United States Patent   Patent Number: 5,428,607
Hiller et al.  Date of Patent: Jim. 27,1995
Thomas L. Hiller, Glen Ellyn;
Ronald A. Spanke; John J. Stanaway,
Jr., both of Wheaton; Alex L.
Wierzbicki, Bolingbrook; Meyer J.
Zola, Oak Park, all of 111.
 Assignee: AT&T Corp., Murray Hill, N.J.
 Appl. No.: 169,915
 Filed: Dec. 20,1993
 Int. CI.6 H04L 12/56; H04L 12/66
 U.S. CI 370/60.1; 370/94.2
 Field of Search 370/58.1, 58.2, 58.3,
 References Cited
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K. Y. Eng et al., "A Framework For A National Broadband (ATM/B-ISDN) Network", International Conference on Communications ICC '90, vol. 2, Apr. 1990, Atlanta, pp. 515-520.
R. Hazell, editor, "Broadband Technology", Electrical Communication, vol. 65, No. 1, (Telecom 91), Oct 1991,
Pulse Code Modulation (PCM) signal streams are converted into Asynchronous Transfer Mode (ATM) cells for switching and transmission across a telecommunications network. Each cell carries one PCM sample of up to 48 different voice connections, the voice connections being selected from the PCM data streams because they have a common destination. The cells are transmitted over ATM virtual paths, each path transmitting one cell every 125 us. The ATM signals are switched by units for switching cells (cell switching), while keeping their payload contents intact, and by units for switching the signals for individual voice connections between cells of an ATM signal (cell remapping). Advantageously, ATM transmission systems interface with PCM systems without adding appreciable delay and without requiring additional buffering. Advantageously, new voice paths can be established most of the time by using available slots in the cells of existing virtual paths. Advantageously, large telecommunication networks can be implemented using a small number of switching units. For use with PCM switches, it is desirable to provide supervisory signals accompanying the PCM data. Advantageously, this arrangement permits supervisory signals to be passed within an access switch thus simplifying compatibility with existing switching systems.
5 Claims, 39 Drawing Sheets