TIA Issues Request for Comment on New xDSL Equipment Technology

Arlington, VA (May 20, 2019): The Telecommunications Industry Association (TIA) TR-41 Engineering Committee on Performance and Accessibility for Communications Products has issued a request for comments on new technology concerning the xDSL equipment industry.

In traditional xDSL deployments, the Central Office (CO) installs a Distribution Point Unit (DPU) that connects on the network side to a fiber optic cable and on the subscriber side to one or more subscriber’s copper lines. Each subscriber line would be terminated at the customer premises by a xDSL modem. In this traditional configuration, the CO DPU is powered locally from the CO.

This new technology employs a “reverse power feeding” configuration where the power for the DPU is not provided by the CO, but instead is provided from the subscriber side CPE. The new CPE xDSL modem has a built in DC power source that applies DC voltage and current to the subscriber line that is received at, and is used to power, the DPU. An alternate configuration is to use a regular xDSL (such as G.fast) modem and use a combiner device (power inserter) to connect 54VDC power to the customer premise subscriber line side to power the DPU.

Reverse power feeding deployments would not be used in conjunction with traditional analog interface telephone services on the same subscriber line.

The reverse power feeding technology is considered critical to the success of the deployment of G.fast due to the short maximum copper line distance that G.fast modems may operate over which is typically less than 250m. The deployment strategy is to move the DPU units closer to the customer premises and connect the DPU fiber optic line remotely to the CO.

TIA TR 41.9 has been asked to comment on:

1. The need to register reverse powering G.fast modems and associated power inserter devices with the Administrative Council for Terminal Attachments; and
2. If the DC power insertion from the CPE side (integrated with a G.fast modem or as an adjunct device) would cause the device to fail any technical requirements, including TIA-968-B.

TIA is requesting interested parties to contact TIA with all comments via email to Teesha Jenkins tjenkins@tiaonline.org by June 10, 2019.

For more information about TR- 41 and how to participate in standards development with TIA, contact Standards at standards@tiaonline.org. A major function of the Telecommunications Industry Association (TIA) is the writing and maintenance of voluntary industry standards and specifications. These activities are carried out by the volunteer members of TIA engineering committees. Recent meeting reports, agendas and notices for upcoming meetings, as well as links to some of the most popular standards from each committee are available on TIA’s public engineering committee pages.

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