope between 150 kHz and 500 kHz. NOTE 2 This frequency range is often not exclusively used for vectored VDSL2 but also for (non-vectored) SHDSL b-ITU-T G.991.2 or ADSL2plus b-ITU-T G.992.5 in the same cable. Due to the crosstalk noise, the acceptable common mode voltage from external sources is high
38、er. Furthermore, the longitudinal conversion loss (LCL) of cables is usually higher in this frequency range, resulting in a lower conversed differential mode signal. 4 Rec. ITU-T G.995.2 (08/2015) A.3 CM measurement method The measurement method for the CM voltage on the line shall be as defined in
39、IEC CISPR 22, however with following deviations: The common mode voltage measurement shall be carried out at the U-R2 reference point in the average detector mode (AV detector) with a measurement bandwidth of 9 kHz. Only the power supply of the equipment shall be connected during the measurement. In
40、stead of the impedance stabilization network (ISN) for category 3 cables, an ISN with a high longitudinal conversion loss (LCL) shall be used in order to reduce the influence of the transmit signal (differential mode) on the measurement result. In this regard, this test should be conducted with rest
41、ricted VDSL2 spectrum usage (e.g., 2.2 MHz) or with an additional attenuation in the VDSL2 signal path. The CM voltage limits defined in clauses A.1 and A.2 are shown in Figure A.1, in overlay with a measurement example of a compliant VDSL2 CPE. Figure A.1 CM voltage limits and measurement example o
42、f a compliant VDSL2 CPE Rec. ITU-T G.995.2 (08/2015) 5 Bibliography b-ITU-T G.991.2 Recommendation ITU-T G.991.2 (2003), Single-pair high-speed digital subscriber line (SHDSL) transceivers. b-ITU-T G.992.5 Recommendation ITU-T G.992.5 (2009), Asymmetric digital subscriber line 2 transceivers (ADSL2)
43、 Extended bandwidth ADSL2 (ADSL2plus). b-ITU-T G.993.5 Recommendation ITU-T G.993.5 (2015), Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers. Printed in Switzerland Geneva, 2015 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff princ
44、iples Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital ne
45、twork Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of out
46、side plant Series M Telecommunication management, including TMN and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Terminals and subjective and objective assessment methods Series Q
47、Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks, open system communications and security Series Y Global information infrastructure, Internet protocol aspects and next-generation networks Series Z Languages and general software aspects for telecommunication systems
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