TDM Versus SDM Switching Arrays - Comparison

In the first paper at the 9th ITC [8], PCM (TDM) switching arrays having up to six stages and up to about 100 000 terminations were investigated with regard to their standardized costs per termination as a function of the cost ratio "gate to memory-bit." In this context, the following were considered: the influence of the number and sequence of stages (
T
-stages,
S
-stages), the number of terminations, the degree of multiplexing (30, 120 time slots per multiplex line). Furthermore, new PCM charts for the quick design of economic PCM switching arrays were developed. The second paper completes these studies by comparisons between PCM switching arrays and their equivalent SDM switching arrays. Handy formulas for the best possible economic design of PCM and SDM arrays, respectively, are presented and derived. The loss versus the carried traffic of PCM arrays having
S = 3
up to six stages and with
M = 30
and 120 time slots per highway are compared with each other and with equivalent SDM link systems. Furthermore, the relative costs per termination are calculated for these PCM and SDM array structures and drawn versus the size of these arrays.