Design of Economic PCM Arrays with a Prescribed Grade of Service

This paper deals with the design of economically structured PCM switching arrays for traffic distribution. The presented switching arrays are symmetrically structured, and have one up to six stages and use different combinations of time stages and space stages , respectively. It is shown how such arrays can be designed for a required grade of service having a prescribed number of terminations and a prescribed carried traffic per time slot. Their relative costs per termination equal to that per time slot are calculated. These are costs for the gates and costs for memory bits, i.e., speech memories and all control memories. All presented PCM switching arrays are mapped into the corresponding space division multiplex (SDM) arrays. This allows a simple comparison with SDM link systems and an easy calculation of the point-to-point loss. The paper concludes comparing the traffic behavior and costs of the various PCM switching arrays. Finally, new "PCM charts" are developed as useful means for the design of economic PCM switching arrays. A second paper of this congress [14] compares traffic equivalent PCM and SDM switching arrays, respectively, with regard to their economic design, their traffic behavior, and their costs per termination.