1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0100512.1994(R2013) Voice-Grade Special Access Network Voiceband Data Transmission As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressing business
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5、ion, visit. AMERICAN NATIONAL STANDARD Approval of an American National Standard requires review by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Sta
6、ndards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward
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8、dards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the Amer
9、ican National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National St
10、andards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer end-to-end (NI-
11、to-NI) performance; voiceband data application performance. The objectives, guidelines, and discussion stated herein reflect the following considerations: end-user needs of end-to-end service; network architectures and equipment used in providing voice-grade special access services at the time of th
12、e development of this standard, as offered by many exchange carriers (ECs) as nonswitched private line or leased line access; normally occurring variations in parameter characteristics of facilities and equipment used in providing voice-grade special access services; operational and economic feasibi
13、lity of providing the standard services; current performance and technical capabilities of terminal equipment as specified in TIA/EIA and ITU standards; the predominately digital network. An informative annex on the relation of transmission performance to end-user application performance is provided
14、. A bibliographic informative annex is also provided. Suggestions for improvement of this standard are welcome. They should be sent to the Alliance for Telecommunications Industry Solutions (formerly the Exchange Carriers Standards Association), Suite 500, 1200 G Street, NW, Washington, DC 20005. Th
15、is standard was processed and approved for submittal to ANSI by the Accredited Standards Committee on Telecommunications, T1. Committee approval of this standard does not necessarily imply that all committee members voted for its approval. At the time it approved this standard, Committee T1 had the
16、following officers and members: Arthur K. Reilly, Chair Gerald H. Peterson, Vice-Chair O. J. Gusella, Secretary Barry Lerich, Senior Editor Organization Represented Name of Representative EXCHANGE CARRIERS Ameritech Services, Inc. . Laurence A. Young Stephen P. Murphy (Alt.) Bell Atlantic . John W.
17、Seazholtz Roger Nucho (Alt.) Bellcore . E. R. Hapeman James C. Staats (Alt.) BellSouth Telecommunications, Inc Leonard Strickland, Jr. William J. McNamara, III (Alt.) Cincinnati Bell Telephone . Kevin R. Sullivan Renee W. Cagle (Alt.) GTE Telephone Operations Bernard J. Harris Richard L. Cochran (Al
18、t.) National Telephone Cooperative Association . Joseph M. Flanigan NYNEX James F. Baskin Jim Papadopoulos (Alt.) Pacific Bell. Sal R. Tesoro Puerto Rico Telephone Company. Alberto E. Morales Segundo Ruiz Southwestern Bell Corporation . C. C. Bailey Joseph Mendoza (Alt.) Sprint Local Telecommunicati
19、ons Division Robert P. McCabe Harold L. Fuller (Alt.) US Telephone Association (USTA). Dennis Byrne Paul Hart (Alt.) US WEST James L. Eitel Darryl Debault (Alt.) INTEREXCHANGE CARRIERS American Mobile Satellite Corporation Michael K. Ward William Garner (Alt.) AT if the far-end interface is a 2-wire
20、 POT, the standard termination is 900 in series with 2.16 F of capacitance. At a 4-wire far-end interface, the standard termination is 600 (with no series capacitance). 4.2.3.2 Return loss measurements When measuring return loss at a 2-wire NI, a hybrid in conjunction with a balancing network compri
21、sing 600 of resistance in series with 2.16 F of capacitance is a necessary part of the measuring system to permit application of the test transmit signal and measurement of the reflected power. Measurements at a 4-wire interface do not require the use of a hybrid in the measuring system, but the ret
22、urn loss measuring set readings may require adjustment for the TLPs at the point of measurement. Specifications for return loss measuring sets can be found in ANSI/IEEE 743. Annex A (informative) Relation of transmission performance to end-user application performance Public and private voice-grade
23、telecommunication services are important vehicles for VBD customers. These customers employ applications such as facsimile, bulk data transmission, and terminal/host systems, to name a few. In cases where the services are provided using VGSA arrangements for access to dedicated or switched POT-POT f
24、acilities, it is important that the end-to-end services be designed so they will meet customer application needs. These end-to-end needs are satisfied by designing the segments to a sufficiently high level of transmission performance such that the concatenated end-to-end impairment levels can be tol
25、erated by the application. The objectives and discussions in this standard are based on the evolution of telecommunication transmission to predominately digital carrier systems. Voice-grade channels that use digital technology end-to-end, exhibit characteristics somewhat different from analog transm
26、ission arrangements. Digital facilities tend to have a smaller statistical spread of impairment values than analog facilities. Furthermore, some measurable parameters do not occur on digital circuits while other parameters need more careful control. In addition to network evolution, Customer Premise
27、s Equipment (CPE) technological development has also progressed to affect application performance. The trend in VBD CPE is to higher data rate, performance monitoring, and built-in protocols. CPE has evolved to take almost full advantage of channel capabilities. For a network to be useful, it must s
28、atisfy the performance needs of the customer applications. It is possible to classify most applications into a few comprehensive categories, depending on their accuracy performance needs. For voiceband data applications, a digital channel is derived from the voiceband channel by using modems. Accura
29、cy metrics often used for the digital channel are Bit Error Ratio (BER) and Block Error Ratio (BLER). Required modem performance as a function of application maps into related network transmission performance. Table A.1 gives classifications by accuracy performance metric and corresponding limits. I
30、f the channels are engineered to overly stringent requirements, from the point of view of the application, the customer may ultimately pay an economic price for this inefficiency. There is, however, according to table A.1, a range of application needs depending on various end-user functions. To appr
31、oach the optimum on a per-application basis, it is therefore reasonable to offer a spectrum of possible services. Each service meets the needs of a subset of applications with similar performance requirements, while at the same time offering appropriate economical treatment. Given the above consider
32、ations, the application is realized through the following process. The customer initially defines the application and its performance needs. In theory, these needs dictate the choices to be made regarding the communication components. The customer chooses modems that have the required features such
33、as data rate, error correction, protocols, ruggedness, etc. These modems are connected to the NIs of the communication channel. The customer should choose network channel segments that, when concatenated, have appropriate noise levels, linear impairments, nonlinear distortion, incidental modulation,
34、 etc. The modem characteristics dictate which of these parameters need to be tightly or loosely controlled. Contributions to the end-to-end parameters come from access, long haul, and egress segments. The modems interface to the access and egress segments that contain analog cable segments, the firs
35、t and final A/D and D/A conversions, equalization equipment, Digital cross-connect systems (DCS), add/drop multiplexers, etc. The number and types of this equipment affect performance of the application. Finally, the customer chooses the connecting long-haul segment of the connection. Impairments on
36、 a digital POT-to-POT segment arise predominately from DCS, propagation delay, and digital errors. For the customer to make these complex/compound choices requires an understanding of the application needs and network capabilities as well as communication vendor assistance. In order to formulate rea
37、listic objectives, it is worthwhile to discuss what is theoretically possible in a digital environment. Figure A.1 shows an (NI-NI) architecture that consists of a single pair of A/D D/A conversions terminated with cable facilities. In this example, the cable facilities contribute mainly to the loss
38、, attenuation distortion, and impulse noise. To a lesser extent, envelope delay distortion and other impairments can occur. Loss, attenuation distortion, and envelope delay distortion can be equalized in the access/egress segments or by modems. Furthermore, the access and egress segments (NI-POT and
39、 POT-NI) contain the A/D and D/A equipment, respectively. This and associated equipment generate quantization noise, nonlinear distortion, and transients. Higher data rate modems tend to be more sensitive to these impairments than lower data rate devices. Some examples of modem susceptibility to tra
40、nsients are given in table A.2. The “Impulse noise level” column labeled “None” refers to the level below which no errors occur; “All” refers to the level above which errors occur for every impulse. Also “Minimum phase hits” are estimated levels of phase hits that begin to cause modem errors. The le
41、vels in table A.2 are only guidelines. Different modem implementations may have different performance characteristics. Also, when multiple impairments are present, one impairment (e.g., noise) will cause the susceptibility to other impairments to be increased. Finally, the long-haul portion of the c
42、hannel is connected digitally to access and egress at the POTs. Except perhaps for additional quantization noise generated by bit robbing in DCS, no new steady state impairments should be added to the connection. However, this segment usually introduces the major component of throughput-affecting pr
43、opagation delay. Furthermore, digital transmission errors can be reflected as analog impairments, particularly impulse noise4). Under the best possible conditions this hypothetical end-to-end connection could be designed to have 3200-Hz bandwidth, no linear impairments, signal-to-C-notched-noise rat
44、io of 39 dB (the theoretical maximum), second, and third, order intermodulation distortion better than 60 dB, no incidental modulation, and no transient impairments. Although this architecture can technically be achieved, the impairment levels may not always meet the above numbers due to statistical
45、 and temporal performance variation in the channel segments. Furthermore, digital access/egress segments with only one A/D conversion in each may not be available at all locations at all times. Access/egress with multiple A/D conversions or DCS may be more readily available with corresponding econom
46、ic advantage to the customer. Finally, in many cases, an application may operate satisfactorily with lower levels of channel performance than this hypothetical connection delivers. Thus, it may be possible to use segments with additional A/D conversions (more quantization noise), or less control of
47、linear impairments for the customers purposes. Annex B (informative) Bibliography ANSI T1.303-1989, Telecommunications Digital processing of voice-band signals Algorithms for 24-, 32-, and 40-kbit/s adaptive differential pulse-code modulation (ADPCM)5)AT&T, ACCUNET Spectrum of Digital Services (ASDS
48、) Technical Reference, Technical Reference TR 62421, 19906) AT&T, Digital Channel Bank Requirements and Objectives, Technical Reference PUB 43801, 19826)Bell Communications Research, Voice Grade Special Access Service Transmission Parameter Limits and Interface Combinations, Technical Reference TR-N
49、WT-000335, Issue 3, May 19937)Bell Communications Research, 1983 Exchange Access Study: Analog Voice and Voiceband Data Transmission Performance Characterization of the Exchange Access Plant, Technical Reference TR-NPL-000037, 19847)1) Parameters measured for circuit acceptance and restoral will depend on the network providers service offerings and may not include all the parameters specified in this standard. 2) Note that V.34 might be specified to have a maximum data rate as high as 28.8 kbit/s. 3)This standard is undergoing revision. Please contact the
