scope:

This standard provides spectrum management requirements and recommendations for the administration of services and technologies that use metallic subscriber loop cables. Spectrum management is the administration of the loop plant in a way that provides spectral compatibility for services and technologies that use pairs in the same cable. In order to achieve spectral compatibility, the ingress energy that transfers into a loop pair, from services and transmission system technologies on other pairs in the same cable, must not cause an unacceptable degradation of performance. In addition, the egress energy from a particular loop pair must not transfer into other pairs in a manner that causes an unacceptable degradation in the performance of services and technologies on those pairs.

This standard includes the following types of requirements and recommendations for defined digital subscriber line spectrum management classes and specified loop technologies:

− Power Spectral Density (PSD);

− Total average power;

− Transverse balance;

− Longitudinal output voltage; and

− Deployment guidelines.

The standard also specifies a generic analytical method (Annexes A and B) to determine the spectral compatibility of loop technologies that do not qualify for one of the spectrum management classes defined in this standard. Additional requirements are specified for Short-Term Stationary systems.

Requirements in this standard are specified for digital subscriber line systems operating on insulated solid copper conductor twisted-pair cables used in the North American subscriber loop environment.

A system that fits in a spectrum management class complies with the Spectrum Management and Spectral Compatibility requirements of this standard. A system that complies with Annex A or B complies with the Spectrum Compatibility requirements of this standard. Compliance with a spectrum management class provides knowledge of the characteristics of the loop system to aid deployment practices that reduce the adverse impact to certain widely deployed loop transmission systems defined in this standard as "basis systems.

DSL transmission systems that meet all of the specifications associated with one of the DSL spectrum management classes are assumed to be spectrally compatible in the same binder group with all of the basis systems defined in this standard. Meeting the specifications associated with one of the spectrum management classes in this standard does not assure spectral compatibility with non-basis loop transmission systems.

The requirements in clauses 5.3 and 5.4 are for applications where all DSL systems are deployed either between a Central Office (CO) and a customer installation (CI) or between a Remote Terminal (RT) site and a CI. The requirements in clause 5.2 are for applications where DSL Systems to a CI are either deployed from both a CO and an RT site or use intermediate repeaters between the CO and CI.

Electromagnetic Compatibility (EMC) is outside of the scope of this standard. In addition, the spectrum management of privately owned twisted-pair cables or customer premises twisted-pair cabling are beyond the scope of this standard, although the information in this standard may be useful in such applications.

The guidelines in this standard are based strictly on spectrum management requirements. It is understood that a technology may have performance capabilities that either exceed or fall short of the loop lengths specified for spectrum management.

The signals that the network and CI apply to the loop are basically of two types: 1) normal telecommunications transmission system voltages and currents; and 2) voltages and currents due to maintenance activities. The normal network and CI signals are addressed in this standard. Voltages and currents due to network maintenance activities may be addressed in a future version of this standard. Abnormal voltages and currents that are the result of the environment (e.g., induced voltages and currents or lightning) are not covered in this standard.

Purpose

The purpose of this standard is to facilitate a reasonable spectral environment for the co-existence of multiple technologies in the loop plant with an acceptable level of crosstalk between them. When only one carrier deploys technologies in the loop plant, it alone has the responsibility for spectral compatibility and may select any combination of compatible loop technologies. However, in an unbundled loop environment, multiple carriers utilize pairs in the same loop cables. In such instances, if services and technologies are deployed without regard to spectral compatibility, they may interfere with each other. This standard assumes that multiple carriers share loop cables and that all carriers share the responsibility for spectral compatibility.

This standard provides information that will help to ensure that twisted-pair transmission systems can coexist without impaired operation due to crosstalk interference. The standard is intended for use by carriers to manage the loop plant and by manufacturers in the design of loop transmission systems.

This standard was also developed to assist carriers, manufacturers, and users of products connected to local loops to understand the characteristics of twisted-pair loop cables. In addition, this standard can be used to determine if new services and loop transmission system technologies are spectrally compatible with the basis systems that are defined in this standard.

This standard is intended to be consistent with technical criteria adopted by the Administrative Council for Terminal Attachments (ACTA) to protect the network from harm caused by customer installation terminal equipment. Some of the digital subscriber line spectrum management classes and technology specific criteria defined in this standard may not be covered by ACTA technical criteria. If ACTA technical criteria are subsequently established for technologies that fall into those categories, the requirements in this standard can be referenced. Tariffs, contracts, or regulatory acts in various jurisdictions may contain requirements different from those in this standard.

The provisions of this standard are also intended to be consistent with applicable requirements concerning safety and environmental conditions.

Application

This standard is applicable to digital subscriber line transmission systems that operate on metallic twistedpair cables in the local loop environment.

All of the loops described in this standard may not be universally available. For example, a loop that supports Basic Rate ISDN (BRI) can only be provided if the facilities serving the CI are qualified to support such technology.

Because of the wide range of network switching systems, network transport systems, subscriber loop plant, and CIs in North America, conformance with this standard does not guarantee acceptable performance under all possible operating conditions. In some cases, measures beyond the scope of this standard may be necessary.

NOTE - Cable pair lengths in this standard are normally expressed in units of kilofeet. Some information on transmission media is, however, expressed in kilometers.