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 J.1107 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2018) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Switched digital video over cable networks Architecture
2、and specification for radio over IP transmission systems Recommendation ITU-T J.1107 Rec. ITU-T J.1107 (03/2018) i Recommendation ITU-T J.1107 Architecture and specification for radio over IP transmission systems Summary As cable television (TV) networks migrate to deep fibre or fibre to the home (F
3、TTH) architectures, it is now possible and easy to provide bidirectional high-quality media services that require very high-speed digital transmission of high-quality content. Cable TV networks provide services by transmitting radio frequency (RF) signals between the headend and a cable modem (CM).
4、The configuration and devices of these networks are optimized for RF signal transmission. When migrating to all-fibre cable TV networks, changing the existing network devices to new network devices for service operators (SOs), who provide broadcasting and various data services through hybrid fibre c
5、oaxial (HFC)-based cable TV networks, is recommended. Therefore, a cost-effective solution for deployable and acceptable migration toward optic-based cable TV networks is required. Recommendation ITU-T J.1107 provides a cost-effective adaptable solution for HFC-based cable TV network devices in opti
6、c-based cable TV networks. The purpose of the radio over Internet protocol (RoIP) system is to transmit data over cable service interface specifications (DOCSIS)-based upstream (US) RF signals of CM to cable modem termination system (CMTS) through IP transmission in optic-based cable TV networks. Hi
7、story Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T J.1107 2018-03-16 9 11.1002/1000/13564 Keywords RoIP. * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/hand
8、le.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T J.1107 (03/2018) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (
9、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 worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every fou
10、r 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 WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the
11、 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 administration and a recognized operating agency. Compliance with this Recommendation is voluntary. H
12、owever, 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 provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negat
13、ive 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 to the possibility that the practice or implementation of this Recommendation may involve the use
14、 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 outside of the Recommendation development process. As of the date of approval of this Recommendation,
15、 ITU had not 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 information and are therefore strongly urged to consult the TSB patent database at http:/www
16、.itu.int/ITU-T/ipr/. ITU 2018 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 J.1107 (03/2018) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.
17、2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 1 5 Conventions 2 6 Overview . 2 7 Functional architecture . 4 7.1 RoIP terminal 4 7.2 RoIP headend 5 8 Service flow 5 8.1 Initialization process . 6 8.2 Data transmission process 7 Bibliography. 9 Rec. ITU-T J.1107 (03/2018) 1
18、Recommendation ITU-T J.1107 Architecture and specification for radio over IP transmission systems 1 Scope This Recommendation describes the architecture and specification for radio over IP transmission (RoIP) systems in hybrid fibre coaxial (HFC)-based networks. The architecture described in this Re
19、commendation is defined according to ITU-T J.1106. The architecture and specifications described in this Recommendation are defined as follows: radio over IP terminal system; radio over IP headend system. 2 References The following ITU-T Recommendations and other references contain provisions which,
20、 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; users of this Recommendation are therefore encouraged to investigate the possibility of appl
21、ying 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 Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T
22、 J.210 Recommendation ITU-T J.210 (2006), Downstream RF interface for cable modem termination systems. ITU-T J.222.1 Recommendation ITU-T J.222.1 (2007), Third-generation transmission systems for interactive cable television services - IP cable modems: Physical layer specification. ITU-T J.222.2 Rec
23、ommendation ITU-T J.222.2 (2007), Third-generation transmission systems for interactive cable television services IP cable modems: MAC and upper layer protocols. ITU-T J.1106 Recommendation ITU-T J.1106 (2017), Requirement for radio over IP transmission system. 3 Definitions 3.1 Terms defined elsewh
24、ere None. 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CM Cable Modem CMTS Cable Modem Termination System DOCSIS Data Over Cable Service Interface Specifications 2 Rec. ITU-T J.1107 (03/2018) DS Downstr
25、eam E/O Electric to Optic FTTH Fibre To The Home HFC Hybrid Fibre Coaxial OLT Optical Line Terminal OMUX Optical Multiplexer PON Passive Optical Network RF Radio Frequency RoIP Radio over IP SO Service Operator STB Set-Top Box US Upstream 5 Conventions In this Recommendation: The keywords “is requir
26、ed to“ indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed. The keywords “is recommended“ indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be p
27、resent to claim conformance. The keywords “is prohibited from“ indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed. The keywords “can optionally“ indicate an optional requirement which is permissible, withou
28、t implying any sense of being recommended. This term is not intended to imply that the vendors implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim con
29、formance with the specification. In the body of this document and its annexes, the words shall, shall not, should, and may sometimes appear, in which case they are to be interpreted, respectively, as is required to, is prohibited from, is recommended, and can optionally. The appearance of such phras
30、es or keywords in an appendix or in material explicitly marked as informative are to be interpreted as having no normative intent. 6 Overview As shown in Figure 1, the RoIP system ITU-T J.1106 consists of an RoIP terminal and an RoIP headend. The RoIP terminal is located at the endpoint of an optic-
31、based cable TV network and the RoIP headend is located between the cable modem termination system (CMTS) and optical network endpoint such as an optical line terminal (OLT). It is required to synchronize and transmit upstream (US) using a data over cable service interface specifications (DOCSIS)-bas
32、ed protocol b-ANSI/SCTE 135-1 2008, b-ANSI/SCTE 135-2 2008, b-ANSI/SCTE 135-4 2008, b-ANSI/SCTE 135-5 2008 for IP transmission. For fibre to the home (FTTH), a broadcast signal and a signal to be output ITU-T J.210 from the CMTS are radio frequency (RF) signals which have different center frequencie
33、s. These signals may be combined as a signal output by a combiner, and an RF signal to be output from the combiner may be output after being input to a downstream optical transmitter. Through the input and the output, an RF electrical signal may be converted to an optical signal. Rec. ITU-T J.1107 (
34、03/2018) 3 An optical signal is different from a passive optical network (PON)-type signal used in general optical communications. The optical signal used in a PON turns on or off an optical source based on a bit value in a bit unit, whereas the optical signal obtained by the conversion in a downstr
35、eam optical transmitter is an optical amplitude modulation signal to change the intensity of an optical source with respect to an amplitude of an RF signal. The signal converted to an optical signal may be transmitted to a splitter through an optical cable after being amplified in an erbium-doped fi
36、bre amplifier (EDFA), and the signal, split at a rate of 1:N in the splitter, may be input to an optical network terminal (ONT) located on a customers premise. In the case of an ONT on a customers premise, in addition to a function of the ONT used for PON-based optical communications, functions of r
37、estoring an optically modulated downstream RF signal and transmitting the signal through a coaxial cable and of detecting an upstream RF signal to be output from the cable modem or the set-top box (STB), digitizing the detected signal, and transmitting the digitized signal via an IP packet ITU-T J.2
38、22.1, ITU-T J.222.2 may be added. It is the RoIP terminal. Unlike the downstream RF signal, the upstream RF signal is converted into a digital signal by the RoIP terminal and transmits it formed of IP packets over the IP networks (i.e., xPON networks). In the RoIP headend, the digital signal include
39、d in the received IP packet is recovered and the original analogue RF signal is transmitted it to the CMTS. For the purpose of transmitting the upstream signal by the CM during the time interval allocated from the CMTS, it should be synchronized among CMTS, RoIP headend, RoIP terminal and CM. Figure
40、 1 System architecture for radio over Internet protocol The RoIP system, including the RoIP headend and RoIP terminal, greatly reduces implementation costs for optical modulation as transmitting upstream RF signals in the optical-based cable TV networks, and it is also possible to reuse existing RF-
41、based broadcasting equipment (e.g., STB, CMTS) operating in the cable-based cable TV networks. 7 Functional architecture 7.1 RoIP terminal As the upstream RF signal is output from the CM or STB, the RoIP terminal detects the RF signal. The RoIP terminal performs an analog to digital conversion (ADC)
42、 on the detected RF signal to digitize the analog RF signal. 4 Rec. ITU-T J.1107 (03/2018) The RoIP terminal converts the detected digitized RF signal to the IP packet and transmits it to the headend. Since upstream traffic transmission is performed through time division multiple access (TDMA), accu
43、rate timing synchronization in the network may be necessary. Thus, the timing synchronization between the RoIP terminal, located on the subscriber side, and the RoIP headend may be performed using a network synchronization protocol. Timing information corresponding to the time when the upstream RF b
44、urst signal, output from the STB and CM, is input to the RoIP terminal after timing synchronization is obtained, is digitized and transmitted as an IP packet when the RF signal is transmitted. After receiving the corresponding IP packet from the RoIP headend and checking timing information, all pack
45、ets have a predetermined delay time and will generate and output an RF signal again. The CMTS then receives the upstream RF signal at the time assigned to each STB or CM. Figure 2 Architecture for radio over Internet protocol terminal As shown in Figure 2, the RoIP terminal consists of the following
46、 five modules: 1) DOCSIS downstream MAC/PHY module: demodulates the downstream signals transmitted from headend devices (e.g., CMTS) to cable terminal devices (e.g., CM, STB) and processes several multicast management messages (e.g., SYNC, UCD, MAP) procedures. 2) Upstream burst receive module: dete
47、cts the upstream analog RF signal output from cable terminal devices (e.g., CM, STB), obtains the time that the RF signal is detected, converts it into a baseband digital signal, and transmits the converted signal with the obtained time to the DOCSIS timing processing module. 3) DOCSIS timing proces
48、sing module: synchronizes the RoIP terminal with the RoIP headend using the RF upstream signal detection time of the cable terminal devices (e.g., CM, STB) and the bandwidth allocation information of the downstream multicast management messages. 4) Burst data processing module: compresses the baseba
49、nd digital signal output from the upstream burst receive module and generates IP frames with information of the detected time and transmits it to IP networks. 5) RoIP terminal control module: analyzes information from the upstream channel and burst of the DOCSIS downstream MAC/PHY module, transmits it to upstream burst receive module. Gathers the status information of modules in the RoIP terminal and manages configuration of the modules. Rec. ITU-T J.1107 (03/2018) 5 7.2 RoIP headend The digitized RF signal transmitted to the headend is inp
