On Switching Networks and Block Designs, II

An important objective in designing switching networks is to minimize the probability of calls being blocked. A number of methods have been developed in the past for designing efficient switching networks that satisfy various constraints on their parameters. In this paper we investigate a special class of subnetworks of a switching network, called channel graphs. It is known that, under the usual assumptions made for calculating blocking probabilities, the blocking probability of a switching network is small if blocking probabilities of its channel graphs are small. With the use of certain combinatorial structures, known as block designs, we construct a large class of nearly optimal channel graphs.