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.9700 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (04/2014) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Access networks Metallic access networks Fast access to subscriber terminals (G.fast) P
2、ower spectral density specification Recommendation ITU-T G.9700 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.2
3、99 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.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPH
4、ONY 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 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMIS
5、SION 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 Metallic access networks G.9700G.9799 Optical line systems for local and access networks G.9800G.9899 In premises networks G.9900G.9999 For
6、 further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.9700 (04/2014) i Recommendation ITU-T G.9700 Fast access to subscriber terminals (G.fast) Power spectral density specification Summary Recommendation ITU-T G.9700 specifies power spectral density (PSD) mask requirement
7、s for fast access to subscriber terminals (G.fast), a set of tools to support reduction of the transmit PSD mask, profile control parameters that determine spectral content, including the allowable maximum aggregate transmit power into a specified termination impedance, and a methodology for transmi
8、t PSD verification. It complements the physical layer (PHY) specification in Recommendation ITU-T G.9701. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.9700 2014-04-04 15 11.1002/1000/12010 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the addre
9、ss 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.9700 (04/2014) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, infor
10、mation 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 standardizing telecommunications on a wor
11、ldwide 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 by the procedure laid down in
12、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 both a telecommunication admin
13、istration 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 when all of these mandatory prov
14、isions 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 PROPERTY RIGHTSITU draws attention t
15、o 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 by ITU members or others outsi
16、de of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest
17、information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2014 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.9700 (04/2014) iii Table of
18、 Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 4 Abbreviations and acronyms 2 5 Conventions 2 6 Transmit PSD mask 2 6.1 Overview 2 6.2 Limit PSD mask (LPM) 3 6.3 Subcarrier masking . 3 6.4 Power spectral density shaping 4 6.5 Notching of specific frequency bands 4 6.6 Low frequency edge
19、 stop-band masking 5 7 Specification of spectral content . 6 7.1 Profile control parameters 6 7.2 PSD mask specifications 7 7.3 Termination impedance 10 7.4 Maximum aggregate transmit power 10 8 Transmit PSD verification 10 Appendix I International amateur radio bands 12 Appendix II Broadcast radio
20、bands . 13 Appendix III Definition of transmitter PSD (TXPSD) for non-continuous transmissions . 14 Rec. ITU-T G.9700 (04/2014) 1 Recommendation ITU-T G.9700 Fast access to subscriber terminals (G.fast) Power spectral density specification 1 Scope This Recommendation complements the physical layer (
21、PHY) specification in ITU-T G.9701. It specifies: power spectral density (PSD) limit mask requirements; a set of tools to support reduction of the transmit PSD mask; profile control parameters that determine spectral content, including the allowable maximum aggregate transmit power into a specified
22、termination impedance; and a methodology for transmit PSD verification. This ensures that the technology can address: regional requirements; operator deployment requirements, for example, compatibility with other digital subscriber line (DSL) technologies; applicable electromagnetic compatibility (E
23、MC) regulations or standards; and local EMC issues. 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 indicated were valid. All Recomme
24、ndations 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 Recommendations is regularly p
25、ublished. 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 (2011), Very high speed digital subscriber line transceivers 2 (VDSL2). ITU-T G.9701 Recommendation ITU-T G.9701 (2
26、014), Fast access to subscriber terminals (G.fast) Physical layer specification. 3 Definitions This Recommendation defines the following terms: 3.1 ceiling(x): The smallest integer which is not less than x. 3.2 floor(x): The largest integer which is not greater than x. 3.3 fSC: A parameter represent
27、ing the frequency of subcarrier spacing. 3.4 subcarrier: A fundamental element of a discrete multitone (DMT) modulator. The modulator partitions the channel bandwidth into a set of parallel subchannels. The centre frequency of each subchannel is a subcarrier onto which bits may be modulated for tran
28、smission over a channel. 2 Rec. ITU-T G.9700 (04/2014) 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: DAB Digital Audio Broadcasting DMT Discrete Multitone DP Distribution Point DSL Digital Subscriber Line EMC Electromagnetic Compatibility FAST (G.fas
29、t) Fast Access to Subscriber Terminals FM Frequency Modulation FTU FAST Transceiver Unit FTU-O FTU at the Optical network unit FTU-R FTU at the Remote site (i.e., subscriber end of the loop) LESM Low-frequency Edge Stop-band Mask LPM Limit PSD Mask MBW Measurement Bandwidth MIB Management Informatio
30、n Base NM Notching Mask PSD Power Spectral Density PSM PSD Shaping Mask QoS Quality of Service SM Subcarrier Mask TDD Time-Division Duplexing TxPSDM Transmit PSD Mask 5 Conventions None. 6 Transmit PSD mask 6.1 Overview The transmit PSD mask (TxPSDM) is constructed from the combination of the follow
31、ing masks: limit PSD mask (LPM); subcarrier mask (SM); PSD shaping mask (PSM); notching mask (NM); and low-frequency edge stop-band mask (LESM). The TxPSDM applied to the FAST transceiver unit (FTU) at the optical network unit (FTU-O) or at the FTU remote site (i.e., subscriber end of the loop) (FTU
32、-R) may be different. For an FTU, the PSD of the transmit signal at any frequency shall never exceed the TxPSDM. Rec. ITU-T G.9700 (04/2014) 3 The LPM (see clause 7.2.1) specifies the absolute maximum limit of the TxPSDM. The subcarrier mask (SM), PSD shaping mask (PSM), notching mask (NM) and low-f
33、requency edge stop-band mask (LESM) provide reduction and shaping of the TxPSDM using four mechanisms: subcarrier masking; notching of specific frequency bands; PSD shaping; and low-frequency edge stop-band masking. Support of these four mechanisms is mandatory in both the FTU-O and the FTU-R. The T
34、xPSDM shall comply with applicable national and regional regulatory requirements. NOTE 1 When determining the correct PSD to use in a particular jurisdiction, operators should use tools provided to ensure compliance with national and regional electromagnetic compatibility (EMC) regulations giving sp
35、ecial consideration to protecting receivers for the safety of life services which may not be immediately adjacent to the drop wires carrying ITU-T G.9701 signals. Examples include various VHF aeronautical radio navigation channels in the band 108-117.975 MHz, and aeronautical emergency communication
36、s channels (e.g., 121.5 MHz) and maritime emergency communications channels in the HF and VHF bands. NOTE 2 In addition to the masks defined in this Recommendation that provide absolute limits to the TxPSDM (both in-band and out-of-band), ITU-T G.9701 defines two mechanisms: a mechanism of discontin
37、uous operation that allows the FTU to dynamically switch off the transmit power in each particular connection when no data is present for transmission and a mechanism of low power mode (L2). Both mechanisms allow the system to further reduce the transmit power to a value that is sufficient to achiev
38、e the given bit rate and quality of service (QoS) targets. NOTE 3 TXPSDM is defined in various averaging bandwidths according to frequency as defined in Table 8-1, except in sub-bands at the low frequency band edge and in the region of MIB defined notches, where TXPSDM_W (1 MHz wideband) and TXPSDM_
39、N (10 kHz narrowband) masks apply as described in clauses 6.5 and 6.6. 6.2 Limit PSD mask (LPM) The limit PSD mask (LPM) defines the absolute maximum PSD limit of the TxPSDM that shall never be exceeded. All the other mask definitions and mechanisms used to construct the TxPSDM can only result in a
40、reduction of the mask from the limits established by the LPM. 6.3 Subcarrier masking Subcarrier masking shall be used to eliminate transmission on one or more subcarriers. The subcarrier mask (SM) is configured in the distribution point management information base (DP-MIB) by use of the ITU-T G.997.
41、1 parameter CARMASK. The transmit power of subcarriers specified in the SM shall be set to zero (linear scale). The SM shall override all other instructions related to the transmit power of the subcarrier. The SM is defined as a number of masked frequency bands. Each band is specified by a start sub
42、carrier index (xL) and a stop subcarrier index (xH), as xL, xH. An SM including S bands can be represented in the following format: SM(S) = xL1, xH1, xL2, xH2, x LS, xHS All subcarriers within the band, i.e., with indices higher than or equal to xL and lower than or equal to xH, shall be switched of
43、f (transmitted with zero power). NOTE The SM is intended to incorporate both masked subcarriers that are defined by an annex defining regional requirements so as to comply with local regulations and masked subcarriers that are defined by the user or service provider to facilitate local deployment pr
44、actices. Protection of radio services is not intended to be addressed by subcarrier masking; it is addressed by notching (see clause 6.5). 4 Rec. ITU-T G.9700 (04/2014) 6.4 Power spectral density shaping Power spectral density (PSD) shaping allows reduction of the TxPSDM in some parts of the spectru
45、m, mainly for spectrum compatibility and coexistence with other access and home network technologies. The PSD shaping mask (PSM) is configured in the DP-MIB by use of the ITU-T G.997.1 parameter PSDMASK. The PSM is defined on the frequency range between the lowest subcarrier x1 (with x1=ceiling(ftr1
46、/fSC) and the highest subcarrier xH (with xH=floor(ftr2/ fSC), and consists of one or more frequency segments. The boundaries of the segments are defined by set breakpoints. Within each segment, the PSM may either be constant or form a linear slope between the given breakpoints (in dBm/Hz) with the
47、frequency expressed in a linear scale. Each breakpoint of the PSM is specified by a subcarrier index xn and a value of PSDn at that subcarrier expressed in dBm/Hz, xn, PSDn. PSD1 shall also apply to subcarriers below x1, and PSDH shall also apply to subcarriers above xH. A PSM including S segments c
48、an be represented by (S+1) breakpoints in the following format: PSM(S) = x1, PSD1, x2, PSD2 xS, PSDS, xH, PSDH An FTU shall support configuration of at least 32 PSM breakpoints. If one or more PSM breakpoints are set above the LPM; the transmit PSD mask shall be set to: TxPSDM = min(PSM, LPM). All v
49、alues of PSDn of PSM breakpoints shall be set above 90 dBm/Hz. 6.5 Notching of specific frequency bands The FTU shall be capable of being configured to notch one or more specific frequency bands in order to protect radio services; for example, amateur radio bands or broadcast radio bands. Each notch in the notching mask (NM) shall be defined in terms of subcarrier indices SCstart and SCstop. The valid range of notch start tone index, S
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