Semiconductor technology achievements have opened up prospects for the development of integrated digital communication networks. Special LSI's have become a base element of communication means. Here, an approach is described for special LSI'sdesigned in the form of functionally complete communication systems of limited capacity-the microcommutators. The microcommutator contains all the subsystems of a switching system which thus make it possible to increase the switching system capacity by connecting the required number of microcommutators. The increase in microcommutator capacity can be achieved through the use of a space-time channel division structure. It is shown that the multistage space-divided microcommutators are preferable for the minimization of microcommutator nomenclature and the unification of a switching network of different capacity. An indication for the need for switching system synchronization is the shortage of space-divided switching networks based on space-time-divided microcommutators. An example of the performance of a local switching system with concentrators is given.

Digital Microcommutators: Structure and Application

The efficiencies of different methods for subscriber-loop digital transmission are compared, using as a criterion the cost per bit/second per kilometer of wire, denoted "CSP". Approaches to reduction of CSP are suggested, in particular the use of opto-electronic transmitters and receivers in a differential connection, resulting in a relatively noise-immune subscriber line. A graphic method for the analysis of opto-electronic digital transmission lines is described.

V. Gorohov

Papers

Subscriber-Loop Digital Transmission Using Opto-Electronic Transmitters and Receivers