One-stage one-sided rearrangeable switching networks

We consider switching networks consisting of subscriber lines and crosswires connected by switches. A connection between two subscribers is made along one crosswire via two switches. We determine the minimum number of switches necessary for such a switching network to be rearrangeably nonblocking and construct a switching arrangement which achieves this minimum for any (even) number of subscriber lines. Two procedures for assignment of crosswires to subscriber line pairs are described. One makes correct choice of connection route without backtracking provided all connections are known beforehand; the other determines a rearrangement of existing assignments when a new connection is required. We characterize the switching networks which have the minimum number of switches for networks with up to eight subscriber lines and give nonisomorphic solutions for larger networks