1、 International Telecommunication Union ITU-T G.9972TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2010) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Access networks In premises networks Coexistence mechanism for wireline home networking transceivers Recommendation ITU-
2、T G.9972 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.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER
3、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 TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS C
4、HARACTERISTICS 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 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANS
5、PORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 In premises networks G.9950G.9999For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.9972 (06/2010) i Recommendation ITU-T G.9972 Coexistence mechanism for wirel
6、ine home networking transceivers Summary Recommendation ITU-T G.9972 specifies a coexistence mechanism for home networking transceivers capable of operating over powerline wiring. The coexistence mechanism allows ITU-T G.996x devices to coexist with other coexisting systems, as defined in this Recom
7、mendation, operating on the same powerline wiring. History Edition Recommendation Approval Study Group 1.0 ITU-T G.9972 2010-06-11 15 ii Rec. ITU-T G.9972 (06/2010) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, i
8、nformation 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
9、 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 by the procedure laid down
10、 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 both a telecommunication a
11、dministration 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
12、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 PROPERTY RIGHTS ITU draws attent
13、ion 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 by ITU members or others
14、outside 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 la
15、test information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2011 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.9972 (06/2010) iii Tab
16、le of Contents Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations 2 5 Overview 3 5.1 Inter-system protocol 3 5.2 Network status 3 5.3 Resource allocation 3 5.4 Start-up and re-synchronization procedures . 4 6 Coexistence signal definition 4 6.1 Signal generation 5 6.2 Phase vectors 8 6.3
17、 Sync point . 9 7 Coexistence signalling scheme . 10 7.1 ISP window 10 7.2 ISP fields 11 7.3 Network status 13 8 Coexistence resources . 14 8.1 Frequency domain multiplex (FDM) 14 8.2 Time domain multiplex (TDM) 15 8.3 FDM/TDM modes 16 8.4 Parameters 17 9 Resource allocation . 18 9.1 TDM resource al
18、location for access systems . 18 9.2 TDM resource allocation 19 10 Start-up and resynchronization procedures 19 10.1 Start-up procedure 20 10.2 Resynchronization procedure . 22 11 Power control procedures . 25 12 Time slot reuse 25 13 Generic management message 25 13.1 State indication messages . 25
19、 13.2 Resynchronization messages 26 14 Signal transmission and detection 28 14.1 Transmit PSD . 28 14.2 Signal detection 29 14.3 Zero-crossing detection 29 iv Rec. ITU-T G.9972 (06/2010) Page Annex A ITU-T G.996x coexistence management messages . 30 A.1 ITU-T G.996x coexistence management message pa
20、rameters . 30 Bibliography. 35 Rec. ITU-T G.9972 (06/2010) 1 Recommendation ITU-T G.9972 Coexistence mechanism for wireline home networking transceivers 1 Scope This Recommendation specifies a coexistence mechanism for home networking transceivers capable of operating over powerline wiring. The coex
21、istence mechanism allows ITU-T G.996x devices to coexist with other coexisting systems, as defined in this Recommendation, operating on the same powerline wiring. Specifically, this Recommendation defines: the coexistence signal structure and characteristics; the coexistence signalling scheme and ti
22、ming requirements; the allocation of resources to each coexisting system; the start-up, synchronization and resynchronization procedures; the generic messages required to be supported by each coexisting system; the time slot reuse requirements; the signal transmission and detection requirements. 2 R
23、eferences 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 Recommendations and other references are subject to revision;
24、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 published. The reference to a document within this Recom
25、mendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.996x Recommendations ITU-T G.996x (in force), Test procedures for digital subscriber line (DSL) transceivers. ITU-T G.9960 Recommendation ITU-T G.9960 (2010), Unified high-speed wire-line based home networ
26、king transceivers System architecture and physical layer specification. 3 Definitions This Recommendation defines the following terms: 3.1 access system: A powerline communications system carrying high-speed digital communications on frequencies above 2 MHz over medium and low voltage electric power
27、lines that distribute electricity to end-user premises enabling a communication link between the power utility infrastructure and the home. The electric powerlines may be both outside and within buildings. 3.2 coexistence: The capability that allows two or more non-interoperable systems to share the
28、 same medium, while minimizing mutual interference to each other. 3.3 coexisting system: A powerline communications system that belongs to one of the coexisting system categories and uses ISP to coexist with other non-interoperable systems. 2 Rec. ITU-T G.9972 (06/2010) 3.4 coexisting systems catego
29、ries: ITU-T G.996x, IHC1, IHC2 and ACC. IHC1, IHC2 and ACC are reserved by ITU-T. ITU-T G.996x is the family of home networking Recommendations including ITU-T G.9960. NOTE IHC1 and IHC2 are to be allocated to b-IEEE 1901. 3.5 ISP field: The region in frequency and time within which an ISP signal is
30、 transmitted. 3.6 ISP phase vector: The sub-carriers of the ISP signal, each of which may be transmitted with either phase 0 or phase . The phase vector defines which sub-carriers are transmitted with which phase. Five phase vectors are defined. 3.7 ISP sequence: A series of consecutive ISP windows
31、to which one or more coexisting systems are synchronized. 3.8 ISP signal: An OFDM-based signal used by coexisting systems to indicate their status or requests to other coexisting systems. ISP signals are transmitted within ISP fields. 3.9 ISP window: A group of two ISP fields that is contiguous in t
32、ime. Consecutive ISP windows are separated by the period TISP. 3.10 master node: A node in a coexisting system that determines the overall ISP timing, resource allocation, and start-up/resynchronization behaviour with other coexisting systems. 3.11 slave node: Any node in a coexisting system other t
33、han the master node. 3.12 synchronization period (TH): The period between consecutive ISP windows of the same type. Consists of several TISPperiods and forms the period for an entire cycle of ISP signalling. 3.13 synchronization point (sync point): A point in time located at multiples of 60 degrees
34、from a zero-crossing point on an AC mains. The first ISP field begins at a set offset (ISP_OFFSET) from a sync point. 3.14 TDM unit (TDMU): A sub-division of the time between consecutive ISP windows. A TDMU is further divided into TDM slots. 3.15 TDM slot (TDMS): The smallest amount of time that may
35、 be allocated to a coexisting system in TDM mode. Particular TDMSs are allocated to particular systems depending upon the current network status. 4 Abbreviations This Recommendation uses the following abbreviations: ACC Access AWGN Additive White Gaussian Noise EMI Electromagnetic Interference FB Fu
36、ll Bandwidth FDM Frequency Domain Multiplex IFFT Inverse Fast Fourier Transform IH In-Home IHC1 In-Home Category 1 IHC2 In-Home Category 2 IH-G ITU-T G.996x ISP Inter-System Protocol Rec. ITU-T G.9972 (06/2010) 3 OFDM Orthogonal Frequency Division Multiplexing PB Partial Bandwidth TDM Time Domain Mu
37、ltiplex TDMA Time Division Multiple Access 5 Overview Inter-system protocol (ISP) allows for the powerline medium to be shared between coexisting systems in the time domain, called time domain multiplex (TDM), the frequency domain, called frequency domain multiplex (FDM), or both. ISP supports coexi
38、stence between up to four non-interoperable coexisting systems. This Recommendation assumes that there is only one access system operating over the distribution lines that provide power to a given customer premises. The frequency range used by ISP signalling ranges from 2 MHz to 50 MHz. Sharing of t
39、he powerline medium between coexisting systems is determined by the following: number of coexisting systems on the powerline; type of coexisting system; access system capacity request. An overview of the ISP is provided in the next clause, followed by clauses describing the details of each component
40、 of the protocol. 5.1 Inter-system protocol 5.1.1 Coexistence signalling Coexistence signalling is carried out by the use of periodically repeating ISP windows that are used to convey information on coexisting system presence, resource requirements and resynchronization request. Each coexisting syst
41、em category is allocated a particular ISP window in a round robin fashion. 5.2 Network status By monitoring the signals transmitted within the ISP windows allocated to other coexisting systems, a coexisting system is able to detect the number and type of other coexisting systems present on the line
42、and the resource requirements of the access system (i.e., partial/full bandwidth). By monitoring the signals within its own ISP window, a coexisting system is able to detect a resynchronization request from one of the other coexisting systems. This set of instantaneous information is termed the netw
43、ork status. Network status is used to determine the allocation of resources to each coexisting system. 5.3 Resource allocation 5.3.1 Frequency domain multiplex (FDM) Within ISP, FDM may only be invoked by an access system. The overall FDM scheme consists of two frequency bands. The upper band is sha
44、red using TDM by in-home systems, the lower band reserved for access systems. One of two FDM band separation frequencies (10 MHz or 14 MHz) is chosen by the access system. 4 Rec. ITU-T G.9972 (06/2010) 5.3.2 Time domain multiplex (TDM) ISP allows TDM to be implemented between coexisting in-home syst
45、ems or between coexisting in-home systems and an access system. The allocation of resources in the time domain is described in clause 9. The period between each ISP window is divided into smaller units and sub-units that are used as the basis for TDM resource allocation. 5.4 Start-up and re-synchron
46、ization procedures In order to allow coexisting systems to synchronize to the appropriate ISP sequence and hence to effectively coexist, the ISP defines: procedures for system start-up; triggers and procedures for re-synchronizing to a different ISP sequence. 6 Coexistence signal definition The stru
47、cture of the ISP signal shall be as follows: The ISP signal consists of 16 consecutive OFDM symbols. Each OFDM symbol is formed using a 512-point inverse fast fourier transform (IFFT) with each sub-carrier having a phase shift defined in clause 6.2. The ISP time domain signal is then multiplied by a
48、 window function W(n) to reduce the out-of-band energy in order to be compliant with the transmit spectrum mask. The window function W(n) is vendor proprietary. The ISP signal is depicted in Figure 6-1. G.9972(10)_F6-1OFDM signals (16 symbols)TssTwTsTtotalTwAn OFDM symbolFigure 6-1 Timing of the ISP
49、 signal The parameters that define the signal are shown in Table 6-1. Table 6-1 ISP signal parameters Symbol Description Time samples (assuming a 100 MHz sampling rate) Time (s) Ts OFDM symbol duration 512 5.12 Tss OFDM signals duration Ttotal 2 * Tw Ttotal 2 * Tw Tw Windowing duration Less than or equal to 1024 Less than or equal to 10.24 Ttotal ISP signal duration 8192 81.92 Rec. ITU-T G.9972 (06/2010) 5 6.1 Signal generation The ISP signal, SI(n), is defined as time-domain samples ass
