Subscriber Line Equipment for an Elastic Carrier Switching System

This is the third of three papers [l], [2] dealing with an elastic carrier-concentrator system. The functioning of the subscriber line equipment is described herein. The system serves 256 telephone subscriber lines by digital concentration switching and transmission of multiplexed message channels over a singleT1transmission line. The concentration switching function is nonblocking. Message channels are the individual communication links between terminals and are created on demand at the request of active subscriber lines. They are not merely inactive without service requests; they do not exist unless service is requested. The created message channels serve for their normal communication function and, in addition, carry for each line the ancillary functions of dialing, ringing, and pay-station coin disposal. Message channels are coded by delta modulation, which permits flexible digital concentration and provides a smooth tradeoff of channel quality versus the instantaneous traffic load. Each of two complementary subscriber line interface units, one per line at each end, provides the delta-modulation encoding and decoding functions for the analog voice-band signal input and output and, by overriding the delta codec, provides the desired signaling functions of dialing, ringing, etc. The line interface units provide the major equipment interface between the subscriber line and the digitalT1line. An integral test facility permits remote loop-back of any selected subscriber line unit via a test channel to the office terminals and at the same time connects the subscriber loop to an auxiliary programmed test facility which may transmit pertinent loop-test results to the office terminal.     

A New Electronic Telephone Accounting System for Local Telephone Calls

Telephone switching systems provide facilities to measure subscriber usage for billing purposes. As new telephone services are offered, additional equipment is often required to appropriately measure this usage. Rate plans are being considered by telephone companies to more appropriately reflect service rendered on local telephone calls and additional equipment is required. This paper describes an electronic local message accounting system to measure local call usage which can be appliquéd to Panel, No. 1 crossbar, No. 5 crossbar, and Step-by-Step switching entities. Magnetic tape records for each local call provide: directory number of the calling party, distance to the called party, duration, and time of call termination. This information allows subscriber billing based on many and varied criteria which are established by software at the revenue accounting office. The system is presently in widespread use. The first installation occurred in January 1972, and now almost 5 percent of all telephones in the United States are served by the system.     

An Approach to Multi-Service Subscriber Loop System Using Packetized Voice/Data Terminals

A new subscriber communication system and its design philosophy are described. In addition to telephone communication, the system is simultaneously able to offer data communication, still picture communication, etc. The system is composed of a packetized voice/data terminal, a multi-service switching equipment and the digital subscriber loop connecting between them. The system utilizes the existing subscriber line efficiently and is entirely suitable for coming telephone and data public digital network. 64 kbit/s PCM coded voice conversation and 48 kbit/s data communication were achieved simultaneously over 96 kbit/s digital subscriber line which was spanned up to 2 km.     

Broadband Switching System Architecture

The architecture, the design concept, and the network organization for NTT's broadband switching system field trials are described. The features of this system are: a variety of connection-type services such as reservation-based and asymmetric connections, the installation of small-size remote concentrating switch, and a system integration using various subscriber transmission media such as optical fiber, satellite, and radio. This paper also presents the system architecture along with a study of the broadband switching system through a close look at the results obtained from field trials.     

Enhanced message addressing capabilities for computer networks

Three message addressing modes are described: 1) Logical adderssing, in which a permanantly,assigned address denotes one or more physical addresses. This permits multiple connections from the subscriber to the network, as well as other functions. 2) Broadcast adderssing, in which a messase is addressed to all subscribers. 3) Group addressing and multidestination addressing, in which a message carries the name of a list of addresses, or the list itself. These methods facilitate many new ways of using computer networks. The paper focuses on two basic issues for each method: efficiency and reliability, and recommends implementation approaches in each case. Significant performance improvements are possible if these addressing methods are implemented with efficient delivery mechanisms. A distinction is made between virtual circuit and datagram systems; virtual circuits are superior for logical addressing, while datagrams are preferable for broadcast, group, and multidestination addressing.     

Progress Towards Digital Subscriber Line Services and Signaling

With digital connectivity, future subscribers will be able to exercise local and network services involving the routine delivery, management, and processing of information. Accelerated by rapidly advancing technology, the evolutionary process towards digital connectivity and integrated voice and data services in the network is underway. This paper describes the methods of integrating voice and information capability into the telecommunications network. The attributes of this network will include the availability of digital connectivity directly to the subscriber, the availability of a robust signaling means between the subscriber and his local switching office, and common channel signaling to implement all interexchange signaling. Issues of interest include an overview of digital subscriber connectivity, signaling and information structures for these kinds of lines, communications protocols, and general network considerations for the provision of information services. Partitioning of intelligence between intelligent subscriber terminals and controllers and their switching system is investigated. The use of message and virtual channel switching facilities to handle limited information rate services is discussed. Finally, an exploratory digital subscriber line under investigation at Bell Laboratories is described.     

Integrated Digital Switching System with Queueing Storage Facility

This paper outlines the features of a new integrated switching system for voice and data. It is composed of integrated subscriber terminals, integrated subscriber lines, an integrated digital switching system, and integrated storage facilities. This paper shows that the introduction of the integrated storage facility can create various new service utilities and improve the traffic capacity of the system.     

Switching System Software Design for ISDN

The ISDN offers various services through multipurpose digital subscriber lines. The switching program for the ISDN should be so designed as to realize the control of various voice and nonvoice services and provide for developing service enhancement. To attain the goal, the ISDN services are classified hierarchically and each category is allocated to appropriate network nodes for implementation. As a result, the local switching program provides an out-slot subscriber line signaling capability and call connection with appropriate compatibility checking including a check for access capability to communications processing nodes. The switching program modules specific to analog services and those specific to digital services are separated to allow the use of the existing program file and to afford easy program design and maintenance. Remote-controlled switching is a suitable means for an economical introduction of the ISDN services to low traffic density areas. Special routing and reliability arrangements as well as the program structure for a remote-controlled switch are discussed.     

Providing Multiple-Channel Communication Using the Experimental Digital Switch

This report describes the functional characteristics of a circuit-switched network which is capable of providing data communication paths as well as voice channels. In the system described, the circuit switch may be shared in order to provide multiple independently switched paths through the network. Unlike a conventional circuit switch, this sharing permits only a fraction of the switching capacity to be consumed which is proportional to the allocated bandwidth of the path. Additional economy is gained by providing multiple communication paths over the single communication resource between the subscriber and the switching machine. The fraction of the communication resource which is used by the subscriber is proportional to the total bandwidth of the channels which have been allocated. This allocation is performed dynamically, in response to subscriber requests. Algorithms are presented which perform this allocation efficiently. The resulting network provides a communication vehicle which provides both data and voice services in an integrated fashion.     

Design and performance of a fiber-optic video distribution systemusing BPSK microwave subcarriers

The design and performance of a fiber-optic video distribution system using bi-phase shift keyed (BPSK) microwave subcarriers to provide each subscriber with 20 107 Mb/s digitized video channels and one voice/data channel at 2.048 Mb/s are described. The combined microwave subcarriers are used to intensity-modulate a 1.3 μm single-mode laser, one dedicated to each subscriber. The penalty in system sensitivity resulting from the use of more than one subcarrier is calculated. The design and implementation of subcarrier generation, BPSK modulation, multiplexing/demultiplexing, and subscriber receivers are described. An experiment procedure to obtain an optimum laser driver level is also described. A bit error rate of 10^-9 or less is achieved at a received optical power of -12 dB (1 mW) for all channels for each subscriber     

One-stage one-sided rearrangeable switching networks

Switching networks consisting of subscriber lines and crosswires connected by switches are considered. A connection between two subscribers is made along one crosswire via two switches. The minimum number of switches necessary for such a switching network to be rearrangeably nonblocking is determined and a switching arrangement which achieves this minimum for any (even) number of subscriber lines is constructed. Two procedures for assignment of crosswires to subscriber line pairs are described. One makes the correct choice of connection route without backtracking provided all connections are known beforehand; the other determines a rearrangement of existing assignments when a new connection is required. The switching networks which have the minimum number of switches for networks with up to eight subscriber lines and give nonisomorphic solutions for larger networks are characterized     

Loop Test System: A New Maintenance Feature for the Distributed Integrated Digital Network

The introduction of the digital Class 5 switch offers unique solutions to the requirements of growth and demands for improved service. For example, remote subscriber switches (RSS's) and subscriber carrier terminals (SCT's) can now be located near subscribers and digitally connected to the Class 5 switch via T1 repeatered lines or radio links. The result is shorter subscriber loops, improved transmission, and deferment or elimination of feeder plant additions. Traditionally, interposing electronics between the subscriber loops and the Class 5 switch resulted in isolating these loops from the office loop testing facilities. Remote testing of RSS and SCT assigned loops is an important step toward minimizing maintenance costs. Loop testing is accomplished in TRW Vidar's ITS5 switching system by locating loop test equipment in the remote RSS and SCT cabinets. This equipment is available to the test operator for real-time testing, and to the switch for automatic line testing. Some of the requirements that the loop test equipment must meet are: low cost, no adjustments, low power consumption, small size, operation in a harsh environment, and centralized testing capability from a test console. The data returned to the office must be in a quantitative form to allow further processing by the console. It must also be compatible with the direct distance dialing (DDD) network to allow transmission not only to the Class 5 switch serving the RSS and SCT, but also to distant service centers. This paper describes a newly developed system that meets the above objectives.     

光纤接入网的用户线交叉连接系统

最近问世的用户线交叉连接系统（ＬＸＭ）属于高速数字式多路交叉连接系统，其作用是充当光纤接入网的窄带业务平台，使其收容的各种用户可以接通交换系统，这些专供光纤接入网使用的ＬＸＭ有利于ＦＴＴＨ（光纤到户）目标的顺利推行，本文对ＬＸＭ的用途及其技术概念做了必要的轮廓性解说。     

Experimental single-chip PABX

Experimental VLSI techniques and an architectural concept are described which permit the realization of an experimental single-chip private automatic branch exchange (PABX) for switching voice and data. Analysis indicates that up to 40 telephones and 40 data terminals could be interconnected with a single chip. The architecture makes it possible to interconnect multiple PABX chips to form a larger system. The single-chip concept is made possible by distributed switching near the subscriber, digital interface, a new `orthogonal' RAM, and a low-power line-driving technique, all of which are included in this investigation.     

Object-oriented design of ISDN call-processing software

The development of object-oriented programming (OOP) software for a prototype switching system, including the DSS1 protocol on integrated services digital network (ISDN) subscriber signaling and the ISDN user part (ISUP) for network signaling, is discussed. The major goal of the project is to determine whether switching system software can be clearly structured by using the rules of OOP, and whether the use of OOP concepts leads to an improvement in productivity and quality for large software systems. The standard classes, application classes, class hierarchy, and layer model with the OOP project are described. The experiences in applying OOP for the development of switching system software are summarized     

SHOT──D_4设备介绍

ＳＨＯＴ—Ｄ４设备是一种专用光电混合端机，它用于程控交换机Ｓ１２４０母局与ＲＡＳＭ（远端模块）局之间的传输，能为两个用户架（即２０００门）提供传输通道。当通信容量超过２０００门时，可采用积木式迭加，组成容量更大的通信系统。采用该设备可以方便地将用户架作为远端模块搬出电信局，而交换设备的投资却不需要增加。     

论用户数据中心在交换网中的重要性

传统的本地交换网中的用户数据是在各个本地网端局中分散管理的,这样的模式已经成为交换技术向软交换甚至更先进的交换技术发展的主要瓶颈.而伴随软交换技术引进的用户数据中心网元,集中了本地网全网的用户数据,通过灵活的协议接口实现与传统交换机、NGN交换机互通,利用自身多元化的业务数据制作能力,克服了传统交换网实现全网网络智能化所遇到的各种阻碍和弊端,已经成为现代固网交换发展的必要网元.文中从用户数据中心引入的必要性入手,阐述了用户数据中心在整个交换网络中的重要性.     

Dr. Hiroshi Inose's pioneering contributions to digital switching systems and his outstanding leadership in informatics

The idea of time slot interchange (TSI), the fundamental concept of implementing time switches in digital switching systems, was first conceived by Dr. Hiroshi Inose, then at the University of Tokyo, Japan, in 1957 while he was a visiting consultant at Bell Telephone Laboratories. The TSI collects each subscriber?s pulse code modulation (PCM)- coded voice information to be stored into a small time interval (time slot), and then aligns multiple time slots on a common transmission bus to constitute a repetitive frame. The TSI enables any time slot to be interchanged with another time slot within a frame once the time slots in the frame are buffered in memories. Thus, TSI gives the time switch functionality equivalent to Ninput by N-output space switch functionality. He built a prototype digital time-division multiplexing (TDM) electronic switching system called CAMPUS, which is based on the TSI principle, using a magnetostrictive delay line as a memory device. TSI received little attention until the end of the 1960s because memory devices were very costly. However, with the rapid advancement of semiconductor technologies in the 1970s, the TSI scheme became more widespread. TSI was first commercially deployed in 1976 as the time switch of AT&T?s no. 4 ESS, the world?s first stored-program control time-division switching system. Since then, TSI has been used in almost all digital central office switching systems and digital private branch exchanges (PBXs). Dr. Inose?s contributions were not limited to research on such things as switching systems, PCM integrated communications, computer communications, and road traffic control systems; he was also actively involved in a number of Japanese governmental and international activities in the area of communications and information processing technologies. His final work was the establishment of the National Institute of Informatics (NII) in 2000, Japan?s sole comprehensive academic institute in the field of informati     

Fiber-optic subscriber loop systems for integrated services--The strategy for introducing fibers into the subscriber network

Two approaches to fiber-optic subscriber loop system development in Japan are described. In the first. Approach I, NTT aims at introducing inexpensive fiber-optic subscriber loop systems using conventional LED's, multimode fiber, and analog transmission techniques in the near future. In the second, Approach II, fiber-optic subscriber loop systems will be made highly functional by evolving from analog to digital transmission. This paper presents system fabrication examples for each approach and the results obtained in the tests.     

Consideration on Call Processing Function Distribution to Subscriber Terminal

This paper proposes a new sharing of call processing functions between a terminal and a switching system, taking recent technology advances into consideration. Information and its processing in an electronic switching system are defined and their calculation method is shown to discuss the function share. Numerical examples of information and its processing amount are obtained using NTT's commercial system, D-10, for an example. Possibility of function distribution to a subscriber terminal is discussed, based on information and its processing amount obtained by the analysis. The amounts of information and its processing in an existing switching system are estimated to both be reduced to about 35 percent by distributing to a terminal function, such as subscriber's action detection, audible signal generation, dialed number storage and display and so on. On the other hand, the information and its processing amount shared by the functional terminal are estimated to amount equivalently only to 5 and 10 percent respectively of those of an existing switching system, because introduction of functional terminals eliminates conventionally required time urgent information processing. Therefore, the total information and its processing amount in the telephone system incorporating functional terminals are estimated to be about 40 and 45 percent of those solely shared by an existing switching system, respectively. It is also mentioned that the functional terminal guarantees the variety of services which enables economical use of the telecommunication network.