Plain Old Telephone Service Research Articles

Introduction strategies towards B-ISDN for business and residential subscribers based on ATM

It is argued that introduction strategies for B-ISDN with a clear evolutionary path to the future must be worked out. Two strategies are described, along with their early application. The first is mainly intended for business customers and offers an initial-phase asynchronous transfer mode (ATM) cross-connect functionality. The second is for residential users and initially offers POTS (plain old telephone service) and narrowband ISDN and analog TV services. Both solutions can easily be upgraded step by step to a full ATM-based B-ISDN. >

The challenges of fibre in the loop

Cable and hardware issues in the loop passive transmission network are examined as they relate to evolving trends and the concerns the designer and outside plant engineer should consider in preparing to install cable and hardware in the loop environment. Logical and physical topologies for fiber in the loop (FITL) are examined. Issues that must be considered when installing fiber in the loop are discussed, focussing on flexibility requirements, the use of standard products and cost. Simple POTS (plain old telephone service) to the curb is seen as the near-term solution.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fiber to the home: the technology behind Heathrow

In July 1989, Southern Bell began deploying a fiber access system capable of carrying 54 cable television (CATV) channels, as well as plain old telephone service (POTS) and integrated services digital network (ISDN) services in Heathrow, Florida. Four areas that must be addressed before these services can be successfully deployed in volume are discussed. They are integrating narrowband and broadband services on the same fiber, choosing a fiber architecture, designing the optical-network interface for multiple services, and designing a centralized digital video-selector switch.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fiber-to-the-curb systems: Architectural alternatives

Abstract Several fiber-to-the-curb (FTTC) systems have been proposed in response to the present high cost of fiber-to-the-home (FTTH) systems for plain old telephone service (POTS). With FTTC systems, fiber is brought only as far as the service access point (SAP). From there, copper drops carry POTS signals from the SAP to several residences. Due to the extensive sharing of optical sources and the fibers running to the SAP, the per-subscriber system cost is reduced to levels comparable to that of a copper-bused digital loop currier distribution system. This paper presents an analysis of three different fiber-to-the-curb distribution networks that serve up to 96 customers, initially providing two POTS channels to each customer. These systems serve four customers per SAP through star, distributed star, or bus topologies that offer differing levels of sharing of fiber and optoelectronic components. We estimate the installed first costs (IFC) of the distribution link (remote node to customer) for the three FT...

Cost of power—the user's perspective

Abstract With the advent of fiber in the loop, transmission of power ceases to be through the traditional communications medium, and the objective of powering voice lines over fiber with the same reliability goals as plain old telephone service (POTS) raises several technological, regulatory, and business issues. In order to power the optical network unit (ONU) and provide backup power for it during commercial power outages, three strategies are identified: 1) providing loop powering from a −48 volt CO/CEV power plant; 2) providing power and backup power locally, from or near the end of the loop in proximity to the OW; and 3) providing power from the curb or a power node. This paper constructs economic models to determine the worth of a watt at the 5-volt logic level at an ONU for each of the powering strategies. By normalizing all costs to the worth of a watt, comparisons can be made and appropriate architectures can be selected for various applications.

A star‐configured fiber‐to‐the‐curb system

AbstractFiber‐to‐the‐curb (FTTC) system proposals have arisen because of the present high cost of fiber‐to‐the‐home (FTTH) systems. With FTTC systems, fiber is brought only as far as the service access point (SAP). From there, copper drops carry signals from the SAP to several residences. Owing to the extensive sharing of optical sources and the fibers running to the SAP, the per‐subscriber system cost is greatly reduced relative to the per‐subscriber cost of a FTTH system. In addition, elimination of the optical network unit (ONU) at the home may offer new options for powering and battery back‐up.This paper presents an analysis of a star‐configured, fiber‐to‐the‐curb distribution network that serves up to ninety‐six customers, initially providing two plain old telephone service (POTS) channels to each customer. Three system variations, serving either four, six, or eight customers per SAP, are examined. We also estimate the installed first costs (IFC) of the distribution link (remote node to customer) for the three FTTC scenarios and compare them to the IFC of a FTTH system with similar capabilities. Star‐configured FTTC architectures can be installed for substantially less ($1180‐$825/customer for four to eight customers per SAP) than the estimated $2920 per subscriber cost associated with FTTH systems. Finally, we propose an upgrade strategy, consistent with the passive photonic loop (PPL) network, to support future high bandwidth services.

Optical networks for local loop applications

Some of the options for optical technology within the local loop environment are examined. In particular, passive shared access networks have been considered in some detail. These networks show great promise for delivering existing telephone services to small to medium business customers (4-30 lines) economically by the early 1990s. Extending fiber to the home will also be possible by virtue of a similar passive network infrastructure for customers requiring new broadband services beyond the single telephone line. For one-line plain old telephone service (POTS) customers, an intermediate approach of terminating the fiber network at the final network distribution point, with copper retained for the final leg, may be used prior to the provision of broadband services. A key feature of the passive optical network architecture is the use of wavelength-division multiplexing (WDM) as an upgrade strategy, allowing graceful upgrading from telephone services to multichannel high-definition television (HDTV) on gigabit/second bearers and full two-way switched broadband services employing wavelength routing across the network.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The analog local loop: a growing revolution in optical transmission

To provide an economic justification for the widespread deployment of optical fiber in the local loop, it may be necessary in some situations to install networks which will carry only telephony but can be upgraded to provide broadband services. Methods by which this may be achieved using analog carrier techniques are discussed. Passive optical networks (PONs) are considered, and the application of plain old telephone service (POTS) and broadband services over PONs is considered. Frequency planning and future trends are summarized. >

TheSLC 96Subscriber Loop Carrier System: Integration With the5ESSSwitching System

A new 5ESS™ switching system peripheral unit provides an efficient integrated interface to Remote Terminals (RTs) of the SLC® 96 digital subscriber loop carrier system. This unit has been named the Digital Carrier Line Unit (DCLU). Each DCLU serves up to six remote terminals [576 Plain Old Telephone Service (POTS) lines]. Each Tl line from an RT terminates on a Digital Facility Interface (DFI) circuit pack, which is the microcomputer-controlled circuit pack used in the 5ESS switching system to interface to Tl lines. The DCLU consists of up to thirty of these DFIs. For purposes of control, the DFIs are separated into two service groups of fifteen DFIs each. There is one control multiplexer circuit pack for each service group. Also there are two data multiplexer circuit packs that are shared by all thirty DFIs. The design of the DFI is described in this paper. The software structure of the 5ESS switching system is explained in general terms and then the software that had to be expanded to support integrated SLC 96 carrier systems is outlined. The paper concludes by describing the topology and traffic-handling capability of the two-stage switching network formed by the DCLU and the remote terminals that are connected to it. The first SLC 96 carrier system integrated into a 5ESS switch went into service on April 14,1984, in Spotsylvania, Virginia.

Installation and Performance of the Chicago Lightwave Transmission System

The first lightwave communications system that provides a wide range of telecommunications services to customers has been carrying commercial traffic in the Chicago Loop area since early May, 1977. The exploratory system furnishes POTS (plain old telephone service), analog data, and digital data services from the Franklin central office (CO) to customers in the Brunswick building, over an optical cable approximately 0.6 mi long. Picturephone <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> meeting service, a 4-MHz video service, is delivered over an optical cable from the Wabash CO to the Franklin CO, then on to the Brunswick building, a total distance of 1.6 mi. The optical cable was placed inside a small plastic pipe, which had been installed previously along the cable route. The plastic pipe, or innerduct, was used to reduce pulling tensions and provide environmental protection. The optical cable was installed using a novel 2-way installation technique by which the two ends of each section were fed successively in opposite directions from an intermediate manhole toward the splicing manholes. The connectorized optical cable was then spliced in five manholes along the cable route. This paper describes the installation and splicing of the lightguide cable and the transmission characteristics of the installed medium. It also contains a discussion of the manner in which the various telecommunication services are provided and a performance evaluation of the lightwave transmission system to date.