Telephone Switching Office Research Articles

The Best Conference You Never Attended [White Hot

The IEEE International Communications Energy Conference (INTELEC). INTELEC has a long history that predates PELS. INTELEC was the brainchild of several Bell Labs engineers who realized the need for such a conference. The first INTELEC was held in 1978 under the auspices of the IEEE Communications Society. INTELEC continued as an annual conference at host cities all over the world. In 1991, INTELEC was transferred to PELS. T he issues a nd themes of INTELEC have evolved over the years. In the 1970s, the papers were often about the newfangled switch mode rectifiers. In the 1980s, the papers were often about the evolving distributed power architectures used in telecom equipment. In the 1990s, a key topic was powering the network as the transmission medium evolved from twisted-pair copper wires to coaxial cable and optical fiber. In the 2000s, much of the discussion focused on powering the far-flung equipment of cellular telephone networks. In today's network, with all traffic, whether voice, video, or data, being digital, the differences between data center, telephone switching office, mobile base station, and telephone central office are blurring and dissolving. The power needs of such a network are rapidly evolving. How we manage and design the power systems and converters for these new networks is the key focus of INTELEC today.

A Heuristic Search Algorithm for the Cellular Telecommunication Network Expansion Problem

This article proposes a very effective heuristic algorithm to address the network expansion problem, and it discusses step-by-step procedures of the proposed algorithm in detail. The input to the algorithm is based on a binary integer programming formulation of the network problem. The solution specifies the connections of each component, cell sites, hubs, and mobile telephone switching office and satisfies the redundancy requirements for each cell site to ensure the traffic flow and to backup any disconnection. The algorithm generates lower and upper bounds on cost of the exact solution, and preliminary testing indicates that it generates very effective results efficiently. The authors hope that in presenting such an algorithm, designers of very large cellular network expansions will have a tool to obtain significantly good solutions in a reasonable time.

Designing Partially Survivable Cellular Telecommunications Networks

In a cellular telecommunications network, a mobile telephone switching office (MTSO) co-ordinates the activities of the mobile units either directly or via intermediate base transceivers or hubs. I...

Design of partially survivable networks for cellular telecommunication systems

In cellular networks, cells are connected to the mobile telephone switching office (MTSO) directly or via hubs. It may also be desirable for some cells to split their traffic to two or more hubs for partial survivability in the case of equipment failures; such cells are said to have a diversity requirement greater than one. Assuming that hubs are connected to the MTSO via self-healing rings, as is common in current cellular implementations, the objective is to find the assignment of cells to hubs – including the MTSO – that meets demand as well as survivability requirements at minimum cost. With the increasing use of fiber for high capacity backbone transmission, networks have become sparser, and the consequences of link failures much more serious. Hence network survivability has taken on added urgency. Our paper models this problem in the context of cellular networks.

Volatile Organic Compounds Measured at a Telephone Switching Center From 5/30/85-12/6/88: A Detailed Case Study

Volatile organic compounds (VOCs) can cause failures in electronic equipment. This paper presents detailed observations from a three year study of VOCs at a telephone switching office in Neenah, Wisconsin. Included are data on matched indoor and outdoor VOC measurements, as well as corresponding data on HVAC fan operation and ventilation rates. The Neenah office has few occupants and hence provides an opportunity to examine factors that influence VOC levels without the complications associated with daily human activities. As reported in other studies, total VOC levels indoors were greater than those outdoors. During normal periods (no renovation or construction) the total VOC levels were inversely proportional to the air exchange rates. The sources with the greatest influence on the VOC levels tended to be those with the greatest surface area. The results demonstrate that low baseline levels of VOCs (total VOCs < 60 μg/m3) can be achieved by minimizing VOC sources and providing adequate ventilation. Even during construction and installation of new switching equipment, the VOC levels, although elevated, remained within tolerable limits (total VOCs < 500 μg/m3). Three months after this activity, levels had returned to pre-installation values. Low concentrations of VOCs and low concentrations of airborne particles were not mutually exclusive, nor was it unduly expensive to achieve such low levels.

The surface composition of copper with indoor exposures ranging from 3 to 49 years

Auger electron spectroscopy (AES) was used to investigate surface films formed on copper bus bar samples installed during the years 1939–1985. The samples were collected from a telephone switching office in a heavily populated area on Long Island, with salt water located less than 5 km to the North and South. The surface films formed on the copper consisted predominantly of carbon, with smaller amounts of oxygen, chlorine and sulfur. Argon ion sputtering yielded surface profiles that were compositionally similar for all years studied. Film thicknesses varied from 10's to 100's of nanometers depending on the age of the samples. The films analysed in this study differed both chemically and in thickness from films formed on copper substrates with outdoor exposures, and from those formed in accelerated atmospheric corrosion chambers.

Automatic Programming of Communications Software Via Nonprocedural Descriptions

This paper describes a method for automatically generating software for a stored program telephone switching office. The system allows users to quickly specify the operation of the switching office using a formal description language. The description language is a set of situation, stimulus, and effect triples which collectively specify the behavior of the phones the switching office controls. The description is automatically compiled into programs which effect the desired behavior. There are two major advantages: 1) nonprogrammers can implement complex features and 2) modifications which require changes throughout the code running the system can be expressed in a single part of the description language.

Synchronized Clock for DMS-100 Family

The advent of digital telephone switches, interconnected by digital carrier systems, makes it possible to route and transmit telephone and data signals virtually without deterioration over many links and through many switching nodes. No bits of the digitized speech or data, however, should be lost en route; an economical method to ensure this is to operate the entire digital telephone system (of a country) synchronously. A highly stable master frequency reference is established from which all digital switching centers derive their clocking, either directly by national distribution of the reference frequency, or through the means of the (pulse-code modulation) PCM transmission systems which interconnect the switches. Operating considerations require that the synchronized clock systems of every switch can survive outages of equipment or synchronizing links without major impact on telephone service. The present paper is concerned with the design and performance of the synchronized clock system as an integral part of a large digital telephone switching office. Clocking and synchronization hardware and software algorithms have been developed to allow a switching office to be synchronized by external reference standards or over digital carrier links. The components of the synchronization system of an office are distributed in peripheral interface hardware, digitally controlled clock hardware, and a feedback algorithm implemented in the software of the switching computer. Steady-state and dynamic behavior are analyzed for a single switch and a timing network. Mathematical analysis is supported by simulation results. Special attention is given to quantization effects and maintenance considerations.

An Automatic Telephone System Employing Magnetic Drum Memory

The use of magnetic drum memory in an automatic telephone switching office is described. A capacitive scanner acts as a time-division connector through which information generated by subscribers' telephone sets is conveyed to storage on magnetic drums. Information thus accumulated is combined with permanent information on the magnetic drums, processed in accordance with built-in programs and dispatched to control call switching circuits. Technical feasibility of this system has been demonstrated by the construction and successful operation of a large-scale laboratory model.