Research Model for Time-Separation Integrated Communication

A communication system requires channels for transmission of information and switching arrangements to interconnect the channels. At present, the transmission problem and switching problems are handled separately. Transmission channels m a y be divided into three classes: space separation, frequency separation and time separation. All have been in use for some time. Switching arrangements m a y be divided into the same three classes. 1 T h e space-separation class includes all telephone switching systems in use today. Frequency separation systems have been studied and are not economically feasible at this time. Exploratory switching systems in the time-separation class are being considered in this country and abroad. This paper reviews the use of time-separation techniques for transmission systems and for switching systems, points out t h a t the availability of solid state devices has revived interest in the subject and 909 910 THE BELL SYSTEM TECHNICAL JOURNAL, J U L Y 1 9 5 9 indicates t h a t techniques using these devices are now feasible for both systems. It shows t h a t an integrated communication system using these techniques is much more attractive t h a n a combination of subsystems using time separation and presents a research model which demonstrates the technical feasibility of such an integrated system T h e research model is primarily a digital system. In it, informationproducing terminals -- in our specific case, telephone subscribers' sets -- in a small group are connected over voice-frequency cable pairs to a small switching unit remote from t h e central switching point.